_ Git - ldk-c-bindings/blob - c-bindings-gen/src/types.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE>
   5 // or the MIT license <LICENSE-MIT>, at your option.
   6 // You may not use this file except in accordance with one or both of these
   7 // licenses.
   8
   9 use std::cell::RefCell;
  10 use std::collections::{HashMap, HashSet};
  11 use std::fs::File;
  12 use std::io::Write;
  13 use std::hash;
  14
  15 use crate::blocks::*;
  16
  17 use proc_macro2::{TokenTree, Span};
  18 use quote::format_ident;
  19 use syn::parse_quote;
  20
  21 // The following utils are used purely to build our known types maps - they break down all the
  22 // types we need to resolve to include the given object, and no more.
  23
  24 pub fn first_seg_self<'a>(t: &'a syn::Type) -> Option<impl Iterator<Item=&syn::PathSegment> + 'a> {
  25         match t {
  26                 syn::Type::Path(p) => {
  27                         if p.qself.is_some() || p.path.leading_colon.is_some() {
  28                                 return None;
  29                         }
  30                         let mut segs = p.path.segments.iter();
  31                         let ty = segs.next().unwrap();
  32                         if !ty.arguments.is_empty() { return None; }
  33                         if format!("{}", ty.ident) == "Self" {
  34                                 Some(segs)
  35                         } else { None }
  36                 },
  37                 _ => None,
  38         }
  39 }
  40
  41 pub fn get_single_remaining_path_seg<'a, I: Iterator<Item=&'a syn::PathSegment>>(segs: &mut I) -> Option<&'a syn::Ident> {
  42         if let Some(ty) = segs.next() {
  43                 if !ty.arguments.is_empty() { unimplemented!(); }
  44                 if segs.next().is_some() { return None; }
  45                 Some(&ty.ident)
  46         } else { None }
  47 }
  48
  49 pub fn first_seg_is_stdlib(first_seg_str: &str) -> bool {
  50         first_seg_str == "std" || first_seg_str == "core" || first_seg_str == "alloc"
  51 }
  52
  53 pub fn single_ident_generic_path_to_ident(p: &syn::Path) -> Option<&syn::Ident> {
  54         if p.segments.len() == 1 {
  55                 Some(&p.segments.iter().next().unwrap().ident)
  56         } else { None }
  57 }
  58
  59 pub fn path_matches_nongeneric(p: &syn::Path, exp: &[&str]) -> bool {
  60         if p.segments.len() != exp.len() { return false; }
  61         for (seg, e) in p.segments.iter().zip(exp.iter()) {
  62                 if seg.arguments != syn::PathArguments::None { return false; }
  63                 if &format!("{}", seg.ident) != *e { return false; }
  64         }
  65         true
  66 }
  67
  68 pub fn string_path_to_syn_path(path: &str) -> syn::Path {
  69         let mut segments = syn::punctuated::Punctuated::new();
  70         for seg in path.split("::") {
  71                 segments.push(syn::PathSegment {
  72                         ident: syn::Ident::new(seg, Span::call_site()),
  73                         arguments: syn::PathArguments::None,
  74                 });
  75         }
  76         syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments }
  77 }
  78
  79 #[derive(Debug, PartialEq)]
  80 pub enum ExportStatus {
  81         Export,
  82         NoExport,
  83         TestOnly,
  84         /// This is used only for traits to indicate that users should not be able to implement their
  85         /// own version of a trait, but we should export Rust implementations of the trait (and the
  86         /// trait itself).
  87         /// Concretly, this means that we do not implement the Rust trait for the C trait struct.
  88         NotImplementable,
  89 }
  90 /// Gets the ExportStatus of an object (struct, fn, etc) given its attributes.
  91 pub fn export_status(attrs: &[syn::Attribute]) -> ExportStatus {
  92         for attr in attrs.iter() {
  93                 let tokens_clone = attr.tokens.clone();
  94                 let mut token_iter = tokens_clone.into_iter();
  95                 if let Some(token) = token_iter.next() {
  96                         match token {
  97                                 TokenTree::Punct(c) if c.as_char() == '=' => {
  98                                         // Really not sure where syn gets '=' from here -
  99                                         // it somehow represents '///' or '//!'
 100                                 },
 101                                 TokenTree::Group(g) => {
 102                                         if format!("{}", single_ident_generic_path_to_ident(&attr.path).unwrap()) == "cfg" {
 103                                                 let mut iter = g.stream().into_iter();
 104                                                 if let TokenTree::Ident(i) = iter.next().unwrap() {
 105                                                         if i == "any" {
 106                                                                 // #[cfg(any(test, feature = ""))]
 107                                                                 if let TokenTree::Group(g) = iter.next().unwrap() {
 108                                                                         let mut all_test = true;
 109                                                                         for token in g.stream().into_iter() {
 110                                                                                 if let TokenTree::Ident(i) = token {
 111                                                                                         match format!("{}", i).as_str() {
 112                                                                                                 "test" => {},
 113                                                                                                 "feature" => {},
 114                                                                                                 _ => all_test = false,
 115                                                                                         }
 116                                                                                 } else if let TokenTree::Literal(lit) = token {
 117                                                                                         if format!("{}", lit) != "fuzztarget" {
 118                                                                                                 all_test = false;
 119                                                                                         }
 120                                                                                 }
 121                                                                         }
 122                                                                         if all_test { return ExportStatus::TestOnly; }
 123                                                                 }
 124                                                         } else if i == "test" {
 125                                                                 return ExportStatus::TestOnly;
 126                                                         }
 127                                                 }
 128                                         }
 129                                         continue; // eg #[derive()]
 130                                 },
 131                                 _ => unimplemented!(),
 132                         }
 133                 } else { continue; }
 134                 match token_iter.next().unwrap() {
 135                         TokenTree::Literal(lit) => {
 136                                 let line = format!("{}", lit);
 137                                 if line.contains("(C-not exported)") || line.contains("This is not exported to bindings users") {
 138                                         return ExportStatus::NoExport;
 139                                 } else if line.contains("(C-not implementable)") {
 140                                         return ExportStatus::NotImplementable;
 141                                 }
 142                         },
 143                         _ => unimplemented!(),
 144                 }
 145         }
 146         ExportStatus::Export
 147 }
 148
 149 pub fn assert_simple_bound(bound: &syn::TraitBound) {
 150         if bound.paren_token.is_some() { unimplemented!(); }
 151         if let syn::TraitBoundModifier::Maybe(_) = bound.modifier { unimplemented!(); }
 152 }
 153
 154 /// Returns true if the enum will be mapped as an opaue (ie struct with a pointer to the underlying
 155 /// type), otherwise it is mapped into a transparent, C-compatible version of itself.
 156 pub fn is_enum_opaque(e: &syn::ItemEnum) -> bool {
 157         for var in e.variants.iter() {
 158                 if let syn::Fields::Named(fields) = &var.fields {
 159                         for field in fields.named.iter() {
 160                                 match export_status(&field.attrs) {
 161                                         ExportStatus::Export|ExportStatus::TestOnly => {},
 162                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 163                                         ExportStatus::NoExport => return true,
 164                                 }
 165                         }
 166                 } else if let syn::Fields::Unnamed(fields) = &var.fields {
 167                         for field in fields.unnamed.iter() {
 168                                 match export_status(&field.attrs) {
 169                                         ExportStatus::Export|ExportStatus::TestOnly => {},
 170                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 171                                         ExportStatus::NoExport => return true,
 172                                 }
 173                         }
 174                 }
 175         }
 176         false
 177 }
 178
 179 /// A stack of sets of generic resolutions.
 180 ///
 181 /// This tracks the template parameters for a function, struct, or trait, allowing resolution into
 182 /// a concrete type. By pushing a new context onto the stack, this can track a function's template
 183 /// parameters inside of a generic struct or trait.
 184 ///
 185 /// It maps both direct types as well as Deref<Target = X>, mapping them via the provided
 186 /// TypeResolver's resolve_path function (ie traits map to the concrete jump table, structs to the
 187 /// concrete C container struct, etc).
 188 #[must_use]
 189 pub struct GenericTypes<'a, 'b> {
 190         self_ty: Option<String>,
 191         parent: Option<&'b GenericTypes<'b, 'b>>,
 192         typed_generics: HashMap<&'a syn::Ident, String>,
 193         default_generics: HashMap<&'a syn::Ident, (syn::Type, syn::Type, syn::Type)>,
 194 }
 195 impl<'a, 'p: 'a> GenericTypes<'a, 'p> {
 196         pub fn new(self_ty: Option<String>) -> Self {
 197                 Self { self_ty, parent: None, typed_generics: HashMap::new(), default_generics: HashMap::new(), }
 198         }
 199
 200         /// push a new context onto the stack, allowing for a new set of generics to be learned which
 201         /// will override any lower contexts, but which will still fall back to resoltion via lower
 202         /// contexts.
 203         pub fn push_ctx<'c>(&'c self) -> GenericTypes<'a, 'c> {
 204                 GenericTypes { self_ty: None, parent: Some(self), typed_generics: HashMap::new(), default_generics: HashMap::new(), }
 205         }
 206
 207         /// Learn the generics in generics in the current context, given a TypeResolver.
 208         pub fn learn_generics_with_impls<'b, 'c>(&mut self, generics: &'a syn::Generics, impld_generics: &'a syn::PathArguments, types: &'b TypeResolver<'a, 'c>) -> bool {
 209                 let mut new_typed_generics = HashMap::new();
 210                 // First learn simple generics...
 211                 for (idx, generic) in generics.params.iter().enumerate() {
 212                         match generic {
 213                                 syn::GenericParam::Type(type_param) => {
 214                                         let mut non_lifetimes_processed = false;
 215                                         'bound_loop: for bound in type_param.bounds.iter() {
 216                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 217                                                         if let Some(ident) = single_ident_generic_path_to_ident(&trait_bound.path) {
 218                                                                 match &format!("{}", ident) as &str { "Send" => continue, "Sync" => continue, "Sized" => continue, _ => {} }
 219                                                         }
 220                                                         if path_matches_nongeneric(&trait_bound.path, &["core", "clone", "Clone"]) { continue; }
 221
 222                                                         assert_simple_bound(&trait_bound);
 223                                                         if let Some(path) = types.maybe_resolve_path(&trait_bound.path, None) {
 224                                                                 if types.skip_path(&path) { continue; }
 225                                                                 if path == "Sized" { continue; }
 226                                                                 if path == "core::fmt::Debug" {
 227                                                                         // #[derive(Debug)] will add Debug bounds on each genericin the
 228                                                                         // auto-generated impl. In cases where the existing generic
 229                                                                         // bound already requires Debug this is redundant and should be
 230                                                                         // ignored (which we do here). However, in cases where this is
 231                                                                         // not redundant, this may cause spurious Debug impls which may
 232                                                                         // fail to compile.
 233                                                                         continue;
 234                                                                 }
 235                                                                 if non_lifetimes_processed { return false; }
 236                                                                 non_lifetimes_processed = true;
 237                                                                 if path != "std::ops::Deref" && path != "core::ops::Deref" &&
 238                                                                         path != "std::ops::DerefMut" && path != "core::ops::DerefMut"  {
 239                                                                         let p = string_path_to_syn_path(&path);
 240                                                                         let ref_ty = parse_quote!(&#p);
 241                                                                         let mut_ref_ty = parse_quote!(&mut #p);
 242                                                                         self.default_generics.insert(&type_param.ident, (syn::Type::Path(syn::TypePath { qself: None, path: p }), ref_ty, mut_ref_ty));
 243                                                                         new_typed_generics.insert(&type_param.ident, Some(path));
 244                                                                 } else {
 245                                                                         // If we're templated on Deref<Target = ConcreteThing>, store
 246                                                                         // the reference type in `default_generics` which handles full
 247                                                                         // types and not just paths.
 248                                                                         if let syn::PathArguments::AngleBracketed(ref args) =
 249                                                                                         trait_bound.path.segments[0].arguments {
 250                                                                                 assert_eq!(trait_bound.path.segments.len(), 1);
 251                                                                                 for subargument in args.args.iter() {
 252                                                                                         match subargument {
 253                                                                                                 syn::GenericArgument::Lifetime(_) => {},
 254                                                                                                 syn::GenericArgument::Binding(ref b) => {
 255                                                                                                         if &format!("{}", b.ident) != "Target" { return false; }
 256                                                                                                         let default = &b.ty;
 257                                                                                                         self.default_generics.insert(&type_param.ident, (parse_quote!(&#default), parse_quote!(&#default), parse_quote!(&mut #default)));
 258                                                                                                         break 'bound_loop;
 259                                                                                                 },
 260                                                                                                 _ => unimplemented!(),
 261                                                                                         }
 262                                                                                 }
 263                                                                         } else {
 264                                                                                 new_typed_generics.insert(&type_param.ident, None);
 265                                                                         }
 266                                                                 }
 267                                                         }
 268                                                 }
 269                                         }
 270                                         if let Some(default) = type_param.default.as_ref() {
 271                                                 assert!(type_param.bounds.is_empty());
 272                                                 self.default_generics.insert(&type_param.ident, (default.clone(), parse_quote!(&#default), parse_quote!(&mut #default)));
 273                                         } else if type_param.bounds.is_empty() {
 274                                                 if let syn::PathArguments::AngleBracketed(args) = impld_generics {
 275                                                         match &args.args[idx] {
 276                                                                 syn::GenericArgument::Type(ty) => {
 277                                                                         self.default_generics.insert(&type_param.ident, (ty.clone(), parse_quote!(&#ty), parse_quote!(&mut #ty)));
 278                                                                 }
 279                                                                 _ => unimplemented!(),
 280                                                         }
 281                                                 }
 282                                         }
 283                                 },
 284                                 _ => {},
 285                         }
 286                 }
 287                 // Then find generics where we are required to pass a Deref<Target=X> and pretend its just X.
 288                 if let Some(wh) = &generics.where_clause {
 289                         for pred in wh.predicates.iter() {
 290                                 if let syn::WherePredicate::Type(t) = pred {
 291                                         if let syn::Type::Path(p) = &t.bounded_ty {
 292                                                 if first_seg_self(&t.bounded_ty).is_some() && p.path.segments.len() == 1 { continue; }
 293                                                 if p.qself.is_some() { return false; }
 294                                                 if p.path.leading_colon.is_some() { return false; }
 295                                                 let mut p_iter = p.path.segments.iter();
 296                                                 let p_ident = &p_iter.next().unwrap().ident;
 297                                                 if let Some(gen) = new_typed_generics.get_mut(p_ident) {
 298                                                         if gen.is_some() { return false; }
 299                                                         if &format!("{}", p_iter.next().unwrap().ident) != "Target" {return false; }
 300
 301                                                         let mut non_lifetimes_processed = false;
 302                                                         for bound in t.bounds.iter() {
 303                                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 304                                                                         if let Some(id) = trait_bound.path.get_ident() {
 305                                                                                 if format!("{}", id) == "Sized" { continue; }
 306                                                                                 if format!("{}", id) == "Send" { continue; }
 307                                                                                 if format!("{}", id) == "Sync" { continue; }
 308                                                                         }
 309                                                                         if non_lifetimes_processed { return false; }
 310                                                                         non_lifetimes_processed = true;
 311                                                                         assert_simple_bound(&trait_bound);
 312                                                                         let resolved = types.resolve_path(&trait_bound.path, None);
 313                                                                         let ty = syn::Type::Path(syn::TypePath {
 314                                                                                 qself: None, path: string_path_to_syn_path(&resolved)
 315                                                                         });
 316                                                                         let ref_ty = parse_quote!(&#ty);
 317                                                                         let mut_ref_ty = parse_quote!(&mut #ty);
 318                                                                         if types.crate_types.traits.get(&resolved).is_some() {
 319                                                                                 self.default_generics.insert(p_ident, (ty, ref_ty, mut_ref_ty));
 320                                                                         } else {
 321                                                                                 self.default_generics.insert(p_ident, (ref_ty.clone(), ref_ty, mut_ref_ty));
 322                                                                         }
 323
 324                                                                         *gen = Some(resolved);
 325                                                                 }
 326                                                         }
 327                                                 } else { return false; }
 328                                         } else { return false; }
 329                                 }
 330                         }
 331                 }
 332                 for (key, value) in new_typed_generics.drain() {
 333                         if let Some(v) = value {
 334                                 assert!(self.typed_generics.insert(key, v).is_none());
 335                         } else { return false; }
 336                 }
 337                 true
 338         }
 339
 340         /// Learn the generics in generics in the current context, given a TypeResolver.
 341         pub fn learn_generics<'b, 'c>(&mut self, generics: &'a syn::Generics, types: &'b TypeResolver<'a, 'c>) -> bool {
 342                 self.learn_generics_with_impls(generics, &syn::PathArguments::None, types)
 343         }
 344
 345         /// Learn the associated types from the trait in the current context.
 346         pub fn learn_associated_types<'b, 'c>(&mut self, t: &'a syn::ItemTrait, types: &'b TypeResolver<'a, 'c>) {
 347                 for item in t.items.iter() {
 348                         match item {
 349                                 &syn::TraitItem::Type(ref t) => {
 350                                         if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
 351                                         let mut bounds_iter = t.bounds.iter();
 352                                         loop {
 353                                                 match bounds_iter.next().unwrap() {
 354                                                         syn::TypeParamBound::Trait(tr) => {
 355                                                                 assert_simple_bound(&tr);
 356                                                                 if let Some(path) = types.maybe_resolve_path(&tr.path, None) {
 357                                                                         if types.skip_path(&path) { continue; }
 358                                                                         // In general we handle Deref<Target=X> as if it were just X (and
 359                                                                         // implement Deref<Target=Self> for relevant types). We don't
 360                                                                         // bother to implement it for associated types, however, so we just
 361                                                                         // ignore such bounds.
 362                                                                         if path != "std::ops::Deref" && path != "core::ops::Deref" &&
 363                                                                         path != "std::ops::DerefMut" && path != "core::ops::DerefMut" {
 364                                                                                 self.typed_generics.insert(&t.ident, path);
 365                                                                         } else {
 366                                                                                 let last_seg_args = &tr.path.segments.last().unwrap().arguments;
 367                                                                                 if let syn::PathArguments::AngleBracketed(args) = last_seg_args {
 368                                                                                         assert_eq!(args.args.len(), 1);
 369                                                                                         if let syn::GenericArgument::Binding(binding) = &args.args[0] {
 370                                                                                                 assert_eq!(format!("{}", binding.ident), "Target");
 371                                                                                                 if let syn::Type::Path(p) = &binding.ty {
 372                                                                                                         // Note that we are assuming the order of type
 373                                                                                                         // declarations here, but that should be easy
 374                                                                                                         // to handle.
 375                                                                                                         let real_path = self.maybe_resolve_path(&p.path).unwrap();
 376                                                                                                         self.typed_generics.insert(&t.ident, real_path.clone());
 377                                                                                                 } else { unimplemented!(); }
 378                                                                                         } else { unimplemented!(); }
 379                                                                                 } else { unimplemented!(); }
 380                                                                         }
 381                                                                 } else { unimplemented!(); }
 382                                                                 for bound in bounds_iter {
 383                                                                         if let syn::TypeParamBound::Trait(t) = bound {
 384                                                                                 // We only allow for `?Sized` here.
 385                                                                                 assert_eq!(t.path.segments.len(), 1);
 386                                                                                 assert_eq!(format!("{}", t.path.segments[0].ident), "Sized");
 387                                                                         }
 388                                                                 }
 389                                                                 break;
 390                                                         },
 391                                                         syn::TypeParamBound::Lifetime(_) => {},
 392                                                 }
 393                                         }
 394                                 },
 395                                 _ => {},
 396                         }
 397                 }
 398         }
 399
 400         /// Attempt to resolve a Path as a generic parameter and return the full path. as both a string
 401         /// and syn::Path.
 402         pub fn maybe_resolve_path<'b>(&'b self, path: &syn::Path) -> Option<&'b String> {
 403                 if let Some(ident) = path.get_ident() {
 404                         if let Some(ty) = &self.self_ty {
 405                                 if format!("{}", ident) == "Self" {
 406                                         return Some(&ty);
 407                                 }
 408                         }
 409                         if let Some(res) = self.typed_generics.get(ident) {
 410                                 return Some(res);
 411                         }
 412                 } else {
 413                         // Associated types are usually specified as "Self::Generic", so we check for that
 414                         // explicitly here.
 415                         let mut it = path.segments.iter();
 416                         if path.segments.len() == 2 && format!("{}", it.next().unwrap().ident) == "Self" {
 417                                 let ident = &it.next().unwrap().ident;
 418                                 if let Some(res) = self.typed_generics.get(ident) {
 419                                         return Some(res);
 420                                 }
 421                         }
 422                 }
 423                 if let Some(parent) = self.parent {
 424                         parent.maybe_resolve_path(path)
 425                 } else {
 426                         None
 427                 }
 428         }
 429 }
 430
 431 pub trait ResolveType<'a> { fn resolve_type(&'a self, ty: &'a syn::Type) -> &'a syn::Type; }
 432 impl<'a, 'b, 'c: 'a + 'b> ResolveType<'c> for Option<&GenericTypes<'a, 'b>> {
 433         fn resolve_type(&'c self, ty: &'c syn::Type) -> &'c syn::Type {
 434                 if let Some(us) = self {
 435                         match ty {
 436                                 syn::Type::Path(p) => {
 437                                         if let Some(ident) = p.path.get_ident() {
 438                                                 if let Some((ty, _, _)) = us.default_generics.get(ident) {
 439                                                         return self.resolve_type(ty);
 440                                                 }
 441                                         }
 442                                 },
 443                                 syn::Type::Reference(syn::TypeReference { elem, mutability, .. }) => {
 444                                         if let syn::Type::Path(p) = &**elem {
 445                                                 if let Some(ident) = p.path.get_ident() {
 446                                                         if let Some((_, refty, mut_ref_ty)) = us.default_generics.get(ident) {
 447                                                                 if mutability.is_some() {
 448                                                                         return self.resolve_type(mut_ref_ty);
 449                                                                 } else {
 450                                                                         return self.resolve_type(refty);
 451                                                                 }
 452                                                         }
 453                                                 }
 454                                         }
 455                                 }
 456                                 _ => {},
 457                         }
 458                         us.parent.resolve_type(ty)
 459                 } else { ty }
 460         }
 461 }
 462
 463 #[derive(Clone, PartialEq)]
 464 // The type of declaration and the object itself
 465 pub enum DeclType<'a> {
 466         MirroredEnum,
 467         Trait(&'a syn::ItemTrait),
 468         StructImported { generics: &'a syn::Generics  },
 469         StructIgnored,
 470         EnumIgnored { generics: &'a syn::Generics },
 471 }
 472
 473 pub struct ImportResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 474         pub crate_name: &'mod_lifetime str,
 475         library: &'crate_lft FullLibraryAST,
 476         module_path: &'mod_lifetime str,
 477         imports: HashMap<syn::Ident, (String, syn::Path)>,
 478         declared: HashMap<syn::Ident, DeclType<'crate_lft>>,
 479         priv_modules: HashSet<syn::Ident>,
 480 }
 481 impl<'mod_lifetime, 'crate_lft: 'mod_lifetime> ImportResolver<'mod_lifetime, 'crate_lft> {
 482         fn walk_use_intern<F: FnMut(syn::Ident, (String, syn::Path))>(
 483                 crate_name: &str, module_path: &str, dependencies: &HashSet<syn::Ident>, u: &syn::UseTree,
 484                 partial_path: &str,
 485                 mut path: syn::punctuated::Punctuated<syn::PathSegment, syn::token::Colon2>, handle_use: &mut F
 486         ) {
 487                 let new_path;
 488                 macro_rules! push_path {
 489                         ($ident: expr, $path_suffix: expr) => {
 490                                 if partial_path == "" && format!("{}", $ident) == "super" {
 491                                         let mut mod_iter = module_path.rsplitn(2, "::");
 492                                         mod_iter.next().unwrap();
 493                                         let super_mod = mod_iter.next().unwrap();
 494                                         new_path = format!("{}{}", super_mod, $path_suffix);
 495                                         assert_eq!(path.len(), 0);
 496                                         for module in super_mod.split("::") {
 497                                                 path.push(syn::PathSegment { ident: syn::Ident::new(module, Span::call_site()), arguments: syn::PathArguments::None });
 498                                         }
 499                                 } else if partial_path == "" && format!("{}", $ident) == "self" {
 500                                         new_path = format!("{}{}", module_path, $path_suffix);
 501                                         for module in module_path.split("::") {
 502                                                 path.push(syn::PathSegment { ident: syn::Ident::new(module, Span::call_site()), arguments: syn::PathArguments::None });
 503                                         }
 504                                 } else if partial_path == "" && format!("{}", $ident) == "crate" {
 505                                         new_path = format!("{}{}", crate_name, $path_suffix);
 506                                         let crate_name_ident = format_ident!("{}", crate_name);
 507                                         path.push(parse_quote!(#crate_name_ident));
 508                                 } else if partial_path == "" && !dependencies.contains(&$ident) {
 509                                         new_path = format!("{}::{}{}", module_path, $ident, $path_suffix);
 510                                         for module in module_path.split("::") {
 511                                                 path.push(syn::PathSegment { ident: syn::Ident::new(module, Span::call_site()), arguments: syn::PathArguments::None });
 512                                         }
 513                                         let ident_str = format_ident!("{}", $ident);
 514                                         path.push(parse_quote!(#ident_str));
 515                                 } else if format!("{}", $ident) == "self" {
 516                                         let mut path_iter = partial_path.rsplitn(2, "::");
 517                                         path_iter.next().unwrap();
 518                                         new_path = path_iter.next().unwrap().to_owned();
 519                                 } else {
 520                                         new_path = format!("{}{}{}", partial_path, $ident, $path_suffix);
 521                                 }
 522                                 let ident = &$ident;
 523                                 path.push(parse_quote!(#ident));
 524                         }
 525                 }
 526                 match u {
 527                         syn::UseTree::Path(p) => {
 528                                 push_path!(p.ident, "::");
 529                                 Self::walk_use_intern(crate_name, module_path, dependencies, &p.tree, &new_path, path, handle_use);
 530                         },
 531                         syn::UseTree::Name(n) => {
 532                                 push_path!(n.ident, "");
 533                                 let imported_ident = syn::Ident::new(new_path.rsplitn(2, "::").next().unwrap(), Span::call_site());
 534                                 handle_use(imported_ident, (new_path, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 535                         },
 536                         syn::UseTree::Group(g) => {
 537                                 for i in g.items.iter() {
 538                                         Self::walk_use_intern(crate_name, module_path, dependencies, i, partial_path, path.clone(), handle_use);
 539                                 }
 540                         },
 541                         syn::UseTree::Rename(r) => {
 542                                 push_path!(r.ident, "");
 543                                 handle_use(r.rename.clone(), (new_path, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 544                         },
 545                         syn::UseTree::Glob(_) => {
 546                                 eprintln!("Ignoring * use for {} - this may result in resolution failures", partial_path);
 547                         },
 548                 }
 549         }
 550
 551         fn process_use_intern(crate_name: &str, module_path: &str, dependencies: &HashSet<syn::Ident>,
 552                 imports: &mut HashMap<syn::Ident, (String, syn::Path)>, u: &syn::UseTree, partial_path: &str,
 553                 path: syn::punctuated::Punctuated<syn::PathSegment, syn::token::Colon2>
 554         ) {
 555                 Self::walk_use_intern(crate_name, module_path, dependencies, u, partial_path, path,
 556                         &mut |k, v| { imports.insert(k, v); });
 557         }
 558
 559         fn process_use(crate_name: &str, module_path: &str, dependencies: &HashSet<syn::Ident>, imports: &mut HashMap<syn::Ident, (String, syn::Path)>, u: &syn::ItemUse) {
 560                 if u.leading_colon.is_some() { eprintln!("Ignoring leading-colon use!"); return; }
 561                 Self::process_use_intern(crate_name, module_path, dependencies, imports, &u.tree, "", syn::punctuated::Punctuated::new());
 562         }
 563
 564         fn insert_primitive(imports: &mut HashMap<syn::Ident, (String, syn::Path)>, id: &str) {
 565                 let ident = format_ident!("{}", id);
 566                 let path = parse_quote!(#ident);
 567                 imports.insert(ident, (id.to_owned(), path));
 568         }
 569
 570         pub fn new(crate_name: &'mod_lifetime str, library: &'crate_lft FullLibraryAST, module_path: &'mod_lifetime str, contents: &'crate_lft [syn::Item]) -> Self {
 571                 Self::from_borrowed_items(crate_name, library, module_path, &contents.iter().map(|a| a).collect::<Vec<_>>())
 572         }
 573         pub fn from_borrowed_items(crate_name: &'mod_lifetime str, library: &'crate_lft FullLibraryAST, module_path: &'mod_lifetime str, contents: &[&'crate_lft syn::Item]) -> Self {
 574                 let mut imports = HashMap::new();
 575                 // Add primitives to the "imports" list:
 576                 Self::insert_primitive(&mut imports, "bool");
 577                 Self::insert_primitive(&mut imports, "u128");
 578                 Self::insert_primitive(&mut imports, "i64");
 579                 Self::insert_primitive(&mut imports, "f64");
 580                 Self::insert_primitive(&mut imports, "u64");
 581                 Self::insert_primitive(&mut imports, "u32");
 582                 Self::insert_primitive(&mut imports, "u16");
 583                 Self::insert_primitive(&mut imports, "u8");
 584                 Self::insert_primitive(&mut imports, "usize");
 585                 Self::insert_primitive(&mut imports, "str");
 586                 Self::insert_primitive(&mut imports, "String");
 587
 588                 // These are here to allow us to print native Rust types in trait fn impls even if we don't
 589                 // have C mappings:
 590                 Self::insert_primitive(&mut imports, "Result");
 591                 Self::insert_primitive(&mut imports, "Vec");
 592                 Self::insert_primitive(&mut imports, "Option");
 593
 594                 let mut declared = HashMap::new();
 595                 let mut priv_modules = HashSet::new();
 596
 597                 for item in contents.iter() {
 598                         match item {
 599                                 syn::Item::Use(u) => Self::process_use(crate_name, module_path, &library.dependencies, &mut imports, &u),
 600                                 syn::Item::Struct(s) => {
 601                                         if let syn::Visibility::Public(_) = s.vis {
 602                                                 match export_status(&s.attrs) {
 603                                                         ExportStatus::Export => { declared.insert(s.ident.clone(), DeclType::StructImported { generics: &s.generics }); },
 604                                                         ExportStatus::NoExport => { declared.insert(s.ident.clone(), DeclType::StructIgnored); },
 605                                                         ExportStatus::TestOnly => continue,
 606                                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 607                                                 }
 608                                         }
 609                                 },
 610                                 syn::Item::Type(t) if export_status(&t.attrs) == ExportStatus::Export => {
 611                                         if let syn::Visibility::Public(_) = t.vis {
 612                                                 declared.insert(t.ident.clone(), DeclType::StructImported { generics: &t.generics });
 613                                         }
 614                                 },
 615                                 syn::Item::Enum(e) => {
 616                                         if let syn::Visibility::Public(_) = e.vis {
 617                                                 match export_status(&e.attrs) {
 618                                                         ExportStatus::Export if is_enum_opaque(e) => { declared.insert(e.ident.clone(), DeclType::EnumIgnored { generics: &e.generics }); },
 619                                                         ExportStatus::Export => { declared.insert(e.ident.clone(), DeclType::MirroredEnum); },
 620                                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 621                                                         _ => continue,
 622                                                 }
 623                                         }
 624                                 },
 625                                 syn::Item::Trait(t) => {
 626                                         if let syn::Visibility::Public(_) = t.vis {
 627                                                 declared.insert(t.ident.clone(), DeclType::Trait(t));
 628                                         }
 629                                 },
 630                                 syn::Item::Mod(m) => {
 631                                         priv_modules.insert(m.ident.clone());
 632                                 },
 633                                 _ => {},
 634                         }
 635                 }
 636
 637                 Self { crate_name, library, module_path, imports, declared, priv_modules }
 638         }
 639
 640         pub fn maybe_resolve_declared(&self, id: &syn::Ident) -> Option<&DeclType<'crate_lft>> {
 641                 self.declared.get(id)
 642         }
 643
 644         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
 645                 if let Some((imp, _)) = self.imports.get(id) {
 646                         Some(imp.clone())
 647                 } else if self.declared.get(id).is_some() {
 648                         Some(self.module_path.to_string() + "::" + &format!("{}", id))
 649                 } else { None }
 650         }
 651
 652         fn maybe_resolve_imported_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
 653                 if let Some(gen_types) = generics {
 654                         if let Some(resp) = gen_types.maybe_resolve_path(p) {
 655                                 return Some(resp.clone());
 656                         }
 657                 }
 658
 659                 if p.leading_colon.is_some() {
 660                         let mut res: String = p.segments.iter().enumerate().map(|(idx, seg)| {
 661                                 format!("{}{}", if idx == 0 { "" } else { "::" }, seg.ident)
 662                         }).collect();
 663                         let firstseg = p.segments.iter().next().unwrap();
 664                         if !self.library.dependencies.contains(&firstseg.ident) {
 665                                 res = self.crate_name.to_owned() + "::" + &res;
 666                         }
 667                         Some(res)
 668                 } else if let Some(id) = p.get_ident() {
 669                         self.maybe_resolve_ident(id)
 670                 } else {
 671                         if p.segments.len() == 1 {
 672                                 let seg = p.segments.iter().next().unwrap();
 673                                 return self.maybe_resolve_ident(&seg.ident);
 674                         }
 675                         let mut seg_iter = p.segments.iter();
 676                         let first_seg = seg_iter.next().unwrap();
 677                         let remaining: String = seg_iter.map(|seg| {
 678                                 format!("::{}", seg.ident)
 679                         }).collect();
 680                         let first_seg_str = format!("{}", first_seg.ident);
 681                         if let Some((imp, _)) = self.imports.get(&first_seg.ident) {
 682                                 if remaining != "" {
 683                                         Some(imp.clone() + &remaining)
 684                                 } else {
 685                                         Some(imp.clone())
 686                                 }
 687                         } else if let Some(_) = self.priv_modules.get(&first_seg.ident) {
 688                                 Some(format!("{}::{}{}", self.module_path, first_seg.ident, remaining))
 689                         } else if first_seg_is_stdlib(&first_seg_str) || self.library.dependencies.contains(&first_seg.ident) {
 690                                 Some(first_seg_str + &remaining)
 691                         } else if first_seg_str == "crate" {
 692                                 Some(self.crate_name.to_owned() + &remaining)
 693                         } else if self.library.modules.get(&format!("{}::{}", self.module_path, first_seg.ident)).is_some() {
 694                                 Some(format!("{}::{}{}", self.module_path, first_seg.ident, remaining))
 695                         } else { None }
 696                 }
 697         }
 698
 699         pub fn maybe_resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
 700                 self.maybe_resolve_imported_path(p, generics).map(|mut path| {
 701                         if path == "core::ops::Deref" || path == "core::ops::DerefMut" {
 702                                 let last_seg = p.segments.last().unwrap();
 703                                 if let syn::PathArguments::AngleBracketed(args) = &last_seg.arguments {
 704                                         assert_eq!(args.args.len(), 1);
 705                                         if let syn::GenericArgument::Binding(binding) = &args.args[0] {
 706                                                 if let syn::Type::Path(p) = &binding.ty {
 707                                                         if let Some(inner_ty) = self.maybe_resolve_path(&p.path, generics) {
 708                                                                 let mut module_riter = inner_ty.rsplitn(2, "::");
 709                                                                 let ty_ident = module_riter.next().unwrap();
 710                                                                 let module_name = module_riter.next().unwrap();
 711                                                                 let module = self.library.modules.get(module_name).unwrap();
 712                                                                 for item in module.items.iter() {
 713                                                                         match item {
 714                                                                                 syn::Item::Trait(t) => {
 715                                                                                         if t.ident == ty_ident {
 716                                                                                                 path = inner_ty;
 717                                                                                                 break;
 718                                                                                         }
 719                                                                                 },
 720                                                                                 _ => {}
 721                                                                         }
 722                                                                 }
 723                                                         }
 724                                                 } else { unimplemented!(); }
 725                                         } else { unimplemented!(); }
 726                                 }
 727                         }
 728                         loop {
 729                                 // Now that we've resolved the path to the path as-imported, check whether the path
 730                                 // is actually a pub(.*) use statement and map it to the real path.
 731                                 let path_tmp = path.clone();
 732                                 let crate_name = path_tmp.splitn(2, "::").next().unwrap();
 733                                 let mut module_riter = path_tmp.rsplitn(2, "::");
 734                                 let obj = module_riter.next().unwrap();
 735                                 if let Some(module_path) = module_riter.next() {
 736                                         if let Some(m) = self.library.modules.get(module_path) {
 737                                                 for item in m.items.iter() {
 738                                                         if let syn::Item::Use(syn::ItemUse { vis, tree, .. }) = item {
 739                                                                 match vis {
 740                                                                         syn::Visibility::Public(_)|
 741                                                                         syn::Visibility::Crate(_)|
 742                                                                         syn::Visibility::Restricted(_) => {
 743                                                                                 Self::walk_use_intern(crate_name, module_path,
 744                                                                                         &self.library.dependencies, tree, "",
 745                                                                                         syn::punctuated::Punctuated::new(), &mut |ident, (use_path, _)| {
 746                                                                                                 if format!("{}", ident) == obj {
 747                                                                                                         path = use_path;
 748                                                                                                 }
 749                                                                                 });
 750                                                                         },
 751                                                                         syn::Visibility::Inherited => {},
 752                                                                 }
 753                                                         }
 754                                                 }
 755                                         }
 756                                 }
 757                                 break;
 758                         }
 759                         path
 760                 })
 761         }
 762
 763         /// Map all the Paths in a Type into absolute paths given a set of imports (generated via process_use_intern)
 764         pub fn resolve_imported_refs(&self, mut ty: syn::Type) -> syn::Type {
 765                 match &mut ty {
 766                         syn::Type::Path(p) => {
 767                                 if p.path.segments.len() != 1 { unimplemented!(); }
 768                                 let mut args = p.path.segments[0].arguments.clone();
 769                                 if let syn::PathArguments::AngleBracketed(ref mut generics) = &mut args {
 770                                         for arg in generics.args.iter_mut() {
 771                                                 if let syn::GenericArgument::Type(ref mut t) = arg {
 772                                                         *t = self.resolve_imported_refs(t.clone());
 773                                                 }
 774                                         }
 775                                 }
 776                                 if let Some((_, newpath)) = self.imports.get(single_ident_generic_path_to_ident(&p.path).unwrap()) {
 777                                         p.path = newpath.clone();
 778                                 }
 779                                 p.path.segments[0].arguments = args;
 780                         },
 781                         syn::Type::Reference(r) => {
 782                                 r.elem = Box::new(self.resolve_imported_refs((*r.elem).clone()));
 783                         },
 784                         syn::Type::Slice(s) => {
 785                                 s.elem = Box::new(self.resolve_imported_refs((*s.elem).clone()));
 786                         },
 787                         syn::Type::Tuple(t) => {
 788                                 for e in t.elems.iter_mut() {
 789                                         *e = self.resolve_imported_refs(e.clone());
 790                                 }
 791                         },
 792                         _ => unimplemented!(),
 793                 }
 794                 ty
 795         }
 796 }
 797
 798 // templates_defined is walked to write the C++ header, so if we use the default hashing it get
 799 // reordered on each genbindings run. Instead, we use SipHasher (which defaults to 0-keys) so that
 800 // the sorting is stable across runs. It is deprecated, but the "replacement" doesn't actually
 801 // accomplish the same goals, so we just ignore it.
 802 #[allow(deprecated)]
 803 pub type NonRandomHash = hash::BuildHasherDefault<hash::SipHasher>;
 804
 805 /// A public module
 806 pub struct ASTModule {
 807         pub attrs: Vec<syn::Attribute>,
 808         pub items: Vec<syn::Item>,
 809         pub submods: Vec<String>,
 810 }
 811 /// A struct containing the syn::File AST for each file in the crate.
 812 pub struct FullLibraryAST {
 813         pub modules: HashMap<String, ASTModule, NonRandomHash>,
 814         pub dependencies: HashSet<syn::Ident>,
 815 }
 816 impl FullLibraryAST {
 817         fn load_module(&mut self, module: String, attrs: Vec<syn::Attribute>, mut items: Vec<syn::Item>) {
 818                 let mut non_mod_items = Vec::with_capacity(items.len());
 819                 let mut submods = Vec::with_capacity(items.len());
 820                 for item in items.drain(..) {
 821                         match item {
 822                                 syn::Item::Mod(m) if m.content.is_some() => {
 823                                         if export_status(&m.attrs) == ExportStatus::Export {
 824                                                 if let syn::Visibility::Public(_) = m.vis {
 825                                                         let modident = format!("{}", m.ident);
 826                                                         let modname = if module != "" {
 827                                                                 module.clone() + "::" + &modident
 828                                                         } else {
 829                                                                 self.dependencies.insert(m.ident);
 830                                                                 modident.clone()
 831                                                         };
 832                                                         self.load_module(modname, m.attrs, m.content.unwrap().1);
 833                                                         submods.push(modident);
 834                                                 } else {
 835                                                         non_mod_items.push(syn::Item::Mod(m));
 836                                                 }
 837                                         }
 838                                 },
 839                                 syn::Item::Mod(_) => panic!("--pretty=expanded output should never have non-body modules"),
 840                                 syn::Item::ExternCrate(c) => {
 841                                         if export_status(&c.attrs) == ExportStatus::Export {
 842                                                 self.dependencies.insert(c.ident);
 843                                         }
 844                                 },
 845                                 _ => { non_mod_items.push(item); }
 846                         }
 847                 }
 848                 self.modules.insert(module, ASTModule { attrs, items: non_mod_items, submods });
 849         }
 850
 851         pub fn load_lib(lib: syn::File) -> Self {
 852                 assert_eq!(export_status(&lib.attrs), ExportStatus::Export);
 853                 let mut res = Self { modules: HashMap::default(), dependencies: HashSet::new() };
 854                 res.load_module("".to_owned(), lib.attrs, lib.items);
 855                 res
 856         }
 857 }
 858
 859 /// List of manually-generated types which are clonable
 860 fn initial_clonable_types() -> HashSet<String> {
 861         let mut res = HashSet::new();
 862         res.insert("crate::c_types::U5".to_owned());
 863         res.insert("crate::c_types::U128".to_owned());
 864         res.insert("crate::c_types::ThreeBytes".to_owned());
 865         res.insert("crate::c_types::FourBytes".to_owned());
 866         res.insert("crate::c_types::TwelveBytes".to_owned());
 867         res.insert("crate::c_types::SixteenBytes".to_owned());
 868         res.insert("crate::c_types::TwentyBytes".to_owned());
 869         res.insert("crate::c_types::ThirtyTwoBytes".to_owned());
 870         res.insert("crate::c_types::EightU16s".to_owned());
 871         res.insert("crate::c_types::SecretKey".to_owned());
 872         res.insert("crate::c_types::PublicKey".to_owned());
 873         res.insert("crate::c_types::TweakedPublicKey".to_owned());
 874         res.insert("crate::c_types::Transaction".to_owned());
 875         res.insert("crate::c_types::Witness".to_owned());
 876         res.insert("crate::c_types::WitnessVersion".to_owned());
 877         res.insert("crate::c_types::WitnessProgram".to_owned());
 878         res.insert("crate::c_types::TxIn".to_owned());
 879         res.insert("crate::c_types::TxOut".to_owned());
 880         res.insert("crate::c_types::ECDSASignature".to_owned());
 881         res.insert("crate::c_types::SchnorrSignature".to_owned());
 882         res.insert("crate::c_types::RecoverableSignature".to_owned());
 883         res.insert("crate::c_types::BigEndianScalar".to_owned());
 884         res.insert("crate::c_types::Bech32Error".to_owned());
 885         res.insert("crate::c_types::Secp256k1Error".to_owned());
 886         res.insert("crate::c_types::IOError".to_owned());
 887         res.insert("crate::c_types::Error".to_owned());
 888         res.insert("crate::c_types::Str".to_owned());
 889
 890         // Because some types are manually-mapped to CVec_u8Z we may end up checking if its clonable
 891         // before we ever get to constructing the type fully via
 892         // `write_c_mangled_container_path_intern` (which will add it here too), so we have to manually
 893         // add it on startup.
 894         res.insert("crate::c_types::derived::CVec_u8Z".to_owned());
 895         res
 896 }
 897
 898 /// Top-level struct tracking everything which has been defined while walking the crate.
 899 pub struct CrateTypes<'a> {
 900         /// This may contain structs or enums, but only when either is mapped as
 901         /// struct X { inner: *mut originalX, .. }
 902         pub opaques: HashMap<String, (&'a syn::Ident, &'a syn::Generics)>,
 903         /// structs that weren't exposed
 904         pub priv_structs: HashMap<String, &'a syn::Generics>,
 905         /// Enums which are mapped as C enums with conversion functions
 906         pub mirrored_enums: HashMap<String, &'a syn::ItemEnum>,
 907         /// Traits which are mapped as a pointer + jump table
 908         pub traits: HashMap<String, &'a syn::ItemTrait>,
 909         /// Aliases from paths to some other Type
 910         pub type_aliases: HashMap<String, syn::Type>,
 911         /// Value is an alias to Key (maybe with some generics)
 912         pub reverse_alias_map: HashMap<String, Vec<(String, syn::PathArguments)>>,
 913         /// Template continer types defined, map from mangled type name -> whether a destructor fn
 914         /// exists.
 915         ///
 916         /// This is used at the end of processing to make C++ wrapper classes
 917         pub templates_defined: RefCell<HashMap<String, bool, NonRandomHash>>,
 918         /// The output file for any created template container types, written to as we find new
 919         /// template containers which need to be defined.
 920         template_file: RefCell<&'a mut File>,
 921         /// Set of containers which are clonable
 922         clonable_types: RefCell<HashSet<String>>,
 923         /// Key impls Value
 924         pub trait_impls: HashMap<String, Vec<String>>,
 925         /// Value impls Key
 926         pub traits_impld: HashMap<String, Vec<String>>,
 927         /// The full set of modules in the crate(s)
 928         pub lib_ast: &'a FullLibraryAST,
 929 }
 930
 931 impl<'a> CrateTypes<'a> {
 932         pub fn new(template_file: &'a mut File, libast: &'a FullLibraryAST) -> Self {
 933                 CrateTypes {
 934                         opaques: HashMap::new(), mirrored_enums: HashMap::new(), traits: HashMap::new(),
 935                         type_aliases: HashMap::new(), reverse_alias_map: HashMap::new(),
 936                         templates_defined: RefCell::new(HashMap::default()), priv_structs: HashMap::new(),
 937                         clonable_types: RefCell::new(initial_clonable_types()),
 938                         trait_impls: HashMap::new(), traits_impld: HashMap::new(),
 939                         template_file: RefCell::new(template_file), lib_ast: &libast,
 940                 }
 941         }
 942         pub fn set_clonable(&self, object: String) {
 943                 self.clonable_types.borrow_mut().insert(object);
 944         }
 945         pub fn is_clonable(&self, object: &str) -> bool {
 946                 self.clonable_types.borrow().contains(object)
 947         }
 948         pub fn write_new_template(&self, mangled_container: String, has_destructor: bool, created_container: &[u8]) {
 949                 self.template_file.borrow_mut().write(created_container).unwrap();
 950                 self.templates_defined.borrow_mut().insert(mangled_container, has_destructor);
 951         }
 952 }
 953
 954 /// A struct which tracks resolving rust types into C-mapped equivalents, exists for one specific
 955 /// module but contains a reference to the overall CrateTypes tracking.
 956 pub struct TypeResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 957         pub module_path: &'mod_lifetime str,
 958         pub crate_types: &'mod_lifetime CrateTypes<'crate_lft>,
 959         pub types: ImportResolver<'mod_lifetime, 'crate_lft>,
 960 }
 961
 962 /// Returned by write_empty_rust_val_check_suffix to indicate what type of dereferencing needs to
 963 /// happen to get the inner value of a generic.
 964 enum EmptyValExpectedTy {
 965         /// A type which has a flag for being empty (eg an array where we treat all-0s as empty).
 966         NonPointer,
 967         /// A Option mapped as a COption_*Z
 968         OptionType,
 969         /// A pointer which we want to convert to a reference.
 970         ReferenceAsPointer,
 971 }
 972
 973 #[derive(PartialEq)]
 974 /// Describes the appropriate place to print a general type-conversion string when converting a
 975 /// container.
 976 enum ContainerPrefixLocation {
 977         /// Prints a general type-conversion string prefix and suffix outside of the
 978         /// container-conversion strings.
 979         OutsideConv,
 980         /// Prints a general type-conversion string prefix and suffix inside of the
 981         /// container-conversion strings.
 982         PerConv,
 983         /// Does not print the usual type-conversion string prefix and suffix.
 984         NoPrefix,
 985 }
 986
 987 impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 988         pub fn new(module_path: &'a str, types: ImportResolver<'a, 'c>, crate_types: &'a CrateTypes<'c>) -> Self {
 989                 Self { module_path, types, crate_types }
 990         }
 991
 992         // *************************************************
 993         // *** Well know type and conversion definitions ***
 994         // *************************************************
 995
 996         /// Returns true we if can just skip passing this to C entirely
 997         pub fn skip_path(&self, full_path: &str) -> bool {
 998                 full_path == "bitcoin::secp256k1::Secp256k1" ||
 999                 full_path == "bitcoin::secp256k1::Signing" ||
1000                 full_path == "bitcoin::secp256k1::Verification"
1001         }
1002         /// Returns true we if can just skip passing this to C entirely
1003         fn no_arg_path_to_rust(&self, full_path: &str) -> &str {
1004                 if full_path == "bitcoin::secp256k1::Secp256k1" {
1005                         "secp256k1::global::SECP256K1"
1006                 } else { unimplemented!(); }
1007         }
1008
1009         /// Returns true if the object is a primitive and is mapped as-is with no conversion
1010         /// whatsoever.
1011         pub fn is_primitive(&self, full_path: &str) -> bool {
1012                 match full_path {
1013                         "bool" => true,
1014                         "i64" => true,
1015                         "f64" => true,
1016                         "u64" => true,
1017                         "u32" => true,
1018                         "u16" => true,
1019                         "u8" => true,
1020                         "usize" => true,
1021                         _ => false,
1022                 }
1023         }
1024         pub fn is_clonable(&self, ty: &str) -> bool {
1025                 if self.crate_types.is_clonable(ty) { return true; }
1026                 if self.is_primitive(ty) { return true; }
1027                 match ty {
1028                         "()" => true,
1029                         _ => false,
1030                 }
1031         }
1032         /// Gets the C-mapped type for types which are outside of the crate, or which are manually
1033         /// ignored by for some reason need mapping anyway.
1034         fn c_type_from_path<'b>(&self, full_path: &'b str, is_ref: bool, _ptr_for_ref: bool) -> Option<&'b str> {
1035                 if self.is_primitive(full_path) {
1036                         return Some(full_path);
1037                 }
1038                 match full_path {
1039                         // Note that no !is_ref types can map to an array because Rust and C's call semantics
1040                         // for arrays are different (https://github.com/eqrion/cbindgen/issues/528)
1041
1042                         "[u8; 33]" if !is_ref => Some("crate::c_types::ThirtyThreeBytes"),
1043                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
1044                         "[u8; 20]" if !is_ref => Some("crate::c_types::TwentyBytes"),
1045                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes"),
1046                         "[u8; 12]" if !is_ref => Some("crate::c_types::TwelveBytes"),
1047                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes"),
1048                         "[u8; 3]" if !is_ref => Some("crate::c_types::ThreeBytes"), // Used for RGB values
1049                         "[u16; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoU16s"),
1050
1051                         "str" if is_ref => Some("crate::c_types::Str"),
1052                         "alloc::string::String"|"String"|"std::path::PathBuf" => Some("crate::c_types::Str"),
1053
1054                         "bitcoin::Address" => Some("crate::c_types::Str"),
1055
1056                         "std::time::Duration"|"core::time::Duration" => Some("u64"),
1057                         "std::time::SystemTime" => Some("u64"),
1058                         "std::io::Error"|"lightning::io::Error"|"lightning::io::ErrorKind" => Some("crate::c_types::IOError"),
1059                         "core::fmt::Arguments" if is_ref => Some("crate::c_types::Str"),
1060
1061                         "core::convert::Infallible" => Some("crate::c_types::NotConstructable"),
1062
1063                         "bitcoin::bech32::Error"|"bech32::Error"
1064                                 if !is_ref => Some("crate::c_types::Bech32Error"),
1065                         "bitcoin::secp256k1::Error"|"secp256k1::Error"
1066                                 if !is_ref => Some("crate::c_types::Secp256k1Error"),
1067
1068                         "core::num::ParseIntError" => Some("crate::c_types::Error"),
1069                         "core::str::Utf8Error" => Some("crate::c_types::Error"),
1070
1071                         "bitcoin::bech32::u5"|"bech32::u5" => Some("crate::c_types::U5"),
1072                         "u128" => Some("crate::c_types::U128"),
1073                         "core::num::NonZeroU8" => Some("u8"),
1074
1075                         "secp256k1::PublicKey"|"bitcoin::secp256k1::PublicKey" => Some("crate::c_types::PublicKey"),
1076                         "bitcoin::key::TweakedPublicKey" => Some("crate::c_types::TweakedPublicKey"),
1077                         "bitcoin::secp256k1::ecdsa::Signature" => Some("crate::c_types::ECDSASignature"),
1078                         "bitcoin::secp256k1::schnorr::Signature" => Some("crate::c_types::SchnorrSignature"),
1079                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some("crate::c_types::RecoverableSignature"),
1080                         "bitcoin::secp256k1::SecretKey" if is_ref  => Some("*const [u8; 32]"),
1081                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some("crate::c_types::SecretKey"),
1082                         "bitcoin::secp256k1::KeyPair" if !is_ref => Some("crate::c_types::SecretKey"),
1083                         "bitcoin::secp256k1::Scalar" if is_ref  => Some("*const crate::c_types::BigEndianScalar"),
1084                         "bitcoin::secp256k1::Scalar" if !is_ref => Some("crate::c_types::BigEndianScalar"),
1085                         "bitcoin::secp256k1::ecdh::SharedSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
1086
1087                         "bitcoin::blockdata::script::Script"|"bitcoin::Script" => Some("crate::c_types::u8slice"),
1088                         "bitcoin::blockdata::script::ScriptBuf"|"bitcoin::ScriptBuf" => Some("crate::c_types::derived::CVec_u8Z"),
1089                         "bitcoin::OutPoint"|"bitcoin::blockdata::transaction::OutPoint" => Some("crate::lightning::chain::transaction::OutPoint"),
1090                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some("crate::c_types::Transaction"),
1091                         "bitcoin::Witness" => Some("crate::c_types::Witness"),
1092                         "bitcoin::TxIn"|"bitcoin::blockdata::transaction::TxIn" if !is_ref => Some("crate::c_types::TxIn"),
1093                         "bitcoin::TxOut"|"bitcoin::blockdata::transaction::TxOut" => Some("crate::c_types::TxOut"),
1094                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network"),
1095                         "bitcoin::address::WitnessVersion" => Some("crate::c_types::WitnessVersion"),
1096                         "bitcoin::address::WitnessProgram" => Some("crate::c_types::WitnessProgram"),
1097                         "bitcoin::blockdata::block::Header" if is_ref  => Some("*const [u8; 80]"),
1098                         "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
1099
1100                         "bitcoin::blockdata::locktime::absolute::LockTime" => Some("u32"),
1101
1102                         "bitcoin::psbt::PartiallySignedTransaction" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
1103
1104                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash"|
1105                         "bitcoin::hash_types::WPubkeyHash"|
1106                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash"
1107                                 if !is_ref => Some("crate::c_types::TwentyBytes"),
1108                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash"|
1109                         "bitcoin::hash_types::WPubkeyHash"|
1110                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash"
1111                                 if is_ref => Some("*const [u8; 20]"),
1112                         "bitcoin::hash_types::WScriptHash"
1113                                 if is_ref => Some("*const [u8; 32]"),
1114
1115                         // Newtypes that we just expose in their original form.
1116                         "bitcoin::hash_types::Txid"|"bitcoin::BlockHash"|"bitcoin::hash_types::BlockHash"|"bitcoin::hashes::sha256::Hash"|"bitcoin::blockdata::constants::ChainHash"
1117                                 if is_ref  => Some("*const [u8; 32]"),
1118                         "bitcoin::hash_types::Txid"|"bitcoin::BlockHash"|"bitcoin::hash_types::BlockHash"|"bitcoin::hashes::sha256::Hash"|"bitcoin::blockdata::constants::ChainHash"
1119                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
1120                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
1121                         "bitcoin::secp256k1::Message" if is_ref => Some("*const [u8; 32]"),
1122                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1123                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1124                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1125                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1126                                 if is_ref => Some("*const [u8; 32]"),
1127                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1128                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1129                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1130                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1131                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
1132
1133                         "lightning::io::Read" => Some("crate::c_types::u8slice"),
1134
1135                         _ => None,
1136                 }
1137         }
1138
1139         fn from_c_conversion_new_var_from_path<'b>(&self, _full_path: &str, _is_ref: bool) -> Option<(&'b str, &'b str)> {
1140                 None
1141         }
1142         fn from_c_conversion_prefix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
1143                 if self.is_primitive(full_path) {
1144                         return Some("".to_owned());
1145                 }
1146                 match full_path {
1147                         "Vec" if !is_ref => Some("local_"),
1148                         "Result" if !is_ref => Some("local_"),
1149                         "Option" if is_ref => Some("&local_"),
1150                         "Option" => Some("local_"),
1151
1152                         "[u8; 33]" if !is_ref => Some(""),
1153                         "[u8; 32]" if is_ref => Some("unsafe { &*"),
1154                         "[u8; 32]" if !is_ref => Some(""),
1155                         "[u8; 20]" if !is_ref => Some(""),
1156                         "[u8; 16]" if !is_ref => Some(""),
1157                         "[u8; 12]" if !is_ref => Some(""),
1158                         "[u8; 4]" if !is_ref => Some(""),
1159                         "[u8; 3]" if !is_ref => Some(""),
1160                         "[u16; 32]" if !is_ref => Some(""),
1161
1162                         "[u8]" if is_ref => Some(""),
1163                         "[usize]" if is_ref => Some(""),
1164
1165                         "str" if is_ref => Some(""),
1166                         "alloc::string::String"|"String"|"std::path::PathBuf" => Some(""),
1167                         "std::io::Error"|"lightning::io::Error"|"lightning::io::ErrorKind" => Some(""),
1168                         // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
1169                         // cannot create a &String.
1170
1171                         "core::convert::Infallible" => Some("panic!(\"You must never construct a NotConstructable! : "),
1172
1173                         "bitcoin::bech32::Error"|"bech32::Error" if !is_ref => Some(""),
1174                         "bitcoin::secp256k1::Error"|"secp256k1::Error" if !is_ref => Some(""),
1175
1176                         "core::num::ParseIntError" => Some("u8::from_str_radix(\" a\", 10).unwrap_err() /*"),
1177                         "core::str::Utf8Error" => Some("core::str::from_utf8(&[0xff]).unwrap_err() /*"),
1178
1179                         "std::time::Duration"|"core::time::Duration" => Some("core::time::Duration::from_secs("),
1180                         "std::time::SystemTime" => Some("(::std::time::SystemTime::UNIX_EPOCH + std::time::Duration::from_secs("),
1181
1182                         "bitcoin::bech32::u5"|"bech32::u5" => Some(""),
1183                         "u128" => Some(""),
1184                         "core::num::NonZeroU8" => Some("core::num::NonZeroU8::new("),
1185
1186                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" if is_ref => Some("&"),
1187                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some(""),
1188                         "bitcoin::key::TweakedPublicKey" if is_ref => Some("&"),
1189                         "bitcoin::key::TweakedPublicKey" => Some(""),
1190                         "bitcoin::secp256k1::ecdsa::Signature"|"bitcoin::secp256k1::schnorr::Signature" if is_ref => Some("&"),
1191                         "bitcoin::secp256k1::ecdsa::Signature"|"bitcoin::secp256k1::schnorr::Signature" => Some(""),
1192                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some(""),
1193                         "bitcoin::secp256k1::SecretKey" if is_ref => Some("&::bitcoin::secp256k1::SecretKey::from_slice(&unsafe { *"),
1194                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some(""),
1195                         "bitcoin::secp256k1::KeyPair" if !is_ref => Some("::bitcoin::secp256k1::KeyPair::from_secret_key(&secp256k1::global::SECP256K1, &"),
1196                         "bitcoin::secp256k1::Scalar" if is_ref => Some("&"),
1197                         "bitcoin::secp256k1::Scalar" if !is_ref => Some(""),
1198                         "bitcoin::secp256k1::ecdh::SharedSecret" if !is_ref => Some("::bitcoin::secp256k1::ecdh::SharedSecret::from_bytes("),
1199
1200                         "bitcoin::blockdata::script::Script"|"bitcoin::Script" => Some("::bitcoin::blockdata::script::Script::from_bytes("),
1201                         "bitcoin::blockdata::script::ScriptBuf"|"bitcoin::ScriptBuf" => Some("::bitcoin::blockdata::script::ScriptBuf::from("),
1202                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" if is_ref => Some("&"),
1203                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some(""),
1204                         "bitcoin::Witness" if is_ref => Some("&"),
1205                         "bitcoin::Witness" => Some(""),
1206                         "bitcoin::OutPoint"|"bitcoin::blockdata::transaction::OutPoint" => Some("crate::c_types::C_to_bitcoin_outpoint("),
1207                         "bitcoin::TxIn"|"bitcoin::blockdata::transaction::TxIn" if !is_ref => Some(""),
1208                         "bitcoin::TxOut"|"bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(""),
1209                         "bitcoin::network::constants::Network" => Some(""),
1210                         "bitcoin::address::WitnessVersion" => Some(""),
1211                         "bitcoin::address::WitnessProgram" if is_ref => Some("&"),
1212                         "bitcoin::address::WitnessProgram" if !is_ref => Some(""),
1213                         "bitcoin::blockdata::block::Header" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
1214                         "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
1215
1216                         "bitcoin::blockdata::locktime::absolute::LockTime" => Some("::bitcoin::blockdata::locktime::absolute::LockTime::from_consensus("),
1217
1218                         "bitcoin::psbt::PartiallySignedTransaction" if !is_ref => Some("::bitcoin::psbt::PartiallySignedTransaction::deserialize("),
1219
1220                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash" if !is_ref =>
1221                                 Some("bitcoin::hash_types::PubkeyHash::from_raw_hash(bitcoin::hashes::Hash::from_byte_array("),
1222                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash" if is_ref =>
1223                                 Some("&bitcoin::hash_types::PubkeyHash::from_raw_hash(bitcoin::hashes::Hash::from_byte_array(unsafe { *"),
1224                         "bitcoin::hash_types::WPubkeyHash" if is_ref =>
1225                                 Some("&bitcoin::hash_types::WPubkeyHash::from_raw_hash(bitcoin::hashes::Hash::from_byte_array(unsafe { *"),
1226                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash" if !is_ref =>
1227                                 Some("bitcoin::hash_types::ScriptHash::from_raw_hash(bitcoin::hashes::Hash::from_byte_array("),
1228                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash" if is_ref =>
1229                                 Some("&bitcoin::hash_types::ScriptHash::from_raw_hash(bitcoin::hashes::Hash::from_byte_array(unsafe { *"),
1230                         "bitcoin::hash_types::WScriptHash" if is_ref =>
1231                                 Some("&bitcoin::hash_types::WScriptHash::from_raw_hash(bitcoin::hashes::Hash::from_byte_array(unsafe { *"),
1232
1233                         // Newtypes that we just expose in their original form.
1234                         "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
1235                         "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
1236                         "bitcoin::hash_types::BlockHash"|"bitcoin::BlockHash" => Some("::bitcoin::hash_types::BlockHash::from_slice(&"),
1237                         "bitcoin::blockdata::constants::ChainHash" => Some("::bitcoin::blockdata::constants::ChainHash::from(&"),
1238                         "lightning::ln::PaymentHash" if !is_ref => Some("::lightning::ln::PaymentHash("),
1239                         "lightning::ln::PaymentHash" if is_ref => Some("&::lightning::ln::PaymentHash(unsafe { *"),
1240                         "lightning::ln::PaymentPreimage" if !is_ref => Some("::lightning::ln::PaymentPreimage("),
1241                         "lightning::ln::PaymentPreimage" if is_ref => Some("&::lightning::ln::PaymentPreimage(unsafe { *"),
1242                         "lightning::ln::PaymentSecret" if !is_ref => Some("::lightning::ln::PaymentSecret("),
1243                         "lightning::ln::channelmanager::PaymentId" if !is_ref => Some("::lightning::ln::channelmanager::PaymentId("),
1244                         "lightning::ln::channelmanager::PaymentId" if is_ref=> Some("&::lightning::ln::channelmanager::PaymentId( unsafe { *"),
1245                         "lightning::ln::channelmanager::InterceptId" if !is_ref => Some("::lightning::ln::channelmanager::InterceptId("),
1246                         "lightning::ln::channelmanager::InterceptId" if is_ref=> Some("&::lightning::ln::channelmanager::InterceptId( unsafe { *"),
1247                         "lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId" if !is_ref => Some("::lightning::ln::ChannelId("),
1248                         "lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId" if is_ref => Some("&::lightning::ln::ChannelId(unsafe { *"),
1249                         "lightning::sign::KeyMaterial" if !is_ref => Some("::lightning::sign::KeyMaterial("),
1250                         "lightning::sign::KeyMaterial" if is_ref=> Some("&::lightning::sign::KeyMaterial( unsafe { *"),
1251                         "lightning::chain::ClaimId" if !is_ref => Some("::lightning::chain::ClaimId("),
1252                         "lightning::chain::ClaimId" if is_ref=> Some("&::lightning::chain::ClaimId( unsafe { *"),
1253
1254                         // List of traits we map (possibly during processing of other files):
1255                         "lightning::io::Read" => Some("&mut "),
1256
1257                         _ => None,
1258                 }.map(|s| s.to_owned())
1259         }
1260         fn from_c_conversion_suffix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
1261                 if self.is_primitive(full_path) {
1262                         return Some("".to_owned());
1263                 }
1264                 match full_path {
1265                         "Vec" if !is_ref => Some(""),
1266                         "Option" => Some(""),
1267                         "Result" if !is_ref => Some(""),
1268
1269                         "[u8; 33]" if !is_ref => Some(".data"),
1270                         "[u8; 32]" if is_ref => Some("}"),
1271                         "[u8; 32]" if !is_ref => Some(".data"),
1272                         "[u8; 20]" if !is_ref => Some(".data"),
1273                         "[u8; 16]" if !is_ref => Some(".data"),
1274                         "[u8; 12]" if !is_ref => Some(".data"),
1275                         "[u8; 4]" if !is_ref => Some(".data"),
1276                         "[u8; 3]" if !is_ref => Some(".data"),
1277                         "[u16; 32]" if !is_ref => Some(".data"),
1278
1279                         "[u8]" if is_ref => Some(".to_slice()"),
1280                         "[usize]" if is_ref => Some(".to_slice()"),
1281
1282                         "str" if is_ref => Some(".into_str()"),
1283                         "alloc::string::String"|"String" => Some(".into_string()"),
1284                         "std::path::PathBuf" => Some(".into_pathbuf()"),
1285                         "std::io::Error"|"lightning::io::Error" => Some(".to_rust()"),
1286                         "lightning::io::ErrorKind" => Some(".to_rust_kind()"),
1287
1288                         "core::convert::Infallible" => Some("\")"),
1289
1290                         "bitcoin::bech32::Error"|"bech32::Error" if !is_ref => Some(".into_rust()"),
1291                         "bitcoin::secp256k1::Error"|"secp256k1::Error" if !is_ref => Some(".into_rust()"),
1292
1293                         "core::num::ParseIntError" => Some("*/"),
1294                         "core::str::Utf8Error" => Some("*/"),
1295
1296                         "std::time::Duration"|"core::time::Duration" => Some(")"),
1297                         "std::time::SystemTime" => Some("))"),
1298
1299                         "bitcoin::bech32::u5"|"bech32::u5" => Some(".into()"),
1300                         "u128" => Some(".into()"),
1301                         "core::num::NonZeroU8" => Some(").expect(\"Value must be non-zero\")"),
1302
1303                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some(".into_rust()"),
1304                         "bitcoin::key::TweakedPublicKey" => Some(".into_rust()"),
1305                         "bitcoin::secp256k1::ecdsa::Signature"|"bitcoin::secp256k1::schnorr::Signature" => Some(".into_rust()"),
1306                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some(".into_rust()"),
1307                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some(".into_rust()"),
1308                         "bitcoin::secp256k1::SecretKey" if is_ref => Some("}[..]).unwrap()"),
1309                         "bitcoin::secp256k1::KeyPair" if !is_ref => Some(".into_rust())"),
1310                         "bitcoin::secp256k1::Scalar" => Some(".into_rust()"),
1311                         "bitcoin::secp256k1::ecdh::SharedSecret" if !is_ref => Some(".data)"),
1312
1313                         "bitcoin::blockdata::script::Script"|"bitcoin::Script" => Some(".to_slice())"),
1314                         "bitcoin::blockdata::script::ScriptBuf"|"bitcoin::ScriptBuf" => Some(".into_rust())"),
1315                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some(".into_bitcoin()"),
1316                         "bitcoin::Witness" => Some(".into_bitcoin()"),
1317                         "bitcoin::OutPoint"|"bitcoin::blockdata::transaction::OutPoint" => Some(")"),
1318                         "bitcoin::TxIn"|"bitcoin::blockdata::transaction::TxIn" if !is_ref => Some(".into_rust()"),
1319                         "bitcoin::TxOut"|"bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(".into_rust()"),
1320                         "bitcoin::network::constants::Network" => Some(".into_bitcoin()"),
1321                         "bitcoin::address::WitnessVersion" => Some(".into()"),
1322                         "bitcoin::address::WitnessProgram" => Some(".into_bitcoin()"),
1323                         "bitcoin::blockdata::block::Header" => Some(" }).unwrap()"),
1324                         "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
1325
1326                         "bitcoin::blockdata::locktime::absolute::LockTime" => Some(")"),
1327
1328                         "bitcoin::psbt::PartiallySignedTransaction" if !is_ref => Some(".as_slice()).expect(\"Invalid PSBT format\")"),
1329
1330                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash"|
1331                         "bitcoin::hash_types::WPubkeyHash"|"bitcoin::hash_types::WScriptHash"|
1332                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash"
1333                                 if !is_ref => Some(".data))"),
1334                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash"|
1335                         "bitcoin::hash_types::WPubkeyHash"|"bitcoin::hash_types::WScriptHash"|
1336                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash"
1337                                 if is_ref => Some(" }.clone()))"),
1338
1339                         // Newtypes that we just expose in their original form.
1340                         "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
1341                         "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
1342                         "bitcoin::hash_types::BlockHash"|"bitcoin::BlockHash" if !is_ref => Some(".data[..]).unwrap()"),
1343                         "bitcoin::blockdata::constants::ChainHash" if !is_ref => Some(".data)"),
1344                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1345                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1346                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1347                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1348                                 if !is_ref => Some(".data)"),
1349                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1350                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1351                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1352                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1353                                 if is_ref => Some(" })"),
1354
1355                         // List of traits we map (possibly during processing of other files):
1356                         "lightning::io::Read" => Some(".to_reader()"),
1357
1358                         _ => None,
1359                 }.map(|s| s.to_owned())
1360         }
1361
1362         fn to_c_conversion_new_var_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<(&'b str, &'b str)> {
1363                 if self.is_primitive(full_path) {
1364                         return None;
1365                 }
1366                 match full_path {
1367                         "[u8]" if is_ref => Some(("crate::c_types::u8slice::from_slice(", ")")),
1368                         "[usize]" if is_ref => Some(("crate::c_types::usizeslice::from_slice(", ")")),
1369
1370                         "bitcoin::blockdata::block::Header" if is_ref => Some(("{ let mut s = [0u8; 80]; s[..].copy_from_slice(&::bitcoin::consensus::encode::serialize(", ")); s }")),
1371                         "bitcoin::blockdata::block::Block" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
1372
1373                         _ => None,
1374                 }.map(|s| s.to_owned())
1375         }
1376         fn to_c_conversion_inline_prefix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
1377                 if self.is_primitive(full_path) {
1378                         return Some("".to_owned());
1379                 }
1380                 match full_path {
1381                         "Result" if !is_ref => Some("local_"),
1382                         "Vec" if !is_ref => Some("local_"),
1383                         "Option" => Some("local_"),
1384
1385                         "[u8; 33]" if is_ref => Some(""),
1386                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1387                         "[u8; 32]" if is_ref => Some(""),
1388                         "[u8; 20]" if !is_ref => Some("crate::c_types::TwentyBytes { data: "),
1389                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes { data: "),
1390                         "[u8; 12]" if !is_ref => Some("crate::c_types::TwelveBytes { data: "),
1391                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes { data: "),
1392                         "[u8; 3]" if is_ref => Some(""),
1393                         "[u16; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoU16s { data: "),
1394
1395                         "[u8]" if is_ref => Some("local_"),
1396                         "[usize]" if is_ref => Some("local_"),
1397
1398                         "str" if is_ref => Some(""),
1399                         "alloc::string::String"|"String"|"std::path::PathBuf" => Some(""),
1400
1401                         "bitcoin::Address" => Some("alloc::string::ToString::to_string(&"),
1402
1403                         "std::time::Duration"|"core::time::Duration" => Some(""),
1404                         "std::time::SystemTime" => Some(""),
1405                         "std::io::Error"|"lightning::io::Error" => Some("crate::c_types::IOError::from_rust("),
1406                         "lightning::io::ErrorKind" => Some("crate::c_types::IOError::from_rust_kind("),
1407                         "core::fmt::Arguments" => Some("alloc::format!(\"{}\", "),
1408
1409                         "core::convert::Infallible" => Some("panic!(\"Cannot construct an Infallible: "),
1410
1411                         "bitcoin::bech32::Error"|"bech32::Error"
1412                                 if !is_ref => Some("crate::c_types::Bech32Error::from_rust("),
1413                         "bitcoin::secp256k1::Error"|"secp256k1::Error"
1414                                 if !is_ref => Some("crate::c_types::Secp256k1Error::from_rust("),
1415
1416                         "core::num::ParseIntError" => Some("crate::c_types::Error { _dummy: 0 } /*"),
1417                         "core::str::Utf8Error" => Some("crate::c_types::Error { _dummy: 0 } /*"),
1418
1419                         "bitcoin::bech32::u5"|"bech32::u5" => Some(""),
1420                         "u128" => Some(""),
1421
1422                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some("crate::c_types::PublicKey::from_rust(&"),
1423                         "bitcoin::key::TweakedPublicKey" => Some("crate::c_types::TweakedPublicKey::from_rust(&"),
1424                         "bitcoin::secp256k1::ecdsa::Signature" => Some("crate::c_types::ECDSASignature::from_rust(&"),
1425                         "bitcoin::secp256k1::schnorr::Signature" => Some("crate::c_types::SchnorrSignature::from_rust(&"),
1426                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some("crate::c_types::RecoverableSignature::from_rust(&"),
1427                         "bitcoin::secp256k1::SecretKey" if is_ref => Some(""),
1428                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
1429                         "bitcoin::secp256k1::KeyPair" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
1430                         "bitcoin::secp256k1::Scalar" if !is_ref => Some("crate::c_types::BigEndianScalar::from_rust(&"),
1431                         "bitcoin::secp256k1::ecdh::SharedSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1432
1433                         "bitcoin::blockdata::script::Script"|"bitcoin::Script" => Some("crate::c_types::u8slice::from_slice("),
1434                         "bitcoin::blockdata::script::ScriptBuf"|"bitcoin::ScriptBuf" => Some(""),
1435                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" if is_ref => Some("crate::c_types::Transaction::from_bitcoin("),
1436                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some("crate::c_types::Transaction::from_bitcoin(&"),
1437                         "bitcoin::Witness" if is_ref => Some("crate::c_types::Witness::from_bitcoin("),
1438                         "bitcoin::Witness" if !is_ref => Some("crate::c_types::Witness::from_bitcoin(&"),
1439                         "bitcoin::OutPoint"|"bitcoin::blockdata::transaction::OutPoint" if is_ref => Some("crate::c_types::bitcoin_to_C_outpoint("),
1440                         "bitcoin::OutPoint"|"bitcoin::blockdata::transaction::OutPoint" if !is_ref => Some("crate::c_types::bitcoin_to_C_outpoint(&"),
1441                         "bitcoin::TxIn"|"bitcoin::blockdata::transaction::TxIn" if !is_ref => Some("crate::c_types::TxIn::from_rust(&"),
1442                         "bitcoin::TxOut"|"bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut::from_rust(&"),
1443                         "bitcoin::TxOut"|"bitcoin::blockdata::transaction::TxOut" if is_ref => Some("crate::c_types::TxOut::from_rust("),
1444                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network::from_bitcoin("),
1445                         "bitcoin::address::WitnessVersion" => Some(""),
1446                         "bitcoin::address::WitnessProgram" => Some("crate::c_types::WitnessProgram::from_bitcoin("),
1447                         "bitcoin::blockdata::block::Header" if is_ref => Some("&local_"),
1448                         "bitcoin::blockdata::block::Block" if is_ref => Some("crate::c_types::u8slice::from_slice(&local_"),
1449
1450                         "bitcoin::blockdata::locktime::absolute::LockTime" => Some(""),
1451
1452                         "bitcoin::psbt::PartiallySignedTransaction" if !is_ref => Some(""),
1453
1454                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash"|
1455                         "bitcoin::hash_types::WPubkeyHash"|"bitcoin::hash_types::WScriptHash"|
1456                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash"
1457                                 if !is_ref => Some("crate::c_types::TwentyBytes { data: *"),
1458
1459                         // Newtypes that we just expose in their original form.
1460                         "bitcoin::hash_types::Txid"|"bitcoin::BlockHash"|"bitcoin::hash_types::BlockHash"|"bitcoin::hashes::sha256::Hash"|"bitcoin::blockdata::constants::ChainHash"
1461                                 if is_ref => Some(""),
1462                         "bitcoin::hash_types::Txid"|"bitcoin::BlockHash"|"bitcoin::hash_types::BlockHash"|"bitcoin::hashes::sha256::Hash"|"bitcoin::blockdata::constants::ChainHash"
1463                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: *"),
1464                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1465                         "bitcoin::secp256k1::Message" if is_ref => Some(""),
1466                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1467                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1468                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1469                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1470                                 if is_ref => Some("&"),
1471                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1472                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1473                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1474                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1475                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1476
1477                         "lightning::io::Read" => Some("crate::c_types::u8slice::from_vec(&crate::c_types::reader_to_vec("),
1478
1479                         _ => None,
1480                 }.map(|s| s.to_owned())
1481         }
1482         fn to_c_conversion_inline_suffix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
1483                 if self.is_primitive(full_path) {
1484                         return Some("".to_owned());
1485                 }
1486                 match full_path {
1487                         "Result" if !is_ref => Some(""),
1488                         "Vec" if !is_ref => Some(".into()"),
1489                         "Option" => Some(""),
1490
1491                         "[u8; 33]" if is_ref => Some(""),
1492                         "[u8; 32]" if !is_ref => Some(" }"),
1493                         "[u8; 32]" if is_ref => Some(""),
1494                         "[u8; 20]" if !is_ref => Some(" }"),
1495                         "[u8; 16]" if !is_ref => Some(" }"),
1496                         "[u8; 12]" if !is_ref => Some(" }"),
1497                         "[u8; 4]" if !is_ref => Some(" }"),
1498                         "[u8; 3]" if is_ref => Some(""),
1499                         "[u16; 32]" if !is_ref => Some(" }"),
1500
1501                         "[u8]" if is_ref => Some(""),
1502                         "[usize]" if is_ref => Some(""),
1503
1504                         "str" if is_ref => Some(".into()"),
1505                         "alloc::string::String"|"String"|"std::path::PathBuf" if is_ref => Some(".as_str().into()"),
1506                         "alloc::string::String"|"String"|"std::path::PathBuf" => Some(".into()"),
1507
1508                         "bitcoin::Address" => Some(").into()"),
1509
1510                         "std::time::Duration"|"core::time::Duration" => Some(".as_secs()"),
1511                         "std::time::SystemTime" => Some(".duration_since(::std::time::SystemTime::UNIX_EPOCH).expect(\"Times must be post-1970\").as_secs()"),
1512                         "std::io::Error"|"lightning::io::Error"|"lightning::io::ErrorKind" => Some(")"),
1513                         "core::fmt::Arguments" => Some(").into()"),
1514
1515                         "core::convert::Infallible" => Some("\")"),
1516
1517                         "bitcoin::secp256k1::Error"|"bech32::Error"
1518                                 if !is_ref => Some(")"),
1519                         "bitcoin::secp256k1::Error"|"secp256k1::Error"
1520                                 if !is_ref => Some(")"),
1521
1522                         "core::num::ParseIntError" => Some("*/"),
1523                         "core::str::Utf8Error" => Some("*/"),
1524
1525                         "bitcoin::bech32::u5"|"bech32::u5" => Some(".into()"),
1526                         "u128" => Some(".into()"),
1527
1528                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some(")"),
1529                         "bitcoin::key::TweakedPublicKey" => Some(")"),
1530                         "bitcoin::secp256k1::ecdsa::Signature"|"bitcoin::secp256k1::schnorr::Signature" => Some(")"),
1531                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some(")"),
1532                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some(")"),
1533                         "bitcoin::secp256k1::SecretKey" if is_ref => Some(".as_ref()"),
1534                         "bitcoin::secp256k1::KeyPair" if !is_ref => Some(".secret_key())"),
1535                         "bitcoin::secp256k1::Scalar" if !is_ref => Some(")"),
1536                         "bitcoin::secp256k1::ecdh::SharedSecret" if !is_ref => Some(".secret_bytes() }"),
1537
1538                         "bitcoin::blockdata::script::Script"|"bitcoin::Script" => Some(".as_ref())"),
1539                         "bitcoin::blockdata::script::ScriptBuf"|"bitcoin::ScriptBuf" if is_ref => Some(".as_bytes().to_vec().into()"),
1540                         "bitcoin::blockdata::script::ScriptBuf"|"bitcoin::ScriptBuf" if !is_ref => Some(".to_bytes().into()"),
1541                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some(")"),
1542                         "bitcoin::Witness" => Some(")"),
1543                         "bitcoin::OutPoint"|"bitcoin::blockdata::transaction::OutPoint" => Some(")"),
1544                         "bitcoin::TxIn"|"bitcoin::blockdata::transaction::TxIn" if !is_ref => Some(")"),
1545                         "bitcoin::TxOut"|"bitcoin::blockdata::transaction::TxOut" => Some(")"),
1546                         "bitcoin::network::constants::Network" => Some(")"),
1547                         "bitcoin::address::WitnessVersion" => Some(".into()"),
1548                         "bitcoin::address::WitnessProgram" => Some(")"),
1549                         "bitcoin::blockdata::block::Header" if is_ref => Some(""),
1550                         "bitcoin::blockdata::block::Block" if is_ref => Some(")"),
1551
1552                         "bitcoin::blockdata::locktime::absolute::LockTime" => Some(".to_consensus_u32()"),
1553
1554                         "bitcoin::psbt::PartiallySignedTransaction" if !is_ref => Some(".serialize().into()"),
1555
1556                         "bitcoin::PubkeyHash"|"bitcoin::hash_types::PubkeyHash"|
1557                         "bitcoin::hash_types::WPubkeyHash"|"bitcoin::hash_types::WScriptHash"|
1558                         "bitcoin::ScriptHash"|"bitcoin::hash_types::ScriptHash"
1559                                 if !is_ref => Some(".as_ref() }"),
1560
1561                         // Newtypes that we just expose in their original form.
1562                         "bitcoin::hash_types::Txid"|"bitcoin::BlockHash"|"bitcoin::hash_types::BlockHash"|"bitcoin::hashes::sha256::Hash"|"bitcoin::blockdata::constants::ChainHash"
1563                                 if is_ref => Some(".as_ref()"),
1564                         "bitcoin::hash_types::Txid"|"bitcoin::BlockHash"|"bitcoin::hash_types::BlockHash"|"bitcoin::hashes::sha256::Hash"|"bitcoin::blockdata::constants::ChainHash"
1565                                 if !is_ref => Some(".as_ref() }"),
1566                         "bitcoin::secp256k1::Message" if !is_ref => Some(".as_ref().clone() }"),
1567                         "bitcoin::secp256k1::Message" if is_ref => Some(".as_ref()"),
1568                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1569                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1570                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1571                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1572                                 if is_ref => Some(".0"),
1573                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1574                         |"lightning::ln::channelmanager::PaymentId"|"lightning::ln::channelmanager::InterceptId"
1575                         |"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
1576                         |"lightning::ln::ChannelId"|"lightning::ln::channel_id::ChannelId"
1577                                 if !is_ref => Some(".0 }"),
1578
1579                         "lightning::io::Read" => Some("))"),
1580
1581                         _ => None,
1582                 }.map(|s| s.to_owned())
1583         }
1584
1585         fn empty_val_check_suffix_from_path(&self, full_path: &str) -> Option<&str> {
1586                 match full_path {
1587                         "secp256k1::PublicKey"|"bitcoin::secp256k1::PublicKey" => Some(".is_null()"),
1588                         _ => None
1589                 }
1590         }
1591
1592         /// When printing a reference to the source crate's rust type, if we need to map it to a
1593         /// different "real" type, it can be done so here.
1594         /// This is useful to work around limitations in the binding type resolver, where we reference
1595         /// a non-public `use` alias.
1596         /// TODO: We should never need to use this!
1597         fn real_rust_type_mapping<'equiv>(&self, thing: &'equiv str) -> &'equiv str {
1598                 match thing {
1599                         "lightning::io::Read" => "crate::c_types::io::Read",
1600                         _ => thing,
1601                 }
1602         }
1603
1604         // ****************************
1605         // *** Container Processing ***
1606         // ****************************
1607
1608         /// Returns the module path in the generated mapping crate to the containers which we generate
1609         /// when writing to CrateTypes::template_file.
1610         pub fn generated_container_path() -> &'static str {
1611                 "crate::c_types::derived"
1612         }
1613         /// Returns the module path in the generated mapping crate to the container templates, which
1614         /// are then concretized and put in the generated container path/template_file.
1615         fn container_templ_path() -> &'static str {
1616                 "crate::c_types"
1617         }
1618
1619         /// This should just be a closure, but doing so gets an error like
1620         /// error: reached the recursion limit while instantiating `types::TypeResolver::is_transpar...c/types.rs:1358:104: 1358:110]>>`
1621         /// which implies the concrete function instantiation of `is_transparent_container` ends up
1622         /// being recursive.
1623         fn deref_type<'one, 'b: 'one> (obj: &'one &'b syn::Type) -> &'b syn::Type { *obj }
1624
1625         /// Returns true if the path containing the given args is a "transparent" container, ie an
1626         /// Option or a container which does not require a generated continer class.
1627         fn is_transparent_container<'i, I: Iterator<Item=&'i syn::Type>>(&self, full_path: &str, _is_ref: bool, mut args: I, generics: Option<&GenericTypes>) -> bool {
1628                 if full_path == "Option" {
1629                         let inner = args.next().unwrap();
1630                         assert!(args.next().is_none());
1631                         match generics.resolve_type(inner) {
1632                                 syn::Type::Reference(r) => {
1633                                         let elem = &*r.elem;
1634                                         match elem {
1635                                                 syn::Type::Path(_) =>
1636                                                         self.is_transparent_container(full_path, true, [elem].iter().map(Self::deref_type), generics),
1637                                                 _ => true,
1638                                         }
1639                                 },
1640                                 syn::Type::Array(a) => {
1641                                         if let syn::Expr::Lit(l) = &a.len {
1642                                                 if let syn::Lit::Int(i) = &l.lit {
1643                                                         if i.base10_digits().parse::<usize>().unwrap() >= 32 {
1644                                                                 let mut buf = Vec::new();
1645                                                                 self.write_rust_type(&mut buf, generics, &a.elem, false);
1646                                                                 let ty = String::from_utf8(buf).unwrap();
1647                                                                 ty == "u8"
1648                                                         } else {
1649                                                                 // Blindly assume that if we're trying to create an empty value for an
1650                                                                 // array < 32 entries that all-0s may be a valid state.
1651                                                                 unimplemented!();
1652                                                         }
1653                                                 } else { unimplemented!(); }
1654                                         } else { unimplemented!(); }
1655                                 },
1656                                 syn::Type::Path(p) => {
1657                                         if let Some(resolved) = self.maybe_resolve_path(&p.path, generics) {
1658                                                 if self.c_type_has_inner_from_path(&resolved) { return true; }
1659                                                 if self.is_primitive(&resolved) { return false; }
1660                                                 // We want to move to using `Option_` mappings where possible rather than
1661                                                 // manual mappings, as it makes downstream bindings simpler and is more
1662                                                 // clear for users. Thus, we default to false but override for a few
1663                                                 // types which had mappings defined when we were avoiding the `Option_`s.
1664                                                 match &resolved as &str {
1665                                                         "secp256k1::PublicKey"|"bitcoin::secp256k1::PublicKey" => true,
1666                                                         _ => false,
1667                                                 }
1668                                         } else { unimplemented!(); }
1669                                 },
1670                                 syn::Type::Tuple(_) => false,
1671                                 _ => unimplemented!(),
1672                         }
1673                 } else { false }
1674         }
1675         /// Returns true if the path is a "transparent" container, ie an Option or a container which does
1676         /// not require a generated continer class.
1677         pub fn is_path_transparent_container(&self, full_path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
1678                 let inner_iter = match &full_path.segments.last().unwrap().arguments {
1679                         syn::PathArguments::None => return false,
1680                         syn::PathArguments::AngleBracketed(args) => args.args.iter().map(|arg| {
1681                                 if let syn::GenericArgument::Type(ref ty) = arg {
1682                                         ty
1683                                 } else { unimplemented!() }
1684                         }),
1685                         syn::PathArguments::Parenthesized(_) => unimplemented!(),
1686                 };
1687                 self.is_transparent_container(&self.resolve_path(full_path, generics), is_ref, inner_iter, generics)
1688         }
1689         /// Returns true if this is a known, supported, non-transparent container.
1690         fn is_known_container(&self, full_path: &str, is_ref: bool) -> bool {
1691                 (full_path == "Result" && !is_ref) || (full_path == "Vec" && !is_ref) || full_path.ends_with("Tuple") || full_path == "Option"
1692         }
1693         fn to_c_conversion_container_new_var<'b>(&self, generics: Option<&GenericTypes>, full_path: &str, is_ref: bool, single_contained: Option<&syn::Type>, var_name: &syn::Ident, var_access: &str)
1694                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
1695                         // expecting one element in the vec per generic type, each of which is inline-converted
1696                         -> Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)> {
1697                 match full_path {
1698                         "Result" if !is_ref => {
1699                                 Some(("match ",
1700                                                 vec![(" { Ok(mut o) => crate::c_types::CResultTempl::ok(".to_string(), "o".to_string()),
1701                                                         (").into(), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
1702                                                 ").into() }", ContainerPrefixLocation::PerConv))
1703                         },
1704                         "Vec" => {
1705                                 if is_ref {
1706                                         // We should only get here if the single contained has an inner
1707                                         assert!(self.c_type_has_inner(single_contained.unwrap()));
1708                                 }
1709                                 Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1710                         },
1711                         "Slice" => {
1712                                 if let Some(syn::Type::Reference(_)) = single_contained {
1713                                         Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "(*item)".to_string())], "); }", ContainerPrefixLocation::PerConv))
1714                                 } else {
1715                                         Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1716                                 }
1717                         },
1718                         "Option" => {
1719                                 let mut is_contained_ref = false;
1720                                 let contained_struct = if let Some(syn::Type::Path(p)) = single_contained {
1721                                         Some(self.resolve_path(&p.path, generics))
1722                                 } else if let Some(syn::Type::Reference(r)) = single_contained {
1723                                         is_contained_ref = true;
1724                                         if let syn::Type::Path(p) = &*r.elem {
1725                                                 Some(self.resolve_path(&p.path, generics))
1726                                         } else { None }
1727                                 } else { None };
1728                                 if let Some(inner_path) = contained_struct {
1729                                         let only_contained_has_inner = self.c_type_has_inner_from_path(&inner_path);
1730                                         if self.c_type_has_inner_from_path(&inner_path) {
1731                                                 let is_inner_ref = if let Some(syn::Type::Reference(_)) = single_contained { true } else { false };
1732                                                 if is_ref {
1733                                                         return Some(("if ", vec![
1734                                                                 (".is_none() { core::ptr::null() } else { ObjOps::nonnull_ptr_to_inner(".to_owned(),
1735                                                                         format!("({}{}.unwrap())", var_access, if is_inner_ref { "" } else { ".as_ref()" }))
1736                                                                 ], ") }", ContainerPrefixLocation::OutsideConv));
1737                                                 } else {
1738                                                         return Some(("if ", vec![
1739                                                                 (".is_none() { core::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
1740                                                                 ], " }", ContainerPrefixLocation::OutsideConv));
1741                                                 }
1742                                         } else if !self.is_transparent_container("Option", is_ref, [single_contained.unwrap()].iter().map(|a| *a), generics) {
1743                                                 if self.is_primitive(&inner_path) || (!is_contained_ref && !is_ref) || only_contained_has_inner {
1744                                                         let inner_name = self.get_c_mangled_container_type(vec![single_contained.unwrap()], generics, "Option").unwrap();
1745                                                         return Some(("if ", vec![
1746                                                                 (format!(".is_none() {{ {}::None }} else {{ {}::Some(", inner_name, inner_name),
1747                                                                  format!("{}.unwrap()", var_access))
1748                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1749                                                 } else {
1750                                                         let inner_name = self.get_c_mangled_container_type(vec![single_contained.unwrap()], generics, "Option").unwrap();
1751                                                         return Some(("if ", vec![
1752                                                                 (format!(".is_none() {{ {}::None }} else {{ {}::Some(/* WARNING: CLONING CONVERSION HERE! &Option<Enum> is otherwise un-expressable. */", inner_name, inner_name),
1753                                                                  format!("(*{}.as_ref().unwrap()).clone()", var_access))
1754                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1755                                                 }
1756                                         } else {
1757                                                 // If c_type_from_path is some (ie there's a manual mapping for the inner
1758                                                 // type), lean on write_empty_rust_val, below.
1759                                         }
1760                                 }
1761                                 if let Some(t) = single_contained {
1762                                         if let syn::Type::Tuple(syn::TypeTuple { elems, .. }) = t {
1763                                                 let inner_name = self.get_c_mangled_container_type(vec![single_contained.unwrap()], generics, "Option").unwrap();
1764                                                 if elems.is_empty() {
1765                                                         return Some(("if ", vec![
1766                                                                 (format!(".is_none() {{ {}::None }} else {{ {}::Some /* ",
1767                                                                         inner_name, inner_name), format!(""))
1768                                                                 ], " */ }", ContainerPrefixLocation::PerConv));
1769                                                 } else {
1770                                                         return Some(("if ", vec![
1771                                                                 (format!(".is_none() {{ {}::None }} else {{ {}::Some(",
1772                                                                         inner_name, inner_name), format!("({}.unwrap())", var_access))
1773                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1774                                                 }
1775                                         }
1776                                         if let syn::Type::Reference(syn::TypeReference { elem, .. }) = t {
1777                                                 if let syn::Type::Slice(_) = &**elem {
1778                                                         return Some(("if ", vec![
1779                                                                         (".is_none() { SmartPtr::null() } else { SmartPtr::from_obj(".to_string(),
1780                                                                          format!("({}.unwrap())", var_access))
1781                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1782                                                 }
1783                                         }
1784                                         let mut v = Vec::new();
1785                                         self.write_empty_rust_val(generics, &mut v, t);
1786                                         let s = String::from_utf8(v).unwrap();
1787                                         return Some(("if ", vec![
1788                                                 (format!(".is_none() {{ {} }} else {{ ", s), format!("({}.unwrap())", var_access))
1789                                                 ], " }", ContainerPrefixLocation::PerConv));
1790                                 } else { unreachable!(); }
1791                         },
1792                         _ => None,
1793                 }
1794         }
1795
1796         /// only_contained_has_inner implies that there is only one contained element in the container
1797         /// and it has an inner field (ie is an "opaque" type we've defined).
1798         fn from_c_conversion_container_new_var<'b>(&self, generics: Option<&GenericTypes>, full_path: &str, is_ref: bool, single_contained: Option<&syn::Type>, var_name: &syn::Ident, var_access: &str)
1799                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
1800                         // expecting one element in the vec per generic type, each of which is inline-converted
1801                         -> Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)> {
1802                 let mut only_contained_has_inner = false;
1803                 let only_contained_resolved = if let Some(syn::Type::Path(p)) = single_contained {
1804                         let res = self.resolve_path(&p.path, generics);
1805                         only_contained_has_inner = self.c_type_has_inner_from_path(&res);
1806                         Some(res)
1807                 } else { None };
1808                 match full_path {
1809                         "Result" if !is_ref => {
1810                                 Some(("match ",
1811                                                 vec![(".result_ok { true => Ok(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.result)) }})", var_access)),
1812                                                      ("), false => Err(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.err)) }})", var_access))],
1813                                                 ")}", ContainerPrefixLocation::PerConv))
1814                         },
1815                         "Slice" if is_ref && only_contained_has_inner => {
1816                                 Some(("Vec::new(); for mut item in ", vec![(format!(".as_slice().iter() {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1817                         },
1818                         "Vec"|"Slice" => {
1819                                 Some(("Vec::new(); for mut item in ", vec![(format!(".into_rust().drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1820                         },
1821                         "Option" => {
1822                                 if let Some(resolved) = only_contained_resolved {
1823                                         if self.is_primitive(&resolved) {
1824                                                 return Some(("if ", vec![(".is_some() { Some(".to_string(), format!("{}.take()", var_access))], ") } else { None }", ContainerPrefixLocation::NoPrefix))
1825                                         } else if only_contained_has_inner {
1826                                                 if is_ref {
1827                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some((*".to_string(), format!("{}", var_access))], ").clone()) }", ContainerPrefixLocation::PerConv))
1828                                                 } else {
1829                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some(".to_string(), format!("{}", var_access))], ") }", ContainerPrefixLocation::PerConv));
1830                                                 }
1831                                         }
1832                                 }
1833
1834                                 if let Some(t) = single_contained {
1835                                         match t {
1836                                                 syn::Type::Reference(_)|syn::Type::Path(_)|syn::Type::Slice(_)|syn::Type::Array(_) => {
1837                                                         let mut v = Vec::new();
1838                                                         let ret_ref = self.write_empty_rust_val_check_suffix(generics, &mut v, t);
1839                                                         let s = String::from_utf8(v).unwrap();
1840                                                         match ret_ref {
1841                                                                 EmptyValExpectedTy::ReferenceAsPointer =>
1842                                                                         return Some(("if ", vec![
1843                                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ &mut *{} }}", var_access))
1844                                                                         ], ") }", ContainerPrefixLocation::NoPrefix)),
1845                                                                 EmptyValExpectedTy::OptionType =>
1846                                                                         return Some(("{ /*", vec![
1847                                                                                 (format!("*/ let {}_opt = {}; if {}_opt{} {{ None }} else {{ Some({{", var_name, var_access, var_name, s),
1848                                                                                 format!("{{ {}_opt.take() }}", var_name))
1849                                                                         ], "})} }", ContainerPrefixLocation::PerConv)),
1850                                                                 EmptyValExpectedTy::NonPointer =>
1851                                                                         return Some(("if ", vec![
1852                                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("{}", var_access))
1853                                                                         ], ") }", ContainerPrefixLocation::PerConv)),
1854                                                         }
1855                                                 },
1856                                                 syn::Type::Tuple(_) => {
1857                                                         return Some(("if ", vec![(".is_some() { Some(".to_string(), format!("{}.take()", var_access))], ") } else { None }", ContainerPrefixLocation::PerConv))
1858                                                 },
1859                                                 _ => unimplemented!(),
1860                                         }
1861                                 } else { unreachable!(); }
1862                         },
1863                         _ => None,
1864                 }
1865         }
1866
1867         /// Constructs a reference to the given type, possibly tweaking the type if relevant to make it
1868         /// convertable to C.
1869         pub fn create_ownable_reference(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> Option<syn::Type> {
1870                 let default_value = Some(syn::Type::Reference(syn::TypeReference {
1871                         and_token: syn::Token!(&)(Span::call_site()), lifetime: None, mutability: None,
1872                         elem: Box::new(t.clone()) }));
1873                 match generics.resolve_type(t) {
1874                         syn::Type::Path(p) => {
1875                                 if let Some(resolved_path) = self.maybe_resolve_path(&p.path, generics) {
1876                                         if resolved_path != "Vec" { return default_value; }
1877                                         if p.path.segments.len() != 1 { unimplemented!(); }
1878                                         let only_seg = p.path.segments.iter().next().unwrap();
1879                                         if let syn::PathArguments::AngleBracketed(args) = &only_seg.arguments {
1880                                                 if args.args.len() != 1 { unimplemented!(); }
1881                                                 let inner_arg = args.args.iter().next().unwrap();
1882                                                 if let syn::GenericArgument::Type(ty) = &inner_arg {
1883                                                         let mut can_create = self.c_type_has_inner(&ty);
1884                                                         if let syn::Type::Path(inner) = ty {
1885                                                                 if inner.path.segments.len() == 1 &&
1886                                                                                 format!("{}", inner.path.segments[0].ident) == "Vec" {
1887                                                                         can_create = true;
1888                                                                 }
1889                                                         }
1890                                                         if !can_create { return default_value; }
1891                                                         if let Some(inner_ty) = self.create_ownable_reference(&ty, generics) {
1892                                                                 return Some(syn::Type::Reference(syn::TypeReference {
1893                                                                         and_token: syn::Token![&](Span::call_site()),
1894                                                                         lifetime: None,
1895                                                                         mutability: None,
1896                                                                         elem: Box::new(syn::Type::Slice(syn::TypeSlice {
1897                                                                                 bracket_token: syn::token::Bracket { span: Span::call_site() },
1898                                                                                 elem: Box::new(inner_ty)
1899                                                                         }))
1900                                                                 }));
1901                                                         } else { return default_value; }
1902                                                 } else { unimplemented!(); }
1903                                         } else { unimplemented!(); }
1904                                 } else { return None; }
1905                         },
1906                         _ => default_value,
1907                 }
1908         }
1909
1910         // *************************************************
1911         // *** Type definition during main.rs processing ***
1912         // *************************************************
1913
1914         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
1915         pub fn c_type_has_inner_from_path(&self, full_path: &str) -> bool {
1916                 self.crate_types.opaques.get(full_path).is_some()
1917         }
1918
1919         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
1920         pub fn c_type_has_inner(&self, ty: &syn::Type) -> bool {
1921                 match ty {
1922                         syn::Type::Path(p) => {
1923                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, None) {
1924                                         self.c_type_has_inner_from_path(&full_path)
1925                                 } else { false }
1926                         },
1927                         syn::Type::Reference(r) => {
1928                                 self.c_type_has_inner(&*r.elem)
1929                         },
1930                         _ => false,
1931                 }
1932         }
1933
1934         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
1935                 self.types.maybe_resolve_ident(id)
1936         }
1937
1938         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
1939                 self.types.maybe_resolve_path(p_arg, generics)
1940         }
1941         pub fn resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> String {
1942                 self.maybe_resolve_path(p, generics).unwrap()
1943         }
1944
1945         // ***********************************
1946         // *** Original Rust Type Printing ***
1947         // ***********************************
1948
1949         fn in_rust_prelude(resolved_path: &str) -> bool {
1950                 match resolved_path {
1951                         "Vec" => true,
1952                         "Result" => true,
1953                         "Option" => true,
1954                         _ => false,
1955                 }
1956         }
1957
1958         fn write_rust_path<W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, path: &syn::Path, with_ref_lifetime: bool, generated_crate_ref: bool) {
1959                 if let Some(resolved) = self.maybe_resolve_path(&path, generics_resolver) {
1960                         if self.is_primitive(&resolved) {
1961                                 write!(w, "{}", path.get_ident().unwrap()).unwrap();
1962                         } else {
1963                                 // TODO: We should have a generic "is from a dependency" check here instead of
1964                                 // checking for "bitcoin" explicitly.
1965                                 if resolved.starts_with("bitcoin::") || Self::in_rust_prelude(&resolved) {
1966                                         write!(w, "{}", resolved).unwrap();
1967                                 } else if !generated_crate_ref {
1968                                         // If we're printing a generic argument, it needs to reference the crate, otherwise
1969                                         // the original crate.
1970                                         write!(w, "{}", self.real_rust_type_mapping(&resolved)).unwrap();
1971                                 } else {
1972                                         write!(w, "crate::{}", resolved).unwrap();
1973                                 }
1974                         }
1975                         if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().last().unwrap().arguments {
1976                                 self.write_rust_generic_arg(w, generics_resolver, args.args.iter(), with_ref_lifetime);
1977                         }
1978                 } else {
1979                         if path.leading_colon.is_some() {
1980                                 write!(w, "::").unwrap();
1981                         }
1982                         for (idx, seg) in path.segments.iter().enumerate() {
1983                                 if idx != 0 { write!(w, "::").unwrap(); }
1984                                 write!(w, "{}", seg.ident).unwrap();
1985                                 if let syn::PathArguments::AngleBracketed(args) = &seg.arguments {
1986                                         self.write_rust_generic_arg(w, generics_resolver, args.args.iter(), with_ref_lifetime);
1987                                 }
1988                         }
1989                 }
1990         }
1991         pub fn write_rust_generic_param<'b, W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, generics: impl Iterator<Item=&'b syn::GenericParam>) {
1992                 let mut had_params = false;
1993                 for (idx, arg) in generics.enumerate() {
1994                         if idx != 0 { write!(w, ", ").unwrap(); } else { write!(w, "<").unwrap(); }
1995                         had_params = true;
1996                         match arg {
1997                                 syn::GenericParam::Lifetime(lt) => write!(w, "'{}", lt.lifetime.ident).unwrap(),
1998                                 syn::GenericParam::Type(t) => {
1999                                         write!(w, "{}", t.ident).unwrap();
2000                                         if t.colon_token.is_some() { write!(w, ":").unwrap(); }
2001                                         for (idx, bound) in t.bounds.iter().enumerate() {
2002                                                 if idx != 0 { write!(w, " + ").unwrap(); }
2003                                                 match bound {
2004                                                         syn::TypeParamBound::Trait(tb) => {
2005                                                                 if tb.paren_token.is_some() || tb.lifetimes.is_some() { unimplemented!(); }
2006                                                                 self.write_rust_path(w, generics_resolver, &tb.path, false, false);
2007                                                         },
2008                                                         _ => unimplemented!(),
2009                                                 }
2010                                         }
2011                                         if t.eq_token.is_some() || t.default.is_some() { unimplemented!(); }
2012                                 },
2013                                 _ => unimplemented!(),
2014                         }
2015                 }
2016                 if had_params { write!(w, ">").unwrap(); }
2017         }
2018
2019         pub fn write_rust_generic_arg<'b, W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, generics: impl Iterator<Item=&'b syn::GenericArgument>, with_ref_lifetime: bool) {
2020                 write!(w, "<").unwrap();
2021                 for (idx, arg) in generics.enumerate() {
2022                         if idx != 0 { write!(w, ", ").unwrap(); }
2023                         match arg {
2024                                 syn::GenericArgument::Type(t) => self.write_rust_type(w, generics_resolver, t, with_ref_lifetime),
2025                                 _ => unimplemented!(),
2026                         }
2027                 }
2028                 write!(w, ">").unwrap();
2029         }
2030         fn do_write_rust_type<W: std::io::Write>(&self, w: &mut W, generics: Option<&GenericTypes>, t: &syn::Type, with_ref_lifetime: bool, force_crate_ref: bool) {
2031                 let real_ty = generics.resolve_type(t);
2032                 let mut generate_crate_ref = force_crate_ref || t != real_ty;
2033                 match real_ty {
2034                         syn::Type::Path(p) => {
2035                                 if p.qself.is_some() {
2036                                         unimplemented!();
2037                                 }
2038                                 if let Some(resolved_ty) = self.maybe_resolve_path(&p.path, generics) {
2039                                         generate_crate_ref |= self.maybe_resolve_path(&p.path, None).as_ref() != Some(&resolved_ty);
2040                                         if self.crate_types.traits.get(&resolved_ty).is_none() { generate_crate_ref = false; }
2041                                 }
2042                                 self.write_rust_path(w, generics, &p.path, with_ref_lifetime, generate_crate_ref);
2043                         },
2044                         syn::Type::Reference(r) => {
2045                                 write!(w, "&").unwrap();
2046                                 if let Some(lft) = &r.lifetime {
2047                                         write!(w, "'{} ", lft.ident).unwrap();
2048                                 } else if with_ref_lifetime {
2049                                         write!(w, "'static ").unwrap();
2050                                 }
2051                                 if r.mutability.is_some() {
2052                                         write!(w, "mut ").unwrap();
2053                                 }
2054                                 self.do_write_rust_type(w, generics, &*r.elem, with_ref_lifetime, generate_crate_ref);
2055                         },
2056                         syn::Type::Array(a) => {
2057                                 write!(w, "[").unwrap();
2058                                 self.do_write_rust_type(w, generics, &a.elem, with_ref_lifetime, generate_crate_ref);
2059                                 if let syn::Expr::Lit(l) = &a.len {
2060                                         if let syn::Lit::Int(i) = &l.lit {
2061                                                 write!(w, "; {}]", i).unwrap();
2062                                         } else { unimplemented!(); }
2063                                 } else { unimplemented!(); }
2064                         }
2065                         syn::Type::Slice(s) => {
2066                                 write!(w, "[").unwrap();
2067                                 self.do_write_rust_type(w, generics, &s.elem, with_ref_lifetime, generate_crate_ref);
2068                                 write!(w, "]").unwrap();
2069                         },
2070                         syn::Type::Tuple(s) => {
2071                                 write!(w, "(").unwrap();
2072                                 for (idx, t) in s.elems.iter().enumerate() {
2073                                         if idx != 0 { write!(w, ", ").unwrap(); }
2074                                         self.do_write_rust_type(w, generics, &t, with_ref_lifetime, generate_crate_ref);
2075                                 }
2076                                 write!(w, ")").unwrap();
2077                         },
2078                         _ => unimplemented!(),
2079                 }
2080         }
2081         pub fn write_rust_type<W: std::io::Write>(&self, w: &mut W, generics: Option<&GenericTypes>, t: &syn::Type, with_ref_lifetime: bool) {
2082                 self.do_write_rust_type(w, generics, t, with_ref_lifetime, false);
2083         }
2084
2085
2086         /// Prints a constructor for something which is "uninitialized" (but obviously not actually
2087         /// unint'd memory).
2088         pub fn write_empty_rust_val<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) {
2089                 match t {
2090                         syn::Type::Reference(r) => {
2091                                 self.write_empty_rust_val(generics, w, &*r.elem)
2092                         },
2093                         syn::Type::Path(p) => {
2094                                 let resolved = self.resolve_path(&p.path, generics);
2095                                 if self.crate_types.opaques.get(&resolved).is_some() {
2096                                         write!(w, "crate::{} {{ inner: core::ptr::null_mut(), is_owned: true }}", resolved).unwrap();
2097                                 } else {
2098                                         // Assume its a manually-mapped C type, where we can just define an null() fn
2099                                         write!(w, "{}::null()", self.c_type_from_path(&resolved, false, false).unwrap()).unwrap();
2100                                 }
2101                         },
2102                         syn::Type::Array(a) => {
2103                                 if let syn::Expr::Lit(l) = &a.len {
2104                                         if let syn::Lit::Int(i) = &l.lit {
2105                                                 if i.base10_digits().parse::<usize>().unwrap() < 32 {
2106                                                         // Blindly assume that if we're trying to create an empty value for an
2107                                                         // array < 32 entries that all-0s may be a valid state.
2108                                                         unimplemented!();
2109                                                 }
2110                                                 let arrty = format!("[u8; {}]", i.base10_digits());
2111                                                 write!(w, "{}", self.to_c_conversion_inline_prefix_from_path(&arrty, false, false).unwrap()).unwrap();
2112                                                 write!(w, "[0; {}]", i.base10_digits()).unwrap();
2113                                                 write!(w, "{}", self.to_c_conversion_inline_suffix_from_path(&arrty, false, false).unwrap()).unwrap();
2114                                         } else { unimplemented!(); }
2115                                 } else { unimplemented!(); }
2116                         }
2117                         _ => unimplemented!(),
2118                 }
2119         }
2120
2121         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
2122         /// See EmptyValExpectedTy for information on return types.
2123         fn write_empty_rust_val_check_suffix<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) -> EmptyValExpectedTy {
2124                 match t {
2125                         syn::Type::Reference(r) => {
2126                                 return self.write_empty_rust_val_check_suffix(generics, w, &*r.elem);
2127                         },
2128                         syn::Type::Path(p) => {
2129                                 let resolved = self.resolve_path(&p.path, generics);
2130                                 if self.crate_types.opaques.get(&resolved).is_some() {
2131                                         write!(w, ".inner.is_null()").unwrap();
2132                                         EmptyValExpectedTy::NonPointer
2133                                 } else {
2134                                         if let Some(suffix) = self.empty_val_check_suffix_from_path(&resolved) {
2135                                                 write!(w, "{}", suffix).unwrap();
2136                                                 // We may eventually need to allow empty_val_check_suffix_from_path to specify if we need a deref or not
2137                                                 EmptyValExpectedTy::NonPointer
2138                                         } else {
2139                                                 write!(w, ".is_none()").unwrap();
2140                                                 EmptyValExpectedTy::OptionType
2141                                         }
2142                                 }
2143                         },
2144                         syn::Type::Array(a) => {
2145                                 if let syn::Expr::Lit(l) = &a.len {
2146                                         if let syn::Lit::Int(i) = &l.lit {
2147                                                 write!(w, ".data == [0; {}]", i.base10_digits()).unwrap();
2148                                                 EmptyValExpectedTy::NonPointer
2149                                         } else { unimplemented!(); }
2150                                 } else { unimplemented!(); }
2151                         },
2152                         syn::Type::Slice(_) => {
2153                                 // Option<[]> always implies that we want to treat len() == 0 differently from
2154                                 // None, so we always map an Option<[]> into a pointer.
2155                                 write!(w, " == core::ptr::null_mut()").unwrap();
2156                                 EmptyValExpectedTy::ReferenceAsPointer
2157                         },
2158                         _ => unimplemented!(),
2159                 }
2160         }
2161
2162         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
2163         pub fn write_empty_rust_val_check<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type, var_access: &str) {
2164                 match t {
2165                         syn::Type::Reference(r) => {
2166                                 self.write_empty_rust_val_check(generics, w, &*r.elem, var_access);
2167                         },
2168                         syn::Type::Path(_) => {
2169                                 write!(w, "{}", var_access).unwrap();
2170                                 self.write_empty_rust_val_check_suffix(generics, w, t);
2171                         },
2172                         syn::Type::Array(a) => {
2173                                 if let syn::Expr::Lit(l) = &a.len {
2174                                         if let syn::Lit::Int(i) = &l.lit {
2175                                                 let arrty = format!("[u8; {}]", i.base10_digits());
2176                                                 // We don't (yet) support a new-var conversion here.
2177                                                 assert!(self.from_c_conversion_new_var_from_path(&arrty, false).is_none());
2178                                                 write!(w, "{}{}{}",
2179                                                         self.from_c_conversion_prefix_from_path(&arrty, false).unwrap(),
2180                                                         var_access,
2181                                                         self.from_c_conversion_suffix_from_path(&arrty, false).unwrap()).unwrap();
2182                                                 self.write_empty_rust_val_check_suffix(generics, w, t);
2183                                         } else { unimplemented!(); }
2184                                 } else { unimplemented!(); }
2185                         }
2186                         _ => unimplemented!(),
2187                 }
2188         }
2189
2190         // ********************************
2191         // *** Type conversion printing ***
2192         // ********************************
2193
2194         /// Returns true we if can just skip passing this to C entirely
2195         pub fn skip_arg(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2196                 match t {
2197                         syn::Type::Path(p) => {
2198                                 if p.qself.is_some() { unimplemented!(); }
2199                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
2200                                         self.skip_path(&full_path)
2201                                 } else { false }
2202                         },
2203                         syn::Type::Reference(r) => {
2204                                 self.skip_arg(&*r.elem, generics)
2205                         },
2206                         _ => false,
2207                 }
2208         }
2209         pub fn no_arg_to_rust<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2210                 match t {
2211                         syn::Type::Path(p) => {
2212                                 if p.qself.is_some() { unimplemented!(); }
2213                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
2214                                         write!(w, "{}", self.no_arg_path_to_rust(&full_path)).unwrap();
2215                                 }
2216                         },
2217                         syn::Type::Reference(r) => {
2218                                 self.no_arg_to_rust(w, &*r.elem, generics);
2219                         },
2220                         _ => {},
2221                 }
2222         }
2223
2224         fn write_conversion_inline_intern<W: std::io::Write,
2225                         LP: Fn(&str, bool, bool) -> Option<String>, DL: Fn(&mut W, &DeclType, &str, bool, bool), SC: Fn(bool, Option<&str>) -> String>
2226                         (&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool,
2227                          tupleconv: &str, prefix: bool, sliceconv: SC, path_lookup: LP, decl_lookup: DL) {
2228                 match generics.resolve_type(t) {
2229                         syn::Type::Reference(r) => {
2230                                 self.write_conversion_inline_intern(w, &*r.elem, generics, true, r.mutability.is_some(),
2231                                         ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
2232                         },
2233                         syn::Type::Path(p) => {
2234                                 if p.qself.is_some() {
2235                                         unimplemented!();
2236                                 }
2237
2238                                 let resolved_path = self.resolve_path(&p.path, generics);
2239                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
2240                                         return self.write_conversion_inline_intern(w, aliased_type, None, is_ref, is_mut, ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
2241                                 } else if self.is_primitive(&resolved_path) {
2242                                         if is_ref && prefix {
2243                                                 write!(w, "*").unwrap();
2244                                         }
2245                                 } else if let Some(c_type) = path_lookup(&resolved_path, is_ref, ptr_for_ref) {
2246                                         write!(w, "{}", c_type).unwrap();
2247                                 } else if let Some((_, generics)) = self.crate_types.opaques.get(&resolved_path) {
2248                                         decl_lookup(w, &DeclType::StructImported { generics: &generics }, &resolved_path, is_ref, is_mut);
2249                                 } else if self.crate_types.mirrored_enums.get(&resolved_path).is_some() {
2250                                         decl_lookup(w, &DeclType::MirroredEnum, &resolved_path, is_ref, is_mut);
2251                                 } else if let Some(t) = self.crate_types.traits.get(&resolved_path) {
2252                                         decl_lookup(w, &DeclType::Trait(t), &resolved_path, is_ref, is_mut);
2253                                 } else if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
2254                                         if let Some(decl_type) = self.types.maybe_resolve_declared(ident) {
2255                                                 decl_lookup(w, decl_type, &self.maybe_resolve_ident(ident).unwrap(), is_ref, is_mut);
2256                                         } else { unimplemented!(); }
2257                                 } else {
2258                                         if let Some(trait_impls) = self.crate_types.traits_impld.get(&resolved_path) {
2259                                                 if trait_impls.len() == 1 {
2260                                                         // If this is a no-export'd crate and there's only one implementation
2261                                                         // in the whole crate, just treat it as a reference to whatever the
2262                                                         // implementor is.
2263                                                         let implementor = self.crate_types.opaques.get(&trait_impls[0]).unwrap();
2264                                                         decl_lookup(w, &DeclType::StructImported { generics: &implementor.1 }, &trait_impls[0], true, is_mut);
2265                                                         return;
2266                                                 }
2267                                         }
2268                                         unimplemented!();
2269                                 }
2270                         },
2271                         syn::Type::Array(a) => {
2272                                 if let syn::Type::Path(p) = &*a.elem {
2273                                         let inner_ty = self.resolve_path(&p.path, generics);
2274                                         if let syn::Expr::Lit(l) = &a.len {
2275                                                 if let syn::Lit::Int(i) = &l.lit {
2276                                                         write!(w, "{}", path_lookup(&format!("[{}; {}]", inner_ty, i.base10_digits()), is_ref, ptr_for_ref).unwrap()).unwrap();
2277                                                 } else { unimplemented!(); }
2278                                         } else { unimplemented!(); }
2279                                 } else { unimplemented!(); }
2280                         },
2281                         syn::Type::Slice(s) => {
2282                                 // We assume all slices contain only literals or references.
2283                                 // This may result in some outputs not compiling.
2284                                 if let syn::Type::Path(p) = &*s.elem {
2285                                         let resolved = self.resolve_path(&p.path, generics);
2286                                         if self.is_primitive(&resolved) {
2287                                                 write!(w, "{}", path_lookup("[u8]", is_ref, ptr_for_ref).unwrap()).unwrap();
2288                                         } else {
2289                                                 write!(w, "{}", sliceconv(true, None)).unwrap();
2290                                         }
2291                                 } else if let syn::Type::Reference(r) = &*s.elem {
2292                                         if let syn::Type::Path(p) = &*r.elem {
2293                                                 write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)), None)).unwrap();
2294                                         } else if let syn::Type::Slice(_) = &*r.elem {
2295                                                 write!(w, "{}", sliceconv(false, None)).unwrap();
2296                                         } else { unimplemented!(); }
2297                                 } else if let syn::Type::Tuple(t) = &*s.elem {
2298                                         assert!(!t.elems.is_empty());
2299                                         if prefix {
2300                                                 write!(w, "{}", sliceconv(false, None)).unwrap();
2301                                         } else {
2302                                                 let mut needs_map = false;
2303                                                 for e in t.elems.iter() {
2304                                                         if let syn::Type::Reference(_) = e {
2305                                                                 needs_map = true;
2306                                                         }
2307                                                 }
2308                                                 if needs_map {
2309                                                         let mut map_str = Vec::new();
2310                                                         write!(&mut map_str, ".map(|(").unwrap();
2311                                                         for i in 0..t.elems.len() {
2312                                                                 write!(&mut map_str, "{}{}", if i != 0 { ", " } else { "" }, ('a' as u8 + i as u8) as char).unwrap();
2313                                                         }
2314                                                         write!(&mut map_str, ")| (").unwrap();
2315                                                         for (idx, e) in t.elems.iter().enumerate() {
2316                                                                 if let syn::Type::Reference(_) = e {
2317                                                                         write!(&mut map_str, "{}{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
2318                                                                 } else if let syn::Type::Path(_) = e {
2319                                                                         write!(&mut map_str, "{}*{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
2320                                                                 } else { unimplemented!(); }
2321                                                         }
2322                                                         write!(&mut map_str, "))").unwrap();
2323                                                         write!(w, "{}", sliceconv(false, Some(&String::from_utf8(map_str).unwrap()))).unwrap();
2324                                                 } else {
2325                                                         write!(w, "{}", sliceconv(false, None)).unwrap();
2326                                                 }
2327                                         }
2328                                 } else if let syn::Type::Array(_) = &*s.elem {
2329                                         write!(w, "{}", sliceconv(false, Some(".map(|a| *a)"))).unwrap();
2330                                 } else { unimplemented!(); }
2331                         },
2332                         syn::Type::Tuple(t) => {
2333                                 if t.elems.is_empty() {
2334                                         // cbindgen has poor support for (), see, eg https://github.com/eqrion/cbindgen/issues/527
2335                                         // so work around it by just pretending its a 0u8
2336                                         write!(w, "{}", tupleconv).unwrap();
2337                                 } else {
2338                                         if prefix { write!(w, "local_").unwrap(); }
2339                                 }
2340                         },
2341                         _ => unimplemented!(),
2342                 }
2343         }
2344
2345         fn write_to_c_conversion_inline_prefix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool, from_ptr: bool) {
2346                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "() /*", true, |_, _| "local_".to_owned(),
2347                                 |a, b, c| self.to_c_conversion_inline_prefix_from_path(a, b, c),
2348                                 |w, decl_type, decl_path, is_ref, _is_mut| {
2349                                         match decl_type {
2350                                                 DeclType::MirroredEnum if is_ref && ptr_for_ref => write!(w, "crate::{}::from_native(", decl_path).unwrap(),
2351                                                 DeclType::MirroredEnum if is_ref => write!(w, "&crate::{}::from_native(", decl_path).unwrap(),
2352                                                 DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
2353                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if is_ref && from_ptr => {
2354                                                         if !ptr_for_ref { write!(w, "&").unwrap(); }
2355                                                         write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap()
2356                                                 },
2357                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if is_ref => {
2358                                                         if !ptr_for_ref { write!(w, "&").unwrap(); }
2359                                                         write!(w, "crate::{} {{ inner: unsafe {{ ObjOps::nonnull_ptr_to_inner((", decl_path).unwrap()
2360                                                 },
2361                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref && from_ptr =>
2362                                                         write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
2363                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref =>
2364                                                         write!(w, "crate::{} {{ inner: ObjOps::heap_alloc(", decl_path).unwrap(),
2365                                                 DeclType::Trait(_) if is_ref => write!(w, "").unwrap(),
2366                                                 DeclType::Trait(_) if !is_ref => write!(w, "Into::into(").unwrap(),
2367                                                 _ => panic!("{:?}", decl_path),
2368                                         }
2369                                 });
2370         }
2371         pub fn write_to_c_conversion_inline_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2372                 self.write_to_c_conversion_inline_prefix_inner(w, t, generics, false, ptr_for_ref, false);
2373         }
2374         fn write_to_c_conversion_inline_suffix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool, from_ptr: bool) {
2375                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "*/", false, |_, _| ".into()".to_owned(),
2376                                 |a, b, c| self.to_c_conversion_inline_suffix_from_path(a, b, c),
2377                                 |w, decl_type, full_path, is_ref, _is_mut| match decl_type {
2378                                         DeclType::MirroredEnum => write!(w, ")").unwrap(),
2379                                         DeclType::EnumIgnored { generics }|DeclType::StructImported { generics } if is_ref => {
2380                                                 write!(w, " as *const {}<", full_path).unwrap();
2381                                                 for param in generics.params.iter() {
2382                                                         if let syn::GenericParam::Lifetime(_) = param {
2383                                                                 write!(w, "'_, ").unwrap();
2384                                                         } else {
2385                                                                 write!(w, "_, ").unwrap();
2386                                                         }
2387                                                 }
2388                                                 if from_ptr {
2389                                                         write!(w, ">) as *mut _ }}, is_owned: false }}").unwrap();
2390                                                 } else {
2391                                                         write!(w, ">) as *mut _) }}, is_owned: false }}").unwrap();
2392                                                 }
2393                                         },
2394                                         DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref && from_ptr =>
2395                                                 write!(w, ", is_owned: true }}").unwrap(),
2396                                         DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref => write!(w, "), is_owned: true }}").unwrap(),
2397                                         DeclType::Trait(_) if is_ref => {},
2398                                         DeclType::Trait(_) => {
2399                                                 // This is used when we're converting a concrete Rust type into a C trait
2400                                                 // for use when a Rust trait method returns an associated type.
2401                                                 // Because all of our C traits implement From<RustTypesImplementingTraits>
2402                                                 // we can just call .into() here and be done.
2403                                                 write!(w, ")").unwrap()
2404                                         },
2405                                         _ => unimplemented!(),
2406                                 });
2407         }
2408         pub fn write_to_c_conversion_inline_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2409                 self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
2410         }
2411
2412         fn write_from_c_conversion_prefix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, _ptr_for_ref: bool) {
2413                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_, _| "&local_".to_owned(),
2414                                 |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
2415                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
2416                                         DeclType::StructImported {..} if is_ref => write!(w, "").unwrap(),
2417                                         DeclType::StructImported {..} if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
2418                                         DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
2419                                         DeclType::MirroredEnum => {},
2420                                         DeclType::Trait(_) => {},
2421                                         _ => unimplemented!(),
2422                                 });
2423         }
2424         pub fn write_from_c_conversion_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2425                 self.write_from_c_conversion_prefix_inner(w, t, generics, false, false);
2426         }
2427         fn write_from_c_conversion_suffix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool) {
2428                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "*/", false,
2429                                 |has_inner, map_str_opt| match (has_inner, map_str_opt) {
2430                                         (false, Some(map_str)) => format!(".iter(){}.collect::<Vec<_>>()[..]", map_str),
2431                                         (false, None) => ".iter().collect::<Vec<_>>()[..]".to_owned(),
2432                                         (true, None) => "[..]".to_owned(),
2433                                         (true, Some(_)) => unreachable!(),
2434                                 },
2435                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
2436                                 |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
2437                                         DeclType::StructImported {..} if is_ref && ptr_for_ref => write!(w, "XXX unimplemented").unwrap(),
2438                                         DeclType::StructImported {..} if is_mut && is_ref => write!(w, ".get_native_mut_ref()").unwrap(),
2439                                         DeclType::StructImported {..} if is_ref => write!(w, ".get_native_ref()").unwrap(),
2440                                         DeclType::StructImported {..} if !is_ref => write!(w, ".take_inner()) }}").unwrap(),
2441                                         DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
2442                                         DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
2443                                         DeclType::Trait(_) => {},
2444                                         _ => unimplemented!(),
2445                                 });
2446         }
2447         pub fn write_from_c_conversion_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2448                 self.write_from_c_conversion_suffix_inner(w, t, generics, false, false);
2449         }
2450         // Note that compared to the above conversion functions, the following two are generally
2451         // significantly undertested:
2452         pub fn write_from_c_conversion_to_ref_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2453                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "() /*", true, |_, _| "&local_".to_owned(),
2454                                 |a, b, _c| {
2455                                         if let Some(conv) = self.from_c_conversion_prefix_from_path(a, b) {
2456                                                 Some(format!("&{}", conv))
2457                                         } else { None }
2458                                 },
2459                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
2460                                         DeclType::StructImported {..} if !is_ref => write!(w, "").unwrap(),
2461                                         _ => unimplemented!(),
2462                                 });
2463         }
2464         pub fn write_from_c_conversion_to_ref_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2465                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "*/", false,
2466                                 |has_inner, map_str_opt| match (has_inner, map_str_opt) {
2467                                         (false, Some(map_str)) => format!(".iter(){}.collect::<Vec<_>>()[..]", map_str),
2468                                         (false, None) => ".iter().collect::<Vec<_>>()[..]".to_owned(),
2469                                         (true, None) => "[..]".to_owned(),
2470                                         (true, Some(_)) => unreachable!(),
2471                                 },
2472                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
2473                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
2474                                         DeclType::StructImported {..} if !is_ref => write!(w, ".get_native_ref()").unwrap(),
2475                                         _ => unimplemented!(),
2476                                 });
2477         }
2478
2479         fn write_conversion_new_var_intern<'b, W: std::io::Write,
2480                 LP: Fn(&str, bool) -> Option<(&str, &str)>,
2481                 LC: Fn(&str, bool, Option<&syn::Type>, &syn::Ident, &str) ->  Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)>,
2482                 VP: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool),
2483                 VS: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool)>
2484                         (&self, w: &mut W, ident: &syn::Ident, var: &str, t: &syn::Type, generics: Option<&GenericTypes>,
2485                          mut is_ref: bool, mut ptr_for_ref: bool, to_c: bool, from_ownable_ref: bool,
2486                          path_lookup: &LP, container_lookup: &LC, var_prefix: &VP, var_suffix: &VS) -> bool {
2487
2488                 macro_rules! convert_container {
2489                         ($container_type: expr, $args_len: expr, $args_iter: expr) => { {
2490                                 // For slices (and Options), we refuse to directly map them as is_ref when they
2491                                 // aren't opaque types containing an inner pointer. This is due to the fact that,
2492                                 // in both cases, the actual higher-level type is non-is_ref.
2493                                 let (ty_has_inner, ty_is_trait) = if $args_len == 1 {
2494                                         let ty = $args_iter().next().unwrap();
2495                                         if $container_type == "Slice" && to_c {
2496                                                 // "To C ptr_for_ref" means "return the regular object with is_owned
2497                                                 // set to false", which is totally what we want in a slice if we're about to
2498                                                 // set ty_has_inner.
2499                                                 ptr_for_ref = true;
2500                                         }
2501                                         if let syn::Type::Reference(t) = ty {
2502                                                 if let syn::Type::Path(p) = &*t.elem {
2503                                                         let resolved = self.resolve_path(&p.path, generics);
2504                                                         (self.c_type_has_inner_from_path(&resolved), self.crate_types.traits.get(&resolved).is_some())
2505                                                 } else { (false, false) }
2506                                         } else if let syn::Type::Path(p) = ty {
2507                                                 let resolved = self.resolve_path(&p.path, generics);
2508                                                 (self.c_type_has_inner_from_path(&resolved), self.crate_types.traits.get(&resolved).is_some())
2509                                         } else { (false, false) }
2510                                 } else { (true, false) };
2511
2512                                 // Options get a bunch of special handling, since in general we map Option<>al
2513                                 // types into the same C type as non-Option-wrapped types. This ends up being
2514                                 // pretty manual here and most of the below special-cases are for Options.
2515                                 let mut needs_ref_map = false;
2516                                 let mut only_contained_type = None;
2517                                 let mut only_contained_type_nonref = None;
2518                                 let mut only_contained_has_inner = false;
2519                                 let mut contains_slice = false;
2520                                 if $args_len == 1 {
2521                                         only_contained_has_inner = ty_has_inner;
2522                                         let arg = $args_iter().next().unwrap();
2523                                         if let syn::Type::Reference(t) = arg {
2524                                                 only_contained_type = Some(arg);
2525                                                 only_contained_type_nonref = Some(&*t.elem);
2526                                                 if let syn::Type::Path(_) = &*t.elem {
2527                                                         is_ref = true;
2528                                                 } else if let syn::Type::Slice(_) = &*t.elem {
2529                                                         contains_slice = true;
2530                                                 } else { return false; }
2531                                                 // If the inner element contains an inner pointer, we will just use that,
2532                                                 // avoiding the need to map elements to references. Otherwise we'll need to
2533                                                 // do an extra mapping step.
2534                                                 needs_ref_map = !only_contained_has_inner && !ty_is_trait && $container_type == "Option";
2535                                         } else {
2536                                                 only_contained_type = Some(arg);
2537                                                 only_contained_type_nonref = Some(arg);
2538                                         }
2539                                 }
2540
2541                                 if let Some((prefix, conversions, suffix, prefix_location)) = container_lookup(&$container_type, is_ref, only_contained_type, ident, var) {
2542                                         assert_eq!(conversions.len(), $args_len);
2543                                         write!(w, "let mut local_{}{} = ", ident,
2544                                                 if (!to_c && needs_ref_map) || (to_c && $container_type == "Option" && contains_slice) {"_base"} else { "" }).unwrap();
2545                                         if prefix_location == ContainerPrefixLocation::OutsideConv {
2546                                                 var_prefix(w, $args_iter().next().unwrap(), generics, is_ref, true, true);
2547                                         }
2548                                         write!(w, "{}{}", prefix, var).unwrap();
2549
2550                                         for ((pfx, var_name), (idx, ty)) in conversions.iter().zip($args_iter().enumerate()) {
2551                                                 let mut var = std::io::Cursor::new(Vec::new());
2552                                                 write!(&mut var, "{}", var_name).unwrap();
2553                                                 let var_access = String::from_utf8(var.into_inner()).unwrap();
2554
2555                                                 let conv_ty = if needs_ref_map { only_contained_type_nonref.as_ref().unwrap() } else { ty };
2556
2557                                                 write!(w, "{} {{ ", pfx).unwrap();
2558                                                 let new_var_name = format!("{}_{}", ident, idx);
2559                                                 let new_var = self.write_conversion_new_var_intern(w, &format_ident!("{}", new_var_name),
2560                                                                 &var_access, conv_ty, generics, contains_slice || (is_ref && ty_has_inner), ptr_for_ref,
2561                                                                 to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix);
2562                                                 if new_var { write!(w, " ").unwrap(); }
2563
2564                                                 if prefix_location == ContainerPrefixLocation::PerConv {
2565                                                         var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2566                                                 } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
2567                                                         write!(w, "ObjOps::heap_alloc(").unwrap();
2568                                                 }
2569
2570                                                 write!(w, "{}{}", if contains_slice && !to_c { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
2571                                                 if prefix_location == ContainerPrefixLocation::PerConv {
2572                                                         var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2573                                                 } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
2574                                                         write!(w, ")").unwrap();
2575                                                 }
2576                                                 write!(w, " }}").unwrap();
2577                                         }
2578                                         write!(w, "{}", suffix).unwrap();
2579                                         if prefix_location == ContainerPrefixLocation::OutsideConv {
2580                                                 var_suffix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
2581                                         }
2582                                         write!(w, ";").unwrap();
2583                                         if !to_c && needs_ref_map {
2584                                                 write!(w, " let mut local_{} = local_{}_base.as_ref()", ident, ident).unwrap();
2585                                                 if contains_slice {
2586                                                         write!(w, ".map(|a| &a[..])").unwrap();
2587                                                 }
2588                                                 write!(w, ";").unwrap();
2589                                         } else if to_c && $container_type == "Option" && contains_slice {
2590                                                 write!(w, " let mut local_{} = *local_{}_base;", ident, ident).unwrap();
2591                                         }
2592                                         return true;
2593                                 }
2594                         } }
2595                 }
2596
2597                 match generics.resolve_type(t) {
2598                         syn::Type::Reference(r) => {
2599                                 if let syn::Type::Slice(_) = &*r.elem {
2600                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, is_ref, ptr_for_ref, to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix)
2601                                 } else {
2602                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, true, ptr_for_ref, to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix)
2603                                 }
2604                         },
2605                         syn::Type::Path(p) => {
2606                                 if p.qself.is_some() {
2607                                         unimplemented!();
2608                                 }
2609                                 let resolved_path = self.resolve_path(&p.path, generics);
2610                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
2611                                         return self.write_conversion_new_var_intern(w, ident, var, aliased_type, None, is_ref, ptr_for_ref, to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix);
2612                                 }
2613                                 if self.is_known_container(&resolved_path, is_ref) || self.is_path_transparent_container(&p.path, generics, is_ref) {
2614                                         if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
2615                                                 convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
2616                                                         if let syn::GenericArgument::Type(ty) = arg {
2617                                                                 generics.resolve_type(ty)
2618                                                         } else { unimplemented!(); }
2619                                                 }));
2620                                         } else { unimplemented!(); }
2621                                 }
2622                                 if self.is_primitive(&resolved_path) {
2623                                         false
2624                                 } else if let Some(ty_ident) = single_ident_generic_path_to_ident(&p.path) {
2625                                         if let Some((prefix, suffix)) = path_lookup(&resolved_path, is_ref) {
2626                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
2627                                                 true
2628                                         } else if self.types.maybe_resolve_declared(ty_ident).is_some() {
2629                                                 false
2630                                         } else { false }
2631                                 } else { false }
2632                         },
2633                         syn::Type::Array(_) => {
2634                                 // We assume all arrays contain only primitive types.
2635                                 // This may result in some outputs not compiling.
2636                                 false
2637                         },
2638                         syn::Type::Slice(s) => {
2639                                 if let syn::Type::Path(p) = &*s.elem {
2640                                         let resolved = self.resolve_path(&p.path, generics);
2641                                         if self.is_primitive(&resolved) {
2642                                                 let slice_path = format!("[{}]", resolved);
2643                                                 if let Some((prefix, suffix)) = path_lookup(&slice_path, true) {
2644                                                         write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
2645                                                         true
2646                                                 } else { false }
2647                                         } else {
2648                                                 let tyref = [&*s.elem];
2649                                                 if to_c {
2650                                                         // If we're converting from a slice to a Vec, assume we can clone the
2651                                                         // elements and clone them into a new Vec first. Next we'll walk the
2652                                                         // new Vec here and convert them to C types.
2653                                                         write!(w, "let mut local_{}_clone = Vec::new(); local_{}_clone.extend_from_slice({}); let mut {} = local_{}_clone; ", ident, ident, ident, ident, ident).unwrap();
2654                                                 }
2655                                                 is_ref = false;
2656                                                 convert_container!("Vec", 1, || tyref.iter().map(|t| generics.resolve_type(*t)));
2657                                                 unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2658                                         }
2659                                 } else if let syn::Type::Reference(ty) = &*s.elem {
2660                                         let tyref = if from_ownable_ref || !to_c { [&*ty.elem] } else { [&*s.elem] };
2661                                         is_ref = true;
2662                                         convert_container!("Slice", 1, || tyref.iter().map(|t| generics.resolve_type(*t)));
2663                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2664                                 } else if let syn::Type::Tuple(t) = &*s.elem {
2665                                         // When mapping into a temporary new var, we need to own all the underlying objects.
2666                                         // Thus, we drop any references inside the tuple and convert with non-reference types.
2667                                         let mut elems = syn::punctuated::Punctuated::new();
2668                                         for elem in t.elems.iter() {
2669                                                 if let syn::Type::Reference(r) = elem {
2670                                                         elems.push((*r.elem).clone());
2671                                                 } else {
2672                                                         elems.push(elem.clone());
2673                                                 }
2674                                         }
2675                                         let ty = [syn::Type::Tuple(syn::TypeTuple {
2676                                                 paren_token: t.paren_token, elems
2677                                         })];
2678                                         is_ref = false;
2679                                         ptr_for_ref = true;
2680                                         convert_container!("Slice", 1, || ty.iter());
2681                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2682                                 } else if let syn::Type::Array(_) = &*s.elem {
2683                                         is_ref = false;
2684                                         ptr_for_ref = true;
2685                                         let arr_elem = [(*s.elem).clone()];
2686                                         convert_container!("Slice", 1, || arr_elem.iter());
2687                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2688                                 } else { unimplemented!() }
2689                         },
2690                         syn::Type::Tuple(t) => {
2691                                 if !t.elems.is_empty() {
2692                                         // We don't (yet) support tuple elements which cannot be converted inline
2693                                         write!(w, "let (").unwrap();
2694                                         for idx in 0..t.elems.len() {
2695                                                 if idx != 0 { write!(w, ", ").unwrap(); }
2696                                                 write!(w, "{} orig_{}_{}", if is_ref { "ref" } else { "mut" }, ident, idx).unwrap();
2697                                         }
2698                                         write!(w, ") = {}{}; ", var, if !to_c { ".to_rust()" } else { "" }).unwrap();
2699                                         // Like other template types, tuples are always mapped as their non-ref
2700                                         // versions for types which have different ref mappings. Thus, we convert to
2701                                         // non-ref versions and handle opaque types with inner pointers manually.
2702                                         for (idx, elem) in t.elems.iter().enumerate() {
2703                                                 if let syn::Type::Path(p) = elem {
2704                                                         let v_name = format!("orig_{}_{}", ident, idx);
2705                                                         let tuple_elem_ident = format_ident!("{}", &v_name);
2706                                                         if self.write_conversion_new_var_intern(w, &tuple_elem_ident, &v_name, elem, generics,
2707                                                                         false, ptr_for_ref, to_c, from_ownable_ref,
2708                                                                         path_lookup, container_lookup, var_prefix, var_suffix) {
2709                                                                 write!(w, " ").unwrap();
2710                                                                 // Opaque types with inner pointers shouldn't ever create new stack
2711                                                                 // variables, so we don't handle it and just assert that it doesn't
2712                                                                 // here.
2713                                                                 assert!(!self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)));
2714                                                         }
2715                                                 }
2716                                         }
2717                                         write!(w, "let mut local_{} = (", ident).unwrap();
2718                                         for (idx, elem) in t.elems.iter().enumerate() {
2719                                                 let real_elem = generics.resolve_type(&elem);
2720                                                 let ty_has_inner = {
2721                                                                 if to_c {
2722                                                                         // "To C ptr_for_ref" means "return the regular object with
2723                                                                         // is_owned set to false", which is totally what we want
2724                                                                         // if we're about to set ty_has_inner.
2725                                                                         ptr_for_ref = true;
2726                                                                 }
2727                                                                 if let syn::Type::Reference(t) = real_elem {
2728                                                                         if let syn::Type::Path(p) = &*t.elem {
2729                                                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
2730                                                                         } else { false }
2731                                                                 } else if let syn::Type::Path(p) = real_elem {
2732                                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
2733                                                                 } else { false }
2734                                                         };
2735                                                 if idx != 0 { write!(w, ", ").unwrap(); }
2736                                                 var_prefix(w, real_elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2737                                                 if is_ref && ty_has_inner {
2738                                                         // For ty_has_inner, the regular var_prefix mapping will take a
2739                                                         // reference, so deref once here to make sure we keep the original ref.
2740                                                         write!(w, "*").unwrap();
2741                                                 }
2742                                                 write!(w, "orig_{}_{}", ident, idx).unwrap();
2743                                                 if is_ref && !ty_has_inner {
2744                                                         // If we don't have an inner variable's reference to maintain, just
2745                                                         // hope the type is Clonable and use that.
2746                                                         write!(w, ".clone()").unwrap();
2747                                                 }
2748                                                 var_suffix(w, real_elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2749                                         }
2750                                         write!(w, "){};", if to_c { ".into()" } else { "" }).unwrap();
2751                                         true
2752                                 } else { false }
2753                         },
2754                         _ => unimplemented!(),
2755                 }
2756         }
2757
2758         pub fn write_to_c_conversion_new_var_inner<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, var_access: &str, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool, from_ownable_ref: bool) -> bool {
2759                 self.write_conversion_new_var_intern(w, ident, var_access, t, generics, from_ownable_ref, ptr_for_ref, true, from_ownable_ref,
2760                         &|a, b| self.to_c_conversion_new_var_from_path(a, b),
2761                         &|a, b, c, d, e| self.to_c_conversion_container_new_var(generics, a, b, c, d, e),
2762                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
2763                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_prefix_inner(a, b, c, d, e, f),
2764                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_suffix_inner(a, b, c, d, e, f))
2765         }
2766         pub fn write_to_c_conversion_new_var<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) -> bool {
2767                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, ptr_for_ref, false)
2768         }
2769         /// Prints new-var conversion for an "ownable_ref" type, ie prints conversion for
2770         /// `create_ownable_reference(t)`, not `t` itself.
2771         pub fn write_to_c_conversion_from_ownable_ref_new_var<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2772                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, true, true)
2773         }
2774         pub fn write_from_c_conversion_new_var<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2775                 self.write_conversion_new_var_intern(w, ident, &format!("{}", ident), t, generics, false, false, false, false,
2776                         &|a, b| self.from_c_conversion_new_var_from_path(a, b),
2777                         &|a, b, c, d, e| self.from_c_conversion_container_new_var(generics, a, b, c, d, e),
2778                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
2779                         &|a, b, c, d, e, _f| self.write_from_c_conversion_prefix_inner(a, b, c, d, e),
2780                         &|a, b, c, d, e, _f| self.write_from_c_conversion_suffix_inner(a, b, c, d, e))
2781         }
2782
2783         // ******************************************************
2784         // *** C Container Type Equivalent and alias Printing ***
2785         // ******************************************************
2786
2787         fn write_template_generics<'b, W: std::io::Write>(&self, w: &mut W, args: &mut dyn Iterator<Item=&'b syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
2788                 for (idx, orig_t) in args.enumerate() {
2789                         if idx != 0 {
2790                                 write!(w, ", ").unwrap();
2791                         }
2792                         let t = generics.resolve_type(orig_t);
2793                         if let syn::Type::Reference(r_arg) = t {
2794                                 assert!(!is_ref); // We don't currently support outer reference types for non-primitive inners
2795
2796                                 if !self.write_c_type_intern(w, &*r_arg.elem, generics, false, false, false, true, true) { return false; }
2797
2798                                 // While write_c_type_intern, above is correct, we don't want to blindly convert a
2799                                 // reference to something stupid, so check that the container is either opaque or a
2800                                 // predefined type (currently only Transaction).
2801                                 if let syn::Type::Path(p_arg) = &*r_arg.elem {
2802                                         let resolved = self.resolve_path(&p_arg.path, generics);
2803                                         assert!(self.crate_types.opaques.get(&resolved).is_some() ||
2804                                                         self.crate_types.traits.get(&resolved).is_some() ||
2805                                                         self.c_type_from_path(&resolved, true, true).is_some(), "Template generics should be opaque or have a predefined mapping");
2806                                 } else { unimplemented!(); }
2807                         } else if let syn::Type::Path(p_arg) = t {
2808                                 if let Some(resolved) = self.maybe_resolve_path(&p_arg.path, generics) {
2809                                         if !self.is_primitive(&resolved) && self.c_type_from_path(&resolved, false, false).is_none() {
2810                                                 if is_ref {
2811                                                         // We don't currently support outer reference types for non-primitive inners
2812                                                         return false;
2813                                                 }
2814                                         }
2815                                 } else {
2816                                         return false;
2817                                 }
2818                                 if !self.write_c_type_intern(w, t, generics, false, false, false, true, true) { return false; }
2819                         } else {
2820                                 // We don't currently support outer reference types for non-primitive inners,
2821                                 // except for the empty tuple.
2822                                 if let syn::Type::Tuple(t_arg) = t {
2823                                         assert!(t_arg.elems.len() == 0 || !is_ref);
2824                                 } else {
2825                                         assert!(!is_ref);
2826                                 }
2827                                 if !self.write_c_type_intern(w, t, generics, false, false, false, true, true) { return false; }
2828                         }
2829                 }
2830                 true
2831         }
2832         fn check_create_container(&self, mangled_container: String, container_type: &str, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
2833                 if !self.crate_types.templates_defined.borrow().get(&mangled_container).is_some() {
2834                         let mut created_container: Vec<u8> = Vec::new();
2835
2836                         if container_type == "Result" {
2837                                 let mut a_ty: Vec<u8> = Vec::new();
2838                                 if let syn::Type::Tuple(tup) = args.iter().next().unwrap() {
2839                                         if tup.elems.is_empty() {
2840                                                 write!(&mut a_ty, "()").unwrap();
2841                                         } else {
2842                                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
2843                                         }
2844                                 } else {
2845                                         if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
2846                                 }
2847
2848                                 let mut b_ty: Vec<u8> = Vec::new();
2849                                 if let syn::Type::Tuple(tup) = args.iter().skip(1).next().unwrap() {
2850                                         if tup.elems.is_empty() {
2851                                                 write!(&mut b_ty, "()").unwrap();
2852                                         } else {
2853                                                 if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
2854                                         }
2855                                 } else {
2856                                         if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
2857                                 }
2858
2859                                 let ok_str = String::from_utf8(a_ty).unwrap();
2860                                 let err_str = String::from_utf8(b_ty).unwrap();
2861                                 let is_clonable = self.is_clonable(&ok_str) && self.is_clonable(&err_str);
2862                                 write_result_block(&mut created_container, &mangled_container, &ok_str, &err_str, is_clonable);
2863                                 if is_clonable {
2864                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2865                                 }
2866                         } else if container_type == "Vec" {
2867                                 let mut a_ty: Vec<u8> = Vec::new();
2868                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t), generics, is_ref) { return false; }
2869                                 let ty = String::from_utf8(a_ty).unwrap();
2870                                 let is_clonable = self.is_clonable(&ty);
2871                                 write_vec_block(&mut created_container, &mangled_container, &ty, is_clonable);
2872                                 if is_clonable {
2873                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2874                                 }
2875                         } else if container_type.ends_with("Tuple") {
2876                                 let mut tuple_args = Vec::new();
2877                                 let mut is_clonable = true;
2878                                 for arg in args.iter() {
2879                                         let mut ty: Vec<u8> = Vec::new();
2880                                         if !self.write_template_generics(&mut ty, &mut [arg].iter().map(|t| **t), generics, is_ref) { return false; }
2881                                         let ty_str = String::from_utf8(ty).unwrap();
2882                                         if !self.is_clonable(&ty_str) {
2883                                                 is_clonable = false;
2884                                         }
2885                                         tuple_args.push(ty_str);
2886                                 }
2887                                 write_tuple_block(&mut created_container, &mangled_container, &tuple_args, is_clonable);
2888                                 if is_clonable {
2889                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2890                                 }
2891                         } else if container_type == "Option" {
2892                                 let mut a_ty: Vec<u8> = Vec::new();
2893                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t), generics, is_ref) { return false; }
2894                                 let ty = String::from_utf8(a_ty).unwrap();
2895                                 let is_clonable = self.is_clonable(&ty);
2896                                 write_option_block(&mut created_container, &mangled_container, &ty, is_clonable);
2897                                 if is_clonable {
2898                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2899                                 }
2900                         } else {
2901                                 unreachable!();
2902                         }
2903                         self.crate_types.write_new_template(mangled_container.clone(), true, &created_container);
2904                 }
2905                 true
2906         }
2907         fn path_to_generic_args(path: &syn::Path) -> Vec<&syn::Type> {
2908                 if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().next().unwrap().arguments {
2909                         args.args.iter().map(|gen| if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }).collect()
2910                 } else { unimplemented!(); }
2911         }
2912         fn write_c_mangled_container_path_intern<W: std::io::Write>
2913                         (&self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool, in_type: bool) -> bool {
2914                 let mut mangled_type: Vec<u8> = Vec::new();
2915                 if !self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) {
2916                         write!(w, "C{}_", ident).unwrap();
2917                         write!(mangled_type, "C{}_", ident).unwrap();
2918                 } else { assert_eq!(args.len(), 1); }
2919                 for arg in args.iter() {
2920                         macro_rules! write_path {
2921                                 ($p_arg: expr, $extra_write: expr) => {
2922                                         if let Some(subtype) = self.maybe_resolve_path(&$p_arg.path, generics) {
2923                                                 if self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) {
2924                                                         if !in_type {
2925                                                                 if self.c_type_has_inner_from_path(&subtype) {
2926                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, is_ref, is_mut, ptr_for_ref, false, true) { return false; }
2927                                                                 } else {
2928                                                                         // Option<T> needs to be converted to a *mut T, ie mut ptr-for-ref
2929                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, true, true, true, false, true) { return false; }
2930                                                                 }
2931                                                         } else {
2932                                                                 write!(w, "{}", $p_arg.path.segments.last().unwrap().ident).unwrap();
2933                                                         }
2934                                                 } else if self.is_known_container(&subtype, is_ref) || self.is_path_transparent_container(&$p_arg.path, generics, is_ref) {
2935                                                         if !self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(&$p_arg.path), generics,
2936                                                                         &subtype, is_ref, is_mut, ptr_for_ref, true) {
2937                                                                 return false;
2938                                                         }
2939                                                         self.write_c_mangled_container_path_intern(&mut mangled_type, Self::path_to_generic_args(&$p_arg.path),
2940                                                                 generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
2941                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
2942                                                                 self.write_c_mangled_container_path_intern(w2, Self::path_to_generic_args(&$p_arg.path),
2943                                                                         generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
2944                                                         }
2945                                                 } else {
2946                                                         let mut resolved = Vec::new();
2947                                                         let id =
2948                                                                 if self.write_c_path_intern(&mut resolved, &$p_arg.path, generics, false, false, false, false, false) {
2949                                                                         let inner = std::str::from_utf8(&resolved).unwrap();
2950                                                                         inner.rsplitn(2, "::").next().unwrap()
2951                                                                 } else {
2952                                                                         subtype.rsplitn(2, "::").next().unwrap()
2953                                                                 };
2954                                                         write!(w, "{}", id).unwrap();
2955                                                         write!(mangled_type, "{}", id).unwrap();
2956                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
2957                                                                 write!(w2, "{}", id).unwrap();
2958                                                         }
2959                                                 }
2960                                         } else { return false; }
2961                                 }
2962                         }
2963                         match generics.resolve_type(arg) {
2964                                 syn::Type::Tuple(tuple) => {
2965                                         if tuple.elems.len() == 0 {
2966                                                 write!(w, "None").unwrap();
2967                                                 write!(mangled_type, "None").unwrap();
2968                                         } else {
2969                                                 let mut mangled_tuple_type: Vec<u8> = Vec::new();
2970
2971                                                 // Figure out what the mangled type should look like. To disambiguate
2972                                                 // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
2973                                                 // them with a Z. Ideally we wouldn't use Z, but not many special chars are
2974                                                 // available for use in type names.
2975                                                 write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
2976                                                 write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
2977                                                 write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
2978                                                 for elem in tuple.elems.iter() {
2979                                                         if let syn::Type::Path(p) = elem {
2980                                                                 write_path!(p, Some(&mut mangled_tuple_type));
2981                                                         } else if let syn::Type::Reference(refelem) = elem {
2982                                                                 if let syn::Type::Path(p) = &*refelem.elem {
2983                                                                         write_path!(p, Some(&mut mangled_tuple_type));
2984                                                                 } else { return false; }
2985                                                         } else if let syn::Type::Array(_) = elem {
2986                                                                 let mut resolved = Vec::new();
2987                                                                 if !self.write_c_type_intern(&mut resolved, &elem, generics, false, false, false, false, false) { return false; }
2988                                                                 let array_inner = String::from_utf8(resolved).unwrap();
2989                                                                 let arr_name = array_inner.rsplitn(2, "::").next().unwrap();
2990                                                                 write!(w, "{}", arr_name).unwrap();
2991                                                                 write!(mangled_type, "{}", arr_name).unwrap();
2992                                                         } else { return false; }
2993                                                 }
2994                                                 write!(w, "Z").unwrap();
2995                                                 write!(mangled_type, "Z").unwrap();
2996                                                 write!(mangled_tuple_type, "Z").unwrap();
2997                                                 if !self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
2998                                                                 &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref) {
2999                                                         return false;
3000                                                 }
3001                                         }
3002                                 },
3003                                 syn::Type::Path(p_arg) => {
3004                                         write_path!(p_arg, None);
3005                                 },
3006                                 syn::Type::Reference(refty) => {
3007                                         if let syn::Type::Path(p_arg) = &*refty.elem {
3008                                                 write_path!(p_arg, None);
3009                                         } else if let syn::Type::Slice(_) = &*refty.elem {
3010                                                 // write_c_type will actually do exactly what we want here, we just need to
3011                                                 // make it a pointer so that its an option. Note that we cannot always convert
3012                                                 // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
3013                                                 // to edit it, hence we use *mut here instead of *const.
3014                                                 if args.len() != 1 { return false; }
3015                                                 write!(w, "*mut ").unwrap();
3016                                                 self.write_c_type(w, arg, None, true);
3017                                         } else { return false; }
3018                                 },
3019                                 syn::Type::Array(a) => {
3020                                         if let syn::Type::Path(p_arg) = &*a.elem {
3021                                                 let resolved = self.resolve_path(&p_arg.path, generics);
3022                                                 if !self.is_primitive(&resolved) { return false; }
3023                                                 if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
3024                                                         if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
3025                                                         if in_type || args.len() != 1 {
3026                                                                 write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
3027                                                                 write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
3028                                                         } else {
3029                                                                 let arrty = format!("[{}; {}]", resolved, len.base10_digits());
3030                                                                 let realty = self.c_type_from_path(&arrty, is_ref, ptr_for_ref).unwrap_or(&arrty);
3031                                                                 write!(w, "{}", realty).unwrap();
3032                                                                 write!(mangled_type, "{}", realty).unwrap();
3033                                                         }
3034                                                 } else { return false; }
3035                                         } else { return false; }
3036                                 },
3037                                 _ => { return false; },
3038                         }
3039                 }
3040                 if self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) { return true; }
3041                 // Push the "end of type" Z
3042                 write!(w, "Z").unwrap();
3043                 write!(mangled_type, "Z").unwrap();
3044
3045                 // Make sure the type is actually defined:
3046                 self.check_create_container(String::from_utf8(mangled_type).unwrap(), ident, args, generics, is_ref)
3047         }
3048         fn write_c_mangled_container_path<W: std::io::Write>(&self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
3049                 if !self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) {
3050                         write!(w, "{}::", Self::generated_container_path()).unwrap();
3051                 }
3052                 self.write_c_mangled_container_path_intern(w, args, generics, ident, is_ref, is_mut, ptr_for_ref, false)
3053         }
3054         pub fn get_c_mangled_container_type(&self, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, template_name: &str) -> Option<String> {
3055                 let mut out = Vec::new();
3056                 if !self.write_c_mangled_container_path(&mut out, args, generics, template_name, false, false, false) {
3057                         return None;
3058                 }
3059                 Some(String::from_utf8(out).unwrap())
3060         }
3061
3062         // **********************************
3063         // *** C Type Equivalent Printing ***
3064         // **********************************
3065
3066         fn write_c_path_intern<W: std::io::Write>(&self, w: &mut W, path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool, with_ref_lifetime: bool, c_ty: bool) -> bool {
3067                 let full_path = match self.maybe_resolve_path(&path, generics) {
3068                         Some(path) => path, None => return false };
3069                 if let Some(c_type) = self.c_type_from_path(&full_path, is_ref, ptr_for_ref) {
3070                         write!(w, "{}", c_type).unwrap();
3071                         true
3072                 } else if self.crate_types.traits.get(&full_path).is_some() {
3073                         // Note that we always use the crate:: prefix here as we are always referring to a
3074                         // concrete object which is of the generated type, it just implements the upstream
3075                         // type.
3076                         if is_ref && ptr_for_ref {
3077                                 write!(w, "*{} crate::{}", if is_mut { "mut" } else { "const" }, full_path).unwrap();
3078                         } else if is_ref {
3079                                 if with_ref_lifetime { unimplemented!(); }
3080                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
3081                         } else {
3082                                 write!(w, "crate::{}", full_path).unwrap();
3083                         }
3084                         true
3085                 } else if self.crate_types.opaques.get(&full_path).is_some() || self.crate_types.mirrored_enums.get(&full_path).is_some() {
3086                         let crate_pfx = if c_ty { "crate::" } else { "" };
3087                         if is_ref && ptr_for_ref {
3088                                 // ptr_for_ref implies we're returning the object, which we can't really do for
3089                                 // opaque or mirrored types without box'ing them, which is quite a waste, so return
3090                                 // the actual object itself (for opaque types we'll set the pointer to the actual
3091                                 // type and note that its a reference).
3092                                 write!(w, "{}{}", crate_pfx, full_path).unwrap();
3093                         } else if is_ref && with_ref_lifetime {
3094                                 assert!(!is_mut);
3095                                 // If we're concretizing something with a lifetime parameter, we have to pick a
3096                                 // lifetime, of which the only real available choice is `static`, obviously.
3097                                 write!(w, "&'static {}", crate_pfx).unwrap();
3098                                 if !c_ty {
3099                                         self.write_rust_path(w, generics, path, with_ref_lifetime, false);
3100                                 } else {
3101                                         // We shouldn't be mapping references in types, so panic here
3102                                         unimplemented!();
3103                                 }
3104                         } else if is_ref {
3105                                 write!(w, "&{}{}{}", if is_mut { "mut " } else { "" }, crate_pfx, full_path).unwrap();
3106                         } else {
3107                                 write!(w, "{}{}", crate_pfx, full_path).unwrap();
3108                         }
3109                         true
3110                 } else {
3111                         if let Some(trait_impls) = self.crate_types.traits_impld.get(&full_path) {
3112                                 if trait_impls.len() == 1 {
3113                                         // If this is a no-export'd crate and there's only one implementation in the
3114                                         // whole crate, just treat it as a reference to whatever the implementor is.
3115                                         if with_ref_lifetime {
3116                                                 // Hope we're being printed in function generics and let rustc derive the
3117                                                 // type.
3118                                                 write!(w, "_").unwrap();
3119                                         } else {
3120                                                 write!(w, "&crate::{}", trait_impls[0]).unwrap();
3121                                         }
3122                                         return true;
3123                                 }
3124                         }
3125                         false
3126                 }
3127         }
3128         fn write_c_type_intern<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool, with_ref_lifetime: bool, c_ty: bool) -> bool {
3129                 match generics.resolve_type(t) {
3130                         syn::Type::Path(p) => {
3131                                 if p.qself.is_some() {
3132                                         return false;
3133                                 }
3134                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
3135                                         if self.is_known_container(&full_path, is_ref) || self.is_path_transparent_container(&p.path, generics, is_ref) {
3136                                                 return self.write_c_mangled_container_path(w, Self::path_to_generic_args(&p.path), generics, &full_path, is_ref, is_mut, ptr_for_ref);
3137                                         }
3138                                         if let Some(aliased_type) = self.crate_types.type_aliases.get(&full_path).cloned() {
3139                                                 return self.write_c_type_intern(w, &aliased_type, None, is_ref, is_mut, ptr_for_ref, with_ref_lifetime, c_ty);
3140                                         }
3141                                 }
3142                                 self.write_c_path_intern(w, &p.path, generics, is_ref, is_mut, ptr_for_ref, with_ref_lifetime, c_ty)
3143                         },
3144                         syn::Type::Reference(r) => {
3145                                 self.write_c_type_intern(w, &*r.elem, generics, true, r.mutability.is_some(), ptr_for_ref, with_ref_lifetime, c_ty)
3146                         },
3147                         syn::Type::Array(a) => {
3148                                 if is_ref && is_mut {
3149                                         write!(w, "*mut [").unwrap();
3150                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref, with_ref_lifetime, c_ty) { return false; }
3151                                 } else if is_ref {
3152                                         write!(w, "*const [").unwrap();
3153                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref, with_ref_lifetime, c_ty) { return false; }
3154                                 }
3155                                 if let syn::Expr::Lit(l) = &a.len {
3156                                         if let syn::Lit::Int(i) = &l.lit {
3157                                                 let mut inner_ty = Vec::new();
3158                                                 if !self.write_c_type_intern(&mut inner_ty, &*a.elem, generics, false, false, ptr_for_ref, false, c_ty) { return false; }
3159                                                 let inner_ty_str = String::from_utf8(inner_ty).unwrap();
3160                                                 if !is_ref {
3161                                                         if let Some(ty) = self.c_type_from_path(&format!("[{}; {}]", inner_ty_str, i.base10_digits()), false, ptr_for_ref) {
3162                                                                 write!(w, "{}", ty).unwrap();
3163                                                                 true
3164                                                         } else { false }
3165                                                 } else {
3166                                                         write!(w, "; {}]", i).unwrap();
3167                                                         true
3168                                                 }
3169                                         } else { false }
3170                                 } else { false }
3171                         }
3172                         syn::Type::Slice(s) => {
3173                                 if !is_ref || is_mut { return false; }
3174                                 if let syn::Type::Path(p) = &*s.elem {
3175                                         let resolved = self.resolve_path(&p.path, generics);
3176                                         if self.is_primitive(&resolved) {
3177                                                 write!(w, "{}::{}slice", Self::container_templ_path(), resolved).unwrap();
3178                                                 true
3179                                         } else {
3180                                                 let mut inner_c_ty = Vec::new();
3181                                                 assert!(self.write_c_path_intern(&mut inner_c_ty, &p.path, generics, true, false, ptr_for_ref, with_ref_lifetime, c_ty));
3182                                                 let inner_ty_str = String::from_utf8(inner_c_ty).unwrap();
3183                                                 if self.is_clonable(&inner_ty_str) {
3184                                                         let inner_ty_ident = inner_ty_str.rsplitn(2, "::").next().unwrap();
3185                                                         let mangled_container = format!("CVec_{}Z", inner_ty_ident);
3186                                                         write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
3187                                                         self.check_create_container(mangled_container, "Vec", vec![&*s.elem], generics, false)
3188                                                 } else { false }
3189                                         }
3190                                 } else if let syn::Type::Reference(r) = &*s.elem {
3191                                         if let syn::Type::Path(p) = &*r.elem {
3192                                                 // Slices with "real types" inside are mapped as the equivalent non-ref Vec
3193                                                 let resolved = self.resolve_path(&p.path, generics);
3194                                                 let mangled_container = if let Some((ident, _)) = self.crate_types.opaques.get(&resolved) {
3195                                                         format!("CVec_{}Z", ident)
3196                                                 } else if let Some(en) = self.crate_types.mirrored_enums.get(&resolved) {
3197                                                         format!("CVec_{}Z", en.ident)
3198                                                 } else if let Some(id) = p.path.get_ident() {
3199                                                         format!("CVec_{}Z", id)
3200                                                 } else { return false; };
3201                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
3202                                                 self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false)
3203                                         } else if let syn::Type::Slice(sl2) = &*r.elem {
3204                                                 if let syn::Type::Reference(r2) = &*sl2.elem {
3205                                                         if let syn::Type::Path(p) = &*r2.elem {
3206                                                                 // Slices with slices with opaque types (with is_owned flags) are mapped as non-ref Vecs
3207                                                                 let resolved = self.resolve_path(&p.path, generics);
3208                                                                 let mangled_container = if let Some((ident, _)) = self.crate_types.opaques.get(&resolved) {
3209                                                                         format!("CVec_CVec_{}ZZ", ident)
3210                                                                 } else { return false; };
3211                                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
3212                                                                 let inner = &r2.elem;
3213                                                                 let vec_ty: syn::Type = syn::parse_quote!(Vec<#inner>);
3214                                                                 self.check_create_container(mangled_container, "Vec", vec![&vec_ty], generics, false)
3215                                                         } else { false }
3216                                                 } else { false }
3217                                         } else { false }
3218                                 } else if let syn::Type::Tuple(_) = &*s.elem {
3219                                         let mut args = syn::punctuated::Punctuated::<_, syn::token::Comma>::new();
3220                                         args.push(syn::GenericArgument::Type((*s.elem).clone()));
3221                                         let mut segments = syn::punctuated::Punctuated::new();
3222                                         segments.push(parse_quote!(Vec<#args>));
3223                                         self.write_c_type_intern(w, &syn::Type::Path(syn::TypePath { qself: None, path: syn::Path { leading_colon: None, segments } }), generics, false, is_mut, ptr_for_ref, with_ref_lifetime, c_ty)
3224                                 } else if let syn::Type::Array(a) = &*s.elem {
3225                                         if let syn::Expr::Lit(l) = &a.len {
3226                                                 if let syn::Lit::Int(i) = &l.lit {
3227                                                         let mut buf = Vec::new();
3228                                                         self.write_rust_type(&mut buf, generics, &*a.elem, false);
3229                                                         let arr_ty = String::from_utf8(buf).unwrap();
3230
3231                                                         let arr_str = format!("[{}; {}]", arr_ty, i.base10_digits());
3232                                                         let ty = self.c_type_from_path(&arr_str, false, ptr_for_ref).unwrap()
3233                                                                 .rsplitn(2, "::").next().unwrap();
3234
3235                                                         let mangled_container = format!("CVec_{}Z", ty);
3236                                                         write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
3237                                                         self.check_create_container(mangled_container, "Vec", vec![&*s.elem], generics, false)
3238                                                 } else { false }
3239                                         } else { false }
3240                                 } else { false }
3241                         },
3242                         syn::Type::Tuple(t) => {
3243                                 if t.elems.len() == 0 {
3244                                         true
3245                                 } else {
3246                                         self.write_c_mangled_container_path(w, t.elems.iter().collect(), generics,
3247                                                 &format!("{}Tuple", t.elems.len()), is_ref, is_mut, ptr_for_ref)
3248                                 }
3249                         },
3250                         _ => false,
3251                 }
3252         }
3253         pub fn write_c_type<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
3254                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref, false, true));
3255         }
3256         pub fn write_c_type_in_generic_param<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
3257                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref, true, false));
3258         }
3259         pub fn understood_c_path(&self, p: &syn::Path) -> bool {
3260                 self.write_c_path_intern(&mut std::io::sink(), p, None, false, false, false, false, true)
3261         }
3262         pub fn understood_c_type(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
3263                 self.write_c_type_intern(&mut std::io::sink(), t, generics, false, false, false, false, true)
3264         }
3265 }