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

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