_ 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::collections::{HashMap, HashSet};
  10 use std::fs::File;
  11 use std::io::Write;
  12 use std::hash;
  13
  14 use crate::blocks::*;
  15
  16 use proc_macro2::{TokenTree, Span};
  17
  18 // The following utils are used purely to build our known types maps - they break down all the
  19 // types we need to resolve to include the given object, and no more.
  20
  21 pub fn first_seg_self<'a>(t: &'a syn::Type) -> Option<impl Iterator<Item=&syn::PathSegment> + 'a> {
  22         match t {
  23                 syn::Type::Path(p) => {
  24                         if p.qself.is_some() || p.path.leading_colon.is_some() {
  25                                 return None;
  26                         }
  27                         let mut segs = p.path.segments.iter();
  28                         let ty = segs.next().unwrap();
  29                         if !ty.arguments.is_empty() { return None; }
  30                         if format!("{}", ty.ident) == "Self" {
  31                                 Some(segs)
  32                         } else { None }
  33                 },
  34                 _ => None,
  35         }
  36 }
  37
  38 pub fn get_single_remaining_path_seg<'a, I: Iterator<Item=&'a syn::PathSegment>>(segs: &mut I) -> Option<&'a syn::Ident> {
  39         if let Some(ty) = segs.next() {
  40                 if !ty.arguments.is_empty() { unimplemented!(); }
  41                 if segs.next().is_some() { return None; }
  42                 Some(&ty.ident)
  43         } else { None }
  44 }
  45
  46 pub fn single_ident_generic_path_to_ident(p: &syn::Path) -> Option<&syn::Ident> {
  47         if p.segments.len() == 1 {
  48                 Some(&p.segments.iter().next().unwrap().ident)
  49         } else { None }
  50 }
  51
  52 pub fn path_matches_nongeneric(p: &syn::Path, exp: &[&str]) -> bool {
  53         if p.segments.len() != exp.len() { return false; }
  54         for (seg, e) in p.segments.iter().zip(exp.iter()) {
  55                 if seg.arguments != syn::PathArguments::None { return false; }
  56                 if &format!("{}", seg.ident) != *e { return false; }
  57         }
  58         true
  59 }
  60
  61 #[derive(Debug, PartialEq)]
  62 pub enum ExportStatus {
  63         Export,
  64         NoExport,
  65         TestOnly,
  66 }
  67 /// Gets the ExportStatus of an object (struct, fn, etc) given its attributes.
  68 pub fn export_status(attrs: &[syn::Attribute]) -> ExportStatus {
  69         for attr in attrs.iter() {
  70                 let tokens_clone = attr.tokens.clone();
  71                 let mut token_iter = tokens_clone.into_iter();
  72                 if let Some(token) = token_iter.next() {
  73                         match token {
  74                                 TokenTree::Punct(c) if c.as_char() == '=' => {
  75                                         // Really not sure where syn gets '=' from here -
  76                                         // it somehow represents '///' or '//!'
  77                                 },
  78                                 TokenTree::Group(g) => {
  79                                         if format!("{}", single_ident_generic_path_to_ident(&attr.path).unwrap()) == "cfg" {
  80                                                 let mut iter = g.stream().into_iter();
  81                                                 if let TokenTree::Ident(i) = iter.next().unwrap() {
  82                                                         if i == "any" {
  83                                                                 // #[cfg(any(test, feature = ""))]
  84                                                                 if let TokenTree::Group(g) = iter.next().unwrap() {
  85                                                                         if let TokenTree::Ident(i) = g.stream().into_iter().next().unwrap() {
  86                                                                                 if i == "test" || i == "feature" {
  87                                                                                         // If its cfg(feature(...)) we assume its test-only
  88                                                                                         return ExportStatus::TestOnly;
  89                                                                                 }
  90                                                                         }
  91                                                                 }
  92                                                         } else if i == "test" || i == "feature" {
  93                                                                 // If its cfg(feature(...)) we assume its test-only
  94                                                                 return ExportStatus::TestOnly;
  95                                                         }
  96                                                 }
  97                                         }
  98                                         continue; // eg #[derive()]
  99                                 },
 100                                 _ => unimplemented!(),
 101                         }
 102                 } else { continue; }
 103                 match token_iter.next().unwrap() {
 104                         TokenTree::Literal(lit) => {
 105                                 let line = format!("{}", lit);
 106                                 if line.contains("(C-not exported)") {
 107                                         return ExportStatus::NoExport;
 108                                 }
 109                         },
 110                         _ => unimplemented!(),
 111                 }
 112         }
 113         ExportStatus::Export
 114 }
 115
 116 pub fn assert_simple_bound(bound: &syn::TraitBound) {
 117         if bound.paren_token.is_some() || bound.lifetimes.is_some() { unimplemented!(); }
 118         if let syn::TraitBoundModifier::Maybe(_) = bound.modifier { unimplemented!(); }
 119 }
 120
 121 /// Returns true if the enum will be mapped as an opaue (ie struct with a pointer to the underlying
 122 /// type), otherwise it is mapped into a transparent, C-compatible version of itself.
 123 pub fn is_enum_opaque(e: &syn::ItemEnum) -> bool {
 124         for var in e.variants.iter() {
 125                 if let syn::Fields::Named(fields) = &var.fields {
 126                         for field in fields.named.iter() {
 127                                 match export_status(&field.attrs) {
 128                                         ExportStatus::Export|ExportStatus::TestOnly => {},
 129                                         ExportStatus::NoExport => return true,
 130                                 }
 131                         }
 132                 } else if let syn::Fields::Unnamed(fields) = &var.fields {
 133                         for field in fields.unnamed.iter() {
 134                                 match export_status(&field.attrs) {
 135                                         ExportStatus::Export|ExportStatus::TestOnly => {},
 136                                         ExportStatus::NoExport => return true,
 137                                 }
 138                         }
 139                 }
 140         }
 141         false
 142 }
 143
 144 /// A stack of sets of generic resolutions.
 145 ///
 146 /// This tracks the template parameters for a function, struct, or trait, allowing resolution into
 147 /// a concrete type. By pushing a new context onto the stack, this can track a function's template
 148 /// parameters inside of a generic struct or trait.
 149 ///
 150 /// It maps both direct types as well as Deref<Target = X>, mapping them via the provided
 151 /// TypeResolver's resolve_path function (ie traits map to the concrete jump table, structs to the
 152 /// concrete C container struct, etc).
 153 pub struct GenericTypes<'a> {
 154         typed_generics: Vec<HashMap<&'a syn::Ident, (String, Option<&'a syn::Path>)>>,
 155 }
 156 impl<'a> GenericTypes<'a> {
 157         pub fn new() -> Self {
 158                 Self { typed_generics: vec![HashMap::new()], }
 159         }
 160
 161         /// push a new context onto the stack, allowing for a new set of generics to be learned which
 162         /// will override any lower contexts, but which will still fall back to resoltion via lower
 163         /// contexts.
 164         pub fn push_ctx(&mut self) {
 165                 self.typed_generics.push(HashMap::new());
 166         }
 167         /// pop the latest context off the stack.
 168         pub fn pop_ctx(&mut self) {
 169                 self.typed_generics.pop();
 170         }
 171
 172         /// Learn the generics in generics in the current context, given a TypeResolver.
 173         pub fn learn_generics<'b, 'c>(&mut self, generics: &'a syn::Generics, types: &'b TypeResolver<'a, 'c>) -> bool {
 174                 // First learn simple generics...
 175                 for generic in generics.params.iter() {
 176                         match generic {
 177                                 syn::GenericParam::Type(type_param) => {
 178                                         let mut non_lifetimes_processed = false;
 179                                         for bound in type_param.bounds.iter() {
 180                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 181                                                         if let Some(ident) = single_ident_generic_path_to_ident(&trait_bound.path) {
 182                                                                 match &format!("{}", ident) as &str { "Send" => continue, "Sync" => continue, _ => {} }
 183                                                         }
 184                                                         if path_matches_nongeneric(&trait_bound.path, &["core", "clone", "Clone"]) { continue; }
 185
 186                                                         assert_simple_bound(&trait_bound);
 187                                                         if let Some(mut path) = types.maybe_resolve_path(&trait_bound.path, None) {
 188                                                                 if types.skip_path(&path) { continue; }
 189                                                                 if non_lifetimes_processed { return false; }
 190                                                                 non_lifetimes_processed = true;
 191                                                                 let new_ident = if path != "std::ops::Deref" {
 192                                                                         path = "crate::".to_string() + &path;
 193                                                                         Some(&trait_bound.path)
 194                                                                 } else { None };
 195                                                                 self.typed_generics.last_mut().unwrap().insert(&type_param.ident, (path, new_ident));
 196                                                         } else { return false; }
 197                                                 }
 198                                         }
 199                                 },
 200                                 _ => {},
 201                         }
 202                 }
 203                 // Then find generics where we are required to pass a Deref<Target=X> and pretend its just X.
 204                 if let Some(wh) = &generics.where_clause {
 205                         for pred in wh.predicates.iter() {
 206                                 if let syn::WherePredicate::Type(t) = pred {
 207                                         if let syn::Type::Path(p) = &t.bounded_ty {
 208                                                 if p.qself.is_some() { return false; }
 209                                                 if p.path.leading_colon.is_some() { return false; }
 210                                                 let mut p_iter = p.path.segments.iter();
 211                                                 if let Some(gen) = self.typed_generics.last_mut().unwrap().get_mut(&p_iter.next().unwrap().ident) {
 212                                                         if gen.0 != "std::ops::Deref" { return false; }
 213                                                         if &format!("{}", p_iter.next().unwrap().ident) != "Target" { return false; }
 214
 215                                                         let mut non_lifetimes_processed = false;
 216                                                         for bound in t.bounds.iter() {
 217                                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 218                                                                         if non_lifetimes_processed { return false; }
 219                                                                         non_lifetimes_processed = true;
 220                                                                         assert_simple_bound(&trait_bound);
 221                                                                         *gen = ("crate::".to_string() + &types.resolve_path(&trait_bound.path, None),
 222                                                                                 Some(&trait_bound.path));
 223                                                                 }
 224                                                         }
 225                                                 } else { return false; }
 226                                         } else { return false; }
 227                                 }
 228                         }
 229                 }
 230                 for (_, (_, ident)) in self.typed_generics.last().unwrap().iter() {
 231                         if ident.is_none() { return false; }
 232                 }
 233                 true
 234         }
 235
 236         /// Learn the associated types from the trait in the current context.
 237         pub fn learn_associated_types<'b, 'c>(&mut self, t: &'a syn::ItemTrait, types: &'b TypeResolver<'a, 'c>) {
 238                 for item in t.items.iter() {
 239                         match item {
 240                                 &syn::TraitItem::Type(ref t) => {
 241                                         if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
 242                                         let mut bounds_iter = t.bounds.iter();
 243                                         match bounds_iter.next().unwrap() {
 244                                                 syn::TypeParamBound::Trait(tr) => {
 245                                                         assert_simple_bound(&tr);
 246                                                         if let Some(mut path) = types.maybe_resolve_path(&tr.path, None) {
 247                                                                 if types.skip_path(&path) { continue; }
 248                                                                 // In general we handle Deref<Target=X> as if it were just X (and
 249                                                                 // implement Deref<Target=Self> for relevant types). We don't
 250                                                                 // bother to implement it for associated types, however, so we just
 251                                                                 // ignore such bounds.
 252                                                                 let new_ident = if path != "std::ops::Deref" {
 253                                                                         path = "crate::".to_string() + &path;
 254                                                                         Some(&tr.path)
 255                                                                 } else { None };
 256                                                                 self.typed_generics.last_mut().unwrap().insert(&t.ident, (path, new_ident));
 257                                                         } else { unimplemented!(); }
 258                                                 },
 259                                                 _ => unimplemented!(),
 260                                         }
 261                                         if bounds_iter.next().is_some() { unimplemented!(); }
 262                                 },
 263                                 _ => {},
 264                         }
 265                 }
 266         }
 267
 268         /// Attempt to resolve an Ident as a generic parameter and return the full path.
 269         pub fn maybe_resolve_ident<'b>(&'b self, ident: &syn::Ident) -> Option<&'b String> {
 270                 for gen in self.typed_generics.iter().rev() {
 271                         if let Some(res) = gen.get(ident).map(|(a, _)| a) {
 272                                 return Some(res);
 273                         }
 274                 }
 275                 None
 276         }
 277         /// Attempt to resolve a Path as a generic parameter and return the full path. as both a string
 278         /// and syn::Path.
 279         pub fn maybe_resolve_path<'b>(&'b self, path: &syn::Path) -> Option<(&'b String, &'a syn::Path)> {
 280                 if let Some(ident) = path.get_ident() {
 281                         for gen in self.typed_generics.iter().rev() {
 282                                 if let Some(res) = gen.get(ident).map(|(a, b)| (a, b.unwrap())) {
 283                                         return Some(res);
 284                                 }
 285                         }
 286                 } else {
 287                         // Associated types are usually specified as "Self::Generic", so we check for that
 288                         // explicitly here.
 289                         let mut it = path.segments.iter();
 290                         if path.segments.len() == 2 && format!("{}", it.next().unwrap().ident) == "Self" {
 291                                 let ident = &it.next().unwrap().ident;
 292                                 for gen in self.typed_generics.iter().rev() {
 293                                         if let Some(res) = gen.get(ident).map(|(a, b)| (a, b.unwrap())) {
 294                                                 return Some(res);
 295                                         }
 296                                 }
 297                         }
 298                 }
 299                 None
 300         }
 301 }
 302
 303 #[derive(Clone, PartialEq)]
 304 // The type of declaration and the object itself
 305 pub enum DeclType<'a> {
 306         MirroredEnum,
 307         Trait(&'a syn::ItemTrait),
 308         StructImported,
 309         StructIgnored,
 310         EnumIgnored,
 311 }
 312
 313 pub struct ImportResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 314         module_path: &'mod_lifetime str,
 315         imports: HashMap<syn::Ident, (String, syn::Path)>,
 316         declared: HashMap<syn::Ident, DeclType<'crate_lft>>,
 317         priv_modules: HashSet<syn::Ident>,
 318 }
 319 impl<'mod_lifetime, 'crate_lft: 'mod_lifetime> ImportResolver<'mod_lifetime, 'crate_lft> {
 320         fn process_use_intern(imports: &mut HashMap<syn::Ident, (String, syn::Path)>, u: &syn::UseTree, partial_path: &str, mut path: syn::punctuated::Punctuated<syn::PathSegment, syn::token::Colon2>) {
 321                 match u {
 322                         syn::UseTree::Path(p) => {
 323                                 let new_path = format!("{}{}::", partial_path, p.ident);
 324                                 path.push(syn::PathSegment { ident: p.ident.clone(), arguments: syn::PathArguments::None });
 325                                 Self::process_use_intern(imports, &p.tree, &new_path, path);
 326                         },
 327                         syn::UseTree::Name(n) => {
 328                                 let full_path = format!("{}{}", partial_path, n.ident);
 329                                 path.push(syn::PathSegment { ident: n.ident.clone(), arguments: syn::PathArguments::None });
 330                                 imports.insert(n.ident.clone(), (full_path, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 331                         },
 332                         syn::UseTree::Group(g) => {
 333                                 for i in g.items.iter() {
 334                                         Self::process_use_intern(imports, i, partial_path, path.clone());
 335                                 }
 336                         },
 337                         syn::UseTree::Rename(r) => {
 338                                 let full_path = format!("{}{}", partial_path, r.ident);
 339                                 path.push(syn::PathSegment { ident: r.ident.clone(), arguments: syn::PathArguments::None });
 340                                 imports.insert(r.rename.clone(), (full_path, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 341                         },
 342                         syn::UseTree::Glob(_) => {
 343                                 eprintln!("Ignoring * use for {} - this may result in resolution failures", partial_path);
 344                         },
 345                 }
 346         }
 347
 348         fn process_use(imports: &mut HashMap<syn::Ident, (String, syn::Path)>, u: &syn::ItemUse) {
 349                 if let syn::Visibility::Public(_) = u.vis {
 350                         // We actually only use these for #[cfg(fuzztarget)]
 351                         eprintln!("Ignoring pub(use) tree!");
 352                         return;
 353                 }
 354                 if u.leading_colon.is_some() { eprintln!("Ignoring leading-colon use!"); return; }
 355                 Self::process_use_intern(imports, &u.tree, "", syn::punctuated::Punctuated::new());
 356         }
 357
 358         fn insert_primitive(imports: &mut HashMap<syn::Ident, (String, syn::Path)>, id: &str) {
 359                 let ident = syn::Ident::new(id, Span::call_site());
 360                 let mut path = syn::punctuated::Punctuated::new();
 361                 path.push(syn::PathSegment { ident: ident.clone(), arguments: syn::PathArguments::None });
 362                 imports.insert(ident, (id.to_owned(), syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 363         }
 364
 365         pub fn new(module_path: &'mod_lifetime str, contents: &'crate_lft [syn::Item]) -> Self {
 366                 let mut imports = HashMap::new();
 367                 // Add primitives to the "imports" list:
 368                 Self::insert_primitive(&mut imports, "bool");
 369                 Self::insert_primitive(&mut imports, "u64");
 370                 Self::insert_primitive(&mut imports, "u32");
 371                 Self::insert_primitive(&mut imports, "u16");
 372                 Self::insert_primitive(&mut imports, "u8");
 373                 Self::insert_primitive(&mut imports, "usize");
 374                 Self::insert_primitive(&mut imports, "str");
 375                 Self::insert_primitive(&mut imports, "String");
 376
 377                 // These are here to allow us to print native Rust types in trait fn impls even if we don't
 378                 // have C mappings:
 379                 Self::insert_primitive(&mut imports, "Result");
 380                 Self::insert_primitive(&mut imports, "Vec");
 381                 Self::insert_primitive(&mut imports, "Option");
 382
 383                 let mut declared = HashMap::new();
 384                 let mut priv_modules = HashSet::new();
 385
 386                 for item in contents.iter() {
 387                         match item {
 388                                 syn::Item::Use(u) => Self::process_use(&mut imports, &u),
 389                                 syn::Item::Struct(s) => {
 390                                         if let syn::Visibility::Public(_) = s.vis {
 391                                                 match export_status(&s.attrs) {
 392                                                         ExportStatus::Export => { declared.insert(s.ident.clone(), DeclType::StructImported); },
 393                                                         ExportStatus::NoExport => { declared.insert(s.ident.clone(), DeclType::StructIgnored); },
 394                                                         ExportStatus::TestOnly => continue,
 395                                                 }
 396                                         }
 397                                 },
 398                                 syn::Item::Type(t) if export_status(&t.attrs) == ExportStatus::Export => {
 399                                         if let syn::Visibility::Public(_) = t.vis {
 400                                                 let mut process_alias = true;
 401                                                 for tok in t.generics.params.iter() {
 402                                                         if let syn::GenericParam::Lifetime(_) = tok {}
 403                                                         else { process_alias = false; }
 404                                                 }
 405                                                 if process_alias {
 406                                                         match &*t.ty {
 407                                                                 syn::Type::Path(_) => { declared.insert(t.ident.clone(), DeclType::StructImported); },
 408                                                                 _ => {},
 409                                                         }
 410                                                 }
 411                                         }
 412                                 },
 413                                 syn::Item::Enum(e) => {
 414                                         if let syn::Visibility::Public(_) = e.vis {
 415                                                 match export_status(&e.attrs) {
 416                                                         ExportStatus::Export if is_enum_opaque(e) => { declared.insert(e.ident.clone(), DeclType::EnumIgnored); },
 417                                                         ExportStatus::Export => { declared.insert(e.ident.clone(), DeclType::MirroredEnum); },
 418                                                         _ => continue,
 419                                                 }
 420                                         }
 421                                 },
 422                                 syn::Item::Trait(t) if export_status(&t.attrs) == ExportStatus::Export => {
 423                                         if let syn::Visibility::Public(_) = t.vis {
 424                                                 declared.insert(t.ident.clone(), DeclType::Trait(t));
 425                                         }
 426                                 },
 427                                 syn::Item::Mod(m) => {
 428                                         priv_modules.insert(m.ident.clone());
 429                                 },
 430                                 _ => {},
 431                         }
 432                 }
 433
 434                 Self { module_path, imports, declared, priv_modules }
 435         }
 436
 437         pub fn get_declared_type(&self, ident: &syn::Ident) -> Option<&DeclType<'crate_lft>> {
 438                 self.declared.get(ident)
 439         }
 440
 441         pub fn maybe_resolve_declared(&self, id: &syn::Ident) -> Option<&DeclType<'crate_lft>> {
 442                 self.declared.get(id)
 443         }
 444
 445         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
 446                 if let Some((imp, _)) = self.imports.get(id) {
 447                         Some(imp.clone())
 448                 } else if self.declared.get(id).is_some() {
 449                         Some(self.module_path.to_string() + "::" + &format!("{}", id))
 450                 } else { None }
 451         }
 452
 453         pub fn maybe_resolve_non_ignored_ident(&self, id: &syn::Ident) -> Option<String> {
 454                 if let Some((imp, _)) = self.imports.get(id) {
 455                         Some(imp.clone())
 456                 } else if let Some(decl_type) = self.declared.get(id) {
 457                         match decl_type {
 458                                 DeclType::StructIgnored => None,
 459                                 _ => Some(self.module_path.to_string() + "::" + &format!("{}", id)),
 460                         }
 461                 } else { None }
 462         }
 463
 464         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
 465                 let p = if let Some(gen_types) = generics {
 466                         if let Some((_, synpath)) = gen_types.maybe_resolve_path(p_arg) {
 467                                 synpath
 468                         } else { p_arg }
 469                 } else { p_arg };
 470
 471                 if p.leading_colon.is_some() {
 472                         Some(p.segments.iter().enumerate().map(|(idx, seg)| {
 473                                 format!("{}{}", if idx == 0 { "" } else { "::" }, seg.ident)
 474                         }).collect())
 475                 } else if let Some(id) = p.get_ident() {
 476                         self.maybe_resolve_ident(id)
 477                 } else {
 478                         if p.segments.len() == 1 {
 479                                 let seg = p.segments.iter().next().unwrap();
 480                                 return self.maybe_resolve_ident(&seg.ident);
 481                         }
 482                         let mut seg_iter = p.segments.iter();
 483                         let first_seg = seg_iter.next().unwrap();
 484                         let remaining: String = seg_iter.map(|seg| {
 485                                 format!("::{}", seg.ident)
 486                         }).collect();
 487                         if let Some((imp, _)) = self.imports.get(&first_seg.ident) {
 488                                 if remaining != "" {
 489                                         Some(imp.clone() + &remaining)
 490                                 } else {
 491                                         Some(imp.clone())
 492                                 }
 493                         } else if let Some(_) = self.priv_modules.get(&first_seg.ident) {
 494                                 Some(format!("{}::{}{}", self.module_path, first_seg.ident, remaining))
 495                         } else { None }
 496                 }
 497         }
 498
 499         /// Map all the Paths in a Type into absolute paths given a set of imports (generated via process_use_intern)
 500         pub fn resolve_imported_refs(&self, mut ty: syn::Type) -> syn::Type {
 501                 match &mut ty {
 502                         syn::Type::Path(p) => {
 503                                 if let Some(ident) = p.path.get_ident() {
 504                                         if let Some((_, newpath)) = self.imports.get(ident) {
 505                                                 p.path = newpath.clone();
 506                                         }
 507                                 } else { unimplemented!(); }
 508                         },
 509                         syn::Type::Reference(r) => {
 510                                 r.elem = Box::new(self.resolve_imported_refs((*r.elem).clone()));
 511                         },
 512                         syn::Type::Slice(s) => {
 513                                 s.elem = Box::new(self.resolve_imported_refs((*s.elem).clone()));
 514                         },
 515                         syn::Type::Tuple(t) => {
 516                                 for e in t.elems.iter_mut() {
 517                                         *e = self.resolve_imported_refs(e.clone());
 518                                 }
 519                         },
 520                         _ => unimplemented!(),
 521                 }
 522                 ty
 523         }
 524 }
 525
 526 // templates_defined is walked to write the C++ header, so if we use the default hashing it get
 527 // reordered on each genbindings run. Instead, we use SipHasher (which defaults to 0-keys) so that
 528 // the sorting is stable across runs. It is deprecated, but the "replacement" doesn't actually
 529 // accomplish the same goals, so we just ignore it.
 530 #[allow(deprecated)]
 531 pub type NonRandomHash = hash::BuildHasherDefault<hash::SipHasher>;
 532
 533 /// Top-level struct tracking everything which has been defined while walking the crate.
 534 pub struct CrateTypes<'a> {
 535         /// This may contain structs or enums, but only when either is mapped as
 536         /// struct X { inner: *mut originalX, .. }
 537         pub opaques: HashMap<String, &'a syn::Ident>,
 538         /// Enums which are mapped as C enums with conversion functions
 539         pub mirrored_enums: HashMap<String, &'a syn::ItemEnum>,
 540         /// Traits which are mapped as a pointer + jump table
 541         pub traits: HashMap<String, &'a syn::ItemTrait>,
 542         /// Aliases from paths to some other Type
 543         pub type_aliases: HashMap<String, syn::Type>,
 544         /// Value is an alias to Key (maybe with some generics)
 545         pub reverse_alias_map: HashMap<String, Vec<(syn::Path, syn::PathArguments)>>,
 546         /// Template continer types defined, map from mangled type name -> whether a destructor fn
 547         /// exists.
 548         ///
 549         /// This is used at the end of processing to make C++ wrapper classes
 550         pub templates_defined: HashMap<String, bool, NonRandomHash>,
 551         /// The output file for any created template container types, written to as we find new
 552         /// template containers which need to be defined.
 553         pub template_file: &'a mut File,
 554         /// Set of containers which are clonable
 555         pub clonable_types: HashSet<String>,
 556         /// Key impls Value
 557         pub trait_impls: HashMap<String, Vec<String>>,
 558 }
 559
 560 /// A struct which tracks resolving rust types into C-mapped equivalents, exists for one specific
 561 /// module but contains a reference to the overall CrateTypes tracking.
 562 pub struct TypeResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 563         pub orig_crate: &'mod_lifetime str,
 564         pub module_path: &'mod_lifetime str,
 565         pub crate_types: &'mod_lifetime mut CrateTypes<'crate_lft>,
 566         types: ImportResolver<'mod_lifetime, 'crate_lft>,
 567 }
 568
 569 /// Returned by write_empty_rust_val_check_suffix to indicate what type of dereferencing needs to
 570 /// happen to get the inner value of a generic.
 571 enum EmptyValExpectedTy {
 572         /// A type which has a flag for being empty (eg an array where we treat all-0s as empty).
 573         NonPointer,
 574         /// A pointer that we want to dereference and move out of.
 575         OwnedPointer,
 576         /// A pointer which we want to convert to a reference.
 577         ReferenceAsPointer,
 578 }
 579
 580 impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 581         pub fn new(orig_crate: &'a str, module_path: &'a str, types: ImportResolver<'a, 'c>, crate_types: &'a mut CrateTypes<'c>) -> Self {
 582                 Self { orig_crate, module_path, types, crate_types }
 583         }
 584
 585         // *************************************************
 586         // *** Well know type and conversion definitions ***
 587         // *************************************************
 588
 589         /// Returns true we if can just skip passing this to C entirely
 590         fn skip_path(&self, full_path: &str) -> bool {
 591                 full_path == "bitcoin::secp256k1::Secp256k1" ||
 592                 full_path == "bitcoin::secp256k1::Signing" ||
 593                 full_path == "bitcoin::secp256k1::Verification"
 594         }
 595         /// Returns true we if can just skip passing this to C entirely
 596         fn no_arg_path_to_rust(&self, full_path: &str) -> &str {
 597                 if full_path == "bitcoin::secp256k1::Secp256k1" {
 598                         "secp256k1::SECP256K1"
 599                 } else { unimplemented!(); }
 600         }
 601
 602         /// Returns true if the object is a primitive and is mapped as-is with no conversion
 603         /// whatsoever.
 604         pub fn is_primitive(&self, full_path: &str) -> bool {
 605                 match full_path {
 606                         "bool" => true,
 607                         "u64" => true,
 608                         "u32" => true,
 609                         "u16" => true,
 610                         "u8" => true,
 611                         "usize" => true,
 612                         _ => false,
 613                 }
 614         }
 615         pub fn is_clonable(&self, ty: &str) -> bool {
 616                 if self.crate_types.clonable_types.contains(ty) { return true; }
 617                 if self.is_primitive(ty) { return true; }
 618                 match ty {
 619                         "()" => true,
 620                         "crate::c_types::Signature" => true,
 621                         "crate::c_types::TxOut" => true,
 622                         _ => false,
 623                 }
 624         }
 625         /// Gets the C-mapped type for types which are outside of the crate, or which are manually
 626         /// ignored by for some reason need mapping anyway.
 627         fn c_type_from_path<'b>(&self, full_path: &'b str, is_ref: bool, _ptr_for_ref: bool) -> Option<&'b str> {
 628                 if self.is_primitive(full_path) {
 629                         return Some(full_path);
 630                 }
 631                 match full_path {
 632                         "Result" => Some("crate::c_types::derived::CResult"),
 633                         "Vec" if !is_ref => Some("crate::c_types::derived::CVec"),
 634                         "Option" => Some(""),
 635
 636                         // Note that no !is_ref types can map to an array because Rust and C's call semantics
 637                         // for arrays are different (https://github.com/eqrion/cbindgen/issues/528)
 638
 639                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 640                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes"),
 641                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes"),
 642                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes"),
 643                         "[u8; 3]" if !is_ref => Some("crate::c_types::ThreeBytes"), // Used for RGB values
 644
 645                         "str" if is_ref => Some("crate::c_types::Str"),
 646                         "String" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 647                         "String" if is_ref => Some("crate::c_types::Str"),
 648
 649                         "std::time::Duration" => Some("u64"),
 650
 651                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey"),
 652                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature"),
 653                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some("*const [u8; 32]"),
 654                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey"),
 655                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error"),
 656                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice"),
 657                         "bitcoin::blockdata::script::Script" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 658                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::chain::transaction::OutPoint"),
 659                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction"),
 660                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut"),
 661                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network"),
 662                         "bitcoin::blockdata::block::BlockHeader" if is_ref  => Some("*const [u8; 80]"),
 663                         "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
 664
 665                         // Newtypes that we just expose in their original form.
 666                         "bitcoin::hash_types::Txid" if is_ref  => Some("*const [u8; 32]"),
 667                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 668                         "bitcoin::hash_types::BlockHash" if is_ref  => Some("*const [u8; 32]"),
 669                         "bitcoin::hash_types::BlockHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 670                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 671                         "ln::channelmanager::PaymentHash" if is_ref => Some("*const [u8; 32]"),
 672                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 673                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("*const [u8; 32]"),
 674                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 675                         "ln::channelmanager::PaymentSecret" if is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 676                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 677
 678                         // Override the default since Records contain an fmt with a lifetime:
 679                         "util::logger::Record" => Some("*const std::os::raw::c_char"),
 680
 681                         _ => None,
 682                 }
 683         }
 684
 685         fn from_c_conversion_new_var_from_path<'b>(&self, _full_path: &str, _is_ref: bool) -> Option<(&'b str, &'b str)> {
 686                 None
 687         }
 688         fn from_c_conversion_prefix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 689                 if self.is_primitive(full_path) {
 690                         return Some("".to_owned());
 691                 }
 692                 match full_path {
 693                         "Vec" if !is_ref => Some("local_"),
 694                         "Result" if !is_ref => Some("local_"),
 695                         "Option" if is_ref => Some("&local_"),
 696                         "Option" => Some("local_"),
 697
 698                         "[u8; 32]" if is_ref => Some("unsafe { &*"),
 699                         "[u8; 32]" if !is_ref => Some(""),
 700                         "[u8; 16]" if !is_ref => Some(""),
 701                         "[u8; 10]" if !is_ref => Some(""),
 702                         "[u8; 4]" if !is_ref => Some(""),
 703                         "[u8; 3]" if !is_ref => Some(""),
 704
 705                         "[u8]" if is_ref => Some(""),
 706                         "[usize]" if is_ref => Some(""),
 707
 708                         "str" if is_ref => Some(""),
 709                         "String" if !is_ref => Some("String::from_utf8("),
 710                         // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
 711                         // cannot create a &String.
 712
 713                         "std::time::Duration" => Some("std::time::Duration::from_secs("),
 714
 715                         "bitcoin::secp256k1::key::PublicKey" if is_ref => Some("&"),
 716                         "bitcoin::secp256k1::key::PublicKey" => Some(""),
 717                         "bitcoin::secp256k1::Signature" if is_ref => Some("&"),
 718                         "bitcoin::secp256k1::Signature" => Some(""),
 719                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("&::bitcoin::secp256k1::key::SecretKey::from_slice(&unsafe { *"),
 720                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(""),
 721                         "bitcoin::blockdata::script::Script" if is_ref => Some("&::bitcoin::blockdata::script::Script::from(Vec::from("),
 722                         "bitcoin::blockdata::script::Script" if !is_ref => Some("::bitcoin::blockdata::script::Script::from("),
 723                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some("&"),
 724                         "bitcoin::blockdata::transaction::Transaction" => Some(""),
 725                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(""),
 726                         "bitcoin::network::constants::Network" => Some(""),
 727                         "bitcoin::blockdata::block::BlockHeader" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
 728                         "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
 729
 730                         // Newtypes that we just expose in their original form.
 731                         "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
 732                         "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
 733                         "bitcoin::hash_types::BlockHash" => Some("::bitcoin::hash_types::BlockHash::from_slice(&"),
 734                         "ln::channelmanager::PaymentHash" if !is_ref => Some("::lightning::ln::channelmanager::PaymentHash("),
 735                         "ln::channelmanager::PaymentHash" if is_ref => Some("&::lightning::ln::channelmanager::PaymentHash(unsafe { *"),
 736                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("::lightning::ln::channelmanager::PaymentPreimage("),
 737                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&::lightning::ln::channelmanager::PaymentPreimage(unsafe { *"),
 738                         "ln::channelmanager::PaymentSecret" => Some("::lightning::ln::channelmanager::PaymentSecret("),
 739
 740                         // List of traits we map (possibly during processing of other files):
 741                         "crate::util::logger::Logger" => Some(""),
 742
 743                         _ => None,
 744                 }.map(|s| s.to_owned())
 745         }
 746         fn from_c_conversion_suffix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 747                 if self.is_primitive(full_path) {
 748                         return Some("".to_owned());
 749                 }
 750                 match full_path {
 751                         "Vec" if !is_ref => Some(""),
 752                         "Option" => Some(""),
 753                         "Result" if !is_ref => Some(""),
 754
 755                         "[u8; 32]" if is_ref => Some("}"),
 756                         "[u8; 32]" if !is_ref => Some(".data"),
 757                         "[u8; 16]" if !is_ref => Some(".data"),
 758                         "[u8; 10]" if !is_ref => Some(".data"),
 759                         "[u8; 4]" if !is_ref => Some(".data"),
 760                         "[u8; 3]" if !is_ref => Some(".data"),
 761
 762                         "[u8]" if is_ref => Some(".to_slice()"),
 763                         "[usize]" if is_ref => Some(".to_slice()"),
 764
 765                         "str" if is_ref => Some(".into()"),
 766                         "String" if !is_ref => Some(".into_rust()).unwrap()"),
 767
 768                         "std::time::Duration" => Some(")"),
 769
 770                         "bitcoin::secp256k1::key::PublicKey" => Some(".into_rust()"),
 771                         "bitcoin::secp256k1::Signature" => Some(".into_rust()"),
 772                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(".into_rust()"),
 773                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("}[..]).unwrap()"),
 774                         "bitcoin::blockdata::script::Script" if is_ref => Some(".to_slice()))"),
 775                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_rust())"),
 776                         "bitcoin::blockdata::transaction::Transaction" => Some(".into_bitcoin()"),
 777                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(".into_rust()"),
 778                         "bitcoin::network::constants::Network" => Some(".into_bitcoin()"),
 779                         "bitcoin::blockdata::block::BlockHeader" => Some(" }).unwrap()"),
 780                         "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
 781
 782                         // Newtypes that we just expose in their original form.
 783                         "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
 784                         "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
 785                         "bitcoin::hash_types::BlockHash" if !is_ref => Some(".data[..]).unwrap()"),
 786                         "ln::channelmanager::PaymentHash" if !is_ref => Some(".data)"),
 787                         "ln::channelmanager::PaymentHash" if is_ref => Some(" })"),
 788                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some(".data)"),
 789                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(" })"),
 790                         "ln::channelmanager::PaymentSecret" => Some(".data)"),
 791
 792                         // List of traits we map (possibly during processing of other files):
 793                         "crate::util::logger::Logger" => Some(""),
 794
 795                         _ => None,
 796                 }.map(|s| s.to_owned())
 797         }
 798
 799         fn to_c_conversion_new_var_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<(&'b str, &'b str)> {
 800                 if self.is_primitive(full_path) {
 801                         return None;
 802                 }
 803                 match full_path {
 804                         "[u8]" if is_ref => Some(("crate::c_types::u8slice::from_slice(", ")")),
 805                         "[usize]" if is_ref => Some(("crate::c_types::usizeslice::from_slice(", ")")),
 806
 807                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 808                         "bitcoin::blockdata::transaction::Transaction" if !is_ref => Some(("::bitcoin::consensus::encode::serialize(&", ")")),
 809                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(("{ let mut s = [0u8; 80]; s[..].copy_from_slice(&::bitcoin::consensus::encode::serialize(", ")); s }")),
 810                         "bitcoin::blockdata::block::Block" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 811                         "bitcoin::hash_types::Txid" => None,
 812
 813                         // Override the default since Records contain an fmt with a lifetime:
 814                         // TODO: We should include the other record fields
 815                         "util::logger::Record" => Some(("std::ffi::CString::new(format!(\"{}\", ", ".args)).unwrap()")),
 816                         _ => None,
 817                 }.map(|s| s.to_owned())
 818         }
 819         fn to_c_conversion_inline_prefix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
 820                 if self.is_primitive(full_path) {
 821                         return Some("".to_owned());
 822                 }
 823                 match full_path {
 824                         "Result" if !is_ref => Some("local_"),
 825                         "Vec" if !is_ref => Some("local_"),
 826                         "Option" => Some("local_"),
 827
 828                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 829                         "[u8; 32]" if is_ref => Some("&"),
 830                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes { data: "),
 831                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes { data: "),
 832                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes { data: "),
 833                         "[u8; 3]" if is_ref => Some("&"),
 834
 835                         "[u8]" if is_ref => Some("local_"),
 836                         "[usize]" if is_ref => Some("local_"),
 837
 838                         "str" if is_ref => Some(""),
 839                         "String" => Some(""),
 840
 841                         "std::time::Duration" => Some(""),
 842
 843                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey::from_rust(&"),
 844                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature::from_rust(&"),
 845                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some(""),
 846                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
 847                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error::from_rust("),
 848                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice::from_slice(&"),
 849                         "bitcoin::blockdata::script::Script" if !is_ref => Some(""),
 850                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction::from_vec(local_"),
 851                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::c_types::bitcoin_to_C_outpoint("),
 852                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut::from_rust("),
 853                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network::from_bitcoin("),
 854                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some("&local_"),
 855                         "bitcoin::blockdata::block::Block" if is_ref => Some("crate::c_types::u8slice::from_slice(&local_"),
 856
 857                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 858
 859                         // Newtypes that we just expose in their original form.
 860                         "bitcoin::hash_types::Txid" if is_ref => Some(""),
 861                         "bitcoin::hash_types::BlockHash" if is_ref => Some(""),
 862                         "bitcoin::hash_types::BlockHash" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 863                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 864                         "ln::channelmanager::PaymentHash" if is_ref => Some("&"),
 865                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 866                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&"),
 867                         "ln::channelmanager::PaymentPreimage" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 868                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 869
 870                         // Override the default since Records contain an fmt with a lifetime:
 871                         "util::logger::Record" => Some("local_"),
 872
 873                         _ => None,
 874                 }.map(|s| s.to_owned())
 875         }
 876         fn to_c_conversion_inline_suffix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
 877                 if self.is_primitive(full_path) {
 878                         return Some("".to_owned());
 879                 }
 880                 match full_path {
 881                         "Result" if !is_ref => Some(""),
 882                         "Vec" if !is_ref => Some(".into()"),
 883                         "Option" => Some(""),
 884
 885                         "[u8; 32]" if !is_ref => Some(" }"),
 886                         "[u8; 32]" if is_ref => Some(""),
 887                         "[u8; 16]" if !is_ref => Some(" }"),
 888                         "[u8; 10]" if !is_ref => Some(" }"),
 889                         "[u8; 4]" if !is_ref => Some(" }"),
 890                         "[u8; 3]" if is_ref => Some(""),
 891
 892                         "[u8]" if is_ref => Some(""),
 893                         "[usize]" if is_ref => Some(""),
 894
 895                         "str" if is_ref => Some(".into()"),
 896                         "String" if !is_ref => Some(".into_bytes().into()"),
 897                         "String" if is_ref => Some(".as_str().into()"),
 898
 899                         "std::time::Duration" => Some(".as_secs()"),
 900
 901                         "bitcoin::secp256k1::key::PublicKey" => Some(")"),
 902                         "bitcoin::secp256k1::Signature" => Some(")"),
 903                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(")"),
 904                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some(".as_ref()"),
 905                         "bitcoin::secp256k1::Error" if !is_ref => Some(")"),
 906                         "bitcoin::blockdata::script::Script" if is_ref => Some("[..])"),
 907                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_bytes().into()"),
 908                         "bitcoin::blockdata::transaction::Transaction" => Some(")"),
 909                         "bitcoin::blockdata::transaction::OutPoint" => Some(")"),
 910                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(")"),
 911                         "bitcoin::network::constants::Network" => Some(")"),
 912                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(""),
 913                         "bitcoin::blockdata::block::Block" if is_ref => Some(")"),
 914
 915                         "bitcoin::hash_types::Txid" if !is_ref => Some(".into_inner() }"),
 916
 917                         // Newtypes that we just expose in their original form.
 918                         "bitcoin::hash_types::Txid" if is_ref => Some(".as_inner()"),
 919                         "bitcoin::hash_types::BlockHash" if is_ref => Some(".as_inner()"),
 920                         "bitcoin::hash_types::BlockHash" => Some(".into_inner() }"),
 921                         "bitcoin::secp256k1::Message" if !is_ref => Some(".as_ref().clone() }"),
 922                         "ln::channelmanager::PaymentHash" if is_ref => Some(".0"),
 923                         "ln::channelmanager::PaymentHash" => Some(".0 }"),
 924                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(".0"),
 925                         "ln::channelmanager::PaymentPreimage" => Some(".0 }"),
 926                         "ln::channelmanager::PaymentSecret" if !is_ref => Some(".0 }"),
 927
 928                         // Override the default since Records contain an fmt with a lifetime:
 929                         "util::logger::Record" => Some(".as_ptr()"),
 930
 931                         _ => None,
 932                 }.map(|s| s.to_owned())
 933         }
 934
 935         fn empty_val_check_suffix_from_path(&self, full_path: &str) -> Option<&str> {
 936                 match full_path {
 937                         "ln::channelmanager::PaymentSecret" => Some(".data == [0; 32]"),
 938                         "bitcoin::secp256k1::key::PublicKey" => Some(".is_null()"),
 939                         "bitcoin::secp256k1::Signature" => Some(".is_null()"),
 940                         _ => None
 941                 }
 942         }
 943
 944         // ****************************
 945         // *** Container Processing ***
 946         // ****************************
 947
 948         /// Returns the module path in the generated mapping crate to the containers which we generate
 949         /// when writing to CrateTypes::template_file.
 950         pub fn generated_container_path() -> &'static str {
 951                 "crate::c_types::derived"
 952         }
 953         /// Returns the module path in the generated mapping crate to the container templates, which
 954         /// are then concretized and put in the generated container path/template_file.
 955         fn container_templ_path() -> &'static str {
 956                 "crate::c_types"
 957         }
 958
 959         /// Returns true if this is a "transparent" container, ie an Option or a container which does
 960         /// not require a generated continer class.
 961         fn is_transparent_container(&self, full_path: &str, _is_ref: bool) -> bool {
 962                 full_path == "Option"
 963         }
 964         /// Returns true if this is a known, supported, non-transparent container.
 965         fn is_known_container(&self, full_path: &str, is_ref: bool) -> bool {
 966                 (full_path == "Result" && !is_ref) || (full_path == "Vec" && !is_ref) || full_path.ends_with("Tuple")
 967         }
 968         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)
 969                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
 970                         // expecting one element in the vec per generic type, each of which is inline-converted
 971                         -> Option<(&'b str, Vec<(String, String)>, &'b str)> {
 972                 match full_path {
 973                         "Result" if !is_ref => {
 974                                 Some(("match ",
 975                                                 vec![(" { Ok(mut o) => crate::c_types::CResultTempl::ok(".to_string(), "o".to_string()),
 976                                                         (").into(), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
 977                                                 ").into() }"))
 978                         },
 979                         "Vec" if !is_ref => {
 980                                 Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 981                         },
 982                         "Slice" => {
 983                                 Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "**item".to_string())], "); }"))
 984                         },
 985                         "Option" => {
 986                                 if let Some(syn::Type::Path(p)) = single_contained {
 987                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
 988                                                 if is_ref {
 989                                                         return Some(("if ", vec![
 990                                                                 (".is_none() { std::ptr::null() } else { ".to_owned(), format!("({}.as_ref().unwrap())", var_access))
 991                                                                 ], " }"));
 992                                                 } else {
 993                                                         return Some(("if ", vec![
 994                                                                 (".is_none() { std::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
 995                                                                 ], " }"));
 996                                                 }
 997                                         }
 998                                 }
 999                                 if let Some(t) = single_contained {
1000                                         let mut v = Vec::new();
1001                                         self.write_empty_rust_val(generics, &mut v, t);
1002                                         let s = String::from_utf8(v).unwrap();
1003                                         return Some(("if ", vec![
1004                                                 (format!(".is_none() {{ {} }} else {{ ", s), format!("({}.unwrap())", var_access))
1005                                                 ], " }"));
1006                                 } else { unreachable!(); }
1007                         },
1008                         _ => None,
1009                 }
1010         }
1011
1012         /// only_contained_has_inner implies that there is only one contained element in the container
1013         /// and it has an inner field (ie is an "opaque" type we've defined).
1014         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)
1015                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
1016                         // expecting one element in the vec per generic type, each of which is inline-converted
1017                         -> Option<(&'b str, Vec<(String, String)>, &'b str)> {
1018                 match full_path {
1019                         "Result" if !is_ref => {
1020                                 Some(("match ",
1021                                                 vec![(".result_ok { true => Ok(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.result)) }})", var_access)),
1022                                                      ("), false => Err(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.err)) }})", var_access))],
1023                                                 ")}"))
1024                         },
1025                         "Vec"|"Slice" if !is_ref => {
1026                                 Some(("Vec::new(); for mut item in ", vec![(format!(".into_rust().drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }"))
1027                         },
1028                         "Slice" if is_ref => {
1029                                 Some(("Vec::new(); for mut item in ", vec![(format!(".as_slice().iter() {{ local_{}.push(", var_name), "item".to_string())], "); }"))
1030                         },
1031                         "Option" => {
1032                                 if let Some(syn::Type::Path(p)) = single_contained {
1033                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
1034                                                 if is_ref {
1035                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some((*".to_string(), format!("{}", var_access))], ").clone()) }"))
1036                                                 } else {
1037                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some(".to_string(), format!("{}", var_access))], ") }"));
1038                                                 }
1039                                         }
1040                                 }
1041
1042                                 if let Some(t) = single_contained {
1043                                         let mut v = Vec::new();
1044                                         let ret_ref = self.write_empty_rust_val_check_suffix(generics, &mut v, t);
1045                                         let s = String::from_utf8(v).unwrap();
1046                                         match ret_ref {
1047                                                 EmptyValExpectedTy::ReferenceAsPointer =>
1048                                                         return Some(("if ", vec![
1049                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ &mut *{} }}", var_access))
1050                                                         ], ") }")),
1051                                                 EmptyValExpectedTy::OwnedPointer =>
1052                                                         return Some(("if ", vec![
1053                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ *Box::from_raw({}) }}", var_access))
1054                                                         ], ") }")),
1055                                                 EmptyValExpectedTy::NonPointer =>
1056                                                         return Some(("if ", vec![
1057                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("{}", var_access))
1058                                                         ], ") }")),
1059                                         }
1060                                 } else { unreachable!(); }
1061                         },
1062                         _ => None,
1063                 }
1064         }
1065
1066         // *************************************************
1067         // *** Type definition during main.rs processing ***
1068         // *************************************************
1069
1070         pub fn get_declared_type(&'a self, ident: &syn::Ident) -> Option<&'a DeclType<'c>> {
1071                 self.types.get_declared_type(ident)
1072         }
1073         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
1074         pub fn c_type_has_inner_from_path(&self, full_path: &str) -> bool{
1075                 self.crate_types.opaques.get(full_path).is_some()
1076         }
1077
1078         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
1079                 self.types.maybe_resolve_ident(id)
1080         }
1081
1082         pub fn maybe_resolve_non_ignored_ident(&self, id: &syn::Ident) -> Option<String> {
1083                 self.types.maybe_resolve_non_ignored_ident(id)
1084         }
1085
1086         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
1087                 self.types.maybe_resolve_path(p_arg, generics)
1088         }
1089         pub fn resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> String {
1090                 self.maybe_resolve_path(p, generics).unwrap()
1091         }
1092
1093         // ***********************************
1094         // *** Original Rust Type Printing ***
1095         // ***********************************
1096
1097         fn in_rust_prelude(resolved_path: &str) -> bool {
1098                 match resolved_path {
1099                         "Vec" => true,
1100                         "Result" => true,
1101                         "Option" => true,
1102                         _ => false,
1103                 }
1104         }
1105
1106         fn write_rust_path<W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, path: &syn::Path) {
1107                 if let Some(resolved) = self.maybe_resolve_path(&path, generics_resolver) {
1108                         if self.is_primitive(&resolved) {
1109                                 write!(w, "{}", path.get_ident().unwrap()).unwrap();
1110                         } else {
1111                                 // TODO: We should have a generic "is from a dependency" check here instead of
1112                                 // checking for "bitcoin" explicitly.
1113                                 if resolved.starts_with("bitcoin::") || Self::in_rust_prelude(&resolved) {
1114                                         write!(w, "{}", resolved).unwrap();
1115                                 // If we're printing a generic argument, it needs to reference the crate, otherwise
1116                                 // the original crate:
1117                                 } else if self.maybe_resolve_path(&path, None).as_ref() == Some(&resolved) {
1118                                         write!(w, "{}::{}", self.orig_crate, resolved).unwrap();
1119                                 } else {
1120                                         write!(w, "crate::{}", resolved).unwrap();
1121                                 }
1122                         }
1123                         if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().last().unwrap().arguments {
1124                                 self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1125                         }
1126                 } else {
1127                         if path.leading_colon.is_some() {
1128                                 write!(w, "::").unwrap();
1129                         }
1130                         for (idx, seg) in path.segments.iter().enumerate() {
1131                                 if idx != 0 { write!(w, "::").unwrap(); }
1132                                 write!(w, "{}", seg.ident).unwrap();
1133                                 if let syn::PathArguments::AngleBracketed(args) = &seg.arguments {
1134                                         self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1135                                 }
1136                         }
1137                 }
1138         }
1139         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>) {
1140                 let mut had_params = false;
1141                 for (idx, arg) in generics.enumerate() {
1142                         if idx != 0 { write!(w, ", ").unwrap(); } else { write!(w, "<").unwrap(); }
1143                         had_params = true;
1144                         match arg {
1145                                 syn::GenericParam::Lifetime(lt) => write!(w, "'{}", lt.lifetime.ident).unwrap(),
1146                                 syn::GenericParam::Type(t) => {
1147                                         write!(w, "{}", t.ident).unwrap();
1148                                         if t.colon_token.is_some() { write!(w, ":").unwrap(); }
1149                                         for (idx, bound) in t.bounds.iter().enumerate() {
1150                                                 if idx != 0 { write!(w, " + ").unwrap(); }
1151                                                 match bound {
1152                                                         syn::TypeParamBound::Trait(tb) => {
1153                                                                 if tb.paren_token.is_some() || tb.lifetimes.is_some() { unimplemented!(); }
1154                                                                 self.write_rust_path(w, generics_resolver, &tb.path);
1155                                                         },
1156                                                         _ => unimplemented!(),
1157                                                 }
1158                                         }
1159                                         if t.eq_token.is_some() || t.default.is_some() { unimplemented!(); }
1160                                 },
1161                                 _ => unimplemented!(),
1162                         }
1163                 }
1164                 if had_params { write!(w, ">").unwrap(); }
1165         }
1166
1167         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>) {
1168                 write!(w, "<").unwrap();
1169                 for (idx, arg) in generics.enumerate() {
1170                         if idx != 0 { write!(w, ", ").unwrap(); }
1171                         match arg {
1172                                 syn::GenericArgument::Type(t) => self.write_rust_type(w, generics_resolver, t),
1173                                 _ => unimplemented!(),
1174                         }
1175                 }
1176                 write!(w, ">").unwrap();
1177         }
1178         pub fn write_rust_type<W: std::io::Write>(&self, w: &mut W, generics: Option<&GenericTypes>, t: &syn::Type) {
1179                 match t {
1180                         syn::Type::Path(p) => {
1181                                 if p.qself.is_some() {
1182                                         unimplemented!();
1183                                 }
1184                                 self.write_rust_path(w, generics, &p.path);
1185                         },
1186                         syn::Type::Reference(r) => {
1187                                 write!(w, "&").unwrap();
1188                                 if let Some(lft) = &r.lifetime {
1189                                         write!(w, "'{} ", lft.ident).unwrap();
1190                                 }
1191                                 if r.mutability.is_some() {
1192                                         write!(w, "mut ").unwrap();
1193                                 }
1194                                 self.write_rust_type(w, generics, &*r.elem);
1195                         },
1196                         syn::Type::Array(a) => {
1197                                 write!(w, "[").unwrap();
1198                                 self.write_rust_type(w, generics, &a.elem);
1199                                 if let syn::Expr::Lit(l) = &a.len {
1200                                         if let syn::Lit::Int(i) = &l.lit {
1201                                                 write!(w, "; {}]", i).unwrap();
1202                                         } else { unimplemented!(); }
1203                                 } else { unimplemented!(); }
1204                         }
1205                         syn::Type::Slice(s) => {
1206                                 write!(w, "[").unwrap();
1207                                 self.write_rust_type(w, generics, &s.elem);
1208                                 write!(w, "]").unwrap();
1209                         },
1210                         syn::Type::Tuple(s) => {
1211                                 write!(w, "(").unwrap();
1212                                 for (idx, t) in s.elems.iter().enumerate() {
1213                                         if idx != 0 { write!(w, ", ").unwrap(); }
1214                                         self.write_rust_type(w, generics, &t);
1215                                 }
1216                                 write!(w, ")").unwrap();
1217                         },
1218                         _ => unimplemented!(),
1219                 }
1220         }
1221
1222         /// Prints a constructor for something which is "uninitialized" (but obviously not actually
1223         /// unint'd memory).
1224         pub fn write_empty_rust_val<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) {
1225                 match t {
1226                         syn::Type::Path(p) => {
1227                                 let resolved = self.resolve_path(&p.path, generics);
1228                                 if self.crate_types.opaques.get(&resolved).is_some() {
1229                                         write!(w, "crate::{} {{ inner: std::ptr::null_mut(), is_owned: true }}", resolved).unwrap();
1230                                 } else {
1231                                         // Assume its a manually-mapped C type, where we can just define an null() fn
1232                                         write!(w, "{}::null()", self.c_type_from_path(&resolved, false, false).unwrap()).unwrap();
1233                                 }
1234                         },
1235                         syn::Type::Array(a) => {
1236                                 if let syn::Expr::Lit(l) = &a.len {
1237                                         if let syn::Lit::Int(i) = &l.lit {
1238                                                 if i.base10_digits().parse::<usize>().unwrap() < 32 {
1239                                                         // Blindly assume that if we're trying to create an empty value for an
1240                                                         // array < 32 entries that all-0s may be a valid state.
1241                                                         unimplemented!();
1242                                                 }
1243                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1244                                                 write!(w, "{}", self.to_c_conversion_inline_prefix_from_path(&arrty, false, false).unwrap()).unwrap();
1245                                                 write!(w, "[0; {}]", i.base10_digits()).unwrap();
1246                                                 write!(w, "{}", self.to_c_conversion_inline_suffix_from_path(&arrty, false, false).unwrap()).unwrap();
1247                                         } else { unimplemented!(); }
1248                                 } else { unimplemented!(); }
1249                         }
1250                         _ => unimplemented!(),
1251                 }
1252         }
1253
1254         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1255         /// See EmptyValExpectedTy for information on return types.
1256         fn write_empty_rust_val_check_suffix<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) -> EmptyValExpectedTy {
1257                 match t {
1258                         syn::Type::Path(p) => {
1259                                 let resolved = self.resolve_path(&p.path, generics);
1260                                 if self.crate_types.opaques.get(&resolved).is_some() {
1261                                         write!(w, ".inner.is_null()").unwrap();
1262                                         EmptyValExpectedTy::NonPointer
1263                                 } else {
1264                                         if let Some(suffix) = self.empty_val_check_suffix_from_path(&resolved) {
1265                                                 write!(w, "{}", suffix).unwrap();
1266                                                 // We may eventually need to allow empty_val_check_suffix_from_path to specify if we need a deref or not
1267                                                 EmptyValExpectedTy::NonPointer
1268                                         } else {
1269                                                 write!(w, " == std::ptr::null_mut()").unwrap();
1270                                                 EmptyValExpectedTy::OwnedPointer
1271                                         }
1272                                 }
1273                         },
1274                         syn::Type::Array(a) => {
1275                                 if let syn::Expr::Lit(l) = &a.len {
1276                                         if let syn::Lit::Int(i) = &l.lit {
1277                                                 write!(w, " == [0; {}]", i.base10_digits()).unwrap();
1278                                                 EmptyValExpectedTy::NonPointer
1279                                         } else { unimplemented!(); }
1280                                 } else { unimplemented!(); }
1281                         },
1282                         syn::Type::Slice(_) => {
1283                                 // Option<[]> always implies that we want to treat len() == 0 differently from
1284                                 // None, so we always map an Option<[]> into a pointer.
1285                                 write!(w, " == std::ptr::null_mut()").unwrap();
1286                                 EmptyValExpectedTy::ReferenceAsPointer
1287                         },
1288                         _ => unimplemented!(),
1289                 }
1290         }
1291
1292         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1293         pub fn write_empty_rust_val_check<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type, var_access: &str) {
1294                 match t {
1295                         syn::Type::Path(_) => {
1296                                 write!(w, "{}", var_access).unwrap();
1297                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1298                         },
1299                         syn::Type::Array(a) => {
1300                                 if let syn::Expr::Lit(l) = &a.len {
1301                                         if let syn::Lit::Int(i) = &l.lit {
1302                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1303                                                 // We don't (yet) support a new-var conversion here.
1304                                                 assert!(self.from_c_conversion_new_var_from_path(&arrty, false).is_none());
1305                                                 write!(w, "{}{}{}",
1306                                                         self.from_c_conversion_prefix_from_path(&arrty, false).unwrap(),
1307                                                         var_access,
1308                                                         self.from_c_conversion_suffix_from_path(&arrty, false).unwrap()).unwrap();
1309                                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1310                                         } else { unimplemented!(); }
1311                                 } else { unimplemented!(); }
1312                         }
1313                         _ => unimplemented!(),
1314                 }
1315         }
1316
1317         // ********************************
1318         // *** Type conversion printing ***
1319         // ********************************
1320
1321         /// Returns true we if can just skip passing this to C entirely
1322         pub fn skip_arg(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
1323                 match t {
1324                         syn::Type::Path(p) => {
1325                                 if p.qself.is_some() { unimplemented!(); }
1326                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1327                                         self.skip_path(&full_path)
1328                                 } else { false }
1329                         },
1330                         syn::Type::Reference(r) => {
1331                                 self.skip_arg(&*r.elem, generics)
1332                         },
1333                         _ => false,
1334                 }
1335         }
1336         pub fn no_arg_to_rust<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1337                 match t {
1338                         syn::Type::Path(p) => {
1339                                 if p.qself.is_some() { unimplemented!(); }
1340                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1341                                         write!(w, "{}", self.no_arg_path_to_rust(&full_path)).unwrap();
1342                                 }
1343                         },
1344                         syn::Type::Reference(r) => {
1345                                 self.no_arg_to_rust(w, &*r.elem, generics);
1346                         },
1347                         _ => {},
1348                 }
1349         }
1350
1351         fn write_conversion_inline_intern<W: std::io::Write,
1352                         LP: Fn(&str, bool, bool) -> Option<String>, DL: Fn(&mut W, &DeclType, &str, bool, bool), SC: Fn(bool) -> &'static str>
1353                         (&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool,
1354                          tupleconv: &str, prefix: bool, sliceconv: SC, path_lookup: LP, decl_lookup: DL) {
1355                 match t {
1356                         syn::Type::Reference(r) => {
1357                                 self.write_conversion_inline_intern(w, &*r.elem, generics, true, r.mutability.is_some(),
1358                                         ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1359                         },
1360                         syn::Type::Path(p) => {
1361                                 if p.qself.is_some() {
1362                                         unimplemented!();
1363                                 }
1364
1365                                 let resolved_path = self.resolve_path(&p.path, generics);
1366                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1367                                         return self.write_conversion_inline_intern(w, aliased_type, None, is_ref, is_mut, ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1368                                 } else if let Some(c_type) = path_lookup(&resolved_path, is_ref, ptr_for_ref) {
1369                                         write!(w, "{}", c_type).unwrap();
1370                                 } else if self.crate_types.opaques.get(&resolved_path).is_some() {
1371                                         decl_lookup(w, &DeclType::StructImported, &resolved_path, is_ref, is_mut);
1372                                 } else if self.crate_types.mirrored_enums.get(&resolved_path).is_some() {
1373                                         decl_lookup(w, &DeclType::MirroredEnum, &resolved_path, is_ref, is_mut);
1374                                 } else if let Some(t) = self.crate_types.traits.get(&resolved_path) {
1375                                         decl_lookup(w, &DeclType::Trait(t), &resolved_path, is_ref, is_mut);
1376                                 } else if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
1377                                         if let Some(decl_type) = self.types.maybe_resolve_declared(ident) {
1378                                                 decl_lookup(w, decl_type, &self.maybe_resolve_ident(ident).unwrap(), is_ref, is_mut);
1379                                         } else { unimplemented!(); }
1380                                 } else { unimplemented!(); }
1381                         },
1382                         syn::Type::Array(a) => {
1383                                 // We assume all arrays contain only [int_literal; X]s.
1384                                 // This may result in some outputs not compiling.
1385                                 if let syn::Expr::Lit(l) = &a.len {
1386                                         if let syn::Lit::Int(i) = &l.lit {
1387                                                 write!(w, "{}", path_lookup(&format!("[u8; {}]", i.base10_digits()), is_ref, ptr_for_ref).unwrap()).unwrap();
1388                                         } else { unimplemented!(); }
1389                                 } else { unimplemented!(); }
1390                         },
1391                         syn::Type::Slice(s) => {
1392                                 // We assume all slices contain only literals or references.
1393                                 // This may result in some outputs not compiling.
1394                                 if let syn::Type::Path(p) = &*s.elem {
1395                                         let resolved = self.resolve_path(&p.path, generics);
1396                                         assert!(self.is_primitive(&resolved));
1397                                         write!(w, "{}", path_lookup("[u8]", is_ref, ptr_for_ref).unwrap()).unwrap();
1398                                 } else if let syn::Type::Reference(r) = &*s.elem {
1399                                         if let syn::Type::Path(p) = &*r.elem {
1400                                                 write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)))).unwrap();
1401                                         } else { unimplemented!(); }
1402                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1403                                         assert!(!t.elems.is_empty());
1404                                         if prefix {
1405                                                 write!(w, "&local_").unwrap();
1406                                         } else {
1407                                                 let mut needs_map = false;
1408                                                 for e in t.elems.iter() {
1409                                                         if let syn::Type::Reference(_) = e {
1410                                                                 needs_map = true;
1411                                                         }
1412                                                 }
1413                                                 if needs_map {
1414                                                         write!(w, ".iter().map(|(").unwrap();
1415                                                         for i in 0..t.elems.len() {
1416                                                                 write!(w, "{}{}", if i != 0 { ", " } else { "" }, ('a' as u8 + i as u8) as char).unwrap();
1417                                                         }
1418                                                         write!(w, ")| (").unwrap();
1419                                                         for (idx, e) in t.elems.iter().enumerate() {
1420                                                                 if let syn::Type::Reference(_) = e {
1421                                                                         write!(w, "{}{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1422                                                                 } else if let syn::Type::Path(_) = e {
1423                                                                         write!(w, "{}*{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1424                                                                 } else { unimplemented!(); }
1425                                                         }
1426                                                         write!(w, ")).collect::<Vec<_>>()[..]").unwrap();
1427                                                 }
1428                                         }
1429                                 } else { unimplemented!(); }
1430                         },
1431                         syn::Type::Tuple(t) => {
1432                                 if t.elems.is_empty() {
1433                                         // cbindgen has poor support for (), see, eg https://github.com/eqrion/cbindgen/issues/527
1434                                         // so work around it by just pretending its a 0u8
1435                                         write!(w, "{}", tupleconv).unwrap();
1436                                 } else {
1437                                         if prefix { write!(w, "local_").unwrap(); }
1438                                 }
1439                         },
1440                         _ => unimplemented!(),
1441                 }
1442         }
1443
1444         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) {
1445                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "0u8 /*", true, |_| "local_",
1446                                 |a, b, c| self.to_c_conversion_inline_prefix_from_path(a, b, c),
1447                                 |w, decl_type, decl_path, is_ref, _is_mut| {
1448                                         match decl_type {
1449                                                 DeclType::MirroredEnum if is_ref && ptr_for_ref => write!(w, "crate::{}::from_native(&", decl_path).unwrap(),
1450                                                 DeclType::MirroredEnum if is_ref => write!(w, "&crate::{}::from_native(&", decl_path).unwrap(),
1451                                                 DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
1452                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1453                                                         write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1454                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1455                                                         write!(w, "crate::{} {{ inner: unsafe {{ ( (&(", decl_path).unwrap(),
1456                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1457                                                         write!(w, "&crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1458                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1459                                                         write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
1460                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref =>
1461                                                         write!(w, "crate::{} {{ inner: Box::into_raw(Box::new(", decl_path).unwrap(),
1462                                                 DeclType::Trait(_) if is_ref => write!(w, "&").unwrap(),
1463                                                 DeclType::Trait(_) if !is_ref => {},
1464                                                 _ => panic!("{:?}", decl_path),
1465                                         }
1466                                 });
1467         }
1468         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) {
1469                 self.write_to_c_conversion_inline_prefix_inner(w, t, generics, false, ptr_for_ref, false);
1470         }
1471         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) {
1472                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "*/", false, |_| ".into()",
1473                                 |a, b, c| self.to_c_conversion_inline_suffix_from_path(a, b, c),
1474                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1475                                         DeclType::MirroredEnum => write!(w, ")").unwrap(),
1476                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1477                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1478                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1479                                                 write!(w, ") as *const _) as *mut _) }}, is_owned: false }}").unwrap(),
1480                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1481                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1482                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1483                                                 write!(w, ", is_owned: true }}").unwrap(),
1484                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref => write!(w, ")), is_owned: true }}").unwrap(),
1485                                         DeclType::Trait(_) if is_ref => {},
1486                                         DeclType::Trait(_) => {
1487                                                 // This is used when we're converting a concrete Rust type into a C trait
1488                                                 // for use when a Rust trait method returns an associated type.
1489                                                 // Because all of our C traits implement From<RustTypesImplementingTraits>
1490                                                 // we can just call .into() here and be done.
1491                                                 write!(w, ".into()").unwrap()
1492                                         },
1493                                         _ => unimplemented!(),
1494                                 });
1495         }
1496         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) {
1497                 self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
1498         }
1499
1500         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) {
1501                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_| "&local_",
1502                                 |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
1503                                 |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
1504                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, "unsafe {{ &*(*").unwrap(),
1505                                         DeclType::StructImported if is_mut && is_ref => write!(w, "unsafe {{ &mut *").unwrap(),
1506                                         DeclType::StructImported if is_ref => write!(w, "unsafe {{ &*").unwrap(),
1507                                         DeclType::StructImported if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
1508                                         DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
1509                                         DeclType::MirroredEnum => {},
1510                                         DeclType::Trait(_) => {},
1511                                         _ => unimplemented!(),
1512                                 });
1513         }
1514         pub fn write_from_c_conversion_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1515                 self.write_from_c_conversion_prefix_inner(w, t, generics, false, false);
1516         }
1517         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) {
1518                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "*/", false,
1519                                 |has_inner| match has_inner {
1520                                         false => ".iter().collect::<Vec<_>>()[..]",
1521                                         true => "[..]",
1522                                 },
1523                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1524                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1525                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, ").inner }}").unwrap(),
1526                                         DeclType::StructImported if is_ref => write!(w, ".inner }}").unwrap(),
1527                                         DeclType::StructImported if !is_ref => write!(w, ".take_inner()) }}").unwrap(),
1528                                         DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
1529                                         DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
1530                                         DeclType::Trait(_) => {},
1531                                         _ => unimplemented!(),
1532                                 });
1533         }
1534         pub fn write_from_c_conversion_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1535                 self.write_from_c_conversion_suffix_inner(w, t, generics, false, false);
1536         }
1537         // Note that compared to the above conversion functions, the following two are generally
1538         // significantly undertested:
1539         pub fn write_from_c_conversion_to_ref_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1540                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "() /*", true, |_| "&local_",
1541                                 |a, b, _c| {
1542                                         if let Some(conv) = self.from_c_conversion_prefix_from_path(a, b) {
1543                                                 Some(format!("&{}", conv))
1544                                         } else { None }
1545                                 },
1546                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1547                                         DeclType::StructImported if !is_ref => write!(w, "unsafe {{ &*").unwrap(),
1548                                         _ => unimplemented!(),
1549                                 });
1550         }
1551         pub fn write_from_c_conversion_to_ref_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1552                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "*/", false,
1553                                 |has_inner| match has_inner {
1554                                         false => ".iter().collect::<Vec<_>>()[..]",
1555                                         true => "[..]",
1556                                 },
1557                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1558                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1559                                         DeclType::StructImported if !is_ref => write!(w, ".inner }}").unwrap(),
1560                                         _ => unimplemented!(),
1561                                 });
1562         }
1563
1564         fn write_conversion_new_var_intern<'b, W: std::io::Write,
1565                 LP: Fn(&str, bool) -> Option<(&str, &str)>,
1566                 LC: Fn(&str, bool, Option<&syn::Type>, &syn::Ident, &str) ->  Option<(&'b str, Vec<(String, String)>, &'b str)>,
1567                 VP: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool),
1568                 VS: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool)>
1569                         (&self, w: &mut W, ident: &syn::Ident, var: &str, t: &syn::Type, generics: Option<&GenericTypes>,
1570                          mut is_ref: bool, mut ptr_for_ref: bool, to_c: bool,
1571                          path_lookup: &LP, container_lookup: &LC, var_prefix: &VP, var_suffix: &VS) -> bool {
1572
1573                 macro_rules! convert_container {
1574                         ($container_type: expr, $args_len: expr, $args_iter: expr) => { {
1575                                 // For slices (and Options), we refuse to directly map them as is_ref when they
1576                                 // aren't opaque types containing an inner pointer. This is due to the fact that,
1577                                 // in both cases, the actual higher-level type is non-is_ref.
1578                                 let ty_has_inner = if self.is_transparent_container(&$container_type, is_ref) || $container_type == "Slice" {
1579                                         let ty = $args_iter().next().unwrap();
1580                                         if $container_type == "Slice" && to_c {
1581                                                 // "To C ptr_for_ref" means "return the regular object with is_owned
1582                                                 // set to false", which is totally what we want in a slice if we're about to
1583                                                 // set ty_has_inner.
1584                                                 ptr_for_ref = true;
1585                                         }
1586                                         if let syn::Type::Reference(t) = ty {
1587                                                 if let syn::Type::Path(p) = &*t.elem {
1588                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1589                                                 } else { false }
1590                                         } else if let syn::Type::Path(p) = ty {
1591                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1592                                         } else { false }
1593                                 } else { true };
1594
1595                                 // Options get a bunch of special handling, since in general we map Option<>al
1596                                 // types into the same C type as non-Option-wrapped types. This ends up being
1597                                 // pretty manual here and most of the below special-cases are for Options.
1598                                 let mut needs_ref_map = false;
1599                                 let mut only_contained_type = None;
1600                                 let mut only_contained_has_inner = false;
1601                                 let mut contains_slice = false;
1602                                 if $args_len == 1 && self.is_transparent_container(&$container_type, is_ref) {
1603                                         only_contained_has_inner = ty_has_inner;
1604                                         let arg = $args_iter().next().unwrap();
1605                                         if let syn::Type::Reference(t) = arg {
1606                                                 only_contained_type = Some(&*t.elem);
1607                                                 if let syn::Type::Path(_) = &*t.elem {
1608                                                         is_ref = true;
1609                                                 } else if let syn::Type::Slice(_) = &*t.elem {
1610                                                         contains_slice = true;
1611                                                 } else { return false; }
1612                                                 needs_ref_map = true;
1613                                         } else if let syn::Type::Path(_) = arg {
1614                                                 only_contained_type = Some(&arg);
1615                                         } else { unimplemented!(); }
1616                                 }
1617
1618                                 if let Some((prefix, conversions, suffix)) = container_lookup(&$container_type, is_ref && ty_has_inner, only_contained_type, ident, var) {
1619                                         assert_eq!(conversions.len(), $args_len);
1620                                         write!(w, "let mut local_{}{} = ", ident, if !to_c && needs_ref_map {"_base"} else { "" }).unwrap();
1621                                         if only_contained_has_inner && to_c {
1622                                                 var_prefix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1623                                         }
1624                                         write!(w, "{}{}", prefix, var).unwrap();
1625
1626                                         for ((pfx, var_name), (idx, ty)) in conversions.iter().zip($args_iter().enumerate()) {
1627                                                 let mut var = std::io::Cursor::new(Vec::new());
1628                                                 write!(&mut var, "{}", var_name).unwrap();
1629                                                 let var_access = String::from_utf8(var.into_inner()).unwrap();
1630
1631                                                 let conv_ty = if needs_ref_map { only_contained_type.as_ref().unwrap() } else { ty };
1632
1633                                                 write!(w, "{} {{ ", pfx).unwrap();
1634                                                 let new_var_name = format!("{}_{}", ident, idx);
1635                                                 let new_var = self.write_conversion_new_var_intern(w, &syn::Ident::new(&new_var_name, Span::call_site()),
1636                                                                 &var_access, conv_ty, generics, contains_slice || (is_ref && ty_has_inner), ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix);
1637                                                 if new_var { write!(w, " ").unwrap(); }
1638                                                 if (!only_contained_has_inner || !to_c) && !contains_slice {
1639                                                         var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1640                                                 }
1641
1642                                                 if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1643                                                         write!(w, "Box::into_raw(Box::new(").unwrap();
1644                                                 }
1645                                                 write!(w, "{}{}", if contains_slice { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
1646                                                 if (!only_contained_has_inner || !to_c) && !contains_slice {
1647                                                         var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1648                                                 }
1649                                                 if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1650                                                         write!(w, "))").unwrap();
1651                                                 }
1652                                                 write!(w, " }}").unwrap();
1653                                         }
1654                                         write!(w, "{}", suffix).unwrap();
1655                                         if only_contained_has_inner && to_c {
1656                                                 var_suffix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1657                                         }
1658                                         write!(w, ";").unwrap();
1659                                         if !to_c && needs_ref_map {
1660                                                 write!(w, " let mut local_{} = local_{}_base.as_ref()", ident, ident).unwrap();
1661                                                 if contains_slice {
1662                                                         write!(w, ".map(|a| &a[..])").unwrap();
1663                                                 }
1664                                                 write!(w, ";").unwrap();
1665                                         }
1666                                         return true;
1667                                 }
1668                         } }
1669                 }
1670
1671                 match t {
1672                         syn::Type::Reference(r) => {
1673                                 if let syn::Type::Slice(_) = &*r.elem {
1674                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, is_ref, ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix)
1675                                 } else {
1676                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, true, ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix)
1677                                 }
1678                         },
1679                         syn::Type::Path(p) => {
1680                                 if p.qself.is_some() {
1681                                         unimplemented!();
1682                                 }
1683                                 let resolved_path = self.resolve_path(&p.path, generics);
1684                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1685                                         return self.write_conversion_new_var_intern(w, ident, var, aliased_type, None, is_ref, ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix);
1686                                 }
1687                                 if self.is_known_container(&resolved_path, is_ref) || self.is_transparent_container(&resolved_path, is_ref) {
1688                                         if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
1689                                                 convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
1690                                                         if let syn::GenericArgument::Type(ty) = arg {
1691                                                                 ty
1692                                                         } else { unimplemented!(); }
1693                                                 }));
1694                                         } else { unimplemented!(); }
1695                                 }
1696                                 if self.is_primitive(&resolved_path) {
1697                                         false
1698                                 } else if let Some(ty_ident) = single_ident_generic_path_to_ident(&p.path) {
1699                                         if let Some((prefix, suffix)) = path_lookup(&resolved_path, is_ref) {
1700                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1701                                                 true
1702                                         } else if self.types.maybe_resolve_declared(ty_ident).is_some() {
1703                                                 false
1704                                         } else { false }
1705                                 } else { false }
1706                         },
1707                         syn::Type::Array(_) => {
1708                                 // We assume all arrays contain only primitive types.
1709                                 // This may result in some outputs not compiling.
1710                                 false
1711                         },
1712                         syn::Type::Slice(s) => {
1713                                 if let syn::Type::Path(p) = &*s.elem {
1714                                         let resolved = self.resolve_path(&p.path, generics);
1715                                         assert!(self.is_primitive(&resolved));
1716                                         let slice_path = format!("[{}]", resolved);
1717                                         if let Some((prefix, suffix)) = path_lookup(&slice_path, true) {
1718                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1719                                                 true
1720                                         } else { false }
1721                                 } else if let syn::Type::Reference(ty) = &*s.elem {
1722                                         let tyref = [&*ty.elem];
1723                                         is_ref = true;
1724                                         convert_container!("Slice", 1, || tyref.iter());
1725                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1726                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1727                                         // When mapping into a temporary new var, we need to own all the underlying objects.
1728                                         // Thus, we drop any references inside the tuple and convert with non-reference types.
1729                                         let mut elems = syn::punctuated::Punctuated::new();
1730                                         for elem in t.elems.iter() {
1731                                                 if let syn::Type::Reference(r) = elem {
1732                                                         elems.push((*r.elem).clone());
1733                                                 } else {
1734                                                         elems.push(elem.clone());
1735                                                 }
1736                                         }
1737                                         let ty = [syn::Type::Tuple(syn::TypeTuple {
1738                                                 paren_token: t.paren_token, elems
1739                                         })];
1740                                         is_ref = false;
1741                                         ptr_for_ref = true;
1742                                         convert_container!("Slice", 1, || ty.iter());
1743                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1744                                 } else { unimplemented!() }
1745                         },
1746                         syn::Type::Tuple(t) => {
1747                                 if !t.elems.is_empty() {
1748                                         // We don't (yet) support tuple elements which cannot be converted inline
1749                                         write!(w, "let (").unwrap();
1750                                         for idx in 0..t.elems.len() {
1751                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1752                                                 write!(w, "{} orig_{}_{}", if is_ref { "ref" } else { "mut" }, ident, idx).unwrap();
1753                                         }
1754                                         write!(w, ") = {}{}; ", var, if !to_c { ".to_rust()" } else { "" }).unwrap();
1755                                         // Like other template types, tuples are always mapped as their non-ref
1756                                         // versions for types which have different ref mappings. Thus, we convert to
1757                                         // non-ref versions and handle opaque types with inner pointers manually.
1758                                         for (idx, elem) in t.elems.iter().enumerate() {
1759                                                 if let syn::Type::Path(p) = elem {
1760                                                         let v_name = format!("orig_{}_{}", ident, idx);
1761                                                         let tuple_elem_ident = syn::Ident::new(&v_name, Span::call_site());
1762                                                         if self.write_conversion_new_var_intern(w, &tuple_elem_ident, &v_name, elem, generics,
1763                                                                         false, ptr_for_ref, to_c,
1764                                                                         path_lookup, container_lookup, var_prefix, var_suffix) {
1765                                                                 write!(w, " ").unwrap();
1766                                                                 // Opaque types with inner pointers shouldn't ever create new stack
1767                                                                 // variables, so we don't handle it and just assert that it doesn't
1768                                                                 // here.
1769                                                                 assert!(!self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)));
1770                                                         }
1771                                                 }
1772                                         }
1773                                         write!(w, "let mut local_{} = (", ident).unwrap();
1774                                         for (idx, elem) in t.elems.iter().enumerate() {
1775                                                 let ty_has_inner = {
1776                                                                 if to_c {
1777                                                                         // "To C ptr_for_ref" means "return the regular object with
1778                                                                         // is_owned set to false", which is totally what we want
1779                                                                         // if we're about to set ty_has_inner.
1780                                                                         ptr_for_ref = true;
1781                                                                 }
1782                                                                 if let syn::Type::Reference(t) = elem {
1783                                                                         if let syn::Type::Path(p) = &*t.elem {
1784                                                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1785                                                                         } else { false }
1786                                                                 } else if let syn::Type::Path(p) = elem {
1787                                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1788                                                                 } else { false }
1789                                                         };
1790                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1791                                                 var_prefix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1792                                                 if is_ref && ty_has_inner {
1793                                                         // For ty_has_inner, the regular var_prefix mapping will take a
1794                                                         // reference, so deref once here to make sure we keep the original ref.
1795                                                         write!(w, "*").unwrap();
1796                                                 }
1797                                                 write!(w, "orig_{}_{}", ident, idx).unwrap();
1798                                                 if is_ref && !ty_has_inner {
1799                                                         // If we don't have an inner variable's reference to maintain, just
1800                                                         // hope the type is Clonable and use that.
1801                                                         write!(w, ".clone()").unwrap();
1802                                                 }
1803                                                 var_suffix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1804                                         }
1805                                         write!(w, "){};", if to_c { ".into()" } else { "" }).unwrap();
1806                                         true
1807                                 } else { false }
1808                         },
1809                         _ => unimplemented!(),
1810                 }
1811         }
1812
1813         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) -> bool {
1814                 self.write_conversion_new_var_intern(w, ident, var_access, t, generics, false, ptr_for_ref, true,
1815                         &|a, b| self.to_c_conversion_new_var_from_path(a, b),
1816                         &|a, b, c, d, e| self.to_c_conversion_container_new_var(generics, a, b, c, d, e),
1817                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1818                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_prefix_inner(a, b, c, d, e, f),
1819                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_suffix_inner(a, b, c, d, e, f))
1820         }
1821         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 {
1822                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, ptr_for_ref)
1823         }
1824         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 {
1825                 self.write_conversion_new_var_intern(w, ident, &format!("{}", ident), t, generics, false, false, false,
1826                         &|a, b| self.from_c_conversion_new_var_from_path(a, b),
1827                         &|a, b, c, d, e| self.from_c_conversion_container_new_var(generics, a, b, c, d, e),
1828                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1829                         &|a, b, c, d, e, _f| self.write_from_c_conversion_prefix_inner(a, b, c, d, e),
1830                         &|a, b, c, d, e, _f| self.write_from_c_conversion_suffix_inner(a, b, c, d, e))
1831         }
1832
1833         // ******************************************************
1834         // *** C Container Type Equivalent and alias Printing ***
1835         // ******************************************************
1836
1837         fn write_template_generics<'b, W: std::io::Write>(&mut self, w: &mut W, args: &mut dyn Iterator<Item=&'b syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
1838                 assert!(!is_ref); // We don't currently support outer reference types
1839                 for (idx, t) in args.enumerate() {
1840                         if idx != 0 {
1841                                 write!(w, ", ").unwrap();
1842                         }
1843                         if let syn::Type::Reference(r_arg) = t {
1844                                 if !self.write_c_type_intern(w, &*r_arg.elem, generics, false, false, false) { return false; }
1845
1846                                 // While write_c_type_intern, above is correct, we don't want to blindly convert a
1847                                 // reference to something stupid, so check that the container is either opaque or a
1848                                 // predefined type (currently only Transaction).
1849                                 if let syn::Type::Path(p_arg) = &*r_arg.elem {
1850                                         let resolved = self.resolve_path(&p_arg.path, generics);
1851                                         assert!(self.crate_types.opaques.get(&resolved).is_some() ||
1852                                                         self.c_type_from_path(&resolved, true, true).is_some(), "Template generics should be opaque or have a predefined mapping");
1853                                 } else { unimplemented!(); }
1854                         } else {
1855                                 if !self.write_c_type_intern(w, t, generics, false, false, false) { return false; }
1856                         }
1857                 }
1858                 true
1859         }
1860         fn check_create_container(&mut self, mangled_container: String, container_type: &str, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
1861                 if !self.crate_types.templates_defined.get(&mangled_container).is_some() {
1862                         let mut created_container: Vec<u8> = Vec::new();
1863
1864                         if container_type == "Result" {
1865                                 let mut a_ty: Vec<u8> = Vec::new();
1866                                 if let syn::Type::Tuple(tup) = args.iter().next().unwrap() {
1867                                         if tup.elems.is_empty() {
1868                                                 write!(&mut a_ty, "()").unwrap();
1869                                         } else {
1870                                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
1871                                         }
1872                                 } else {
1873                                         if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
1874                                 }
1875
1876                                 let mut b_ty: Vec<u8> = Vec::new();
1877                                 if let syn::Type::Tuple(tup) = args.iter().skip(1).next().unwrap() {
1878                                         if tup.elems.is_empty() {
1879                                                 write!(&mut b_ty, "()").unwrap();
1880                                         } else {
1881                                                 if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
1882                                         }
1883                                 } else {
1884                                         if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
1885                                 }
1886
1887                                 let ok_str = String::from_utf8(a_ty).unwrap();
1888                                 let err_str = String::from_utf8(b_ty).unwrap();
1889                                 let is_clonable = self.is_clonable(&ok_str) && self.is_clonable(&err_str);
1890                                 write_result_block(&mut created_container, &mangled_container, &ok_str, &err_str, is_clonable);
1891                                 if is_clonable {
1892                                         self.crate_types.clonable_types.insert(Self::generated_container_path().to_owned() + "::" + &mangled_container);
1893                                 }
1894                         } else if container_type == "Vec" {
1895                                 let mut a_ty: Vec<u8> = Vec::new();
1896                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t), generics, is_ref) { return false; }
1897                                 let ty = String::from_utf8(a_ty).unwrap();
1898                                 let is_clonable = self.is_clonable(&ty);
1899                                 write_vec_block(&mut created_container, &mangled_container, &ty, is_clonable);
1900                                 if is_clonable {
1901                                         self.crate_types.clonable_types.insert(Self::generated_container_path().to_owned() + "::" + &mangled_container);
1902                                 }
1903                         } else if container_type.ends_with("Tuple") {
1904                                 let mut tuple_args = Vec::new();
1905                                 let mut is_clonable = true;
1906                                 for arg in args.iter() {
1907                                         let mut ty: Vec<u8> = Vec::new();
1908                                         if !self.write_template_generics(&mut ty, &mut [arg].iter().map(|t| **t), generics, is_ref) { return false; }
1909                                         let ty_str = String::from_utf8(ty).unwrap();
1910                                         if !self.is_clonable(&ty_str) {
1911                                                 is_clonable = false;
1912                                         }
1913                                         tuple_args.push(ty_str);
1914                                 }
1915                                 write_tuple_block(&mut created_container, &mangled_container, &tuple_args, is_clonable);
1916                                 if is_clonable {
1917                                         self.crate_types.clonable_types.insert(Self::generated_container_path().to_owned() + "::" + &mangled_container);
1918                                 }
1919                         } else {
1920                                 unreachable!();
1921                         }
1922                         self.crate_types.templates_defined.insert(mangled_container.clone(), true);
1923
1924                         self.crate_types.template_file.write(&created_container).unwrap();
1925                 }
1926                 true
1927         }
1928         fn path_to_generic_args(path: &syn::Path) -> Vec<&syn::Type> {
1929                 if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().next().unwrap().arguments {
1930                         args.args.iter().map(|gen| if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }).collect()
1931                 } else { unimplemented!(); }
1932         }
1933         fn write_c_mangled_container_path_intern<W: std::io::Write>
1934                         (&mut 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 {
1935                 let mut mangled_type: Vec<u8> = Vec::new();
1936                 if !self.is_transparent_container(ident, is_ref) {
1937                         write!(w, "C{}_", ident).unwrap();
1938                         write!(mangled_type, "C{}_", ident).unwrap();
1939                 } else { assert_eq!(args.len(), 1); }
1940                 for arg in args.iter() {
1941                         macro_rules! write_path {
1942                                 ($p_arg: expr, $extra_write: expr) => {
1943                                         if let Some(subtype) = self.maybe_resolve_path(&$p_arg.path, generics) {
1944                                                 if self.is_transparent_container(ident, is_ref) {
1945                                                         // We dont (yet) support primitives or containers inside transparent
1946                                                         // containers, so check for that first:
1947                                                         if self.is_primitive(&subtype) { return false; }
1948                                                         if self.is_known_container(&subtype, is_ref) { return false; }
1949                                                         if !in_type {
1950                                                                 if self.c_type_has_inner_from_path(&subtype) {
1951                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, is_ref, is_mut, ptr_for_ref) { return false; }
1952                                                                 } else {
1953                                                                         // Option<T> needs to be converted to a *mut T, ie mut ptr-for-ref
1954                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, true, true, true) { return false; }
1955                                                                 }
1956                                                         } else {
1957                                                                 write!(w, "{}", $p_arg.path.segments.last().unwrap().ident).unwrap();
1958                                                         }
1959                                                 } else if self.is_known_container(&subtype, is_ref) || self.is_transparent_container(&subtype, is_ref) {
1960                                                         if !self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(&$p_arg.path), generics,
1961                                                                         &subtype, is_ref, is_mut, ptr_for_ref, true) {
1962                                                                 return false;
1963                                                         }
1964                                                         self.write_c_mangled_container_path_intern(&mut mangled_type, Self::path_to_generic_args(&$p_arg.path),
1965                                                                 generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1966                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1967                                                                 self.write_c_mangled_container_path_intern(w2, Self::path_to_generic_args(&$p_arg.path),
1968                                                                         generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1969                                                         }
1970                                                 } else {
1971                                                         let id = subtype.rsplitn(2, ':').next().unwrap(); // Get the "Base" name of the resolved type
1972                                                         write!(w, "{}", id).unwrap();
1973                                                         write!(mangled_type, "{}", id).unwrap();
1974                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1975                                                                 write!(w2, "{}", id).unwrap();
1976                                                         }
1977                                                 }
1978                                         } else { return false; }
1979                                 }
1980                         }
1981                         if let syn::Type::Tuple(tuple) = arg {
1982                                 if tuple.elems.len() == 0 {
1983                                         write!(w, "None").unwrap();
1984                                         write!(mangled_type, "None").unwrap();
1985                                 } else {
1986                                         let mut mangled_tuple_type: Vec<u8> = Vec::new();
1987
1988                                         // Figure out what the mangled type should look like. To disambiguate
1989                                         // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
1990                                         // them with a Z. Ideally we wouldn't use Z, but not many special chars are
1991                                         // available for use in type names.
1992                                         write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
1993                                         write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
1994                                         write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
1995                                         for elem in tuple.elems.iter() {
1996                                                 if let syn::Type::Path(p) = elem {
1997                                                         write_path!(p, Some(&mut mangled_tuple_type));
1998                                                 } else if let syn::Type::Reference(refelem) = elem {
1999                                                         if let syn::Type::Path(p) = &*refelem.elem {
2000                                                                 write_path!(p, Some(&mut mangled_tuple_type));
2001                                                         } else { return false; }
2002                                                 } else { return false; }
2003                                         }
2004                                         write!(w, "Z").unwrap();
2005                                         write!(mangled_type, "Z").unwrap();
2006                                         write!(mangled_tuple_type, "Z").unwrap();
2007                                         if !self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
2008                                                         &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref) {
2009                                                 return false;
2010                                         }
2011                                 }
2012                         } else if let syn::Type::Path(p_arg) = arg {
2013                                 write_path!(p_arg, None);
2014                         } else if let syn::Type::Reference(refty) = arg {
2015                                 if let syn::Type::Path(p_arg) = &*refty.elem {
2016                                         write_path!(p_arg, None);
2017                                 } else if let syn::Type::Slice(_) = &*refty.elem {
2018                                         // write_c_type will actually do exactly what we want here, we just need to
2019                                         // make it a pointer so that its an option. Note that we cannot always convert
2020                                         // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
2021                                         // to edit it, hence we use *mut here instead of *const.
2022                                         if args.len() != 1 { return false; }
2023                                         write!(w, "*mut ").unwrap();
2024                                         self.write_c_type(w, arg, None, true);
2025                                 } else { return false; }
2026                         } else if let syn::Type::Array(a) = arg {
2027                                 if let syn::Type::Path(p_arg) = &*a.elem {
2028                                         let resolved = self.resolve_path(&p_arg.path, generics);
2029                                         if !self.is_primitive(&resolved) { return false; }
2030                                         if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
2031                                                 if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
2032                                                 write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
2033                                                 write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
2034                                         } else { return false; }
2035                                 } else { return false; }
2036                         } else { return false; }
2037                 }
2038                 if self.is_transparent_container(ident, is_ref) { return true; }
2039                 // Push the "end of type" Z
2040                 write!(w, "Z").unwrap();
2041                 write!(mangled_type, "Z").unwrap();
2042
2043                 // Make sure the type is actually defined:
2044                 self.check_create_container(String::from_utf8(mangled_type).unwrap(), ident, args, generics, is_ref)
2045         }
2046         fn write_c_mangled_container_path<W: std::io::Write>(&mut self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
2047                 if !self.is_transparent_container(ident, is_ref) {
2048                         write!(w, "{}::", Self::generated_container_path()).unwrap();
2049                 }
2050                 self.write_c_mangled_container_path_intern(w, args, generics, ident, is_ref, is_mut, ptr_for_ref, false)
2051         }
2052
2053         // **********************************
2054         // *** C Type Equivalent Printing ***
2055         // **********************************
2056
2057         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) -> bool {
2058                 let full_path = match self.maybe_resolve_path(&path, generics) {
2059                         Some(path) => path, None => return false };
2060                 if let Some(c_type) = self.c_type_from_path(&full_path, is_ref, ptr_for_ref) {
2061                         write!(w, "{}", c_type).unwrap();
2062                         true
2063                 } else if self.crate_types.traits.get(&full_path).is_some() {
2064                         if is_ref && ptr_for_ref {
2065                                 write!(w, "*{} crate::{}", if is_mut { "mut" } else { "const" }, full_path).unwrap();
2066                         } else if is_ref {
2067                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
2068                         } else {
2069                                 write!(w, "crate::{}", full_path).unwrap();
2070                         }
2071                         true
2072                 } else if self.crate_types.opaques.get(&full_path).is_some() || self.crate_types.mirrored_enums.get(&full_path).is_some() {
2073                         if is_ref && ptr_for_ref {
2074                                 // ptr_for_ref implies we're returning the object, which we can't really do for
2075                                 // opaque or mirrored types without box'ing them, which is quite a waste, so return
2076                                 // the actual object itself (for opaque types we'll set the pointer to the actual
2077                                 // type and note that its a reference).
2078                                 write!(w, "crate::{}", full_path).unwrap();
2079                         } else if is_ref {
2080                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
2081                         } else {
2082                                 write!(w, "crate::{}", full_path).unwrap();
2083                         }
2084                         true
2085                 } else {
2086                         false
2087                 }
2088         }
2089         fn write_c_type_intern<W: std::io::Write>(&mut self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
2090                 match t {
2091                         syn::Type::Path(p) => {
2092                                 if p.qself.is_some() {
2093                                         return false;
2094                                 }
2095                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
2096                                         if self.is_known_container(&full_path, is_ref) || self.is_transparent_container(&full_path, is_ref) {
2097                                                 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);
2098                                         }
2099                                         if let Some(aliased_type) = self.crate_types.type_aliases.get(&full_path).cloned() {
2100                                                 return self.write_c_type_intern(w, &aliased_type, None, is_ref, is_mut, ptr_for_ref);
2101                                         }
2102                                 }
2103                                 self.write_c_path_intern(w, &p.path, generics, is_ref, is_mut, ptr_for_ref)
2104                         },
2105                         syn::Type::Reference(r) => {
2106                                 self.write_c_type_intern(w, &*r.elem, generics, true, r.mutability.is_some(), ptr_for_ref)
2107                         },
2108                         syn::Type::Array(a) => {
2109                                 if is_ref && is_mut {
2110                                         write!(w, "*mut [").unwrap();
2111                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2112                                 } else if is_ref {
2113                                         write!(w, "*const [").unwrap();
2114                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2115                                 } else {
2116                                         let mut typecheck = Vec::new();
2117                                         if !self.write_c_type_intern(&mut typecheck, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2118                                         if typecheck[..] != ['u' as u8, '8' as u8] { return false; }
2119                                 }
2120                                 if let syn::Expr::Lit(l) = &a.len {
2121                                         if let syn::Lit::Int(i) = &l.lit {
2122                                                 if !is_ref {
2123                                                         if let Some(ty) = self.c_type_from_path(&format!("[u8; {}]", i.base10_digits()), false, ptr_for_ref) {
2124                                                                 write!(w, "{}", ty).unwrap();
2125                                                                 true
2126                                                         } else { false }
2127                                                 } else {
2128                                                         write!(w, "; {}]", i).unwrap();
2129                                                         true
2130                                                 }
2131                                         } else { false }
2132                                 } else { false }
2133                         }
2134                         syn::Type::Slice(s) => {
2135                                 if !is_ref || is_mut { return false; }
2136                                 if let syn::Type::Path(p) = &*s.elem {
2137                                         let resolved = self.resolve_path(&p.path, generics);
2138                                         if self.is_primitive(&resolved) {
2139                                                 write!(w, "{}::{}slice", Self::container_templ_path(), resolved).unwrap();
2140                                                 true
2141                                         } else { false }
2142                                 } else if let syn::Type::Reference(r) = &*s.elem {
2143                                         if let syn::Type::Path(p) = &*r.elem {
2144                                                 // Slices with "real types" inside are mapped as the equivalent non-ref Vec
2145                                                 let resolved = self.resolve_path(&p.path, generics);
2146                                                 let mangled_container = if let Some(ident) = self.crate_types.opaques.get(&resolved) {
2147                                                         format!("CVec_{}Z", ident)
2148                                                 } else if let Some(en) = self.crate_types.mirrored_enums.get(&resolved) {
2149                                                         format!("CVec_{}Z", en.ident)
2150                                                 } else if let Some(id) = p.path.get_ident() {
2151                                                         format!("CVec_{}Z", id)
2152                                                 } else { return false; };
2153                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2154                                                 self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false)
2155                                         } else { false }
2156                                 } else if let syn::Type::Tuple(_) = &*s.elem {
2157                                         let mut args = syn::punctuated::Punctuated::new();
2158                                         args.push(syn::GenericArgument::Type((*s.elem).clone()));
2159                                         let mut segments = syn::punctuated::Punctuated::new();
2160                                         segments.push(syn::PathSegment {
2161                                                 ident: syn::Ident::new("Vec", Span::call_site()),
2162                                                 arguments: syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
2163                                                         colon2_token: None, lt_token: syn::Token![<](Span::call_site()), args, gt_token: syn::Token![>](Span::call_site()),
2164                                                 })
2165                                         });
2166                                         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)
2167                                 } else { false }
2168                         },
2169                         syn::Type::Tuple(t) => {
2170                                 if t.elems.len() == 0 {
2171                                         true
2172                                 } else {
2173                                         self.write_c_mangled_container_path(w, t.elems.iter().collect(), generics,
2174                                                 &format!("{}Tuple", t.elems.len()), is_ref, is_mut, ptr_for_ref)
2175                                 }
2176                         },
2177                         _ => false,
2178                 }
2179         }
2180         pub fn write_c_type<W: std::io::Write>(&mut self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2181                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref));
2182         }
2183         pub fn understood_c_path(&mut self, p: &syn::Path) -> bool {
2184                 if p.leading_colon.is_some() { return false; }
2185                 self.write_c_path_intern(&mut std::io::sink(), p, None, false, false, false)
2186         }
2187         pub fn understood_c_type(&mut self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2188                 self.write_c_type_intern(&mut std::io::sink(), t, generics, false, false, false)
2189         }
2190 }