_ 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 #[derive(PartialEq)]
 581 /// Describes the appropriate place to print a general type-conversion string when converting a
 582 /// container.
 583 enum ContainerPrefixLocation {
 584         /// Prints a general type-conversion string prefix and suffix outside of the
 585         /// container-conversion strings.
 586         OutsideConv,
 587         /// Prints a general type-conversion string prefix and suffix inside of the
 588         /// container-conversion strings.
 589         PerConv,
 590         /// Does not print the usual type-conversion string prefix and suffix.
 591         NoPrefix,
 592 }
 593
 594 impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 595         pub fn new(orig_crate: &'a str, module_path: &'a str, types: ImportResolver<'a, 'c>, crate_types: &'a mut CrateTypes<'c>) -> Self {
 596                 Self { orig_crate, module_path, types, crate_types }
 597         }
 598
 599         // *************************************************
 600         // *** Well know type and conversion definitions ***
 601         // *************************************************
 602
 603         /// Returns true we if can just skip passing this to C entirely
 604         fn skip_path(&self, full_path: &str) -> bool {
 605                 full_path == "bitcoin::secp256k1::Secp256k1" ||
 606                 full_path == "bitcoin::secp256k1::Signing" ||
 607                 full_path == "bitcoin::secp256k1::Verification"
 608         }
 609         /// Returns true we if can just skip passing this to C entirely
 610         fn no_arg_path_to_rust(&self, full_path: &str) -> &str {
 611                 if full_path == "bitcoin::secp256k1::Secp256k1" {
 612                         "secp256k1::SECP256K1"
 613                 } else { unimplemented!(); }
 614         }
 615
 616         /// Returns true if the object is a primitive and is mapped as-is with no conversion
 617         /// whatsoever.
 618         pub fn is_primitive(&self, full_path: &str) -> bool {
 619                 match full_path {
 620                         "bool" => true,
 621                         "u64" => true,
 622                         "u32" => true,
 623                         "u16" => true,
 624                         "u8" => true,
 625                         "usize" => true,
 626                         _ => false,
 627                 }
 628         }
 629         pub fn is_clonable(&self, ty: &str) -> bool {
 630                 if self.crate_types.clonable_types.contains(ty) { return true; }
 631                 if self.is_primitive(ty) { return true; }
 632                 match ty {
 633                         "()" => true,
 634                         "crate::c_types::Signature" => true,
 635                         "crate::c_types::TxOut" => true,
 636                         _ => false,
 637                 }
 638         }
 639         /// Gets the C-mapped type for types which are outside of the crate, or which are manually
 640         /// ignored by for some reason need mapping anyway.
 641         fn c_type_from_path<'b>(&self, full_path: &'b str, is_ref: bool, _ptr_for_ref: bool) -> Option<&'b str> {
 642                 if self.is_primitive(full_path) {
 643                         return Some(full_path);
 644                 }
 645                 match full_path {
 646                         "Result" => Some("crate::c_types::derived::CResult"),
 647                         "Vec" if !is_ref => Some("crate::c_types::derived::CVec"),
 648                         "Option" => Some(""),
 649
 650                         // Note that no !is_ref types can map to an array because Rust and C's call semantics
 651                         // for arrays are different (https://github.com/eqrion/cbindgen/issues/528)
 652
 653                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 654                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes"),
 655                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes"),
 656                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes"),
 657                         "[u8; 3]" if !is_ref => Some("crate::c_types::ThreeBytes"), // Used for RGB values
 658
 659                         "str" if is_ref => Some("crate::c_types::Str"),
 660                         "String" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 661                         "String" if is_ref => Some("crate::c_types::Str"),
 662
 663                         "std::time::Duration" => Some("u64"),
 664
 665                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey"),
 666                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature"),
 667                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some("*const [u8; 32]"),
 668                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey"),
 669                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error"),
 670                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice"),
 671                         "bitcoin::blockdata::script::Script" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 672                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::chain::transaction::OutPoint"),
 673                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction"),
 674                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut"),
 675                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network"),
 676                         "bitcoin::blockdata::block::BlockHeader" if is_ref  => Some("*const [u8; 80]"),
 677                         "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
 678
 679                         // Newtypes that we just expose in their original form.
 680                         "bitcoin::hash_types::Txid" if is_ref  => Some("*const [u8; 32]"),
 681                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 682                         "bitcoin::hash_types::BlockHash" if is_ref  => Some("*const [u8; 32]"),
 683                         "bitcoin::hash_types::BlockHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 684                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 685                         "ln::channelmanager::PaymentHash" if is_ref => Some("*const [u8; 32]"),
 686                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 687                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("*const [u8; 32]"),
 688                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 689                         "ln::channelmanager::PaymentSecret" if is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 690                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 691
 692                         // Override the default since Records contain an fmt with a lifetime:
 693                         "util::logger::Record" => Some("*const std::os::raw::c_char"),
 694
 695                         _ => None,
 696                 }
 697         }
 698
 699         fn from_c_conversion_new_var_from_path<'b>(&self, _full_path: &str, _is_ref: bool) -> Option<(&'b str, &'b str)> {
 700                 None
 701         }
 702         fn from_c_conversion_prefix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 703                 if self.is_primitive(full_path) {
 704                         return Some("".to_owned());
 705                 }
 706                 match full_path {
 707                         "Vec" if !is_ref => Some("local_"),
 708                         "Result" if !is_ref => Some("local_"),
 709                         "Option" if is_ref => Some("&local_"),
 710                         "Option" => Some("local_"),
 711
 712                         "[u8; 32]" if is_ref => Some("unsafe { &*"),
 713                         "[u8; 32]" if !is_ref => Some(""),
 714                         "[u8; 16]" if !is_ref => Some(""),
 715                         "[u8; 10]" if !is_ref => Some(""),
 716                         "[u8; 4]" if !is_ref => Some(""),
 717                         "[u8; 3]" if !is_ref => Some(""),
 718
 719                         "[u8]" if is_ref => Some(""),
 720                         "[usize]" if is_ref => Some(""),
 721
 722                         "str" if is_ref => Some(""),
 723                         "String" if !is_ref => Some("String::from_utf8("),
 724                         // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
 725                         // cannot create a &String.
 726
 727                         "std::time::Duration" => Some("std::time::Duration::from_secs("),
 728
 729                         "bitcoin::secp256k1::key::PublicKey" if is_ref => Some("&"),
 730                         "bitcoin::secp256k1::key::PublicKey" => Some(""),
 731                         "bitcoin::secp256k1::Signature" if is_ref => Some("&"),
 732                         "bitcoin::secp256k1::Signature" => Some(""),
 733                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("&::bitcoin::secp256k1::key::SecretKey::from_slice(&unsafe { *"),
 734                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(""),
 735                         "bitcoin::blockdata::script::Script" if is_ref => Some("&::bitcoin::blockdata::script::Script::from(Vec::from("),
 736                         "bitcoin::blockdata::script::Script" if !is_ref => Some("::bitcoin::blockdata::script::Script::from("),
 737                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some("&"),
 738                         "bitcoin::blockdata::transaction::Transaction" => Some(""),
 739                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(""),
 740                         "bitcoin::network::constants::Network" => Some(""),
 741                         "bitcoin::blockdata::block::BlockHeader" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
 742                         "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
 743
 744                         // Newtypes that we just expose in their original form.
 745                         "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
 746                         "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
 747                         "bitcoin::hash_types::BlockHash" => Some("::bitcoin::hash_types::BlockHash::from_slice(&"),
 748                         "ln::channelmanager::PaymentHash" if !is_ref => Some("::lightning::ln::channelmanager::PaymentHash("),
 749                         "ln::channelmanager::PaymentHash" if is_ref => Some("&::lightning::ln::channelmanager::PaymentHash(unsafe { *"),
 750                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("::lightning::ln::channelmanager::PaymentPreimage("),
 751                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&::lightning::ln::channelmanager::PaymentPreimage(unsafe { *"),
 752                         "ln::channelmanager::PaymentSecret" => Some("::lightning::ln::channelmanager::PaymentSecret("),
 753
 754                         // List of traits we map (possibly during processing of other files):
 755                         "crate::util::logger::Logger" => Some(""),
 756
 757                         _ => None,
 758                 }.map(|s| s.to_owned())
 759         }
 760         fn from_c_conversion_suffix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 761                 if self.is_primitive(full_path) {
 762                         return Some("".to_owned());
 763                 }
 764                 match full_path {
 765                         "Vec" if !is_ref => Some(""),
 766                         "Option" => Some(""),
 767                         "Result" if !is_ref => Some(""),
 768
 769                         "[u8; 32]" if is_ref => Some("}"),
 770                         "[u8; 32]" if !is_ref => Some(".data"),
 771                         "[u8; 16]" if !is_ref => Some(".data"),
 772                         "[u8; 10]" if !is_ref => Some(".data"),
 773                         "[u8; 4]" if !is_ref => Some(".data"),
 774                         "[u8; 3]" if !is_ref => Some(".data"),
 775
 776                         "[u8]" if is_ref => Some(".to_slice()"),
 777                         "[usize]" if is_ref => Some(".to_slice()"),
 778
 779                         "str" if is_ref => Some(".into()"),
 780                         "String" if !is_ref => Some(".into_rust()).unwrap()"),
 781
 782                         "std::time::Duration" => Some(")"),
 783
 784                         "bitcoin::secp256k1::key::PublicKey" => Some(".into_rust()"),
 785                         "bitcoin::secp256k1::Signature" => Some(".into_rust()"),
 786                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(".into_rust()"),
 787                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("}[..]).unwrap()"),
 788                         "bitcoin::blockdata::script::Script" if is_ref => Some(".to_slice()))"),
 789                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_rust())"),
 790                         "bitcoin::blockdata::transaction::Transaction" => Some(".into_bitcoin()"),
 791                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(".into_rust()"),
 792                         "bitcoin::network::constants::Network" => Some(".into_bitcoin()"),
 793                         "bitcoin::blockdata::block::BlockHeader" => Some(" }).unwrap()"),
 794                         "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
 795
 796                         // Newtypes that we just expose in their original form.
 797                         "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
 798                         "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
 799                         "bitcoin::hash_types::BlockHash" if !is_ref => Some(".data[..]).unwrap()"),
 800                         "ln::channelmanager::PaymentHash" if !is_ref => Some(".data)"),
 801                         "ln::channelmanager::PaymentHash" if is_ref => Some(" })"),
 802                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some(".data)"),
 803                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(" })"),
 804                         "ln::channelmanager::PaymentSecret" => Some(".data)"),
 805
 806                         // List of traits we map (possibly during processing of other files):
 807                         "crate::util::logger::Logger" => Some(""),
 808
 809                         _ => None,
 810                 }.map(|s| s.to_owned())
 811         }
 812
 813         fn to_c_conversion_new_var_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<(&'b str, &'b str)> {
 814                 if self.is_primitive(full_path) {
 815                         return None;
 816                 }
 817                 match full_path {
 818                         "[u8]" if is_ref => Some(("crate::c_types::u8slice::from_slice(", ")")),
 819                         "[usize]" if is_ref => Some(("crate::c_types::usizeslice::from_slice(", ")")),
 820
 821                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 822                         "bitcoin::blockdata::transaction::Transaction" if !is_ref => Some(("::bitcoin::consensus::encode::serialize(&", ")")),
 823                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(("{ let mut s = [0u8; 80]; s[..].copy_from_slice(&::bitcoin::consensus::encode::serialize(", ")); s }")),
 824                         "bitcoin::blockdata::block::Block" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 825                         "bitcoin::hash_types::Txid" => None,
 826
 827                         // Override the default since Records contain an fmt with a lifetime:
 828                         // TODO: We should include the other record fields
 829                         "util::logger::Record" => Some(("std::ffi::CString::new(format!(\"{}\", ", ".args)).unwrap()")),
 830                         _ => None,
 831                 }.map(|s| s.to_owned())
 832         }
 833         fn to_c_conversion_inline_prefix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
 834                 if self.is_primitive(full_path) {
 835                         return Some("".to_owned());
 836                 }
 837                 match full_path {
 838                         "Result" if !is_ref => Some("local_"),
 839                         "Vec" if !is_ref => Some("local_"),
 840                         "Option" => Some("local_"),
 841
 842                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 843                         "[u8; 32]" if is_ref => Some("&"),
 844                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes { data: "),
 845                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes { data: "),
 846                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes { data: "),
 847                         "[u8; 3]" if is_ref => Some("&"),
 848
 849                         "[u8]" if is_ref => Some("local_"),
 850                         "[usize]" if is_ref => Some("local_"),
 851
 852                         "str" if is_ref => Some(""),
 853                         "String" => Some(""),
 854
 855                         "std::time::Duration" => Some(""),
 856
 857                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey::from_rust(&"),
 858                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature::from_rust(&"),
 859                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some(""),
 860                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
 861                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error::from_rust("),
 862                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice::from_slice(&"),
 863                         "bitcoin::blockdata::script::Script" if !is_ref => Some(""),
 864                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction::from_vec(local_"),
 865                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::c_types::bitcoin_to_C_outpoint("),
 866                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut::from_rust("),
 867                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network::from_bitcoin("),
 868                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some("&local_"),
 869                         "bitcoin::blockdata::block::Block" if is_ref => Some("crate::c_types::u8slice::from_slice(&local_"),
 870
 871                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 872
 873                         // Newtypes that we just expose in their original form.
 874                         "bitcoin::hash_types::Txid" if is_ref => Some(""),
 875                         "bitcoin::hash_types::BlockHash" if is_ref => Some(""),
 876                         "bitcoin::hash_types::BlockHash" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 877                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 878                         "ln::channelmanager::PaymentHash" if is_ref => Some("&"),
 879                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 880                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&"),
 881                         "ln::channelmanager::PaymentPreimage" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 882                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 883
 884                         // Override the default since Records contain an fmt with a lifetime:
 885                         "util::logger::Record" => Some("local_"),
 886
 887                         _ => None,
 888                 }.map(|s| s.to_owned())
 889         }
 890         fn to_c_conversion_inline_suffix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
 891                 if self.is_primitive(full_path) {
 892                         return Some("".to_owned());
 893                 }
 894                 match full_path {
 895                         "Result" if !is_ref => Some(""),
 896                         "Vec" if !is_ref => Some(".into()"),
 897                         "Option" => Some(""),
 898
 899                         "[u8; 32]" if !is_ref => Some(" }"),
 900                         "[u8; 32]" if is_ref => Some(""),
 901                         "[u8; 16]" if !is_ref => Some(" }"),
 902                         "[u8; 10]" if !is_ref => Some(" }"),
 903                         "[u8; 4]" if !is_ref => Some(" }"),
 904                         "[u8; 3]" if is_ref => Some(""),
 905
 906                         "[u8]" if is_ref => Some(""),
 907                         "[usize]" if is_ref => Some(""),
 908
 909                         "str" if is_ref => Some(".into()"),
 910                         "String" if !is_ref => Some(".into_bytes().into()"),
 911                         "String" if is_ref => Some(".as_str().into()"),
 912
 913                         "std::time::Duration" => Some(".as_secs()"),
 914
 915                         "bitcoin::secp256k1::key::PublicKey" => Some(")"),
 916                         "bitcoin::secp256k1::Signature" => Some(")"),
 917                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(")"),
 918                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some(".as_ref()"),
 919                         "bitcoin::secp256k1::Error" if !is_ref => Some(")"),
 920                         "bitcoin::blockdata::script::Script" if is_ref => Some("[..])"),
 921                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_bytes().into()"),
 922                         "bitcoin::blockdata::transaction::Transaction" => Some(")"),
 923                         "bitcoin::blockdata::transaction::OutPoint" => Some(")"),
 924                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(")"),
 925                         "bitcoin::network::constants::Network" => Some(")"),
 926                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(""),
 927                         "bitcoin::blockdata::block::Block" if is_ref => Some(")"),
 928
 929                         "bitcoin::hash_types::Txid" if !is_ref => Some(".into_inner() }"),
 930
 931                         // Newtypes that we just expose in their original form.
 932                         "bitcoin::hash_types::Txid" if is_ref => Some(".as_inner()"),
 933                         "bitcoin::hash_types::BlockHash" if is_ref => Some(".as_inner()"),
 934                         "bitcoin::hash_types::BlockHash" => Some(".into_inner() }"),
 935                         "bitcoin::secp256k1::Message" if !is_ref => Some(".as_ref().clone() }"),
 936                         "ln::channelmanager::PaymentHash" if is_ref => Some(".0"),
 937                         "ln::channelmanager::PaymentHash" => Some(".0 }"),
 938                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(".0"),
 939                         "ln::channelmanager::PaymentPreimage" => Some(".0 }"),
 940                         "ln::channelmanager::PaymentSecret" if !is_ref => Some(".0 }"),
 941
 942                         // Override the default since Records contain an fmt with a lifetime:
 943                         "util::logger::Record" => Some(".as_ptr()"),
 944
 945                         _ => None,
 946                 }.map(|s| s.to_owned())
 947         }
 948
 949         fn empty_val_check_suffix_from_path(&self, full_path: &str) -> Option<&str> {
 950                 match full_path {
 951                         "ln::channelmanager::PaymentSecret" => Some(".data == [0; 32]"),
 952                         "bitcoin::secp256k1::key::PublicKey" => Some(".is_null()"),
 953                         "bitcoin::secp256k1::Signature" => Some(".is_null()"),
 954                         _ => None
 955                 }
 956         }
 957
 958         // ****************************
 959         // *** Container Processing ***
 960         // ****************************
 961
 962         /// Returns the module path in the generated mapping crate to the containers which we generate
 963         /// when writing to CrateTypes::template_file.
 964         pub fn generated_container_path() -> &'static str {
 965                 "crate::c_types::derived"
 966         }
 967         /// Returns the module path in the generated mapping crate to the container templates, which
 968         /// are then concretized and put in the generated container path/template_file.
 969         fn container_templ_path() -> &'static str {
 970                 "crate::c_types"
 971         }
 972
 973         /// Returns true if this is a "transparent" container, ie an Option or a container which does
 974         /// not require a generated continer class.
 975         fn is_transparent_container(&self, full_path: &str, _is_ref: bool) -> bool {
 976                 full_path == "Option"
 977         }
 978         /// Returns true if this is a known, supported, non-transparent container.
 979         fn is_known_container(&self, full_path: &str, is_ref: bool) -> bool {
 980                 (full_path == "Result" && !is_ref) || (full_path == "Vec" && !is_ref) || full_path.ends_with("Tuple")
 981         }
 982         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)
 983                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
 984                         // expecting one element in the vec per generic type, each of which is inline-converted
 985                         -> Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)> {
 986                 match full_path {
 987                         "Result" if !is_ref => {
 988                                 Some(("match ",
 989                                                 vec![(" { Ok(mut o) => crate::c_types::CResultTempl::ok(".to_string(), "o".to_string()),
 990                                                         (").into(), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
 991                                                 ").into() }", ContainerPrefixLocation::PerConv))
 992                         },
 993                         "Vec" if !is_ref => {
 994                                 Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
 995                         },
 996                         "Slice" => {
 997                                 Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "**item".to_string())], "); }", ContainerPrefixLocation::PerConv))
 998                         },
 999                         "Option" => {
1000                                 if let Some(syn::Type::Path(p)) = single_contained {
1001                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
1002                                                 if is_ref {
1003                                                         return Some(("if ", vec![
1004                                                                 (".is_none() { std::ptr::null() } else { ".to_owned(), format!("({}.as_ref().unwrap())", var_access))
1005                                                                 ], " }", ContainerPrefixLocation::OutsideConv));
1006                                                 } else {
1007                                                         return Some(("if ", vec![
1008                                                                 (".is_none() { std::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
1009                                                                 ], " }", ContainerPrefixLocation::OutsideConv));
1010                                                 }
1011                                         }
1012                                 }
1013                                 if let Some(t) = single_contained {
1014                                         let mut v = Vec::new();
1015                                         self.write_empty_rust_val(generics, &mut v, t);
1016                                         let s = String::from_utf8(v).unwrap();
1017                                         return Some(("if ", vec![
1018                                                 (format!(".is_none() {{ {} }} else {{ ", s), format!("({}.unwrap())", var_access))
1019                                                 ], " }", ContainerPrefixLocation::PerConv));
1020                                 } else { unreachable!(); }
1021                         },
1022                         _ => None,
1023                 }
1024         }
1025
1026         /// only_contained_has_inner implies that there is only one contained element in the container
1027         /// and it has an inner field (ie is an "opaque" type we've defined).
1028         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)
1029                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
1030                         // expecting one element in the vec per generic type, each of which is inline-converted
1031                         -> Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)> {
1032                 match full_path {
1033                         "Result" if !is_ref => {
1034                                 Some(("match ",
1035                                                 vec![(".result_ok { true => Ok(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.result)) }})", var_access)),
1036                                                      ("), false => Err(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.err)) }})", var_access))],
1037                                                 ")}", ContainerPrefixLocation::PerConv))
1038                         },
1039                         "Slice" if is_ref => {
1040                                 Some(("Vec::new(); for mut item in ", vec![(format!(".as_slice().iter() {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1041                         },
1042                         "Vec"|"Slice" => {
1043                                 Some(("Vec::new(); for mut item in ", vec![(format!(".into_rust().drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1044                         },
1045                         "Option" => {
1046                                 if let Some(syn::Type::Path(p)) = single_contained {
1047                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
1048                                                 if is_ref {
1049                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some((*".to_string(), format!("{}", var_access))], ").clone()) }", ContainerPrefixLocation::PerConv))
1050                                                 } else {
1051                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some(".to_string(), format!("{}", var_access))], ") }", ContainerPrefixLocation::PerConv));
1052                                                 }
1053                                         }
1054                                 }
1055
1056                                 if let Some(t) = single_contained {
1057                                         let mut v = Vec::new();
1058                                         let ret_ref = self.write_empty_rust_val_check_suffix(generics, &mut v, t);
1059                                         let s = String::from_utf8(v).unwrap();
1060                                         match ret_ref {
1061                                                 EmptyValExpectedTy::ReferenceAsPointer =>
1062                                                         return Some(("if ", vec![
1063                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ &mut *{} }}", var_access))
1064                                                         ], ") }", ContainerPrefixLocation::NoPrefix)),
1065                                                 EmptyValExpectedTy::OwnedPointer =>
1066                                                         return Some(("if ", vec![
1067                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ *Box::from_raw({}) }}", var_access))
1068                                                         ], ") }", ContainerPrefixLocation::NoPrefix)),
1069                                                 EmptyValExpectedTy::NonPointer =>
1070                                                         return Some(("if ", vec![
1071                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("{}", var_access))
1072                                                         ], ") }", ContainerPrefixLocation::PerConv)),
1073                                         }
1074                                 } else { unreachable!(); }
1075                         },
1076                         _ => None,
1077                 }
1078         }
1079
1080         // *************************************************
1081         // *** Type definition during main.rs processing ***
1082         // *************************************************
1083
1084         pub fn get_declared_type(&'a self, ident: &syn::Ident) -> Option<&'a DeclType<'c>> {
1085                 self.types.get_declared_type(ident)
1086         }
1087         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
1088         pub fn c_type_has_inner_from_path(&self, full_path: &str) -> bool{
1089                 self.crate_types.opaques.get(full_path).is_some()
1090         }
1091
1092         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
1093                 self.types.maybe_resolve_ident(id)
1094         }
1095
1096         pub fn maybe_resolve_non_ignored_ident(&self, id: &syn::Ident) -> Option<String> {
1097                 self.types.maybe_resolve_non_ignored_ident(id)
1098         }
1099
1100         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
1101                 self.types.maybe_resolve_path(p_arg, generics)
1102         }
1103         pub fn resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> String {
1104                 self.maybe_resolve_path(p, generics).unwrap()
1105         }
1106
1107         // ***********************************
1108         // *** Original Rust Type Printing ***
1109         // ***********************************
1110
1111         fn in_rust_prelude(resolved_path: &str) -> bool {
1112                 match resolved_path {
1113                         "Vec" => true,
1114                         "Result" => true,
1115                         "Option" => true,
1116                         _ => false,
1117                 }
1118         }
1119
1120         fn write_rust_path<W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, path: &syn::Path) {
1121                 if let Some(resolved) = self.maybe_resolve_path(&path, generics_resolver) {
1122                         if self.is_primitive(&resolved) {
1123                                 write!(w, "{}", path.get_ident().unwrap()).unwrap();
1124                         } else {
1125                                 // TODO: We should have a generic "is from a dependency" check here instead of
1126                                 // checking for "bitcoin" explicitly.
1127                                 if resolved.starts_with("bitcoin::") || Self::in_rust_prelude(&resolved) {
1128                                         write!(w, "{}", resolved).unwrap();
1129                                 // If we're printing a generic argument, it needs to reference the crate, otherwise
1130                                 // the original crate:
1131                                 } else if self.maybe_resolve_path(&path, None).as_ref() == Some(&resolved) {
1132                                         write!(w, "{}::{}", self.orig_crate, resolved).unwrap();
1133                                 } else {
1134                                         write!(w, "crate::{}", resolved).unwrap();
1135                                 }
1136                         }
1137                         if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().last().unwrap().arguments {
1138                                 self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1139                         }
1140                 } else {
1141                         if path.leading_colon.is_some() {
1142                                 write!(w, "::").unwrap();
1143                         }
1144                         for (idx, seg) in path.segments.iter().enumerate() {
1145                                 if idx != 0 { write!(w, "::").unwrap(); }
1146                                 write!(w, "{}", seg.ident).unwrap();
1147                                 if let syn::PathArguments::AngleBracketed(args) = &seg.arguments {
1148                                         self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1149                                 }
1150                         }
1151                 }
1152         }
1153         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>) {
1154                 let mut had_params = false;
1155                 for (idx, arg) in generics.enumerate() {
1156                         if idx != 0 { write!(w, ", ").unwrap(); } else { write!(w, "<").unwrap(); }
1157                         had_params = true;
1158                         match arg {
1159                                 syn::GenericParam::Lifetime(lt) => write!(w, "'{}", lt.lifetime.ident).unwrap(),
1160                                 syn::GenericParam::Type(t) => {
1161                                         write!(w, "{}", t.ident).unwrap();
1162                                         if t.colon_token.is_some() { write!(w, ":").unwrap(); }
1163                                         for (idx, bound) in t.bounds.iter().enumerate() {
1164                                                 if idx != 0 { write!(w, " + ").unwrap(); }
1165                                                 match bound {
1166                                                         syn::TypeParamBound::Trait(tb) => {
1167                                                                 if tb.paren_token.is_some() || tb.lifetimes.is_some() { unimplemented!(); }
1168                                                                 self.write_rust_path(w, generics_resolver, &tb.path);
1169                                                         },
1170                                                         _ => unimplemented!(),
1171                                                 }
1172                                         }
1173                                         if t.eq_token.is_some() || t.default.is_some() { unimplemented!(); }
1174                                 },
1175                                 _ => unimplemented!(),
1176                         }
1177                 }
1178                 if had_params { write!(w, ">").unwrap(); }
1179         }
1180
1181         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>) {
1182                 write!(w, "<").unwrap();
1183                 for (idx, arg) in generics.enumerate() {
1184                         if idx != 0 { write!(w, ", ").unwrap(); }
1185                         match arg {
1186                                 syn::GenericArgument::Type(t) => self.write_rust_type(w, generics_resolver, t),
1187                                 _ => unimplemented!(),
1188                         }
1189                 }
1190                 write!(w, ">").unwrap();
1191         }
1192         pub fn write_rust_type<W: std::io::Write>(&self, w: &mut W, generics: Option<&GenericTypes>, t: &syn::Type) {
1193                 match t {
1194                         syn::Type::Path(p) => {
1195                                 if p.qself.is_some() {
1196                                         unimplemented!();
1197                                 }
1198                                 self.write_rust_path(w, generics, &p.path);
1199                         },
1200                         syn::Type::Reference(r) => {
1201                                 write!(w, "&").unwrap();
1202                                 if let Some(lft) = &r.lifetime {
1203                                         write!(w, "'{} ", lft.ident).unwrap();
1204                                 }
1205                                 if r.mutability.is_some() {
1206                                         write!(w, "mut ").unwrap();
1207                                 }
1208                                 self.write_rust_type(w, generics, &*r.elem);
1209                         },
1210                         syn::Type::Array(a) => {
1211                                 write!(w, "[").unwrap();
1212                                 self.write_rust_type(w, generics, &a.elem);
1213                                 if let syn::Expr::Lit(l) = &a.len {
1214                                         if let syn::Lit::Int(i) = &l.lit {
1215                                                 write!(w, "; {}]", i).unwrap();
1216                                         } else { unimplemented!(); }
1217                                 } else { unimplemented!(); }
1218                         }
1219                         syn::Type::Slice(s) => {
1220                                 write!(w, "[").unwrap();
1221                                 self.write_rust_type(w, generics, &s.elem);
1222                                 write!(w, "]").unwrap();
1223                         },
1224                         syn::Type::Tuple(s) => {
1225                                 write!(w, "(").unwrap();
1226                                 for (idx, t) in s.elems.iter().enumerate() {
1227                                         if idx != 0 { write!(w, ", ").unwrap(); }
1228                                         self.write_rust_type(w, generics, &t);
1229                                 }
1230                                 write!(w, ")").unwrap();
1231                         },
1232                         _ => unimplemented!(),
1233                 }
1234         }
1235
1236         /// Prints a constructor for something which is "uninitialized" (but obviously not actually
1237         /// unint'd memory).
1238         pub fn write_empty_rust_val<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) {
1239                 match t {
1240                         syn::Type::Path(p) => {
1241                                 let resolved = self.resolve_path(&p.path, generics);
1242                                 if self.crate_types.opaques.get(&resolved).is_some() {
1243                                         write!(w, "crate::{} {{ inner: std::ptr::null_mut(), is_owned: true }}", resolved).unwrap();
1244                                 } else {
1245                                         // Assume its a manually-mapped C type, where we can just define an null() fn
1246                                         write!(w, "{}::null()", self.c_type_from_path(&resolved, false, false).unwrap()).unwrap();
1247                                 }
1248                         },
1249                         syn::Type::Array(a) => {
1250                                 if let syn::Expr::Lit(l) = &a.len {
1251                                         if let syn::Lit::Int(i) = &l.lit {
1252                                                 if i.base10_digits().parse::<usize>().unwrap() < 32 {
1253                                                         // Blindly assume that if we're trying to create an empty value for an
1254                                                         // array < 32 entries that all-0s may be a valid state.
1255                                                         unimplemented!();
1256                                                 }
1257                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1258                                                 write!(w, "{}", self.to_c_conversion_inline_prefix_from_path(&arrty, false, false).unwrap()).unwrap();
1259                                                 write!(w, "[0; {}]", i.base10_digits()).unwrap();
1260                                                 write!(w, "{}", self.to_c_conversion_inline_suffix_from_path(&arrty, false, false).unwrap()).unwrap();
1261                                         } else { unimplemented!(); }
1262                                 } else { unimplemented!(); }
1263                         }
1264                         _ => unimplemented!(),
1265                 }
1266         }
1267
1268         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1269         /// See EmptyValExpectedTy for information on return types.
1270         fn write_empty_rust_val_check_suffix<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) -> EmptyValExpectedTy {
1271                 match t {
1272                         syn::Type::Path(p) => {
1273                                 let resolved = self.resolve_path(&p.path, generics);
1274                                 if self.crate_types.opaques.get(&resolved).is_some() {
1275                                         write!(w, ".inner.is_null()").unwrap();
1276                                         EmptyValExpectedTy::NonPointer
1277                                 } else {
1278                                         if let Some(suffix) = self.empty_val_check_suffix_from_path(&resolved) {
1279                                                 write!(w, "{}", suffix).unwrap();
1280                                                 // We may eventually need to allow empty_val_check_suffix_from_path to specify if we need a deref or not
1281                                                 EmptyValExpectedTy::NonPointer
1282                                         } else {
1283                                                 write!(w, " == std::ptr::null_mut()").unwrap();
1284                                                 EmptyValExpectedTy::OwnedPointer
1285                                         }
1286                                 }
1287                         },
1288                         syn::Type::Array(a) => {
1289                                 if let syn::Expr::Lit(l) = &a.len {
1290                                         if let syn::Lit::Int(i) = &l.lit {
1291                                                 write!(w, " == [0; {}]", i.base10_digits()).unwrap();
1292                                                 EmptyValExpectedTy::NonPointer
1293                                         } else { unimplemented!(); }
1294                                 } else { unimplemented!(); }
1295                         },
1296                         syn::Type::Slice(_) => {
1297                                 // Option<[]> always implies that we want to treat len() == 0 differently from
1298                                 // None, so we always map an Option<[]> into a pointer.
1299                                 write!(w, " == std::ptr::null_mut()").unwrap();
1300                                 EmptyValExpectedTy::ReferenceAsPointer
1301                         },
1302                         _ => unimplemented!(),
1303                 }
1304         }
1305
1306         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1307         pub fn write_empty_rust_val_check<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type, var_access: &str) {
1308                 match t {
1309                         syn::Type::Path(_) => {
1310                                 write!(w, "{}", var_access).unwrap();
1311                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1312                         },
1313                         syn::Type::Array(a) => {
1314                                 if let syn::Expr::Lit(l) = &a.len {
1315                                         if let syn::Lit::Int(i) = &l.lit {
1316                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1317                                                 // We don't (yet) support a new-var conversion here.
1318                                                 assert!(self.from_c_conversion_new_var_from_path(&arrty, false).is_none());
1319                                                 write!(w, "{}{}{}",
1320                                                         self.from_c_conversion_prefix_from_path(&arrty, false).unwrap(),
1321                                                         var_access,
1322                                                         self.from_c_conversion_suffix_from_path(&arrty, false).unwrap()).unwrap();
1323                                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1324                                         } else { unimplemented!(); }
1325                                 } else { unimplemented!(); }
1326                         }
1327                         _ => unimplemented!(),
1328                 }
1329         }
1330
1331         // ********************************
1332         // *** Type conversion printing ***
1333         // ********************************
1334
1335         /// Returns true we if can just skip passing this to C entirely
1336         pub fn skip_arg(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
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                                         self.skip_path(&full_path)
1342                                 } else { false }
1343                         },
1344                         syn::Type::Reference(r) => {
1345                                 self.skip_arg(&*r.elem, generics)
1346                         },
1347                         _ => false,
1348                 }
1349         }
1350         pub fn no_arg_to_rust<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1351                 match t {
1352                         syn::Type::Path(p) => {
1353                                 if p.qself.is_some() { unimplemented!(); }
1354                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1355                                         write!(w, "{}", self.no_arg_path_to_rust(&full_path)).unwrap();
1356                                 }
1357                         },
1358                         syn::Type::Reference(r) => {
1359                                 self.no_arg_to_rust(w, &*r.elem, generics);
1360                         },
1361                         _ => {},
1362                 }
1363         }
1364
1365         fn write_conversion_inline_intern<W: std::io::Write,
1366                         LP: Fn(&str, bool, bool) -> Option<String>, DL: Fn(&mut W, &DeclType, &str, bool, bool), SC: Fn(bool) -> &'static str>
1367                         (&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool,
1368                          tupleconv: &str, prefix: bool, sliceconv: SC, path_lookup: LP, decl_lookup: DL) {
1369                 match t {
1370                         syn::Type::Reference(r) => {
1371                                 self.write_conversion_inline_intern(w, &*r.elem, generics, true, r.mutability.is_some(),
1372                                         ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1373                         },
1374                         syn::Type::Path(p) => {
1375                                 if p.qself.is_some() {
1376                                         unimplemented!();
1377                                 }
1378
1379                                 let resolved_path = self.resolve_path(&p.path, generics);
1380                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1381                                         return self.write_conversion_inline_intern(w, aliased_type, None, is_ref, is_mut, ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1382                                 } else if let Some(c_type) = path_lookup(&resolved_path, is_ref, ptr_for_ref) {
1383                                         write!(w, "{}", c_type).unwrap();
1384                                 } else if self.crate_types.opaques.get(&resolved_path).is_some() {
1385                                         decl_lookup(w, &DeclType::StructImported, &resolved_path, is_ref, is_mut);
1386                                 } else if self.crate_types.mirrored_enums.get(&resolved_path).is_some() {
1387                                         decl_lookup(w, &DeclType::MirroredEnum, &resolved_path, is_ref, is_mut);
1388                                 } else if let Some(t) = self.crate_types.traits.get(&resolved_path) {
1389                                         decl_lookup(w, &DeclType::Trait(t), &resolved_path, is_ref, is_mut);
1390                                 } else if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
1391                                         if let Some(decl_type) = self.types.maybe_resolve_declared(ident) {
1392                                                 decl_lookup(w, decl_type, &self.maybe_resolve_ident(ident).unwrap(), is_ref, is_mut);
1393                                         } else { unimplemented!(); }
1394                                 } else { unimplemented!(); }
1395                         },
1396                         syn::Type::Array(a) => {
1397                                 // We assume all arrays contain only [int_literal; X]s.
1398                                 // This may result in some outputs not compiling.
1399                                 if let syn::Expr::Lit(l) = &a.len {
1400                                         if let syn::Lit::Int(i) = &l.lit {
1401                                                 write!(w, "{}", path_lookup(&format!("[u8; {}]", i.base10_digits()), is_ref, ptr_for_ref).unwrap()).unwrap();
1402                                         } else { unimplemented!(); }
1403                                 } else { unimplemented!(); }
1404                         },
1405                         syn::Type::Slice(s) => {
1406                                 // We assume all slices contain only literals or references.
1407                                 // This may result in some outputs not compiling.
1408                                 if let syn::Type::Path(p) = &*s.elem {
1409                                         let resolved = self.resolve_path(&p.path, generics);
1410                                         assert!(self.is_primitive(&resolved));
1411                                         write!(w, "{}", path_lookup("[u8]", is_ref, ptr_for_ref).unwrap()).unwrap();
1412                                 } else if let syn::Type::Reference(r) = &*s.elem {
1413                                         if let syn::Type::Path(p) = &*r.elem {
1414                                                 write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)))).unwrap();
1415                                         } else { unimplemented!(); }
1416                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1417                                         assert!(!t.elems.is_empty());
1418                                         if prefix {
1419                                                 write!(w, "&local_").unwrap();
1420                                         } else {
1421                                                 let mut needs_map = false;
1422                                                 for e in t.elems.iter() {
1423                                                         if let syn::Type::Reference(_) = e {
1424                                                                 needs_map = true;
1425                                                         }
1426                                                 }
1427                                                 if needs_map {
1428                                                         write!(w, ".iter().map(|(").unwrap();
1429                                                         for i in 0..t.elems.len() {
1430                                                                 write!(w, "{}{}", if i != 0 { ", " } else { "" }, ('a' as u8 + i as u8) as char).unwrap();
1431                                                         }
1432                                                         write!(w, ")| (").unwrap();
1433                                                         for (idx, e) in t.elems.iter().enumerate() {
1434                                                                 if let syn::Type::Reference(_) = e {
1435                                                                         write!(w, "{}{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1436                                                                 } else if let syn::Type::Path(_) = e {
1437                                                                         write!(w, "{}*{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1438                                                                 } else { unimplemented!(); }
1439                                                         }
1440                                                         write!(w, ")).collect::<Vec<_>>()[..]").unwrap();
1441                                                 }
1442                                         }
1443                                 } else { unimplemented!(); }
1444                         },
1445                         syn::Type::Tuple(t) => {
1446                                 if t.elems.is_empty() {
1447                                         // cbindgen has poor support for (), see, eg https://github.com/eqrion/cbindgen/issues/527
1448                                         // so work around it by just pretending its a 0u8
1449                                         write!(w, "{}", tupleconv).unwrap();
1450                                 } else {
1451                                         if prefix { write!(w, "local_").unwrap(); }
1452                                 }
1453                         },
1454                         _ => unimplemented!(),
1455                 }
1456         }
1457
1458         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) {
1459                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "0u8 /*", true, |_| "local_",
1460                                 |a, b, c| self.to_c_conversion_inline_prefix_from_path(a, b, c),
1461                                 |w, decl_type, decl_path, is_ref, _is_mut| {
1462                                         match decl_type {
1463                                                 DeclType::MirroredEnum if is_ref && ptr_for_ref => write!(w, "crate::{}::from_native(&", decl_path).unwrap(),
1464                                                 DeclType::MirroredEnum if is_ref => write!(w, "&crate::{}::from_native(&", decl_path).unwrap(),
1465                                                 DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
1466                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1467                                                         write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1468                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1469                                                         write!(w, "crate::{} {{ inner: unsafe {{ ( (&(", decl_path).unwrap(),
1470                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1471                                                         write!(w, "&crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1472                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1473                                                         write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
1474                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref =>
1475                                                         write!(w, "crate::{} {{ inner: Box::into_raw(Box::new(", decl_path).unwrap(),
1476                                                 DeclType::Trait(_) if is_ref => write!(w, "&").unwrap(),
1477                                                 DeclType::Trait(_) if !is_ref => {},
1478                                                 _ => panic!("{:?}", decl_path),
1479                                         }
1480                                 });
1481         }
1482         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) {
1483                 self.write_to_c_conversion_inline_prefix_inner(w, t, generics, false, ptr_for_ref, false);
1484         }
1485         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) {
1486                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "*/", false, |_| ".into()",
1487                                 |a, b, c| self.to_c_conversion_inline_suffix_from_path(a, b, c),
1488                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1489                                         DeclType::MirroredEnum => write!(w, ")").unwrap(),
1490                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1491                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1492                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1493                                                 write!(w, ") as *const _) as *mut _) }}, is_owned: false }}").unwrap(),
1494                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1495                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1496                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1497                                                 write!(w, ", is_owned: true }}").unwrap(),
1498                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref => write!(w, ")), is_owned: true }}").unwrap(),
1499                                         DeclType::Trait(_) if is_ref => {},
1500                                         DeclType::Trait(_) => {
1501                                                 // This is used when we're converting a concrete Rust type into a C trait
1502                                                 // for use when a Rust trait method returns an associated type.
1503                                                 // Because all of our C traits implement From<RustTypesImplementingTraits>
1504                                                 // we can just call .into() here and be done.
1505                                                 write!(w, ".into()").unwrap()
1506                                         },
1507                                         _ => unimplemented!(),
1508                                 });
1509         }
1510         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) {
1511                 self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
1512         }
1513
1514         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) {
1515                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_| "&local_",
1516                                 |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
1517                                 |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
1518                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, "unsafe {{ &*(*").unwrap(),
1519                                         DeclType::StructImported if is_mut && is_ref => write!(w, "unsafe {{ &mut *").unwrap(),
1520                                         DeclType::StructImported if is_ref => write!(w, "unsafe {{ &*").unwrap(),
1521                                         DeclType::StructImported if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
1522                                         DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
1523                                         DeclType::MirroredEnum => {},
1524                                         DeclType::Trait(_) => {},
1525                                         _ => unimplemented!(),
1526                                 });
1527         }
1528         pub fn write_from_c_conversion_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1529                 self.write_from_c_conversion_prefix_inner(w, t, generics, false, false);
1530         }
1531         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) {
1532                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "*/", false,
1533                                 |has_inner| match has_inner {
1534                                         false => ".iter().collect::<Vec<_>>()[..]",
1535                                         true => "[..]",
1536                                 },
1537                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1538                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1539                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, ").inner }}").unwrap(),
1540                                         DeclType::StructImported if is_ref => write!(w, ".inner }}").unwrap(),
1541                                         DeclType::StructImported if !is_ref => write!(w, ".take_inner()) }}").unwrap(),
1542                                         DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
1543                                         DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
1544                                         DeclType::Trait(_) => {},
1545                                         _ => unimplemented!(),
1546                                 });
1547         }
1548         pub fn write_from_c_conversion_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1549                 self.write_from_c_conversion_suffix_inner(w, t, generics, false, false);
1550         }
1551         // Note that compared to the above conversion functions, the following two are generally
1552         // significantly undertested:
1553         pub fn write_from_c_conversion_to_ref_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1554                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "() /*", true, |_| "&local_",
1555                                 |a, b, _c| {
1556                                         if let Some(conv) = self.from_c_conversion_prefix_from_path(a, b) {
1557                                                 Some(format!("&{}", conv))
1558                                         } else { None }
1559                                 },
1560                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1561                                         DeclType::StructImported if !is_ref => write!(w, "unsafe {{ &*").unwrap(),
1562                                         _ => unimplemented!(),
1563                                 });
1564         }
1565         pub fn write_from_c_conversion_to_ref_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1566                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "*/", false,
1567                                 |has_inner| match has_inner {
1568                                         false => ".iter().collect::<Vec<_>>()[..]",
1569                                         true => "[..]",
1570                                 },
1571                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1572                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1573                                         DeclType::StructImported if !is_ref => write!(w, ".inner }}").unwrap(),
1574                                         _ => unimplemented!(),
1575                                 });
1576         }
1577
1578         fn write_conversion_new_var_intern<'b, W: std::io::Write,
1579                 LP: Fn(&str, bool) -> Option<(&str, &str)>,
1580                 LC: Fn(&str, bool, Option<&syn::Type>, &syn::Ident, &str) ->  Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)>,
1581                 VP: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool),
1582                 VS: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool)>
1583                         (&self, w: &mut W, ident: &syn::Ident, var: &str, t: &syn::Type, generics: Option<&GenericTypes>,
1584                          mut is_ref: bool, mut ptr_for_ref: bool, to_c: bool,
1585                          path_lookup: &LP, container_lookup: &LC, var_prefix: &VP, var_suffix: &VS) -> bool {
1586
1587                 macro_rules! convert_container {
1588                         ($container_type: expr, $args_len: expr, $args_iter: expr) => { {
1589                                 // For slices (and Options), we refuse to directly map them as is_ref when they
1590                                 // aren't opaque types containing an inner pointer. This is due to the fact that,
1591                                 // in both cases, the actual higher-level type is non-is_ref.
1592                                 let ty_has_inner = if $args_len == 1 {
1593                                         let ty = $args_iter().next().unwrap();
1594                                         if $container_type == "Slice" && to_c {
1595                                                 // "To C ptr_for_ref" means "return the regular object with is_owned
1596                                                 // set to false", which is totally what we want in a slice if we're about to
1597                                                 // set ty_has_inner.
1598                                                 ptr_for_ref = true;
1599                                         }
1600                                         if let syn::Type::Reference(t) = ty {
1601                                                 if let syn::Type::Path(p) = &*t.elem {
1602                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1603                                                 } else { false }
1604                                         } else if let syn::Type::Path(p) = ty {
1605                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1606                                         } else { false }
1607                                 } else { true };
1608
1609                                 // Options get a bunch of special handling, since in general we map Option<>al
1610                                 // types into the same C type as non-Option-wrapped types. This ends up being
1611                                 // pretty manual here and most of the below special-cases are for Options.
1612                                 let mut needs_ref_map = false;
1613                                 let mut only_contained_type = None;
1614                                 let mut only_contained_has_inner = false;
1615                                 let mut contains_slice = false;
1616                                 if $args_len == 1 {
1617                                         only_contained_has_inner = ty_has_inner;
1618                                         let arg = $args_iter().next().unwrap();
1619                                         if let syn::Type::Reference(t) = arg {
1620                                                 only_contained_type = Some(&*t.elem);
1621                                                 if let syn::Type::Path(_) = &*t.elem {
1622                                                         is_ref = true;
1623                                                 } else if let syn::Type::Slice(_) = &*t.elem {
1624                                                         contains_slice = true;
1625                                                 } else { return false; }
1626                                                 // If the inner element contains an inner pointer, we will just use that,
1627                                                 // avoiding the need to map elements to references. Otherwise we'll need to
1628                                                 // do an extra mapping step.
1629                                                 needs_ref_map = !only_contained_has_inner;
1630                                         } else {
1631                                                 only_contained_type = Some(&arg);
1632                                         }
1633                                 }
1634
1635                                 if let Some((prefix, conversions, suffix, prefix_location)) = container_lookup(&$container_type, is_ref && ty_has_inner, only_contained_type, ident, var) {
1636                                         assert_eq!(conversions.len(), $args_len);
1637                                         write!(w, "let mut local_{}{} = ", ident, if !to_c && needs_ref_map {"_base"} else { "" }).unwrap();
1638                                         if prefix_location == ContainerPrefixLocation::OutsideConv {
1639                                                 var_prefix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1640                                         }
1641                                         write!(w, "{}{}", prefix, var).unwrap();
1642
1643                                         for ((pfx, var_name), (idx, ty)) in conversions.iter().zip($args_iter().enumerate()) {
1644                                                 let mut var = std::io::Cursor::new(Vec::new());
1645                                                 write!(&mut var, "{}", var_name).unwrap();
1646                                                 let var_access = String::from_utf8(var.into_inner()).unwrap();
1647
1648                                                 let conv_ty = if needs_ref_map { only_contained_type.as_ref().unwrap() } else { ty };
1649
1650                                                 write!(w, "{} {{ ", pfx).unwrap();
1651                                                 let new_var_name = format!("{}_{}", ident, idx);
1652                                                 let new_var = self.write_conversion_new_var_intern(w, &syn::Ident::new(&new_var_name, Span::call_site()),
1653                                                                 &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);
1654                                                 if new_var { write!(w, " ").unwrap(); }
1655
1656                                                 if prefix_location == ContainerPrefixLocation::PerConv {
1657                                                         var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1658                                                 } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1659                                                         write!(w, "Box::into_raw(Box::new(").unwrap();
1660                                                 }
1661
1662                                                 write!(w, "{}{}", if contains_slice { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
1663                                                 if prefix_location == ContainerPrefixLocation::PerConv {
1664                                                         var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1665                                                 } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1666                                                         write!(w, "))").unwrap();
1667                                                 }
1668                                                 write!(w, " }}").unwrap();
1669                                         }
1670                                         write!(w, "{}", suffix).unwrap();
1671                                         if prefix_location == ContainerPrefixLocation::OutsideConv {
1672                                                 var_suffix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1673                                         }
1674                                         write!(w, ";").unwrap();
1675                                         if !to_c && needs_ref_map {
1676                                                 write!(w, " let mut local_{} = local_{}_base.as_ref()", ident, ident).unwrap();
1677                                                 if contains_slice {
1678                                                         write!(w, ".map(|a| &a[..])").unwrap();
1679                                                 }
1680                                                 write!(w, ";").unwrap();
1681                                         }
1682                                         return true;
1683                                 }
1684                         } }
1685                 }
1686
1687                 match t {
1688                         syn::Type::Reference(r) => {
1689                                 if let syn::Type::Slice(_) = &*r.elem {
1690                                         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)
1691                                 } else {
1692                                         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)
1693                                 }
1694                         },
1695                         syn::Type::Path(p) => {
1696                                 if p.qself.is_some() {
1697                                         unimplemented!();
1698                                 }
1699                                 let resolved_path = self.resolve_path(&p.path, generics);
1700                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1701                                         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);
1702                                 }
1703                                 if self.is_known_container(&resolved_path, is_ref) || self.is_transparent_container(&resolved_path, is_ref) {
1704                                         if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
1705                                                 convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
1706                                                         if let syn::GenericArgument::Type(ty) = arg {
1707                                                                 ty
1708                                                         } else { unimplemented!(); }
1709                                                 }));
1710                                         } else { unimplemented!(); }
1711                                 }
1712                                 if self.is_primitive(&resolved_path) {
1713                                         false
1714                                 } else if let Some(ty_ident) = single_ident_generic_path_to_ident(&p.path) {
1715                                         if let Some((prefix, suffix)) = path_lookup(&resolved_path, is_ref) {
1716                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1717                                                 true
1718                                         } else if self.types.maybe_resolve_declared(ty_ident).is_some() {
1719                                                 false
1720                                         } else { false }
1721                                 } else { false }
1722                         },
1723                         syn::Type::Array(_) => {
1724                                 // We assume all arrays contain only primitive types.
1725                                 // This may result in some outputs not compiling.
1726                                 false
1727                         },
1728                         syn::Type::Slice(s) => {
1729                                 if let syn::Type::Path(p) = &*s.elem {
1730                                         let resolved = self.resolve_path(&p.path, generics);
1731                                         assert!(self.is_primitive(&resolved));
1732                                         let slice_path = format!("[{}]", resolved);
1733                                         if let Some((prefix, suffix)) = path_lookup(&slice_path, true) {
1734                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1735                                                 true
1736                                         } else { false }
1737                                 } else if let syn::Type::Reference(ty) = &*s.elem {
1738                                         let tyref = [&*ty.elem];
1739                                         is_ref = true;
1740                                         convert_container!("Slice", 1, || tyref.iter());
1741                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1742                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1743                                         // When mapping into a temporary new var, we need to own all the underlying objects.
1744                                         // Thus, we drop any references inside the tuple and convert with non-reference types.
1745                                         let mut elems = syn::punctuated::Punctuated::new();
1746                                         for elem in t.elems.iter() {
1747                                                 if let syn::Type::Reference(r) = elem {
1748                                                         elems.push((*r.elem).clone());
1749                                                 } else {
1750                                                         elems.push(elem.clone());
1751                                                 }
1752                                         }
1753                                         let ty = [syn::Type::Tuple(syn::TypeTuple {
1754                                                 paren_token: t.paren_token, elems
1755                                         })];
1756                                         is_ref = false;
1757                                         ptr_for_ref = true;
1758                                         convert_container!("Slice", 1, || ty.iter());
1759                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1760                                 } else { unimplemented!() }
1761                         },
1762                         syn::Type::Tuple(t) => {
1763                                 if !t.elems.is_empty() {
1764                                         // We don't (yet) support tuple elements which cannot be converted inline
1765                                         write!(w, "let (").unwrap();
1766                                         for idx in 0..t.elems.len() {
1767                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1768                                                 write!(w, "{} orig_{}_{}", if is_ref { "ref" } else { "mut" }, ident, idx).unwrap();
1769                                         }
1770                                         write!(w, ") = {}{}; ", var, if !to_c { ".to_rust()" } else { "" }).unwrap();
1771                                         // Like other template types, tuples are always mapped as their non-ref
1772                                         // versions for types which have different ref mappings. Thus, we convert to
1773                                         // non-ref versions and handle opaque types with inner pointers manually.
1774                                         for (idx, elem) in t.elems.iter().enumerate() {
1775                                                 if let syn::Type::Path(p) = elem {
1776                                                         let v_name = format!("orig_{}_{}", ident, idx);
1777                                                         let tuple_elem_ident = syn::Ident::new(&v_name, Span::call_site());
1778                                                         if self.write_conversion_new_var_intern(w, &tuple_elem_ident, &v_name, elem, generics,
1779                                                                         false, ptr_for_ref, to_c,
1780                                                                         path_lookup, container_lookup, var_prefix, var_suffix) {
1781                                                                 write!(w, " ").unwrap();
1782                                                                 // Opaque types with inner pointers shouldn't ever create new stack
1783                                                                 // variables, so we don't handle it and just assert that it doesn't
1784                                                                 // here.
1785                                                                 assert!(!self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)));
1786                                                         }
1787                                                 }
1788                                         }
1789                                         write!(w, "let mut local_{} = (", ident).unwrap();
1790                                         for (idx, elem) in t.elems.iter().enumerate() {
1791                                                 let ty_has_inner = {
1792                                                                 if to_c {
1793                                                                         // "To C ptr_for_ref" means "return the regular object with
1794                                                                         // is_owned set to false", which is totally what we want
1795                                                                         // if we're about to set ty_has_inner.
1796                                                                         ptr_for_ref = true;
1797                                                                 }
1798                                                                 if let syn::Type::Reference(t) = elem {
1799                                                                         if let syn::Type::Path(p) = &*t.elem {
1800                                                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1801                                                                         } else { false }
1802                                                                 } else if let syn::Type::Path(p) = elem {
1803                                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1804                                                                 } else { false }
1805                                                         };
1806                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1807                                                 var_prefix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1808                                                 if is_ref && ty_has_inner {
1809                                                         // For ty_has_inner, the regular var_prefix mapping will take a
1810                                                         // reference, so deref once here to make sure we keep the original ref.
1811                                                         write!(w, "*").unwrap();
1812                                                 }
1813                                                 write!(w, "orig_{}_{}", ident, idx).unwrap();
1814                                                 if is_ref && !ty_has_inner {
1815                                                         // If we don't have an inner variable's reference to maintain, just
1816                                                         // hope the type is Clonable and use that.
1817                                                         write!(w, ".clone()").unwrap();
1818                                                 }
1819                                                 var_suffix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1820                                         }
1821                                         write!(w, "){};", if to_c { ".into()" } else { "" }).unwrap();
1822                                         true
1823                                 } else { false }
1824                         },
1825                         _ => unimplemented!(),
1826                 }
1827         }
1828
1829         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 {
1830                 self.write_conversion_new_var_intern(w, ident, var_access, t, generics, false, ptr_for_ref, true,
1831                         &|a, b| self.to_c_conversion_new_var_from_path(a, b),
1832                         &|a, b, c, d, e| self.to_c_conversion_container_new_var(generics, a, b, c, d, e),
1833                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1834                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_prefix_inner(a, b, c, d, e, f),
1835                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_suffix_inner(a, b, c, d, e, f))
1836         }
1837         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 {
1838                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, ptr_for_ref)
1839         }
1840         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 {
1841                 self.write_conversion_new_var_intern(w, ident, &format!("{}", ident), t, generics, false, false, false,
1842                         &|a, b| self.from_c_conversion_new_var_from_path(a, b),
1843                         &|a, b, c, d, e| self.from_c_conversion_container_new_var(generics, a, b, c, d, e),
1844                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1845                         &|a, b, c, d, e, _f| self.write_from_c_conversion_prefix_inner(a, b, c, d, e),
1846                         &|a, b, c, d, e, _f| self.write_from_c_conversion_suffix_inner(a, b, c, d, e))
1847         }
1848
1849         // ******************************************************
1850         // *** C Container Type Equivalent and alias Printing ***
1851         // ******************************************************
1852
1853         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 {
1854                 assert!(!is_ref); // We don't currently support outer reference types
1855                 for (idx, t) in args.enumerate() {
1856                         if idx != 0 {
1857                                 write!(w, ", ").unwrap();
1858                         }
1859                         if let syn::Type::Reference(r_arg) = t {
1860                                 if !self.write_c_type_intern(w, &*r_arg.elem, generics, false, false, false) { return false; }
1861
1862                                 // While write_c_type_intern, above is correct, we don't want to blindly convert a
1863                                 // reference to something stupid, so check that the container is either opaque or a
1864                                 // predefined type (currently only Transaction).
1865                                 if let syn::Type::Path(p_arg) = &*r_arg.elem {
1866                                         let resolved = self.resolve_path(&p_arg.path, generics);
1867                                         assert!(self.crate_types.opaques.get(&resolved).is_some() ||
1868                                                         self.c_type_from_path(&resolved, true, true).is_some(), "Template generics should be opaque or have a predefined mapping");
1869                                 } else { unimplemented!(); }
1870                         } else {
1871                                 if !self.write_c_type_intern(w, t, generics, false, false, false) { return false; }
1872                         }
1873                 }
1874                 true
1875         }
1876         fn check_create_container(&mut self, mangled_container: String, container_type: &str, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
1877                 if !self.crate_types.templates_defined.get(&mangled_container).is_some() {
1878                         let mut created_container: Vec<u8> = Vec::new();
1879
1880                         if container_type == "Result" {
1881                                 let mut a_ty: Vec<u8> = Vec::new();
1882                                 if let syn::Type::Tuple(tup) = args.iter().next().unwrap() {
1883                                         if tup.elems.is_empty() {
1884                                                 write!(&mut a_ty, "()").unwrap();
1885                                         } else {
1886                                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
1887                                         }
1888                                 } else {
1889                                         if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
1890                                 }
1891
1892                                 let mut b_ty: Vec<u8> = Vec::new();
1893                                 if let syn::Type::Tuple(tup) = args.iter().skip(1).next().unwrap() {
1894                                         if tup.elems.is_empty() {
1895                                                 write!(&mut b_ty, "()").unwrap();
1896                                         } else {
1897                                                 if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
1898                                         }
1899                                 } else {
1900                                         if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
1901                                 }
1902
1903                                 let ok_str = String::from_utf8(a_ty).unwrap();
1904                                 let err_str = String::from_utf8(b_ty).unwrap();
1905                                 let is_clonable = self.is_clonable(&ok_str) && self.is_clonable(&err_str);
1906                                 write_result_block(&mut created_container, &mangled_container, &ok_str, &err_str, is_clonable);
1907                                 if is_clonable {
1908                                         self.crate_types.clonable_types.insert(Self::generated_container_path().to_owned() + "::" + &mangled_container);
1909                                 }
1910                         } else if container_type == "Vec" {
1911                                 let mut a_ty: Vec<u8> = Vec::new();
1912                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t), generics, is_ref) { return false; }
1913                                 let ty = String::from_utf8(a_ty).unwrap();
1914                                 let is_clonable = self.is_clonable(&ty);
1915                                 write_vec_block(&mut created_container, &mangled_container, &ty, is_clonable);
1916                                 if is_clonable {
1917                                         self.crate_types.clonable_types.insert(Self::generated_container_path().to_owned() + "::" + &mangled_container);
1918                                 }
1919                         } else if container_type.ends_with("Tuple") {
1920                                 let mut tuple_args = Vec::new();
1921                                 let mut is_clonable = true;
1922                                 for arg in args.iter() {
1923                                         let mut ty: Vec<u8> = Vec::new();
1924                                         if !self.write_template_generics(&mut ty, &mut [arg].iter().map(|t| **t), generics, is_ref) { return false; }
1925                                         let ty_str = String::from_utf8(ty).unwrap();
1926                                         if !self.is_clonable(&ty_str) {
1927                                                 is_clonable = false;
1928                                         }
1929                                         tuple_args.push(ty_str);
1930                                 }
1931                                 write_tuple_block(&mut created_container, &mangled_container, &tuple_args, is_clonable);
1932                                 if is_clonable {
1933                                         self.crate_types.clonable_types.insert(Self::generated_container_path().to_owned() + "::" + &mangled_container);
1934                                 }
1935                         } else {
1936                                 unreachable!();
1937                         }
1938                         self.crate_types.templates_defined.insert(mangled_container.clone(), true);
1939
1940                         self.crate_types.template_file.write(&created_container).unwrap();
1941                 }
1942                 true
1943         }
1944         fn path_to_generic_args(path: &syn::Path) -> Vec<&syn::Type> {
1945                 if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().next().unwrap().arguments {
1946                         args.args.iter().map(|gen| if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }).collect()
1947                 } else { unimplemented!(); }
1948         }
1949         fn write_c_mangled_container_path_intern<W: std::io::Write>
1950                         (&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 {
1951                 let mut mangled_type: Vec<u8> = Vec::new();
1952                 if !self.is_transparent_container(ident, is_ref) {
1953                         write!(w, "C{}_", ident).unwrap();
1954                         write!(mangled_type, "C{}_", ident).unwrap();
1955                 } else { assert_eq!(args.len(), 1); }
1956                 for arg in args.iter() {
1957                         macro_rules! write_path {
1958                                 ($p_arg: expr, $extra_write: expr) => {
1959                                         if let Some(subtype) = self.maybe_resolve_path(&$p_arg.path, generics) {
1960                                                 if self.is_transparent_container(ident, is_ref) {
1961                                                         // We dont (yet) support primitives or containers inside transparent
1962                                                         // containers, so check for that first:
1963                                                         if self.is_primitive(&subtype) { return false; }
1964                                                         if self.is_known_container(&subtype, is_ref) { return false; }
1965                                                         if !in_type {
1966                                                                 if self.c_type_has_inner_from_path(&subtype) {
1967                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, is_ref, is_mut, ptr_for_ref) { return false; }
1968                                                                 } else {
1969                                                                         // Option<T> needs to be converted to a *mut T, ie mut ptr-for-ref
1970                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, true, true, true) { return false; }
1971                                                                 }
1972                                                         } else {
1973                                                                 write!(w, "{}", $p_arg.path.segments.last().unwrap().ident).unwrap();
1974                                                         }
1975                                                 } else if self.is_known_container(&subtype, is_ref) || self.is_transparent_container(&subtype, is_ref) {
1976                                                         if !self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(&$p_arg.path), generics,
1977                                                                         &subtype, is_ref, is_mut, ptr_for_ref, true) {
1978                                                                 return false;
1979                                                         }
1980                                                         self.write_c_mangled_container_path_intern(&mut mangled_type, Self::path_to_generic_args(&$p_arg.path),
1981                                                                 generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1982                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1983                                                                 self.write_c_mangled_container_path_intern(w2, Self::path_to_generic_args(&$p_arg.path),
1984                                                                         generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1985                                                         }
1986                                                 } else {
1987                                                         let id = subtype.rsplitn(2, ':').next().unwrap(); // Get the "Base" name of the resolved type
1988                                                         write!(w, "{}", id).unwrap();
1989                                                         write!(mangled_type, "{}", id).unwrap();
1990                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1991                                                                 write!(w2, "{}", id).unwrap();
1992                                                         }
1993                                                 }
1994                                         } else { return false; }
1995                                 }
1996                         }
1997                         if let syn::Type::Tuple(tuple) = arg {
1998                                 if tuple.elems.len() == 0 {
1999                                         write!(w, "None").unwrap();
2000                                         write!(mangled_type, "None").unwrap();
2001                                 } else {
2002                                         let mut mangled_tuple_type: Vec<u8> = Vec::new();
2003
2004                                         // Figure out what the mangled type should look like. To disambiguate
2005                                         // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
2006                                         // them with a Z. Ideally we wouldn't use Z, but not many special chars are
2007                                         // available for use in type names.
2008                                         write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
2009                                         write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
2010                                         write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
2011                                         for elem in tuple.elems.iter() {
2012                                                 if let syn::Type::Path(p) = elem {
2013                                                         write_path!(p, Some(&mut mangled_tuple_type));
2014                                                 } else if let syn::Type::Reference(refelem) = elem {
2015                                                         if let syn::Type::Path(p) = &*refelem.elem {
2016                                                                 write_path!(p, Some(&mut mangled_tuple_type));
2017                                                         } else { return false; }
2018                                                 } else { return false; }
2019                                         }
2020                                         write!(w, "Z").unwrap();
2021                                         write!(mangled_type, "Z").unwrap();
2022                                         write!(mangled_tuple_type, "Z").unwrap();
2023                                         if !self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
2024                                                         &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref) {
2025                                                 return false;
2026                                         }
2027                                 }
2028                         } else if let syn::Type::Path(p_arg) = arg {
2029                                 write_path!(p_arg, None);
2030                         } else if let syn::Type::Reference(refty) = arg {
2031                                 if let syn::Type::Path(p_arg) = &*refty.elem {
2032                                         write_path!(p_arg, None);
2033                                 } else if let syn::Type::Slice(_) = &*refty.elem {
2034                                         // write_c_type will actually do exactly what we want here, we just need to
2035                                         // make it a pointer so that its an option. Note that we cannot always convert
2036                                         // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
2037                                         // to edit it, hence we use *mut here instead of *const.
2038                                         if args.len() != 1 { return false; }
2039                                         write!(w, "*mut ").unwrap();
2040                                         self.write_c_type(w, arg, None, true);
2041                                 } else { return false; }
2042                         } else if let syn::Type::Array(a) = arg {
2043                                 if let syn::Type::Path(p_arg) = &*a.elem {
2044                                         let resolved = self.resolve_path(&p_arg.path, generics);
2045                                         if !self.is_primitive(&resolved) { return false; }
2046                                         if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
2047                                                 if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
2048                                                 write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
2049                                                 write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
2050                                         } else { return false; }
2051                                 } else { return false; }
2052                         } else { return false; }
2053                 }
2054                 if self.is_transparent_container(ident, is_ref) { return true; }
2055                 // Push the "end of type" Z
2056                 write!(w, "Z").unwrap();
2057                 write!(mangled_type, "Z").unwrap();
2058
2059                 // Make sure the type is actually defined:
2060                 self.check_create_container(String::from_utf8(mangled_type).unwrap(), ident, args, generics, is_ref)
2061         }
2062         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 {
2063                 if !self.is_transparent_container(ident, is_ref) {
2064                         write!(w, "{}::", Self::generated_container_path()).unwrap();
2065                 }
2066                 self.write_c_mangled_container_path_intern(w, args, generics, ident, is_ref, is_mut, ptr_for_ref, false)
2067         }
2068
2069         // **********************************
2070         // *** C Type Equivalent Printing ***
2071         // **********************************
2072
2073         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 {
2074                 let full_path = match self.maybe_resolve_path(&path, generics) {
2075                         Some(path) => path, None => return false };
2076                 if let Some(c_type) = self.c_type_from_path(&full_path, is_ref, ptr_for_ref) {
2077                         write!(w, "{}", c_type).unwrap();
2078                         true
2079                 } else if self.crate_types.traits.get(&full_path).is_some() {
2080                         if is_ref && ptr_for_ref {
2081                                 write!(w, "*{} crate::{}", if is_mut { "mut" } else { "const" }, full_path).unwrap();
2082                         } else if is_ref {
2083                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
2084                         } else {
2085                                 write!(w, "crate::{}", full_path).unwrap();
2086                         }
2087                         true
2088                 } else if self.crate_types.opaques.get(&full_path).is_some() || self.crate_types.mirrored_enums.get(&full_path).is_some() {
2089                         if is_ref && ptr_for_ref {
2090                                 // ptr_for_ref implies we're returning the object, which we can't really do for
2091                                 // opaque or mirrored types without box'ing them, which is quite a waste, so return
2092                                 // the actual object itself (for opaque types we'll set the pointer to the actual
2093                                 // type and note that its a reference).
2094                                 write!(w, "crate::{}", full_path).unwrap();
2095                         } else if is_ref {
2096                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
2097                         } else {
2098                                 write!(w, "crate::{}", full_path).unwrap();
2099                         }
2100                         true
2101                 } else {
2102                         false
2103                 }
2104         }
2105         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 {
2106                 match t {
2107                         syn::Type::Path(p) => {
2108                                 if p.qself.is_some() {
2109                                         return false;
2110                                 }
2111                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
2112                                         if self.is_known_container(&full_path, is_ref) || self.is_transparent_container(&full_path, is_ref) {
2113                                                 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);
2114                                         }
2115                                         if let Some(aliased_type) = self.crate_types.type_aliases.get(&full_path).cloned() {
2116                                                 return self.write_c_type_intern(w, &aliased_type, None, is_ref, is_mut, ptr_for_ref);
2117                                         }
2118                                 }
2119                                 self.write_c_path_intern(w, &p.path, generics, is_ref, is_mut, ptr_for_ref)
2120                         },
2121                         syn::Type::Reference(r) => {
2122                                 self.write_c_type_intern(w, &*r.elem, generics, true, r.mutability.is_some(), ptr_for_ref)
2123                         },
2124                         syn::Type::Array(a) => {
2125                                 if is_ref && is_mut {
2126                                         write!(w, "*mut [").unwrap();
2127                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2128                                 } else if is_ref {
2129                                         write!(w, "*const [").unwrap();
2130                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2131                                 } else {
2132                                         let mut typecheck = Vec::new();
2133                                         if !self.write_c_type_intern(&mut typecheck, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2134                                         if typecheck[..] != ['u' as u8, '8' as u8] { return false; }
2135                                 }
2136                                 if let syn::Expr::Lit(l) = &a.len {
2137                                         if let syn::Lit::Int(i) = &l.lit {
2138                                                 if !is_ref {
2139                                                         if let Some(ty) = self.c_type_from_path(&format!("[u8; {}]", i.base10_digits()), false, ptr_for_ref) {
2140                                                                 write!(w, "{}", ty).unwrap();
2141                                                                 true
2142                                                         } else { false }
2143                                                 } else {
2144                                                         write!(w, "; {}]", i).unwrap();
2145                                                         true
2146                                                 }
2147                                         } else { false }
2148                                 } else { false }
2149                         }
2150                         syn::Type::Slice(s) => {
2151                                 if !is_ref || is_mut { return false; }
2152                                 if let syn::Type::Path(p) = &*s.elem {
2153                                         let resolved = self.resolve_path(&p.path, generics);
2154                                         if self.is_primitive(&resolved) {
2155                                                 write!(w, "{}::{}slice", Self::container_templ_path(), resolved).unwrap();
2156                                                 true
2157                                         } else { false }
2158                                 } else if let syn::Type::Reference(r) = &*s.elem {
2159                                         if let syn::Type::Path(p) = &*r.elem {
2160                                                 // Slices with "real types" inside are mapped as the equivalent non-ref Vec
2161                                                 let resolved = self.resolve_path(&p.path, generics);
2162                                                 let mangled_container = if let Some(ident) = self.crate_types.opaques.get(&resolved) {
2163                                                         format!("CVec_{}Z", ident)
2164                                                 } else if let Some(en) = self.crate_types.mirrored_enums.get(&resolved) {
2165                                                         format!("CVec_{}Z", en.ident)
2166                                                 } else if let Some(id) = p.path.get_ident() {
2167                                                         format!("CVec_{}Z", id)
2168                                                 } else { return false; };
2169                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2170                                                 self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false)
2171                                         } else { false }
2172                                 } else if let syn::Type::Tuple(_) = &*s.elem {
2173                                         let mut args = syn::punctuated::Punctuated::new();
2174                                         args.push(syn::GenericArgument::Type((*s.elem).clone()));
2175                                         let mut segments = syn::punctuated::Punctuated::new();
2176                                         segments.push(syn::PathSegment {
2177                                                 ident: syn::Ident::new("Vec", Span::call_site()),
2178                                                 arguments: syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
2179                                                         colon2_token: None, lt_token: syn::Token![<](Span::call_site()), args, gt_token: syn::Token![>](Span::call_site()),
2180                                                 })
2181                                         });
2182                                         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)
2183                                 } else { false }
2184                         },
2185                         syn::Type::Tuple(t) => {
2186                                 if t.elems.len() == 0 {
2187                                         true
2188                                 } else {
2189                                         self.write_c_mangled_container_path(w, t.elems.iter().collect(), generics,
2190                                                 &format!("{}Tuple", t.elems.len()), is_ref, is_mut, ptr_for_ref)
2191                                 }
2192                         },
2193                         _ => false,
2194                 }
2195         }
2196         pub fn write_c_type<W: std::io::Write>(&mut self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2197                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref));
2198         }
2199         pub fn understood_c_path(&mut self, p: &syn::Path) -> bool {
2200                 if p.leading_colon.is_some() { return false; }
2201                 self.write_c_path_intern(&mut std::io::sink(), p, None, false, false, false)
2202         }
2203         pub fn understood_c_type(&mut self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2204                 self.write_c_type_intern(&mut std::io::sink(), t, generics, false, false, false)
2205         }
2206 }