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