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