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