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

   1 use std::collections::HashMap;
   2 use std::fs::File;
   3 use std::io::Write;
   4 use std::hash;
   5
   6 use proc_macro2::{TokenTree, Span};
   7
   8 // The following utils are used purely to build our known types maps - they break down all the
   9 // types we need to resolve to include the given object, and no more.
  10
  11 pub fn first_seg_self<'a>(t: &'a syn::Type) -> Option<impl Iterator<Item=&syn::PathSegment> + 'a> {
  12         match t {
  13                 syn::Type::Path(p) => {
  14                         if p.qself.is_some() || p.path.leading_colon.is_some() {
  15                                 return None;
  16                         }
  17                         let mut segs = p.path.segments.iter();
  18                         let ty = segs.next().unwrap();
  19                         if !ty.arguments.is_empty() { return None; }
  20                         if format!("{}", ty.ident) == "Self" {
  21                                 Some(segs)
  22                         } else { None }
  23                 },
  24                 _ => None,
  25         }
  26 }
  27
  28 pub fn get_single_remaining_path_seg<'a, I: Iterator<Item=&'a syn::PathSegment>>(segs: &mut I) -> Option<&'a syn::Ident> {
  29         if let Some(ty) = segs.next() {
  30                 if !ty.arguments.is_empty() { unimplemented!(); }
  31                 if segs.next().is_some() { return None; }
  32                 Some(&ty.ident)
  33         } else { None }
  34 }
  35
  36 pub fn single_ident_generic_path_to_ident(p: &syn::Path) -> Option<&syn::Ident> {
  37         if p.segments.len() == 1 {
  38                 Some(&p.segments.iter().next().unwrap().ident)
  39         } else { None }
  40 }
  41
  42 #[derive(Debug, PartialEq)]
  43 pub enum ExportStatus {
  44         Export,
  45         NoExport,
  46         TestOnly,
  47 }
  48 /// Gets the ExportStatus of an object (struct, fn, etc) given its attributes.
  49 pub fn export_status(attrs: &[syn::Attribute]) -> ExportStatus {
  50         for attr in attrs.iter() {
  51                 let tokens_clone = attr.tokens.clone();
  52                 let mut token_iter = tokens_clone.into_iter();
  53                 if let Some(token) = token_iter.next() {
  54                         match token {
  55                                 TokenTree::Punct(c) if c.as_char() == '=' => {
  56                                         // Really not sure where syn gets '=' from here -
  57                                         // it somehow represents '///' or '//!'
  58                                 },
  59                                 TokenTree::Group(g) => {
  60                                         if format!("{}", single_ident_generic_path_to_ident(&attr.path).unwrap()) == "cfg" {
  61                                                 let mut iter = g.stream().into_iter();
  62                                                 if let TokenTree::Ident(i) = iter.next().unwrap() {
  63                                                         if i == "any" {
  64                                                                 // #[cfg(any(test, feature = ""))]
  65                                                                 if let TokenTree::Group(g) = iter.next().unwrap() {
  66                                                                         if let TokenTree::Ident(i) = g.stream().into_iter().next().unwrap() {
  67                                                                                 if i == "test" || i == "feature" {
  68                                                                                         // If its cfg(feature(...)) we assume its test-only
  69                                                                                         return ExportStatus::TestOnly;
  70                                                                                 }
  71                                                                         }
  72                                                                 }
  73                                                         } else if i == "test" || i == "feature" {
  74                                                                 // If its cfg(feature(...)) we assume its test-only
  75                                                                 return ExportStatus::TestOnly;
  76                                                         }
  77                                                 }
  78                                         }
  79                                         continue; // eg #[derive()]
  80                                 },
  81                                 _ => unimplemented!(),
  82                         }
  83                 } else { continue; }
  84                 match token_iter.next().unwrap() {
  85                         TokenTree::Literal(lit) => {
  86                                 let line = format!("{}", lit);
  87                                 if line.contains("(C-not exported)") {
  88                                         return ExportStatus::NoExport;
  89                                 }
  90                         },
  91                         _ => unimplemented!(),
  92                 }
  93         }
  94         ExportStatus::Export
  95 }
  96
  97 pub fn assert_simple_bound(bound: &syn::TraitBound) {
  98         if bound.paren_token.is_some() || bound.lifetimes.is_some() { unimplemented!(); }
  99         if let syn::TraitBoundModifier::Maybe(_) = bound.modifier { unimplemented!(); }
 100 }
 101
 102 /// A stack of sets of generic resolutions.
 103 ///
 104 /// This tracks the template parameters for a function, struct, or trait, allowing resolution into
 105 /// a concrete type. By pushing a new context onto the stack, this can track a function's template
 106 /// parameters inside of a generic struct or trait.
 107 ///
 108 /// It maps both direct types as well as Deref<Target = X>, mapping them via the provided
 109 /// TypeResolver's resolve_path function (ie traits map to the concrete jump table, structs to the
 110 /// concrete C container struct, etc).
 111 pub struct GenericTypes<'a> {
 112         typed_generics: Vec<HashMap<&'a syn::Ident, (String, Option<&'a syn::Path>)>>,
 113 }
 114 impl<'a> GenericTypes<'a> {
 115         pub fn new() -> Self {
 116                 Self { typed_generics: vec![HashMap::new()], }
 117         }
 118
 119         /// push a new context onto the stack, allowing for a new set of generics to be learned which
 120         /// will override any lower contexts, but which will still fall back to resoltion via lower
 121         /// contexts.
 122         pub fn push_ctx(&mut self) {
 123                 self.typed_generics.push(HashMap::new());
 124         }
 125         /// pop the latest context off the stack.
 126         pub fn pop_ctx(&mut self) {
 127                 self.typed_generics.pop();
 128         }
 129
 130         /// Learn the generics in generics in the current context, given a TypeResolver.
 131         pub fn learn_generics<'b, 'c>(&mut self, generics: &'a syn::Generics, types: &'b TypeResolver<'a, 'c>) -> bool {
 132                 for generic in generics.params.iter() {
 133                         match generic {
 134                                 syn::GenericParam::Type(type_param) => {
 135                                         let mut non_lifetimes_processed = false;
 136                                         for bound in type_param.bounds.iter() {
 137                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 138                                                         if let Some(ident) = single_ident_generic_path_to_ident(&trait_bound.path) {
 139                                                                 match &format!("{}", ident) as &str { "Send" => continue, "Sync" => continue, _ => {} }
 140                                                         }
 141
 142                                                         assert_simple_bound(&trait_bound);
 143                                                         if let Some(mut path) = types.maybe_resolve_path(&trait_bound.path, None) {
 144                                                                 if types.skip_path(&path) { continue; }
 145                                                                 if non_lifetimes_processed { return false; }
 146                                                                 non_lifetimes_processed = true;
 147                                                                 let new_ident = if path != "std::ops::Deref" {
 148                                                                         path = "crate::".to_string() + &path;
 149                                                                         Some(&trait_bound.path)
 150                                                                 } else { None };
 151                                                                 self.typed_generics.last_mut().unwrap().insert(&type_param.ident, (path, new_ident));
 152                                                         } else { return false; }
 153                                                 }
 154                                         }
 155                                 },
 156                                 _ => {},
 157                         }
 158                 }
 159                 if let Some(wh) = &generics.where_clause {
 160                         for pred in wh.predicates.iter() {
 161                                 if let syn::WherePredicate::Type(t) = pred {
 162                                         if let syn::Type::Path(p) = &t.bounded_ty {
 163                                                 if p.qself.is_some() { return false; }
 164                                                 if p.path.leading_colon.is_some() { return false; }
 165                                                 let mut p_iter = p.path.segments.iter();
 166                                                 if let Some(gen) = self.typed_generics.last_mut().unwrap().get_mut(&p_iter.next().unwrap().ident) {
 167                                                         if gen.0 != "std::ops::Deref" { return false; }
 168                                                         if &format!("{}", p_iter.next().unwrap().ident) != "Target" { return false; }
 169
 170                                                         let mut non_lifetimes_processed = false;
 171                                                         for bound in t.bounds.iter() {
 172                                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 173                                                                         if non_lifetimes_processed { return false; }
 174                                                                         non_lifetimes_processed = true;
 175                                                                         assert_simple_bound(&trait_bound);
 176                                                                         *gen = ("crate::".to_string() + &types.resolve_path(&trait_bound.path, None),
 177                                                                                 Some(&trait_bound.path));
 178                                                                 }
 179                                                         }
 180                                                 } else { return false; }
 181                                         } else { return false; }
 182                                 }
 183                         }
 184                 }
 185                 for (_, (_, ident)) in self.typed_generics.last().unwrap().iter() {
 186                         if ident.is_none() { return false; }
 187                 }
 188                 true
 189         }
 190
 191         /// Learn the associated types from the trait in the current context.
 192         pub fn learn_associated_types<'b, 'c>(&mut self, t: &'a syn::ItemTrait, types: &'b TypeResolver<'a, 'c>) {
 193                 for item in t.items.iter() {
 194                         match item {
 195                                 &syn::TraitItem::Type(ref t) => {
 196                                         if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
 197                                         let mut bounds_iter = t.bounds.iter();
 198                                         match bounds_iter.next().unwrap() {
 199                                                 syn::TypeParamBound::Trait(tr) => {
 200                                                         assert_simple_bound(&tr);
 201                                                         if let Some(mut path) = types.maybe_resolve_path(&tr.path, None) {
 202                                                                 if types.skip_path(&path) { continue; }
 203                                                                 let new_ident = if path != "std::ops::Deref" {
 204                                                                         path = "crate::".to_string() + &path;
 205                                                                         Some(&tr.path)
 206                                                                 } else { None };
 207                                                                 self.typed_generics.last_mut().unwrap().insert(&t.ident, (path, new_ident));
 208                                                         } else { unimplemented!(); }
 209                                                 },
 210                                                 _ => unimplemented!(),
 211                                         }
 212                                         if bounds_iter.next().is_some() { unimplemented!(); }
 213                                 },
 214                                 _ => {},
 215                         }
 216                 }
 217         }
 218
 219         /// Attempt to resolve an Ident as a generic parameter and return the full path.
 220         pub fn maybe_resolve_ident<'b>(&'b self, ident: &syn::Ident) -> Option<&'b String> {
 221                 for gen in self.typed_generics.iter().rev() {
 222                         if let Some(res) = gen.get(ident).map(|(a, _)| a) {
 223                                 return Some(res);
 224                         }
 225                 }
 226                 None
 227         }
 228         /// Attempt to resolve a Path as a generic parameter and return the full path. as both a string
 229         /// and syn::Path.
 230         pub fn maybe_resolve_path<'b>(&'b self, path: &syn::Path) -> Option<(&'b String, &'a syn::Path)> {
 231                 if let Some(ident) = path.get_ident() {
 232                         for gen in self.typed_generics.iter().rev() {
 233                                 if let Some(res) = gen.get(ident).map(|(a, b)| (a, b.unwrap())) {
 234                                         return Some(res);
 235                                 }
 236                         }
 237                 } else {
 238                         let mut it = path.segments.iter();
 239                         if path.segments.len() == 2 && format!("{}", it.next().unwrap().ident) == "Self" {
 240                                 let ident = &it.next().unwrap().ident;
 241                                 for gen in self.typed_generics.iter().rev() {
 242                                         if let Some(res) = gen.get(ident).map(|(a, b)| (a, b.unwrap())) {
 243                                                 return Some(res);
 244                                         }
 245                                 }
 246                         }
 247                 }
 248                 None
 249         }
 250 }
 251
 252 #[derive(Clone, PartialEq)]
 253 // The type of declaration and the object itself
 254 pub enum DeclType<'a> {
 255         MirroredEnum,
 256         Trait(&'a syn::ItemTrait),
 257         StructImported,
 258         StructIgnored,
 259         EnumIgnored,
 260 }
 261
 262 // templates_defined is walked to write the C++ header, so if we use the default hashing it get
 263 // reordered on each genbindings run. Instead, we use SipHasher (which defaults to 0-keys) so that
 264 // the sorting is stable across runs. It is deprecated, but the "replacement" doesn't actually
 265 // accomplish the same goals, so we just ignore it.
 266 #[allow(deprecated)]
 267 type NonRandomHash = hash::BuildHasherDefault<hash::SipHasher>;
 268
 269 /// Top-level struct tracking everything which has been defined while walking the crate.
 270 pub struct CrateTypes<'a> {
 271         /// This may contain structs or enums, but only when either is mapped as
 272         /// struct X { inner: *mut originalX, .. }
 273         pub opaques: HashMap<String, &'a syn::Ident>,
 274         /// Enums which are mapped as C enums with conversion functions
 275         pub mirrored_enums: HashMap<String, &'a syn::ItemEnum>,
 276         /// Traits which are mapped as a pointer + jump table
 277         pub traits: HashMap<String, &'a syn::ItemTrait>,
 278         /// Aliases from paths to some other Type
 279         pub type_aliases: HashMap<String, syn::Type>,
 280         /// Template continer types defined, map from mangled type name -> whether a destructor fn
 281         /// exists.
 282         ///
 283         /// This is used at the end of processing to make C++ wrapper classes
 284         pub templates_defined: HashMap<String, bool, NonRandomHash>,
 285         /// The output file for any created template container types, written to as we find new
 286         /// template containers which need to be defined.
 287         pub template_file: &'a mut File,
 288 }
 289
 290 /// A struct which tracks resolving rust types into C-mapped equivalents, exists for one specific
 291 /// module but contains a reference to the overall CrateTypes tracking.
 292 pub struct TypeResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 293         pub orig_crate: &'mod_lifetime str,
 294         pub module_path: &'mod_lifetime str,
 295         imports: HashMap<syn::Ident, String>,
 296         // ident -> is-mirrored-enum
 297         declared: HashMap<syn::Ident, DeclType<'crate_lft>>,
 298         pub crate_types: &'mod_lifetime mut CrateTypes<'crate_lft>,
 299 }
 300
 301 /// Returned by write_empty_rust_val_check_suffix to indicate what type of dereferencing needs to
 302 /// happen to get the inner value of a generic.
 303 enum EmptyValExpectedTy {
 304         /// A type which has a flag for being empty (eg an array where we treat all-0s as empty).
 305         NonPointer,
 306         /// A pointer that we want to dereference and move out of.
 307         OwnedPointer,
 308         /// A pointer which we want to convert to a reference.
 309         ReferenceAsPointer,
 310 }
 311
 312 impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 313         pub fn new(orig_crate: &'a str, module_path: &'a str, crate_types: &'a mut CrateTypes<'c>) -> Self {
 314                 let mut imports = HashMap::new();
 315                 // Add primitives to the "imports" list:
 316                 imports.insert(syn::Ident::new("bool", Span::call_site()), "bool".to_string());
 317                 imports.insert(syn::Ident::new("u64", Span::call_site()), "u64".to_string());
 318                 imports.insert(syn::Ident::new("u32", Span::call_site()), "u32".to_string());
 319                 imports.insert(syn::Ident::new("u16", Span::call_site()), "u16".to_string());
 320                 imports.insert(syn::Ident::new("u8", Span::call_site()), "u8".to_string());
 321                 imports.insert(syn::Ident::new("usize", Span::call_site()), "usize".to_string());
 322                 imports.insert(syn::Ident::new("str", Span::call_site()), "str".to_string());
 323                 imports.insert(syn::Ident::new("String", Span::call_site()), "String".to_string());
 324
 325                 // These are here to allow us to print native Rust types in trait fn impls even if we don't
 326                 // have C mappings:
 327                 imports.insert(syn::Ident::new("Result", Span::call_site()), "Result".to_string());
 328                 imports.insert(syn::Ident::new("Vec", Span::call_site()), "Vec".to_string());
 329                 imports.insert(syn::Ident::new("Option", Span::call_site()), "Option".to_string());
 330                 Self { orig_crate, module_path, imports, declared: HashMap::new(), crate_types }
 331         }
 332
 333         // *************************************************
 334         // *** Well know type and conversion definitions ***
 335         // *************************************************
 336
 337         /// Returns true we if can just skip passing this to C entirely
 338         fn skip_path(&self, full_path: &str) -> bool {
 339                 full_path == "bitcoin::secp256k1::Secp256k1" ||
 340                 full_path == "bitcoin::secp256k1::Signing" ||
 341                 full_path == "bitcoin::secp256k1::Verification"
 342         }
 343         /// Returns true we if can just skip passing this to C entirely
 344         fn no_arg_path_to_rust(&self, full_path: &str) -> &str {
 345                 if full_path == "bitcoin::secp256k1::Secp256k1" {
 346                         "&bitcoin::secp256k1::Secp256k1::new()"
 347                 } else { unimplemented!(); }
 348         }
 349
 350         /// Returns true if the object is a primitive and is mapped as-is with no conversion
 351         /// whatsoever.
 352         pub fn is_primitive(&self, full_path: &str) -> bool {
 353                 match full_path {
 354                         "bool" => true,
 355                         "u64" => true,
 356                         "u32" => true,
 357                         "u16" => true,
 358                         "u8" => true,
 359                         "usize" => true,
 360                         _ => false,
 361                 }
 362         }
 363         /// Gets the C-mapped type for types which are outside of the crate, or which are manually
 364         /// ignored by for some reason need mapping anyway.
 365         fn c_type_from_path<'b>(&self, full_path: &'b str, is_ref: bool, ptr_for_ref: bool) -> Option<&'b str> {
 366                 if self.is_primitive(full_path) {
 367                         return Some(full_path);
 368                 }
 369                 match full_path {
 370                         "Result" => Some("crate::c_types::derived::CResult"),
 371                         "Vec" if !is_ref => Some("crate::c_types::derived::CVec"),
 372                         "Option" => Some(""),
 373
 374                         // Note that no !is_ref types can map to an array because Rust and C's call semantics
 375                         // for arrays are different (https://github.com/eqrion/cbindgen/issues/528)
 376
 377                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 378                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes"),
 379                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes"),
 380                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes"),
 381                         "[u8; 3]" if !is_ref => Some("crate::c_types::ThreeBytes"), // Used for RGB values
 382
 383                         "str" if is_ref => Some("crate::c_types::Str"),
 384                         "String" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 385                         "String" if is_ref => Some("crate::c_types::Str"),
 386
 387                         "std::time::Duration" => Some("u64"),
 388
 389                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey"),
 390                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature"),
 391                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some("*const [u8; 32]"),
 392                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey"),
 393                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error"),
 394                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice"),
 395                         "bitcoin::blockdata::script::Script" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 396                         "bitcoin::blockdata::transaction::OutPoint" if is_ref => Some("crate::chain::transaction::OutPoint"),
 397                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction"),
 398                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut"),
 399                         "bitcoin::OutPoint" => Some("crate::chain::transaction::OutPoint"),
 400                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network"),
 401                         "bitcoin::blockdata::block::BlockHeader" if is_ref  => Some("*const [u8; 80]"),
 402                         "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
 403
 404                         // Newtypes that we just expose in their original form.
 405                         "bitcoin::hash_types::Txid" if is_ref  => Some("*const [u8; 32]"),
 406                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 407                         "bitcoin::hash_types::BlockHash" if is_ref  => Some("*const [u8; 32]"),
 408                         "bitcoin::hash_types::BlockHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 409                         "ln::channelmanager::PaymentHash" if is_ref => Some("*const [u8; 32]"),
 410                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 411                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("*const [u8; 32]"),
 412                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 413                         "ln::channelmanager::PaymentSecret" if is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 414                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 415
 416                         // Override the default since Records contain an fmt with a lifetime:
 417                         "util::logger::Record" => Some("*const std::os::raw::c_char"),
 418
 419                         // List of structs we map that aren't detected:
 420                         "ln::features::InitFeatures" if is_ref && ptr_for_ref => Some("crate::ln::features::InitFeatures"),
 421                         "ln::features::InitFeatures" if is_ref => Some("*const crate::ln::features::InitFeatures"),
 422                         "ln::features::InitFeatures" => Some("crate::ln::features::InitFeatures"),
 423                         _ => {
 424                                 eprintln!("    Type {} (ref: {}) unresolvable in C", full_path, is_ref);
 425                                 None
 426                         },
 427                 }
 428         }
 429
 430         fn from_c_conversion_new_var_from_path<'b>(&self, _full_path: &str, _is_ref: bool) -> Option<(&'b str, &'b str)> {
 431                 None
 432         }
 433         fn from_c_conversion_prefix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 434                 if self.is_primitive(full_path) {
 435                         return Some("".to_owned());
 436                 }
 437                 match full_path {
 438                         "Vec" if !is_ref => Some("local_"),
 439                         "Result" if !is_ref => Some("local_"),
 440                         "Option" if is_ref => Some("&local_"),
 441                         "Option" => Some("local_"),
 442
 443                         "[u8; 32]" if is_ref => Some("unsafe { &*"),
 444                         "[u8; 32]" if !is_ref => Some(""),
 445                         "[u8; 16]" if !is_ref => Some(""),
 446                         "[u8; 10]" if !is_ref => Some(""),
 447                         "[u8; 4]" if !is_ref => Some(""),
 448                         "[u8; 3]" if !is_ref => Some(""),
 449
 450                         "[u8]" if is_ref => Some(""),
 451                         "[usize]" if is_ref => Some(""),
 452
 453                         "str" if is_ref => Some(""),
 454                         "String" if !is_ref => Some("String::from_utf8("),
 455                         // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
 456                         // cannot create a &String.
 457
 458                         "std::time::Duration" => Some("std::time::Duration::from_secs("),
 459
 460                         "bitcoin::secp256k1::key::PublicKey" if is_ref => Some("&"),
 461                         "bitcoin::secp256k1::key::PublicKey" => Some(""),
 462                         "bitcoin::secp256k1::Signature" if is_ref => Some("&"),
 463                         "bitcoin::secp256k1::Signature" => Some(""),
 464                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("&::bitcoin::secp256k1::key::SecretKey::from_slice(&unsafe { *"),
 465                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(""),
 466                         "bitcoin::blockdata::script::Script" if is_ref => Some("&::bitcoin::blockdata::script::Script::from(Vec::from("),
 467                         "bitcoin::blockdata::script::Script" if !is_ref => Some("::bitcoin::blockdata::script::Script::from("),
 468                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some("&"),
 469                         "bitcoin::blockdata::transaction::Transaction" => Some(""),
 470                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(""),
 471                         "bitcoin::network::constants::Network" => Some(""),
 472                         "bitcoin::blockdata::block::BlockHeader" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
 473                         "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
 474
 475                         // Newtypes that we just expose in their original form.
 476                         "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
 477                         "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
 478                         "bitcoin::hash_types::BlockHash" => Some("::bitcoin::hash_types::BlockHash::from_slice(&"),
 479                         "ln::channelmanager::PaymentHash" if !is_ref => Some("::lightning::ln::channelmanager::PaymentHash("),
 480                         "ln::channelmanager::PaymentHash" if is_ref => Some("&::lightning::ln::channelmanager::PaymentHash(unsafe { *"),
 481                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("::lightning::ln::channelmanager::PaymentPreimage("),
 482                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&::lightning::ln::channelmanager::PaymentPreimage(unsafe { *"),
 483                         "ln::channelmanager::PaymentSecret" => Some("::lightning::ln::channelmanager::PaymentSecret("),
 484
 485                         // List of structs we map (possibly during processing of other files):
 486                         "ln::features::InitFeatures" if !is_ref => Some("*unsafe { Box::from_raw("),
 487
 488                         // List of traits we map (possibly during processing of other files):
 489                         "crate::util::logger::Logger" => Some(""),
 490
 491                         _ => {
 492                                 eprintln!("    Type {} unconvertable from C", full_path);
 493                                 None
 494                         },
 495                 }.map(|s| s.to_owned())
 496         }
 497         fn from_c_conversion_suffix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 498                 if self.is_primitive(full_path) {
 499                         return Some("".to_owned());
 500                 }
 501                 match full_path {
 502                         "Vec" if !is_ref => Some(""),
 503                         "Option" => Some(""),
 504                         "Result" if !is_ref => Some(""),
 505
 506                         "[u8; 32]" if is_ref => Some("}"),
 507                         "[u8; 32]" if !is_ref => Some(".data"),
 508                         "[u8; 16]" if !is_ref => Some(".data"),
 509                         "[u8; 10]" if !is_ref => Some(".data"),
 510                         "[u8; 4]" if !is_ref => Some(".data"),
 511                         "[u8; 3]" if !is_ref => Some(".data"),
 512
 513                         "[u8]" if is_ref => Some(".to_slice()"),
 514                         "[usize]" if is_ref => Some(".to_slice()"),
 515
 516                         "str" if is_ref => Some(".into()"),
 517                         "String" if !is_ref => Some(".into_rust()).unwrap()"),
 518
 519                         "std::time::Duration" => Some(")"),
 520
 521                         "bitcoin::secp256k1::key::PublicKey" => Some(".into_rust()"),
 522                         "bitcoin::secp256k1::Signature" => Some(".into_rust()"),
 523                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(".into_rust()"),
 524                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("}[..]).unwrap()"),
 525                         "bitcoin::blockdata::script::Script" if is_ref => Some(".to_slice()))"),
 526                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_rust())"),
 527                         "bitcoin::blockdata::transaction::Transaction" => Some(".into_bitcoin()"),
 528                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(".into_rust()"),
 529                         "bitcoin::network::constants::Network" => Some(".into_bitcoin()"),
 530                         "bitcoin::blockdata::block::BlockHeader" => Some(" }).unwrap()"),
 531                         "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
 532
 533                         // Newtypes that we just expose in their original form.
 534                         "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
 535                         "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
 536                         "bitcoin::hash_types::BlockHash" if !is_ref => Some(".data[..]).unwrap()"),
 537                         "ln::channelmanager::PaymentHash" if !is_ref => Some(".data)"),
 538                         "ln::channelmanager::PaymentHash" if is_ref => Some(" })"),
 539                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some(".data)"),
 540                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(" })"),
 541                         "ln::channelmanager::PaymentSecret" => Some(".data)"),
 542
 543                         // List of structs we map (possibly during processing of other files):
 544                         "ln::features::InitFeatures" if is_ref => Some(".inner) }"),
 545                         "ln::features::InitFeatures" if !is_ref => Some(".take_ptr()) }"),
 546
 547                         // List of traits we map (possibly during processing of other files):
 548                         "crate::util::logger::Logger" => Some(""),
 549
 550                         _ => {
 551                                 eprintln!("    Type {} unconvertable from C", full_path);
 552                                 None
 553                         },
 554                 }.map(|s| s.to_owned())
 555         }
 556
 557         fn to_c_conversion_new_var_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<(&'b str, &'b str)> {
 558                 if self.is_primitive(full_path) {
 559                         return None;
 560                 }
 561                 match full_path {
 562                         "[u8]" if is_ref => Some(("crate::c_types::u8slice::from_slice(", ")")),
 563                         "[usize]" if is_ref => Some(("crate::c_types::usizeslice::from_slice(", ")")),
 564
 565                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 566                         "bitcoin::blockdata::transaction::Transaction" if !is_ref => Some(("::bitcoin::consensus::encode::serialize(&", ")")),
 567                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(("{ let mut s = [0u8; 80]; s[..].copy_from_slice(&::bitcoin::consensus::encode::serialize(", ")); s }")),
 568                         "bitcoin::blockdata::block::Block" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 569                         "bitcoin::hash_types::Txid" => None,
 570
 571                         // Override the default since Records contain an fmt with a lifetime:
 572                         // TODO: We should include the other record fields
 573                         "util::logger::Record" => Some(("std::ffi::CString::new(format!(\"{}\", ", ".args)).unwrap()")),
 574                         _ => None,
 575                 }.map(|s| s.to_owned())
 576         }
 577         fn to_c_conversion_inline_prefix_from_path(&self, full_path: &str, is_ref: bool, ptr_for_ref: bool) -> Option<String> {
 578                 if self.is_primitive(full_path) {
 579                         return Some("".to_owned());
 580                 }
 581                 match full_path {
 582                         "Result" if !is_ref => Some("local_"),
 583                         "Vec" if !is_ref => Some("local_"),
 584                         "Option" => Some("local_"),
 585
 586                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 587                         "[u8; 32]" if is_ref => Some("&"),
 588                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes { data: "),
 589                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes { data: "),
 590                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes { data: "),
 591                         "[u8; 3]" if is_ref => Some("&"),
 592
 593                         "[u8]" if is_ref => Some("local_"),
 594                         "[usize]" if is_ref => Some("local_"),
 595
 596                         "str" if is_ref => Some(""),
 597                         "String" => Some(""),
 598
 599                         "std::time::Duration" => Some(""),
 600
 601                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey::from_rust(&"),
 602                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature::from_rust(&"),
 603                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some(""),
 604                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
 605                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error::from_rust("),
 606                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice::from_slice(&"),
 607                         "bitcoin::blockdata::script::Script" if !is_ref => Some(""),
 608                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction::from_vec(local_"),
 609                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut::from_rust("),
 610                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some("&local_"),
 611                         "bitcoin::blockdata::block::Block" if is_ref => Some("crate::c_types::u8slice::from_slice(&local_"),
 612
 613                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 614
 615                         // Newtypes that we just expose in their original form.
 616                         "bitcoin::hash_types::Txid" if is_ref => Some(""),
 617                         "bitcoin::hash_types::BlockHash" if is_ref => Some(""),
 618                         "bitcoin::hash_types::BlockHash" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 619                         "ln::channelmanager::PaymentHash" if is_ref => Some("&"),
 620                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 621                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&"),
 622                         "ln::channelmanager::PaymentPreimage" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 623                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 624
 625                         // Override the default since Records contain an fmt with a lifetime:
 626                         "util::logger::Record" => Some("local_"),
 627
 628                         // List of structs we map (possibly during processing of other files):
 629                         "ln::features::InitFeatures" if is_ref && ptr_for_ref => Some("crate::ln::features::InitFeatures { inner: &mut "),
 630                         "ln::features::InitFeatures" if is_ref => Some("Box::into_raw(Box::new(crate::ln::features::InitFeatures { inner: &mut "),
 631                         "ln::features::InitFeatures" if !is_ref => Some("crate::ln::features::InitFeatures { inner: Box::into_raw(Box::new("),
 632
 633                         _ => {
 634                                 eprintln!("    Type {} (is_ref: {}) unconvertable to C", full_path, is_ref);
 635                                 None
 636                         },
 637                 }.map(|s| s.to_owned())
 638         }
 639         fn to_c_conversion_inline_suffix_from_path(&self, full_path: &str, is_ref: bool, ptr_for_ref: bool) -> Option<String> {
 640                 if self.is_primitive(full_path) {
 641                         return Some("".to_owned());
 642                 }
 643                 match full_path {
 644                         "Result" if !is_ref => Some(""),
 645                         "Vec" if !is_ref => Some(".into()"),
 646                         "Option" => Some(""),
 647
 648                         "[u8; 32]" if !is_ref => Some(" }"),
 649                         "[u8; 32]" if is_ref => Some(""),
 650                         "[u8; 16]" if !is_ref => Some(" }"),
 651                         "[u8; 10]" if !is_ref => Some(" }"),
 652                         "[u8; 4]" if !is_ref => Some(" }"),
 653                         "[u8; 3]" if is_ref => Some(""),
 654
 655                         "[u8]" if is_ref => Some(""),
 656                         "[usize]" if is_ref => Some(""),
 657
 658                         "str" if is_ref => Some(".into()"),
 659                         "String" if !is_ref => Some(".into_bytes().into()"),
 660                         "String" if is_ref => Some(".as_str().into()"),
 661
 662                         "std::time::Duration" => Some(".as_secs()"),
 663
 664                         "bitcoin::secp256k1::key::PublicKey" => Some(")"),
 665                         "bitcoin::secp256k1::Signature" => Some(")"),
 666                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(")"),
 667                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some(".as_ref()"),
 668                         "bitcoin::secp256k1::Error" if !is_ref => Some(")"),
 669                         "bitcoin::blockdata::script::Script" if is_ref => Some("[..])"),
 670                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_bytes().into()"),
 671                         "bitcoin::blockdata::transaction::Transaction" => Some(")"),
 672                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(")"),
 673                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(""),
 674                         "bitcoin::blockdata::block::Block" if is_ref => Some(")"),
 675
 676                         "bitcoin::hash_types::Txid" if !is_ref => Some(".into_inner() }"),
 677
 678                         // Newtypes that we just expose in their original form.
 679                         "bitcoin::hash_types::Txid" if is_ref => Some(".as_inner()"),
 680                         "bitcoin::hash_types::BlockHash" if is_ref => Some(".as_inner()"),
 681                         "bitcoin::hash_types::BlockHash" => Some(".into_inner() }"),
 682                         "ln::channelmanager::PaymentHash" if is_ref => Some(".0"),
 683                         "ln::channelmanager::PaymentHash" => Some(".0 }"),
 684                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(".0"),
 685                         "ln::channelmanager::PaymentPreimage" => Some(".0 }"),
 686                         "ln::channelmanager::PaymentSecret" if !is_ref => Some(".0 }"),
 687
 688                         // Override the default since Records contain an fmt with a lifetime:
 689                         "util::logger::Record" => Some(".as_ptr()"),
 690
 691                         // List of structs we map (possibly during processing of other files):
 692                         "ln::features::InitFeatures" if is_ref && ptr_for_ref => Some(", is_owned: false }"),
 693                         "ln::features::InitFeatures" if is_ref => Some(", is_owned: false }))"),
 694                         "ln::features::InitFeatures" => Some(")), is_owned: true }"),
 695
 696                         _ => {
 697                                 eprintln!("    Type {} unconvertable to C", full_path);
 698                                 None
 699                         },
 700                 }.map(|s| s.to_owned())
 701         }
 702
 703         fn empty_val_check_suffix_from_path(&self, full_path: &str) -> Option<&str> {
 704                 match full_path {
 705                         "ln::channelmanager::PaymentSecret" => Some(".data == [0; 32]"),
 706                         "bitcoin::secp256k1::key::PublicKey" => Some(".is_null()"),
 707                         "bitcoin::secp256k1::Signature" => Some(".is_null()"),
 708                         _ => None
 709                 }
 710         }
 711
 712         // ****************************
 713         // *** Container Processing ***
 714         // ****************************
 715
 716         /// Returns the module path in the generated mapping crate to the containers which we generate
 717         /// when writing to CrateTypes::template_file.
 718         fn generated_container_path() -> &'static str {
 719                 "crate::c_types::derived"
 720         }
 721         /// Returns the module path in the generated mapping crate to the container templates, which
 722         /// are then concretized and put in the generated container path/template_file.
 723         fn container_templ_path() -> &'static str {
 724                 "crate::c_types"
 725         }
 726
 727         /// Returns true if this is a "transparent" container, ie an Option or a container which does
 728         /// not require a generated continer class.
 729         fn is_transparent_container(&self, full_path: &str, _is_ref: bool) -> bool {
 730                 full_path == "Option"
 731         }
 732         /// Returns true if this is a known, supported, non-transparent container.
 733         fn is_known_container(&self, full_path: &str, is_ref: bool) -> bool {
 734                 (full_path == "Result" && !is_ref) || (full_path == "Vec" && !is_ref) || full_path.ends_with("Tuple")
 735         }
 736         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)
 737                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
 738                         // expecting one element in the vec per generic type, each of which is inline-converted
 739                         -> Option<(&'b str, Vec<(String, String)>, &'b str)> {
 740                 match full_path {
 741                         "Result" if !is_ref => {
 742                                 Some(("match ",
 743                                                 vec![(" { Ok(mut o) => crate::c_types::CResultTempl::ok(".to_string(), "o".to_string()),
 744                                                         ("), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
 745                                                 ") }"))
 746                         },
 747                         "Vec" if !is_ref => {
 748                                 Some(("Vec::new(); for item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 749                         },
 750                         "Slice" => {
 751                                 Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "**item".to_string())], "); }"))
 752                         },
 753                         "Option" => {
 754                                 if let Some(syn::Type::Path(p)) = single_contained {
 755                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
 756                                                 if is_ref {
 757                                                         return Some(("if ", vec![
 758                                                                 (".is_none() { std::ptr::null() } else { ".to_owned(), format!("({}.as_ref().unwrap())", var_access))
 759                                                                 ], " }"));
 760                                                 } else {
 761                                                         return Some(("if ", vec![
 762                                                                 (".is_none() { std::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
 763                                                                 ], " }"));
 764                                                 }
 765                                         }
 766                                 }
 767                                 if let Some(t) = single_contained {
 768                                         let mut v = Vec::new();
 769                                         self.write_empty_rust_val(generics, &mut v, t);
 770                                         let s = String::from_utf8(v).unwrap();
 771                                         return Some(("if ", vec![
 772                                                 (format!(".is_none() {{ {} }} else {{ ", s), format!("({}.unwrap())", var_access))
 773                                                 ], " }"));
 774                                 } else { unreachable!(); }
 775                         },
 776                         _ => None,
 777                 }
 778         }
 779
 780         /// only_contained_has_inner implies that there is only one contained element in the container
 781         /// and it has an inner field (ie is an "opaque" type we've defined).
 782         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)
 783                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
 784                         // expecting one element in the vec per generic type, each of which is inline-converted
 785                         -> Option<(&'b str, Vec<(String, String)>, &'b str)> {
 786                 match full_path {
 787                         "Result" if !is_ref => {
 788                                 Some(("match ",
 789                                                 vec![(".result_ok { true => Ok(".to_string(), format!("(*unsafe {{ Box::from_raw({}.contents.result.take_ptr()) }})", var_name)),
 790                                                      ("), false => Err(".to_string(), format!("(*unsafe {{ Box::from_raw({}.contents.err.take_ptr()) }})", var_name))],
 791                                                 ")}"))
 792                         },
 793                         "Vec"|"Slice" if !is_ref => {
 794                                 Some(("Vec::new(); for mut item in ", vec![(format!(".into_rust().drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 795                         },
 796                         "Slice" if is_ref => {
 797                                 Some(("Vec::new(); for mut item in ", vec![(format!(".as_slice().iter() {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 798                         },
 799                         "Option" => {
 800                                 if let Some(syn::Type::Path(p)) = single_contained {
 801                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
 802                                                 if is_ref {
 803                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some((*".to_string(), format!("{}", var_name))], ").clone()) }"))
 804                                                 } else {
 805                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some(".to_string(), format!("{}", var_name))], ") }"));
 806                                                 }
 807                                         }
 808                                 }
 809
 810                                 if let Some(t) = single_contained {
 811                                         let mut v = Vec::new();
 812                                         let ret_ref = self.write_empty_rust_val_check_suffix(generics, &mut v, t);
 813                                         let s = String::from_utf8(v).unwrap();
 814                                         match ret_ref {
 815                                                 EmptyValExpectedTy::ReferenceAsPointer =>
 816                                                         return Some(("if ", vec![
 817                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ &mut *{} }}", var_access))
 818                                                         ], ") }")),
 819                                                 EmptyValExpectedTy::OwnedPointer =>
 820                                                         return Some(("if ", vec![
 821                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ *Box::from_raw({}) }}", var_access))
 822                                                         ], ") }")),
 823                                                 EmptyValExpectedTy::NonPointer =>
 824                                                         return Some(("if ", vec![
 825                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("{}", var_access))
 826                                                         ], ") }")),
 827                                         }
 828                                 } else { unreachable!(); }
 829                         },
 830                         _ => None,
 831                 }
 832         }
 833
 834         // *************************************************
 835         // *** Type definition during main.rs processing ***
 836         // *************************************************
 837
 838         fn process_use_intern<W: std::io::Write>(&mut self, w: &mut W, u: &syn::UseTree, partial_path: &str) {
 839                 match u {
 840                         syn::UseTree::Path(p) => {
 841                                 let new_path = format!("{}::{}", partial_path, p.ident);
 842                                 self.process_use_intern(w, &p.tree, &new_path);
 843                         },
 844                         syn::UseTree::Name(n) => {
 845                                 let full_path = format!("{}::{}", partial_path, n.ident);
 846                                 self.imports.insert(n.ident.clone(), full_path);
 847                         },
 848                         syn::UseTree::Group(g) => {
 849                                 for i in g.items.iter() {
 850                                         self.process_use_intern(w, i, partial_path);
 851                                 }
 852                         },
 853                         syn::UseTree::Rename(r) => {
 854                                 let full_path = format!("{}::{}", partial_path, r.ident);
 855                                 self.imports.insert(r.rename.clone(), full_path);
 856                         },
 857                         syn::UseTree::Glob(_) => {
 858                                 eprintln!("Ignoring * use for {} - this may result in resolution failures", partial_path);
 859                         },
 860                 }
 861         }
 862         pub fn process_use<W: std::io::Write>(&mut self, w: &mut W, u: &syn::ItemUse) {
 863                 if let syn::Visibility::Public(_) = u.vis {
 864                         // We actually only use these for #[cfg(fuzztarget)]
 865                         eprintln!("Ignoring pub(use) tree!");
 866                         return;
 867                 }
 868                 match &u.tree {
 869                         syn::UseTree::Path(p) => {
 870                                 let new_path = format!("{}", p.ident);
 871                                 self.process_use_intern(w, &p.tree, &new_path);
 872                         },
 873                         syn::UseTree::Name(n) => {
 874                                 let full_path = format!("{}", n.ident);
 875                                 self.imports.insert(n.ident.clone(), full_path);
 876                         },
 877                         _ => unimplemented!(),
 878                 }
 879                 if u.leading_colon.is_some() { unimplemented!() }
 880         }
 881
 882         pub fn mirrored_enum_declared(&mut self, ident: &syn::Ident) {
 883                 eprintln!("{} mirrored", ident);
 884                 self.declared.insert(ident.clone(), DeclType::MirroredEnum);
 885         }
 886         pub fn enum_ignored(&mut self, ident: &'c syn::Ident) {
 887                 self.declared.insert(ident.clone(), DeclType::EnumIgnored);
 888         }
 889         pub fn struct_imported(&mut self, ident: &'c syn::Ident, named: String) {
 890                 eprintln!("Imported {} as {}", ident, named);
 891                 self.declared.insert(ident.clone(), DeclType::StructImported);
 892         }
 893         pub fn struct_ignored(&mut self, ident: &syn::Ident) {
 894                 eprintln!("Not importing {}", ident);
 895                 self.declared.insert(ident.clone(), DeclType::StructIgnored);
 896         }
 897         pub fn trait_declared(&mut self, ident: &syn::Ident, t: &'c syn::ItemTrait) {
 898                 eprintln!("Trait {} created", ident);
 899                 self.declared.insert(ident.clone(), DeclType::Trait(t));
 900         }
 901         pub fn get_declared_type(&'a self, ident: &syn::Ident) -> Option<&'a DeclType<'c>> {
 902                 self.declared.get(ident)
 903         }
 904         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
 905         fn c_type_has_inner_from_path(&self, full_path: &str) -> bool{
 906                 self.crate_types.opaques.get(full_path).is_some()
 907         }
 908
 909         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
 910                 if let Some(imp) = self.imports.get(id) {
 911                         Some(imp.clone())
 912                 } else if self.declared.get(id).is_some() {
 913                         Some(self.module_path.to_string() + "::" + &format!("{}", id))
 914                 } else { None }
 915         }
 916
 917         pub fn maybe_resolve_non_ignored_ident(&self, id: &syn::Ident) -> Option<String> {
 918                 if let Some(imp) = self.imports.get(id) {
 919                         Some(imp.clone())
 920                 } else if let Some(decl_type) = self.declared.get(id) {
 921                         match decl_type {
 922                                 DeclType::StructIgnored => None,
 923                                 _ => Some(self.module_path.to_string() + "::" + &format!("{}", id)),
 924                         }
 925                 } else { None }
 926         }
 927
 928         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
 929                 let p = if let Some(gen_types) = generics {
 930                         if let Some((_, synpath)) = gen_types.maybe_resolve_path(p_arg) {
 931                                 synpath
 932                         } else { p_arg }
 933                 } else { p_arg };
 934
 935                 if p.leading_colon.is_some() {
 936                         Some(p.segments.iter().enumerate().map(|(idx, seg)| {
 937                                 format!("{}{}", if idx == 0 { "" } else { "::" }, seg.ident)
 938                         }).collect())
 939                 } else if let Some(id) = p.get_ident() {
 940                         self.maybe_resolve_ident(id)
 941                 } else {
 942                         if p.segments.len() == 1 {
 943                                 let seg = p.segments.iter().next().unwrap();
 944                                 return self.maybe_resolve_ident(&seg.ident);
 945                         }
 946                         let mut seg_iter = p.segments.iter();
 947                         let first_seg = seg_iter.next().unwrap();
 948                         let remaining: String = seg_iter.map(|seg| {
 949                                 format!("::{}", seg.ident)
 950                         }).collect();
 951                         if let Some(imp) = self.imports.get(&first_seg.ident) {
 952                                 if remaining != "" {
 953                                         Some(imp.clone() + &remaining)
 954                                 } else {
 955                                         Some(imp.clone())
 956                                 }
 957                         } else { None }
 958                 }
 959         }
 960         pub fn resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> String {
 961                 self.maybe_resolve_path(p, generics).unwrap()
 962         }
 963
 964         // ***********************************
 965         // *** Original Rust Type Printing ***
 966         // ***********************************
 967
 968         fn in_rust_prelude(resolved_path: &str) -> bool {
 969                 match resolved_path {
 970                         "Vec" => true,
 971                         "Result" => true,
 972                         "Option" => true,
 973                         _ => false,
 974                 }
 975         }
 976
 977         fn write_rust_path<W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, path: &syn::Path) {
 978                 if let Some(resolved) = self.maybe_resolve_path(&path, generics_resolver) {
 979                         if self.is_primitive(&resolved) {
 980                                 write!(w, "{}", path.get_ident().unwrap()).unwrap();
 981                         } else {
 982                                 // TODO: We should have a generic "is from a dependency" check here instead of
 983                                 // checking for "bitcoin" explicitly.
 984                                 if resolved.starts_with("bitcoin::") || Self::in_rust_prelude(&resolved) {
 985                                         write!(w, "{}", resolved).unwrap();
 986                                 // If we're printing a generic argument, it needs to reference the crate, otherwise
 987                                 // the original crate:
 988                                 } else if self.maybe_resolve_path(&path, None).as_ref() == Some(&resolved) {
 989                                         write!(w, "{}::{}", self.orig_crate, resolved).unwrap();
 990                                 } else {
 991                                         write!(w, "crate::{}", resolved).unwrap();
 992                                 }
 993                         }
 994                         if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().last().unwrap().arguments {
 995                                 self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
 996                         }
 997                 } else {
 998                         if path.leading_colon.is_some() {
 999                                 write!(w, "::").unwrap();
1000                         }
1001                         for (idx, seg) in path.segments.iter().enumerate() {
1002                                 if idx != 0 { write!(w, "::").unwrap(); }
1003                                 write!(w, "{}", seg.ident).unwrap();
1004                                 if let syn::PathArguments::AngleBracketed(args) = &seg.arguments {
1005                                         self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1006                                 }
1007                         }
1008                 }
1009         }
1010         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>) {
1011                 let mut had_params = false;
1012                 for (idx, arg) in generics.enumerate() {
1013                         if idx != 0 { write!(w, ", ").unwrap(); } else { write!(w, "<").unwrap(); }
1014                         had_params = true;
1015                         match arg {
1016                                 syn::GenericParam::Lifetime(lt) => write!(w, "'{}", lt.lifetime.ident).unwrap(),
1017                                 syn::GenericParam::Type(t) => {
1018                                         write!(w, "{}", t.ident).unwrap();
1019                                         if t.colon_token.is_some() { write!(w, ":").unwrap(); }
1020                                         for (idx, bound) in t.bounds.iter().enumerate() {
1021                                                 if idx != 0 { write!(w, " + ").unwrap(); }
1022                                                 match bound {
1023                                                         syn::TypeParamBound::Trait(tb) => {
1024                                                                 if tb.paren_token.is_some() || tb.lifetimes.is_some() { unimplemented!(); }
1025                                                                 self.write_rust_path(w, generics_resolver, &tb.path);
1026                                                         },
1027                                                         _ => unimplemented!(),
1028                                                 }
1029                                         }
1030                                         if t.eq_token.is_some() || t.default.is_some() { unimplemented!(); }
1031                                 },
1032                                 _ => unimplemented!(),
1033                         }
1034                 }
1035                 if had_params { write!(w, ">").unwrap(); }
1036         }
1037
1038         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>) {
1039                 write!(w, "<").unwrap();
1040                 for (idx, arg) in generics.enumerate() {
1041                         if idx != 0 { write!(w, ", ").unwrap(); }
1042                         match arg {
1043                                 syn::GenericArgument::Type(t) => self.write_rust_type(w, generics_resolver, t),
1044                                 _ => unimplemented!(),
1045                         }
1046                 }
1047                 write!(w, ">").unwrap();
1048         }
1049         pub fn write_rust_type<W: std::io::Write>(&self, w: &mut W, generics: Option<&GenericTypes>, t: &syn::Type) {
1050                 match t {
1051                         syn::Type::Path(p) => {
1052                                 if p.qself.is_some() || p.path.leading_colon.is_some() {
1053                                         unimplemented!();
1054                                 }
1055                                 self.write_rust_path(w, generics, &p.path);
1056                         },
1057                         syn::Type::Reference(r) => {
1058                                 write!(w, "&").unwrap();
1059                                 if let Some(lft) = &r.lifetime {
1060                                         write!(w, "'{} ", lft.ident).unwrap();
1061                                 }
1062                                 if r.mutability.is_some() {
1063                                         write!(w, "mut ").unwrap();
1064                                 }
1065                                 self.write_rust_type(w, generics, &*r.elem);
1066                         },
1067                         syn::Type::Array(a) => {
1068                                 write!(w, "[").unwrap();
1069                                 self.write_rust_type(w, generics, &a.elem);
1070                                 if let syn::Expr::Lit(l) = &a.len {
1071                                         if let syn::Lit::Int(i) = &l.lit {
1072                                                 write!(w, "; {}]", i).unwrap();
1073                                         } else { unimplemented!(); }
1074                                 } else { unimplemented!(); }
1075                         }
1076                         syn::Type::Slice(s) => {
1077                                 write!(w, "[").unwrap();
1078                                 self.write_rust_type(w, generics, &s.elem);
1079                                 write!(w, "]").unwrap();
1080                         },
1081                         syn::Type::Tuple(s) => {
1082                                 write!(w, "(").unwrap();
1083                                 for (idx, t) in s.elems.iter().enumerate() {
1084                                         if idx != 0 { write!(w, ", ").unwrap(); }
1085                                         self.write_rust_type(w, generics, &t);
1086                                 }
1087                                 write!(w, ")").unwrap();
1088                         },
1089                         _ => unimplemented!(),
1090                 }
1091         }
1092
1093         /// Prints a constructor for something which is "uninitialized" (but obviously not actually
1094         /// unint'd memory).
1095         pub fn write_empty_rust_val<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) {
1096                 match t {
1097                         syn::Type::Path(p) => {
1098                                 let resolved = self.resolve_path(&p.path, generics);
1099                                 if self.crate_types.opaques.get(&resolved).is_some() {
1100                                         write!(w, "crate::{} {{ inner: std::ptr::null_mut(), is_owned: true }}", resolved).unwrap();
1101                                 } else {
1102                                         // Assume its a manually-mapped C type, where we can just define an null() fn
1103                                         write!(w, "{}::null()", self.c_type_from_path(&resolved, false, false).unwrap()).unwrap();
1104                                 }
1105                         },
1106                         syn::Type::Array(a) => {
1107                                 if let syn::Expr::Lit(l) = &a.len {
1108                                         if let syn::Lit::Int(i) = &l.lit {
1109                                                 if i.base10_digits().parse::<usize>().unwrap() < 32 {
1110                                                         // Blindly assume that if we're trying to create an empty value for an
1111                                                         // array < 32 entries that all-0s may be a valid state.
1112                                                         unimplemented!();
1113                                                 }
1114                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1115                                                 write!(w, "{}", self.to_c_conversion_inline_prefix_from_path(&arrty, false, false).unwrap()).unwrap();
1116                                                 write!(w, "[0; {}]", i.base10_digits()).unwrap();
1117                                                 write!(w, "{}", self.to_c_conversion_inline_suffix_from_path(&arrty, false, false).unwrap()).unwrap();
1118                                         } else { unimplemented!(); }
1119                                 } else { unimplemented!(); }
1120                         }
1121                         _ => unimplemented!(),
1122                 }
1123         }
1124
1125         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1126         /// See EmptyValExpectedTy for information on return types.
1127         fn write_empty_rust_val_check_suffix<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) -> EmptyValExpectedTy {
1128                 match t {
1129                         syn::Type::Path(p) => {
1130                                 let resolved = self.resolve_path(&p.path, generics);
1131                                 if self.crate_types.opaques.get(&resolved).is_some() {
1132                                         write!(w, ".inner.is_null()").unwrap();
1133                                         EmptyValExpectedTy::NonPointer
1134                                 } else {
1135                                         if let Some(suffix) = self.empty_val_check_suffix_from_path(&resolved) {
1136                                                 write!(w, "{}", suffix).unwrap();
1137                                                 // We may eventually need to allow empty_val_check_suffix_from_path to specify if we need a deref or not
1138                                                 EmptyValExpectedTy::NonPointer
1139                                         } else {
1140                                                 write!(w, " == std::ptr::null_mut()").unwrap();
1141                                                 EmptyValExpectedTy::OwnedPointer
1142                                         }
1143                                 }
1144                         },
1145                         syn::Type::Array(a) => {
1146                                 if let syn::Expr::Lit(l) = &a.len {
1147                                         if let syn::Lit::Int(i) = &l.lit {
1148                                                 write!(w, " == [0; {}]", i.base10_digits()).unwrap();
1149                                                 EmptyValExpectedTy::NonPointer
1150                                         } else { unimplemented!(); }
1151                                 } else { unimplemented!(); }
1152                         },
1153                         syn::Type::Slice(_) => {
1154                                 // Option<[]> always implies that we want to treat len() == 0 differently from
1155                                 // None, so we always map an Option<[]> into a pointer.
1156                                 write!(w, " == std::ptr::null_mut()").unwrap();
1157                                 EmptyValExpectedTy::ReferenceAsPointer
1158                         },
1159                         _ => unimplemented!(),
1160                 }
1161         }
1162
1163         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1164         pub fn write_empty_rust_val_check<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type, var_access: &str) {
1165                 match t {
1166                         syn::Type::Path(_) => {
1167                                 write!(w, "{}", var_access).unwrap();
1168                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1169                         },
1170                         syn::Type::Array(a) => {
1171                                 if let syn::Expr::Lit(l) = &a.len {
1172                                         if let syn::Lit::Int(i) = &l.lit {
1173                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1174                                                 // We don't (yet) support a new-var conversion here.
1175                                                 assert!(self.from_c_conversion_new_var_from_path(&arrty, false).is_none());
1176                                                 write!(w, "{}{}{}",
1177                                                         self.from_c_conversion_prefix_from_path(&arrty, false).unwrap(),
1178                                                         var_access,
1179                                                         self.from_c_conversion_suffix_from_path(&arrty, false).unwrap()).unwrap();
1180                                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1181                                         } else { unimplemented!(); }
1182                                 } else { unimplemented!(); }
1183                         }
1184                         _ => unimplemented!(),
1185                 }
1186         }
1187
1188         // ********************************
1189         // *** Type conversion printing ***
1190         // ********************************
1191
1192         /// Returns true we if can just skip passing this to C entirely
1193         pub fn skip_arg(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
1194                 match t {
1195                         syn::Type::Path(p) => {
1196                                 if p.qself.is_some() { unimplemented!(); }
1197                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1198                                         self.skip_path(&full_path)
1199                                 } else { false }
1200                         },
1201                         syn::Type::Reference(r) => {
1202                                 self.skip_arg(&*r.elem, generics)
1203                         },
1204                         _ => false,
1205                 }
1206         }
1207         pub fn no_arg_to_rust<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1208                 match t {
1209                         syn::Type::Path(p) => {
1210                                 if p.qself.is_some() { unimplemented!(); }
1211                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1212                                         write!(w, "{}", self.no_arg_path_to_rust(&full_path)).unwrap();
1213                                 }
1214                         },
1215                         syn::Type::Reference(r) => {
1216                                 self.no_arg_to_rust(w, &*r.elem, generics);
1217                         },
1218                         _ => {},
1219                 }
1220         }
1221
1222         fn write_conversion_inline_intern<W: std::io::Write,
1223                         LP: Fn(&str, bool, bool) -> Option<String>, DL: Fn(&mut W, &DeclType, &str, bool, bool), SC: Fn(bool) -> &'static str>
1224                         (&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool,
1225                          tupleconv: &str, prefix: bool, sliceconv: SC, path_lookup: LP, decl_lookup: DL) {
1226                 match t {
1227                         syn::Type::Reference(r) => {
1228                                 self.write_conversion_inline_intern(w, &*r.elem, generics, true, r.mutability.is_some(),
1229                                         ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1230                         },
1231                         syn::Type::Path(p) => {
1232                                 if p.qself.is_some() {
1233                                         unimplemented!();
1234                                 }
1235
1236                                 let resolved_path = self.resolve_path(&p.path, generics);
1237                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1238                                         return self.write_conversion_inline_intern(w, aliased_type, None, is_ref, is_mut, ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1239                                 } else if let Some(c_type) = path_lookup(&resolved_path, is_ref, ptr_for_ref) {
1240                                         write!(w, "{}", c_type).unwrap();
1241                                 } else if self.crate_types.opaques.get(&resolved_path).is_some() {
1242                                         decl_lookup(w, &DeclType::StructImported, &resolved_path, is_ref, is_mut);
1243                                 } else if self.crate_types.mirrored_enums.get(&resolved_path).is_some() {
1244                                         decl_lookup(w, &DeclType::MirroredEnum, &resolved_path, is_ref, is_mut);
1245                                 } else if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
1246                                         if let Some(t) = self.crate_types.traits.get(&resolved_path) {
1247                                                 decl_lookup(w, &DeclType::Trait(t), &resolved_path, is_ref, is_mut);
1248                                                 return;
1249                                         } else if let Some(_) = self.imports.get(ident) {
1250                                                 // crate_types lookup has to have succeeded:
1251                                                 panic!("Failed to print inline conversion for {}", ident);
1252                                         } else if let Some(decl_type) = self.declared.get(ident) {
1253                                                 decl_lookup(w, decl_type, &self.maybe_resolve_ident(ident).unwrap(), is_ref, is_mut);
1254                                         } else { unimplemented!(); }
1255                                 }
1256                         },
1257                         syn::Type::Array(a) => {
1258                                 // We assume all arrays contain only [int_literal; X]s.
1259                                 // This may result in some outputs not compiling.
1260                                 if let syn::Expr::Lit(l) = &a.len {
1261                                         if let syn::Lit::Int(i) = &l.lit {
1262                                                 write!(w, "{}", path_lookup(&format!("[u8; {}]", i.base10_digits()), is_ref, ptr_for_ref).unwrap()).unwrap();
1263                                         } else { unimplemented!(); }
1264                                 } else { unimplemented!(); }
1265                         },
1266                         syn::Type::Slice(s) => {
1267                                 // We assume all slices contain only literals or references.
1268                                 // This may result in some outputs not compiling.
1269                                 if let syn::Type::Path(p) = &*s.elem {
1270                                         let resolved = self.resolve_path(&p.path, generics);
1271                                         assert!(self.is_primitive(&resolved));
1272                                         write!(w, "{}", path_lookup("[u8]", is_ref, ptr_for_ref).unwrap()).unwrap();
1273                                 } else if let syn::Type::Reference(r) = &*s.elem {
1274                                         if let syn::Type::Path(p) = &*r.elem {
1275                                                 write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)))).unwrap();
1276                                         } else { unimplemented!(); }
1277                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1278                                         assert!(!t.elems.is_empty());
1279                                         if prefix {
1280                                                 write!(w, "&local_").unwrap();
1281                                         } else {
1282                                                 let mut needs_map = false;
1283                                                 for e in t.elems.iter() {
1284                                                         if let syn::Type::Reference(_) = e {
1285                                                                 needs_map = true;
1286                                                         }
1287                                                 }
1288                                                 if needs_map {
1289                                                         write!(w, ".iter().map(|(").unwrap();
1290                                                         for i in 0..t.elems.len() {
1291                                                                 write!(w, "{}{}", if i != 0 { ", " } else { "" }, ('a' as u8 + i as u8) as char).unwrap();
1292                                                         }
1293                                                         write!(w, ")| (").unwrap();
1294                                                         for (idx, e) in t.elems.iter().enumerate() {
1295                                                                 if let syn::Type::Reference(_) = e {
1296                                                                         write!(w, "{}{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1297                                                                 } else if let syn::Type::Path(_) = e {
1298                                                                         write!(w, "{}*{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1299                                                                 } else { unimplemented!(); }
1300                                                         }
1301                                                         write!(w, ")).collect::<Vec<_>>()[..]").unwrap();
1302                                                 }
1303                                         }
1304                                 } else { unimplemented!(); }
1305                         },
1306                         syn::Type::Tuple(t) => {
1307                                 if t.elems.is_empty() {
1308                                         // cbindgen has poor support for (), see, eg https://github.com/eqrion/cbindgen/issues/527
1309                                         // so work around it by just pretending its a 0u8
1310                                         write!(w, "{}", tupleconv).unwrap();
1311                                 } else {
1312                                         if prefix { write!(w, "local_").unwrap(); }
1313                                 }
1314                         },
1315                         _ => unimplemented!(),
1316                 }
1317         }
1318
1319         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) {
1320                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "0u8 /*", true, |_| "local_",
1321                                 |a, b, c| self.to_c_conversion_inline_prefix_from_path(a, b, c),
1322                                 |w, decl_type, decl_path, is_ref, _is_mut| {
1323                                         match decl_type {
1324                                                 DeclType::MirroredEnum if is_ref && ptr_for_ref => write!(w, "crate::{}::from_native(&", decl_path).unwrap(),
1325                                                 DeclType::MirroredEnum if is_ref => write!(w, "&crate::{}::from_native(&", decl_path).unwrap(),
1326                                                 DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
1327                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1328                                                         write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1329                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1330                                                         write!(w, "crate::{} {{ inner: unsafe {{ ( (&(", decl_path).unwrap(),
1331                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1332                                                         write!(w, "&crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1333                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1334                                                         write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
1335                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref =>
1336                                                         write!(w, "crate::{} {{ inner: Box::into_raw(Box::new(", decl_path).unwrap(),
1337                                                 DeclType::Trait(_) if is_ref => write!(w, "&").unwrap(),
1338                                                 _ => panic!("{:?}", decl_path),
1339                                         }
1340                                 });
1341         }
1342         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) {
1343                 self.write_to_c_conversion_inline_prefix_inner(w, t, generics, false, ptr_for_ref, false);
1344         }
1345         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) {
1346                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "*/", false, |_| ".into()",
1347                                 |a, b, c| self.to_c_conversion_inline_suffix_from_path(a, b, c),
1348                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1349                                         DeclType::MirroredEnum => write!(w, ")").unwrap(),
1350                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1351                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1352                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1353                                                 write!(w, ") as *const _) as *mut _) }}, is_owned: false }}").unwrap(),
1354                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1355                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1356                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1357                                                 write!(w, ", is_owned: true }}").unwrap(),
1358                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref => write!(w, ")), is_owned: true }}").unwrap(),
1359                                         DeclType::Trait(_) if is_ref => {},
1360                                         _ => unimplemented!(),
1361                                 });
1362         }
1363         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) {
1364                 self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
1365         }
1366
1367         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) {
1368                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_| "&local_",
1369                                 |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
1370                                 |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
1371                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, "unsafe {{ &*(*").unwrap(),
1372                                         DeclType::StructImported if is_mut && is_ref => write!(w, "unsafe {{ &mut *").unwrap(),
1373                                         DeclType::StructImported if is_ref => write!(w, "unsafe {{ &*").unwrap(),
1374                                         DeclType::StructImported if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
1375                                         DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
1376                                         DeclType::MirroredEnum => {},
1377                                         DeclType::Trait(_) => {},
1378                                         _ => unimplemented!(),
1379                                 });
1380         }
1381         pub fn write_from_c_conversion_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1382                 self.write_from_c_conversion_prefix_inner(w, t, generics, false, false);
1383         }
1384         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) {
1385                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "*/", false,
1386                                 |has_inner| match has_inner {
1387                                         false => ".iter().collect::<Vec<_>>()[..]",
1388                                         true => "[..]",
1389                                 },
1390                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1391                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1392                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, ").inner }}").unwrap(),
1393                                         DeclType::StructImported if is_ref => write!(w, ".inner }}").unwrap(),
1394                                         DeclType::StructImported if !is_ref => write!(w, ".take_ptr()) }}").unwrap(),
1395                                         DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
1396                                         DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
1397                                         DeclType::Trait(_) => {},
1398                                         _ => unimplemented!(),
1399                                 });
1400         }
1401         pub fn write_from_c_conversion_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1402                 self.write_from_c_conversion_suffix_inner(w, t, generics, false, false);
1403         }
1404         // Note that compared to the above conversion functions, the following two are generally
1405         // significantly undertested:
1406         pub fn write_from_c_conversion_to_ref_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1407                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "() /*", true, |_| "&local_",
1408                                 |a, b, _c| {
1409                                         if let Some(conv) = self.from_c_conversion_prefix_from_path(a, b) {
1410                                                 Some(format!("&{}", conv))
1411                                         } else { None }
1412                                 },
1413                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1414                                         DeclType::StructImported if !is_ref => write!(w, "unsafe {{ &*").unwrap(),
1415                                         _ => unimplemented!(),
1416                                 });
1417         }
1418         pub fn write_from_c_conversion_to_ref_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1419                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "*/", false,
1420                                 |has_inner| match has_inner {
1421                                         false => ".iter().collect::<Vec<_>>()[..]",
1422                                         true => "[..]",
1423                                 },
1424                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1425                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1426                                         DeclType::StructImported if !is_ref => write!(w, ".inner }}").unwrap(),
1427                                         _ => unimplemented!(),
1428                                 });
1429         }
1430
1431         fn write_conversion_new_var_intern<'b, W: std::io::Write,
1432                 LP: Fn(&str, bool) -> Option<(&str, &str)>,
1433                 LC: Fn(&str, bool, Option<&syn::Type>, &syn::Ident, &str) ->  Option<(&'b str, Vec<(String, String)>, &'b str)>,
1434                 VP: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool),
1435                 VS: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool)>
1436                         (&self, w: &mut W, ident: &syn::Ident, var: &str, t: &syn::Type, generics: Option<&GenericTypes>,
1437                          mut is_ref: bool, mut ptr_for_ref: bool, to_c: bool,
1438                          path_lookup: &LP, container_lookup: &LC, var_prefix: &VP, var_suffix: &VS) -> bool {
1439
1440                 macro_rules! convert_container {
1441                         ($container_type: expr, $args_len: expr, $args_iter: expr) => { {
1442                                 // For slices (and Options), we refuse to directly map them as is_ref when they
1443                                 // aren't opaque types containing an inner pointer. This is due to the fact that,
1444                                 // in both cases, the actual higher-level type is non-is_ref.
1445                                 let ty_has_inner = if self.is_transparent_container(&$container_type, is_ref) || $container_type == "Slice" {
1446                                         let ty = $args_iter().next().unwrap();
1447                                         if $container_type == "Slice" && to_c {
1448                                                 // "To C ptr_for_ref" means "return the regular object with is_owned
1449                                                 // set to false", which is totally what we want in a slice if we're about to
1450                                                 // set ty_has_inner.
1451                                                 ptr_for_ref = true;
1452                                         }
1453                                         if let syn::Type::Reference(t) = ty {
1454                                                 if let syn::Type::Path(p) = &*t.elem {
1455                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1456                                                 } else { false }
1457                                         } else if let syn::Type::Path(p) = ty {
1458                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1459                                         } else { false }
1460                                 } else { true };
1461
1462                                 // Options get a bunch of special handling, since in general we map Option<>al
1463                                 // types into the same C type as non-Option-wrapped types. This ends up being
1464                                 // pretty manual here and most of the below special-cases are for Options.
1465                                 let mut needs_ref_map = false;
1466                                 let mut only_contained_type = None;
1467                                 let mut only_contained_has_inner = false;
1468                                 let mut contains_slice = false;
1469                                 if $args_len == 1 && self.is_transparent_container(&$container_type, is_ref) {
1470                                         only_contained_has_inner = ty_has_inner;
1471                                         let arg = $args_iter().next().unwrap();
1472                                         if let syn::Type::Reference(t) = arg {
1473                                                 only_contained_type = Some(&*t.elem);
1474                                                 if let syn::Type::Path(_) = &*t.elem {
1475                                                         is_ref = true;
1476                                                 } else if let syn::Type::Slice(_) = &*t.elem {
1477                                                         contains_slice = true;
1478                                                 } else { return false; }
1479                                                 needs_ref_map = true;
1480                                         } else if let syn::Type::Path(_) = arg {
1481                                                 only_contained_type = Some(&arg);
1482                                         } else { unimplemented!(); }
1483                                 }
1484
1485                                 if let Some((prefix, conversions, suffix)) = container_lookup(&$container_type, is_ref && ty_has_inner, only_contained_type, ident, var) {
1486                                         assert_eq!(conversions.len(), $args_len);
1487                                         write!(w, "let mut local_{}{} = ", ident, if !to_c && needs_ref_map {"_base"} else { "" }).unwrap();
1488                                         if only_contained_has_inner && to_c {
1489                                                 var_prefix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1490                                         }
1491                                         write!(w, "{}{}", prefix, var).unwrap();
1492
1493                                         for ((pfx, var_name), (idx, ty)) in conversions.iter().zip($args_iter().enumerate()) {
1494                                                 let mut var = std::io::Cursor::new(Vec::new());
1495                                                 write!(&mut var, "{}", var_name).unwrap();
1496                                                 let var_access = String::from_utf8(var.into_inner()).unwrap();
1497
1498                                                 let conv_ty = if needs_ref_map { only_contained_type.as_ref().unwrap() } else { ty };
1499
1500                                                 write!(w, "{} {{ ", pfx).unwrap();
1501                                                 let new_var_name = format!("{}_{}", ident, idx);
1502                                                 let new_var = self.write_conversion_new_var_intern(w, &syn::Ident::new(&new_var_name, Span::call_site()),
1503                                                                 &var_access, conv_ty, generics, contains_slice || (is_ref && ty_has_inner), ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix);
1504                                                 if new_var { write!(w, " ").unwrap(); }
1505                                                 if (!only_contained_has_inner || !to_c) && !contains_slice {
1506                                                         var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1507                                                 }
1508
1509                                                 if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1510                                                         write!(w, "Box::into_raw(Box::new(").unwrap();
1511                                                 }
1512                                                 write!(w, "{}{}", if contains_slice { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
1513                                                 if (!only_contained_has_inner || !to_c) && !contains_slice {
1514                                                         var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1515                                                 }
1516                                                 if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1517                                                         write!(w, "))").unwrap();
1518                                                 }
1519                                                 write!(w, " }}").unwrap();
1520                                         }
1521                                         write!(w, "{}", suffix).unwrap();
1522                                         if only_contained_has_inner && to_c {
1523                                                 var_suffix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1524                                         }
1525                                         write!(w, ";").unwrap();
1526                                         if !to_c && needs_ref_map {
1527                                                 write!(w, " let mut local_{} = local_{}_base.as_ref()", ident, ident).unwrap();
1528                                                 if contains_slice {
1529                                                         write!(w, ".map(|a| &a[..])").unwrap();
1530                                                 }
1531                                                 write!(w, ";").unwrap();
1532                                         }
1533                                         return true;
1534                                 }
1535                         } }
1536                 }
1537
1538                 match t {
1539                         syn::Type::Reference(r) => {
1540                                 if let syn::Type::Slice(_) = &*r.elem {
1541                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, is_ref, ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix)
1542                                 } else {
1543                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, true, ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix)
1544                                 }
1545                         },
1546                         syn::Type::Path(p) => {
1547                                 if p.qself.is_some() {
1548                                         unimplemented!();
1549                                 }
1550                                 let resolved_path = self.resolve_path(&p.path, generics);
1551                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1552                                         return self.write_conversion_new_var_intern(w, ident, var, aliased_type, None, is_ref, ptr_for_ref, to_c, path_lookup, container_lookup, var_prefix, var_suffix);
1553                                 }
1554                                 if self.is_known_container(&resolved_path, is_ref) || self.is_transparent_container(&resolved_path, is_ref) {
1555                                         if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
1556                                                 convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
1557                                                         if let syn::GenericArgument::Type(ty) = arg {
1558                                                                 ty
1559                                                         } else { unimplemented!(); }
1560                                                 }));
1561                                         } else { unimplemented!(); }
1562                                 }
1563                                 if self.is_primitive(&resolved_path) {
1564                                         false
1565                                 } else if let Some(ty_ident) = single_ident_generic_path_to_ident(&p.path) {
1566                                         if let Some((prefix, suffix)) = path_lookup(&resolved_path, is_ref) {
1567                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1568                                                 true
1569                                         } else if self.declared.get(ty_ident).is_some() {
1570                                                 false
1571                                         } else { false }
1572                                 } else { false }
1573                         },
1574                         syn::Type::Array(_) => {
1575                                 // We assume all arrays contain only primitive types.
1576                                 // This may result in some outputs not compiling.
1577                                 false
1578                         },
1579                         syn::Type::Slice(s) => {
1580                                 if let syn::Type::Path(p) = &*s.elem {
1581                                         let resolved = self.resolve_path(&p.path, generics);
1582                                         assert!(self.is_primitive(&resolved));
1583                                         let slice_path = format!("[{}]", resolved);
1584                                         if let Some((prefix, suffix)) = path_lookup(&slice_path, true) {
1585                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1586                                                 true
1587                                         } else { false }
1588                                 } else if let syn::Type::Reference(ty) = &*s.elem {
1589                                         let tyref = [&*ty.elem];
1590                                         is_ref = true;
1591                                         convert_container!("Slice", 1, || tyref.iter());
1592                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1593                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1594                                         // When mapping into a temporary new var, we need to own all the underlying objects.
1595                                         // Thus, we drop any references inside the tuple and convert with non-reference types.
1596                                         let mut elems = syn::punctuated::Punctuated::new();
1597                                         for elem in t.elems.iter() {
1598                                                 if let syn::Type::Reference(r) = elem {
1599                                                         elems.push((*r.elem).clone());
1600                                                 } else {
1601                                                         elems.push(elem.clone());
1602                                                 }
1603                                         }
1604                                         let ty = [syn::Type::Tuple(syn::TypeTuple {
1605                                                 paren_token: t.paren_token, elems
1606                                         })];
1607                                         is_ref = false;
1608                                         ptr_for_ref = true;
1609                                         convert_container!("Slice", 1, || ty.iter());
1610                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1611                                 } else { unimplemented!() }
1612                         },
1613                         syn::Type::Tuple(t) => {
1614                                 if !t.elems.is_empty() {
1615                                         // We don't (yet) support tuple elements which cannot be converted inline
1616                                         write!(w, "let (").unwrap();
1617                                         for idx in 0..t.elems.len() {
1618                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1619                                                 write!(w, "{} orig_{}_{}", if is_ref { "ref" } else { "mut" }, ident, idx).unwrap();
1620                                         }
1621                                         write!(w, ") = {}{}; ", var, if !to_c { ".to_rust()" } else { "" }).unwrap();
1622                                         // Like other template types, tuples are always mapped as their non-ref
1623                                         // versions for types which have different ref mappings. Thus, we convert to
1624                                         // non-ref versions and handle opaque types with inner pointers manually.
1625                                         for (idx, elem) in t.elems.iter().enumerate() {
1626                                                 if let syn::Type::Path(p) = elem {
1627                                                         let v_name = format!("orig_{}_{}", ident, idx);
1628                                                         let tuple_elem_ident = syn::Ident::new(&v_name, Span::call_site());
1629                                                         if self.write_conversion_new_var_intern(w, &tuple_elem_ident, &v_name, elem, generics,
1630                                                                         false, ptr_for_ref, to_c,
1631                                                                         path_lookup, container_lookup, var_prefix, var_suffix) {
1632                                                                 write!(w, " ").unwrap();
1633                                                                 // Opaque types with inner pointers shouldn't ever create new stack
1634                                                                 // variables, so we don't handle it and just assert that it doesn't
1635                                                                 // here.
1636                                                                 assert!(!self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)));
1637                                                         }
1638                                                 }
1639                                         }
1640                                         write!(w, "let mut local_{} = (", ident).unwrap();
1641                                         for (idx, elem) in t.elems.iter().enumerate() {
1642                                                 let ty_has_inner = {
1643                                                                 if to_c {
1644                                                                         // "To C ptr_for_ref" means "return the regular object with
1645                                                                         // is_owned set to false", which is totally what we want
1646                                                                         // if we're about to set ty_has_inner.
1647                                                                         ptr_for_ref = true;
1648                                                                 }
1649                                                                 if let syn::Type::Reference(t) = elem {
1650                                                                         if let syn::Type::Path(p) = &*t.elem {
1651                                                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1652                                                                         } else { false }
1653                                                                 } else if let syn::Type::Path(p) = elem {
1654                                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1655                                                                 } else { false }
1656                                                         };
1657                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1658                                                 var_prefix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1659                                                 if is_ref && ty_has_inner {
1660                                                         // For ty_has_inner, the regular var_prefix mapping will take a
1661                                                         // reference, so deref once here to make sure we keep the original ref.
1662                                                         write!(w, "*").unwrap();
1663                                                 }
1664                                                 write!(w, "orig_{}_{}", ident, idx).unwrap();
1665                                                 if is_ref && !ty_has_inner {
1666                                                         // If we don't have an inner variable's reference to maintain, just
1667                                                         // hope the type is Clonable and use that.
1668                                                         write!(w, ".clone()").unwrap();
1669                                                 }
1670                                                 var_suffix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1671                                         }
1672                                         write!(w, "){};", if to_c { ".into()" } else { "" }).unwrap();
1673                                         true
1674                                 } else { false }
1675                         },
1676                         _ => unimplemented!(),
1677                 }
1678         }
1679
1680         pub fn write_to_c_conversion_new_var_inner<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, var_access: &str, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) -> bool {
1681                 self.write_conversion_new_var_intern(w, ident, var_access, t, generics, false, ptr_for_ref, true,
1682                         &|a, b| self.to_c_conversion_new_var_from_path(a, b),
1683                         &|a, b, c, d, e| self.to_c_conversion_container_new_var(generics, a, b, c, d, e),
1684                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1685                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_prefix_inner(a, b, c, d, e, f),
1686                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_suffix_inner(a, b, c, d, e, f))
1687         }
1688         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 {
1689                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, ptr_for_ref)
1690         }
1691         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 {
1692                 self.write_conversion_new_var_intern(w, ident, &format!("{}", ident), t, generics, false, false, false,
1693                         &|a, b| self.from_c_conversion_new_var_from_path(a, b),
1694                         &|a, b, c, d, e| self.from_c_conversion_container_new_var(generics, a, b, c, d, e),
1695                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1696                         &|a, b, c, d, e, _f| self.write_from_c_conversion_prefix_inner(a, b, c, d, e),
1697                         &|a, b, c, d, e, _f| self.write_from_c_conversion_suffix_inner(a, b, c, d, e))
1698         }
1699
1700         // ******************************************************
1701         // *** C Container Type Equivalent and alias Printing ***
1702         // ******************************************************
1703
1704         fn write_template_constructor<W: std::io::Write>(&mut self, w: &mut W, container_type: &str, mangled_container: &str, args: &Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) {
1705                 if container_type == "Result" {
1706                         assert_eq!(args.len(), 2);
1707                         macro_rules! write_fn {
1708                                 ($call: expr) => { {
1709                                         writeln!(w, "#[no_mangle]\npub extern \"C\" fn {}_{}() -> {} {{", mangled_container, $call, mangled_container).unwrap();
1710                                         writeln!(w, "\t{}::CResultTempl::{}(0)\n}}\n", Self::container_templ_path(), $call).unwrap();
1711                                 } }
1712                         }
1713                         macro_rules! write_alias {
1714                                 ($call: expr, $item: expr) => { {
1715                                         write!(w, "#[no_mangle]\npub static {}_{}: extern \"C\" fn (", mangled_container, $call).unwrap();
1716                                         if let syn::Type::Path(syn::TypePath { path, .. }) = $item {
1717                                                 let resolved = self.resolve_path(path, generics);
1718                                                 if self.is_known_container(&resolved, is_ref) || self.is_transparent_container(&resolved, is_ref) {
1719                                                         self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(path), generics,
1720                                                                 &format!("{}", single_ident_generic_path_to_ident(path).unwrap()), is_ref, false, false, false);
1721                                                 } else {
1722                                                         self.write_template_generics(w, &mut [$item].iter().map(|t| *t), is_ref, true);
1723                                                 }
1724                                         } else if let syn::Type::Tuple(syn::TypeTuple { elems, .. }) = $item {
1725                                                 self.write_c_mangled_container_path_intern(w, elems.iter().collect(), generics,
1726                                                         &format!("{}Tuple", elems.len()), is_ref, false, false, false);
1727                                         } else { unimplemented!(); }
1728                                         write!(w, ") -> {} =\n\t{}::CResultTempl::<", mangled_container, Self::container_templ_path()).unwrap();
1729                                         self.write_template_generics(w, &mut args.iter().map(|t| *t), is_ref, true);
1730                                         writeln!(w, ">::{};\n", $call).unwrap();
1731                                 } }
1732                         }
1733                         match args[0] {
1734                                 syn::Type::Tuple(t) if t.elems.is_empty() => write_fn!("ok"),
1735                                 _ => write_alias!("ok", args[0]),
1736                         }
1737                         match args[1] {
1738                                 syn::Type::Tuple(t) if t.elems.is_empty() => write_fn!("err"),
1739                                 _ => write_alias!("err", args[1]),
1740                         }
1741                 } else if container_type.ends_with("Tuple") {
1742                         write!(w, "#[no_mangle]\npub extern \"C\" fn {}_new(", mangled_container).unwrap();
1743                         for (idx, gen) in args.iter().enumerate() {
1744                                 write!(w, "{}{}: ", if idx != 0 { ", " } else { "" }, ('a' as u8 + idx as u8) as char).unwrap();
1745                                 assert!(self.write_c_type_intern(w, gen, None, false, false, false));
1746                         }
1747                         writeln!(w, ") -> {} {{", mangled_container).unwrap();
1748                         write!(w, "\t{} {{ ", mangled_container).unwrap();
1749                         for idx in 0..args.len() {
1750                                 write!(w, "{}, ", ('a' as u8 + idx as u8) as char).unwrap();
1751                         }
1752                         writeln!(w, "}}\n}}\n").unwrap();
1753                 } else {
1754                         writeln!(w, "").unwrap();
1755                 }
1756         }
1757
1758         fn write_template_generics<'b, W: std::io::Write>(&self, w: &mut W, args: &mut dyn Iterator<Item=&'b syn::Type>, is_ref: bool, in_crate: bool) {
1759                 for (idx, t) in args.enumerate() {
1760                         if idx != 0 {
1761                                 write!(w, ", ").unwrap();
1762                         }
1763                         if let syn::Type::Tuple(tup) = t {
1764                                 if tup.elems.is_empty() {
1765                                         write!(w, "u8").unwrap();
1766                                 } else {
1767                                         write!(w, "{}::C{}TupleTempl<", Self::container_templ_path(), tup.elems.len()).unwrap();
1768                                         self.write_template_generics(w, &mut tup.elems.iter(), is_ref, in_crate);
1769                                         write!(w, ">").unwrap();
1770                                 }
1771                         } else if let syn::Type::Path(p_arg) = t {
1772                                 let resolved_generic = self.resolve_path(&p_arg.path, None);
1773                                 if self.is_primitive(&resolved_generic) {
1774                                         write!(w, "{}", resolved_generic).unwrap();
1775                                 } else if let Some(c_type) = self.c_type_from_path(&resolved_generic, is_ref, false) {
1776                                         if self.is_known_container(&resolved_generic, is_ref) {
1777                                                         write!(w, "{}::C{}Templ<", Self::container_templ_path(), single_ident_generic_path_to_ident(&p_arg.path).unwrap()).unwrap();
1778                                                 assert_eq!(p_arg.path.segments.len(), 1);
1779                                                 if let syn::PathArguments::AngleBracketed(args) = &p_arg.path.segments.iter().next().unwrap().arguments {
1780                                                         self.write_template_generics(w, &mut args.args.iter().map(|gen|
1781                                                                 if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }),
1782                                                                 is_ref, in_crate);
1783                                                 } else { unimplemented!(); }
1784                                                 write!(w, ">").unwrap();
1785                                         } else if resolved_generic == "Option" {
1786                                                 if let syn::PathArguments::AngleBracketed(args) = &p_arg.path.segments.iter().next().unwrap().arguments {
1787                                                         self.write_template_generics(w, &mut args.args.iter().map(|gen|
1788                                                                 if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }),
1789                                                                 is_ref, in_crate);
1790                                                 } else { unimplemented!(); }
1791                                         } else if in_crate {
1792                                                 write!(w, "{}", c_type).unwrap();
1793                                         } else {
1794                                                 self.write_rust_type(w, None, &t);
1795                                         }
1796                                 } else {
1797                                         // If we just write out resolved_generic, it may mostly work, however for
1798                                         // original types which are generic, we need the template args. We could
1799                                         // figure them out and write them out, too, but its much easier to just
1800                                         // reference the native{} type alias which exists at least for opaque types.
1801                                         if in_crate {
1802                                                 write!(w, "crate::{}", resolved_generic).unwrap();
1803                                         } else {
1804                                                 let path_name: Vec<&str> = resolved_generic.rsplitn(2, "::").collect();
1805                                                 if path_name.len() > 1 {
1806                                                         write!(w, "crate::{}::native{}", path_name[1], path_name[0]).unwrap();
1807                                                 } else {
1808                                                         write!(w, "crate::native{}", path_name[0]).unwrap();
1809                                                 }
1810                                         }
1811                                 }
1812                         } else if let syn::Type::Reference(r_arg) = t {
1813                                 if let syn::Type::Path(p_arg) = &*r_arg.elem {
1814                                         let resolved = self.resolve_path(&p_arg.path, None);
1815                                         if self.crate_types.opaques.get(&resolved).is_some() {
1816                                                 write!(w, "crate::{}", resolved).unwrap();
1817                                         } else {
1818                                                 let cty = self.c_type_from_path(&resolved, true, true).expect("Template generics should be opaque or have a predefined mapping");
1819                                                 w.write(cty.as_bytes()).unwrap();
1820                                         }
1821                                 } else { unimplemented!(); }
1822                         } else if let syn::Type::Array(a_arg) = t {
1823                                 if let syn::Type::Path(p_arg) = &*a_arg.elem {
1824                                         let resolved = self.resolve_path(&p_arg.path, None);
1825                                         assert!(self.is_primitive(&resolved));
1826                                         if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a_arg.len {
1827                                                 write!(w, "{}",
1828                                                         self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, false).unwrap()).unwrap();
1829                                         }
1830                                 }
1831                         }
1832                 }
1833         }
1834         fn check_create_container(&mut self, mangled_container: String, container_type: &str, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) {
1835                 if !self.crate_types.templates_defined.get(&mangled_container).is_some() {
1836                         self.crate_types.templates_defined.insert(mangled_container.clone(), true);
1837                         let mut created_container: Vec<u8> = Vec::new();
1838
1839                         write!(&mut created_container, "#[no_mangle]\npub type {} = ", mangled_container).unwrap();
1840                         write!(&mut created_container, "{}::C{}Templ<", Self::container_templ_path(), container_type).unwrap();
1841                         self.write_template_generics(&mut created_container, &mut args.iter().map(|t| *t), is_ref, true);
1842                         writeln!(&mut created_container, ">;").unwrap();
1843
1844                         write!(&mut created_container, "#[no_mangle]\npub static {}_free: extern \"C\" fn({}) = ", mangled_container, mangled_container).unwrap();
1845                         write!(&mut created_container, "{}::C{}Templ_free::<", Self::container_templ_path(), container_type).unwrap();
1846                         self.write_template_generics(&mut created_container, &mut args.iter().map(|t| *t), is_ref, true);
1847                         writeln!(&mut created_container, ">;").unwrap();
1848
1849                         self.write_template_constructor(&mut created_container, container_type, &mangled_container, &args, generics, is_ref);
1850
1851                         self.crate_types.template_file.write(&created_container).unwrap();
1852                 }
1853         }
1854         fn path_to_generic_args(path: &syn::Path) -> Vec<&syn::Type> {
1855                 if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().next().unwrap().arguments {
1856                         args.args.iter().map(|gen| if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }).collect()
1857                 } else { unimplemented!(); }
1858         }
1859         fn write_c_mangled_container_path_intern<W: std::io::Write>
1860                         (&mut self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool, in_type: bool) -> bool {
1861                 let mut mangled_type: Vec<u8> = Vec::new();
1862                 if !self.is_transparent_container(ident, is_ref) {
1863                         write!(w, "C{}_", ident).unwrap();
1864                         write!(mangled_type, "C{}_", ident).unwrap();
1865                 } else { assert_eq!(args.len(), 1); }
1866                 for arg in args.iter() {
1867                         macro_rules! write_path {
1868                                 ($p_arg: expr, $extra_write: expr) => {
1869                                         let subtype = self.resolve_path(&$p_arg.path, generics);
1870                                         if self.is_transparent_container(ident, is_ref) {
1871                                                 // We dont (yet) support primitives or containers inside transparent
1872                                                 // containers, so check for that first:
1873                                                 if self.is_primitive(&subtype) { return false; }
1874                                                 if self.is_known_container(&subtype, is_ref) { return false; }
1875                                                 if !in_type {
1876                                                         if self.c_type_has_inner_from_path(&subtype) {
1877                                                                 if !self.write_c_path_intern(w, &$p_arg.path, generics, is_ref, is_mut, ptr_for_ref) { return false; }
1878                                                         } else {
1879                                                                 // Option<T> needs to be converted to a *mut T, ie mut ptr-for-ref
1880                                                                 if !self.write_c_path_intern(w, &$p_arg.path, generics, true, true, true) { return false; }
1881                                                         }
1882                                                 } else {
1883                                                         if $p_arg.path.segments.len() == 1 {
1884                                                                 write!(w, "{}", $p_arg.path.segments.iter().next().unwrap().ident).unwrap();
1885                                                         } else {
1886                                                                 return false;
1887                                                         }
1888                                                 }
1889                                         } else if self.is_known_container(&subtype, is_ref) || self.is_transparent_container(&subtype, is_ref) {
1890                                                 if !self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(&$p_arg.path), generics,
1891                                                                 &subtype, is_ref, is_mut, ptr_for_ref, true) {
1892                                                         return false;
1893                                                 }
1894                                                 self.write_c_mangled_container_path_intern(&mut mangled_type, Self::path_to_generic_args(&$p_arg.path),
1895                                                         generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1896                                                 if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1897                                                         self.write_c_mangled_container_path_intern(w2, Self::path_to_generic_args(&$p_arg.path),
1898                                                                 generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1899                                                 }
1900                                         } else {
1901                                                 let id = &&$p_arg.path.segments.iter().rev().next().unwrap().ident;
1902                                                 write!(w, "{}", id).unwrap();
1903                                                 write!(mangled_type, "{}", id).unwrap();
1904                                                 if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1905                                                         write!(w2, "{}", id).unwrap();
1906                                                 }
1907                                         }
1908                                 }
1909                         }
1910                         if let syn::Type::Tuple(tuple) = arg {
1911                                 if tuple.elems.len() == 0 {
1912                                         write!(w, "None").unwrap();
1913                                         write!(mangled_type, "None").unwrap();
1914                                 } else {
1915                                         let mut mangled_tuple_type: Vec<u8> = Vec::new();
1916
1917                                         // Figure out what the mangled type should look like. To disambiguate
1918                                         // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
1919                                         // them with a Z. Ideally we wouldn't use Z, but not many special chars are
1920                                         // available for use in type names.
1921                                         write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
1922                                         write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
1923                                         write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
1924                                         for elem in tuple.elems.iter() {
1925                                                 if let syn::Type::Path(p) = elem {
1926                                                         write_path!(p, Some(&mut mangled_tuple_type));
1927                                                 } else if let syn::Type::Reference(refelem) = elem {
1928                                                         if let syn::Type::Path(p) = &*refelem.elem {
1929                                                                 write_path!(p, Some(&mut mangled_tuple_type));
1930                                                         } else { return false; }
1931                                                 } else { return false; }
1932                                         }
1933                                         write!(w, "Z").unwrap();
1934                                         write!(mangled_type, "Z").unwrap();
1935                                         write!(mangled_tuple_type, "Z").unwrap();
1936                                         self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
1937                                                 &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref);
1938                                 }
1939                         } else if let syn::Type::Path(p_arg) = arg {
1940                                 write_path!(p_arg, None);
1941                         } else if let syn::Type::Reference(refty) = arg {
1942                                 if args.len() != 1 { return false; }
1943                                 if let syn::Type::Path(p_arg) = &*refty.elem {
1944                                         write_path!(p_arg, None);
1945                                 } else if let syn::Type::Slice(_) = &*refty.elem {
1946                                         // write_c_type will actually do exactly what we want here, we just need to
1947                                         // make it a pointer so that its an option. Note that we cannot always convert
1948                                         // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
1949                                         // to edit it, hence we use *mut here instead of *const.
1950                                         write!(w, "*mut ").unwrap();
1951                                         self.write_c_type(w, arg, None, true);
1952                                 } else { return false; }
1953                         } else if let syn::Type::Array(a) = arg {
1954                                 if let syn::Type::Path(p_arg) = &*a.elem {
1955                                         let resolved = self.resolve_path(&p_arg.path, generics);
1956                                         if !self.is_primitive(&resolved) { return false; }
1957                                         if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
1958                                                 if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
1959                                                 write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
1960                                                 write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
1961                                         } else { return false; }
1962                                 } else { return false; }
1963                         } else { return false; }
1964                 }
1965                 if self.is_transparent_container(ident, is_ref) { return true; }
1966                 // Push the "end of type" Z
1967                 write!(w, "Z").unwrap();
1968                 write!(mangled_type, "Z").unwrap();
1969
1970                 // Make sure the type is actually defined:
1971                 self.check_create_container(String::from_utf8(mangled_type).unwrap(), ident, args, generics, is_ref);
1972                 true
1973         }
1974         fn write_c_mangled_container_path<W: std::io::Write>(&mut self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
1975                 if !self.is_transparent_container(ident, is_ref) {
1976                         write!(w, "{}::", Self::generated_container_path()).unwrap();
1977                 }
1978                 self.write_c_mangled_container_path_intern(w, args, generics, ident, is_ref, is_mut, ptr_for_ref, false)
1979         }
1980
1981         // **********************************
1982         // *** C Type Equivalent Printing ***
1983         // **********************************
1984
1985         fn write_c_path_intern<W: std::io::Write>(&self, w: &mut W, path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
1986                 let full_path = match self.maybe_resolve_path(&path, generics) {
1987                         Some(path) => path, None => return false };
1988                 if let Some(c_type) = self.c_type_from_path(&full_path, is_ref, ptr_for_ref) {
1989                         write!(w, "{}", c_type).unwrap();
1990                         true
1991                 } else if self.crate_types.traits.get(&full_path).is_some() {
1992                         if is_ref && ptr_for_ref {
1993                                 write!(w, "*{} crate::{}", if is_mut { "mut" } else { "const" }, full_path).unwrap();
1994                         } else if is_ref {
1995                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
1996                         } else {
1997                                 write!(w, "crate::{}", full_path).unwrap();
1998                         }
1999                         true
2000                 } else if self.crate_types.opaques.get(&full_path).is_some() || self.crate_types.mirrored_enums.get(&full_path).is_some() {
2001                         if is_ref && ptr_for_ref {
2002                                 // ptr_for_ref implies we're returning the object, which we can't really do for
2003                                 // opaque or mirrored types without box'ing them, which is quite a waste, so return
2004                                 // the actual object itself (for opaque types we'll set the pointer to the actual
2005                                 // type and note that its a reference).
2006                                 write!(w, "crate::{}", full_path).unwrap();
2007                         } else if is_ref {
2008                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
2009                         } else {
2010                                 write!(w, "crate::{}", full_path).unwrap();
2011                         }
2012                         true
2013                 } else {
2014                         false
2015                 }
2016         }
2017         fn write_c_type_intern<W: std::io::Write>(&mut self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
2018                 match t {
2019                         syn::Type::Path(p) => {
2020                                 if p.qself.is_some() {
2021                                         return false;
2022                                 }
2023                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
2024                                         if self.is_known_container(&full_path, is_ref) || self.is_transparent_container(&full_path, is_ref) {
2025                                                 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);
2026                                         }
2027                                         if let Some(aliased_type) = self.crate_types.type_aliases.get(&full_path).cloned() {
2028                                                 return self.write_c_type_intern(w, &aliased_type, None, is_ref, is_mut, ptr_for_ref);
2029                                         }
2030                                 }
2031                                 self.write_c_path_intern(w, &p.path, generics, is_ref, is_mut, ptr_for_ref)
2032                         },
2033                         syn::Type::Reference(r) => {
2034                                 self.write_c_type_intern(w, &*r.elem, generics, true, r.mutability.is_some(), ptr_for_ref)
2035                         },
2036                         syn::Type::Array(a) => {
2037                                 if is_ref && is_mut {
2038                                         write!(w, "*mut [").unwrap();
2039                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2040                                 } else if is_ref {
2041                                         write!(w, "*const [").unwrap();
2042                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2043                                 } else {
2044                                         let mut typecheck = Vec::new();
2045                                         if !self.write_c_type_intern(&mut typecheck, &a.elem, generics, false, false, ptr_for_ref) { return false; }
2046                                         if typecheck[..] != ['u' as u8, '8' as u8] { return false; }
2047                                 }
2048                                 if let syn::Expr::Lit(l) = &a.len {
2049                                         if let syn::Lit::Int(i) = &l.lit {
2050                                                 if !is_ref {
2051                                                         if let Some(ty) = self.c_type_from_path(&format!("[u8; {}]", i.base10_digits()), false, ptr_for_ref) {
2052                                                                 write!(w, "{}", ty).unwrap();
2053                                                                 true
2054                                                         } else { false }
2055                                                 } else {
2056                                                         write!(w, "; {}]", i).unwrap();
2057                                                         true
2058                                                 }
2059                                         } else { false }
2060                                 } else { false }
2061                         }
2062                         syn::Type::Slice(s) => {
2063                                 if !is_ref || is_mut { return false; }
2064                                 if let syn::Type::Path(p) = &*s.elem {
2065                                         let resolved = self.resolve_path(&p.path, generics);
2066                                         if self.is_primitive(&resolved) {
2067                                                 write!(w, "{}::{}slice", Self::container_templ_path(), resolved).unwrap();
2068                                                 true
2069                                         } else { false }
2070                                 } else if let syn::Type::Reference(r) = &*s.elem {
2071                                         if let syn::Type::Path(p) = &*r.elem {
2072                                                 // Slices with "real types" inside are mapped as the equivalent non-ref Vec
2073                                                 let resolved = self.resolve_path(&p.path, generics);
2074                                                 let mangled_container = if let Some(ident) = self.crate_types.opaques.get(&resolved) {
2075                                                         format!("CVec_{}Z", ident)
2076                                                 } else if let Some(en) = self.crate_types.mirrored_enums.get(&resolved) {
2077                                                         format!("CVec_{}Z", en.ident)
2078                                                 } else if let Some(id) = p.path.get_ident() {
2079                                                         format!("CVec_{}Z", id)
2080                                                 } else { return false; };
2081                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2082                                                 self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false);
2083                                                 true
2084                                         } else { false }
2085                                 } else if let syn::Type::Tuple(_) = &*s.elem {
2086                                         let mut args = syn::punctuated::Punctuated::new();
2087                                         args.push(syn::GenericArgument::Type((*s.elem).clone()));
2088                                         let mut segments = syn::punctuated::Punctuated::new();
2089                                         segments.push(syn::PathSegment {
2090                                                 ident: syn::Ident::new("Vec", Span::call_site()),
2091                                                 arguments: syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
2092                                                         colon2_token: None, lt_token: syn::Token![<](Span::call_site()), args, gt_token: syn::Token![>](Span::call_site()),
2093                                                 })
2094                                         });
2095                                         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)
2096                                 } else { false }
2097                         },
2098                         syn::Type::Tuple(t) => {
2099                                 if t.elems.len() == 0 {
2100                                         true
2101                                 } else {
2102                                         self.write_c_mangled_container_path(w, t.elems.iter().collect(), generics,
2103                                                 &format!("{}Tuple", t.elems.len()), is_ref, is_mut, ptr_for_ref)
2104                                 }
2105                         },
2106                         _ => false,
2107                 }
2108         }
2109         pub fn write_c_type<W: std::io::Write>(&mut self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2110                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref));
2111         }
2112         pub fn understood_c_path(&mut self, p: &syn::Path) -> bool {
2113                 if p.leading_colon.is_some() { return false; }
2114                 self.write_c_path_intern(&mut std::io::sink(), p, None, false, false, false)
2115         }
2116         pub fn understood_c_type(&mut self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2117                 self.write_c_type_intern(&mut std::io::sink(), t, generics, false, false, false)
2118         }
2119 }