_ 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" => Some("crate::c_types::Transaction"),
 344                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut"),
 345                         "bitcoin::OutPoint" => Some("crate::chain::transaction::OutPoint"),
 346                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network"),
 347                         "bitcoin::blockdata::block::BlockHeader" if is_ref  => Some("*const [u8; 80]"),
 348                         "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
 349
 350                         // Newtypes that we just expose in their original form.
 351                         "bitcoin::hash_types::Txid" if is_ref  => Some("*const [u8; 32]"),
 352                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 353                         "bitcoin::hash_types::BlockHash" if is_ref  => Some("*const [u8; 32]"),
 354                         "bitcoin::hash_types::BlockHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 355                         "ln::channelmanager::PaymentHash" if is_ref => Some("*const [u8; 32]"),
 356                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 357                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("*const [u8; 32]"),
 358                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 359                         "ln::channelmanager::PaymentSecret" if is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 360                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 361
 362                         // Override the default since Records contain an fmt with a lifetime:
 363                         "util::logger::Record" => Some("*const std::os::raw::c_char"),
 364
 365                         // List of structs we map that aren't detected:
 366                         "ln::features::InitFeatures" if is_ref && ptr_for_ref => Some("crate::ln::features::InitFeatures"),
 367                         "ln::features::InitFeatures" if is_ref => Some("*const crate::ln::features::InitFeatures"),
 368                         "ln::features::InitFeatures" => Some("crate::ln::features::InitFeatures"),
 369                         _ => {
 370                                 eprintln!("    Type {} (ref: {}) unresolvable in C", full_path, is_ref);
 371                                 None
 372                         },
 373                 }
 374         }
 375
 376         fn from_c_conversion_new_var_from_path<'b>(&self, _full_path: &str, _is_ref: bool) -> Option<(&'b str, &'b str)> {
 377                 None
 378         }
 379         fn from_c_conversion_prefix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 380                 if self.is_primitive(full_path) {
 381                         return Some("".to_owned());
 382                 }
 383                 match full_path {
 384                         "Vec" if !is_ref => Some("local_"),
 385                         "Result" if !is_ref => Some("local_"),
 386                         "Option" if is_ref => Some("&local_"),
 387                         "Option" => Some("local_"),
 388
 389                         "[u8; 32]" if is_ref => Some("unsafe { &*"),
 390                         "[u8; 32]" if !is_ref => Some(""),
 391                         "[u8; 16]" if !is_ref => Some(""),
 392                         "[u8; 10]" if !is_ref => Some(""),
 393                         "[u8; 4]" if !is_ref => Some(""),
 394                         "[u8; 3]" if !is_ref => Some(""),
 395
 396                         "[u8]" if is_ref => Some(""),
 397                         "[usize]" if is_ref => Some(""),
 398
 399                         "str" if is_ref => Some(""),
 400                         "String" if !is_ref => Some("String::from_utf8("),
 401                         // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
 402                         // cannot create a &String.
 403
 404                         "std::time::Duration" => Some("std::time::Duration::from_secs("),
 405
 406                         "bitcoin::secp256k1::key::PublicKey" if is_ref => Some("&"),
 407                         "bitcoin::secp256k1::key::PublicKey" => Some(""),
 408                         "bitcoin::secp256k1::Signature" if is_ref => Some("&"),
 409                         "bitcoin::secp256k1::Signature" => Some(""),
 410                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("&::bitcoin::secp256k1::key::SecretKey::from_slice(&unsafe { *"),
 411                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(""),
 412                         "bitcoin::blockdata::script::Script" if is_ref => Some("&::bitcoin::blockdata::script::Script::from(Vec::from("),
 413                         "bitcoin::blockdata::script::Script" if !is_ref => Some("::bitcoin::blockdata::script::Script::from("),
 414                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some("&"),
 415                         "bitcoin::blockdata::transaction::Transaction" => Some(""),
 416                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(""),
 417                         "bitcoin::network::constants::Network" => Some(""),
 418                         "bitcoin::blockdata::block::BlockHeader" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
 419                         "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
 420
 421                         // Newtypes that we just expose in their original form.
 422                         "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
 423                         "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
 424                         "bitcoin::hash_types::BlockHash" => Some("::bitcoin::hash_types::BlockHash::from_slice(&"),
 425                         "ln::channelmanager::PaymentHash" if !is_ref => Some("::lightning::ln::channelmanager::PaymentHash("),
 426                         "ln::channelmanager::PaymentHash" if is_ref => Some("&::lightning::ln::channelmanager::PaymentHash(unsafe { *"),
 427                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some("::lightning::ln::channelmanager::PaymentPreimage("),
 428                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&::lightning::ln::channelmanager::PaymentPreimage(unsafe { *"),
 429                         "ln::channelmanager::PaymentSecret" => Some("::lightning::ln::channelmanager::PaymentSecret("),
 430
 431                         // List of structs we map (possibly during processing of other files):
 432                         "ln::features::InitFeatures" if !is_ref => Some("*unsafe { Box::from_raw("),
 433
 434                         // List of traits we map (possibly during processing of other files):
 435                         "crate::util::logger::Logger" => Some(""),
 436
 437                         _ => {
 438                                 eprintln!("    Type {} unconvertable from C", full_path);
 439                                 None
 440                         },
 441                 }.map(|s| s.to_owned())
 442         }
 443         fn from_c_conversion_suffix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 444                 if self.is_primitive(full_path) {
 445                         return Some("".to_owned());
 446                 }
 447                 match full_path {
 448                         "Vec" if !is_ref => Some(""),
 449                         "Option" => Some(""),
 450                         "Result" if !is_ref => Some(""),
 451
 452                         "[u8; 32]" if is_ref => Some("}"),
 453                         "[u8; 32]" if !is_ref => Some(".data"),
 454                         "[u8; 16]" if !is_ref => Some(".data"),
 455                         "[u8; 10]" if !is_ref => Some(".data"),
 456                         "[u8; 4]" if !is_ref => Some(".data"),
 457                         "[u8; 3]" if !is_ref => Some(".data"),
 458
 459                         "[u8]" if is_ref => Some(".to_slice()"),
 460                         "[usize]" if is_ref => Some(".to_slice()"),
 461
 462                         "str" if is_ref => Some(".into()"),
 463                         "String" if !is_ref => Some(".into_rust()).unwrap()"),
 464
 465                         "std::time::Duration" => Some(")"),
 466
 467                         "bitcoin::secp256k1::key::PublicKey" => Some(".into_rust()"),
 468                         "bitcoin::secp256k1::Signature" => Some(".into_rust()"),
 469                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(".into_rust()"),
 470                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some("}[..]).unwrap()"),
 471                         "bitcoin::blockdata::script::Script" if is_ref => Some(".to_slice()))"),
 472                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_rust())"),
 473                         "bitcoin::blockdata::transaction::Transaction" => Some(".into_bitcoin()"),
 474                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(".into_rust()"),
 475                         "bitcoin::network::constants::Network" => Some(".into_bitcoin()"),
 476                         "bitcoin::blockdata::block::BlockHeader" => Some(" }).unwrap()"),
 477                         "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
 478
 479                         // Newtypes that we just expose in their original form.
 480                         "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
 481                         "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
 482                         "bitcoin::hash_types::BlockHash" if !is_ref => Some(".data[..]).unwrap()"),
 483                         "ln::channelmanager::PaymentHash" if !is_ref => Some(".data)"),
 484                         "ln::channelmanager::PaymentHash" if is_ref => Some(" })"),
 485                         "ln::channelmanager::PaymentPreimage" if !is_ref => Some(".data)"),
 486                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(" })"),
 487                         "ln::channelmanager::PaymentSecret" => Some(".data)"),
 488
 489                         // List of structs we map (possibly during processing of other files):
 490                         "ln::features::InitFeatures" if is_ref => Some(".inner) }"),
 491                         "ln::features::InitFeatures" if !is_ref => Some(".take_ptr()) }"),
 492
 493                         // List of traits we map (possibly during processing of other files):
 494                         "crate::util::logger::Logger" => Some(""),
 495
 496                         _ => {
 497                                 eprintln!("    Type {} unconvertable from C", full_path);
 498                                 None
 499                         },
 500                 }.map(|s| s.to_owned())
 501         }
 502
 503         fn to_c_conversion_new_var_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<(&'b str, &'b str)> {
 504                 if self.is_primitive(full_path) {
 505                         return None;
 506                 }
 507                 match full_path {
 508                         "[u8]" if is_ref => Some(("crate::c_types::u8slice::from_slice(", ")")),
 509                         "[usize]" if is_ref => Some(("crate::c_types::usizeslice::from_slice(", ")")),
 510
 511                         "bitcoin::blockdata::transaction::Transaction" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 512                         "bitcoin::blockdata::transaction::Transaction" if !is_ref => Some(("::bitcoin::consensus::encode::serialize(&", ")")),
 513                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(("{ let mut s = [0u8; 80]; s[..].copy_from_slice(&::bitcoin::consensus::encode::serialize(", ")); s }")),
 514                         "bitcoin::blockdata::block::Block" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
 515                         "bitcoin::hash_types::Txid" => None,
 516
 517                         // Override the default since Records contain an fmt with a lifetime:
 518                         // TODO: We should include the other record fields
 519                         "util::logger::Record" => Some(("std::ffi::CString::new(format!(\"{}\", ", ".args)).unwrap()")),
 520                         _ => None,
 521                 }.map(|s| s.to_owned())
 522         }
 523         fn to_c_conversion_inline_prefix_from_path(&self, full_path: &str, is_ref: bool, ptr_for_ref: bool) -> Option<String> {
 524                 if self.is_primitive(full_path) {
 525                         return Some("".to_owned());
 526                 }
 527                 match full_path {
 528                         "Result" if !is_ref => Some("local_"),
 529                         "Vec" if !is_ref => Some("local_"),
 530                         "Option" => Some("local_"),
 531
 532                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 533                         "[u8; 32]" if is_ref => Some("&"),
 534                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes { data: "),
 535                         "[u8; 10]" if !is_ref => Some("crate::c_types::TenBytes { data: "),
 536                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes { data: "),
 537                         "[u8; 3]" if is_ref => Some("&"),
 538
 539                         "[u8]" if is_ref => Some("local_"),
 540                         "[usize]" if is_ref => Some("local_"),
 541
 542                         "str" if is_ref => Some(""),
 543                         "String" => Some(""),
 544
 545                         "std::time::Duration" => Some(""),
 546
 547                         "bitcoin::secp256k1::key::PublicKey" => Some("crate::c_types::PublicKey::from_rust(&"),
 548                         "bitcoin::secp256k1::Signature" => Some("crate::c_types::Signature::from_rust(&"),
 549                         "bitcoin::secp256k1::key::SecretKey" if is_ref  => Some(""),
 550                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
 551                         "bitcoin::secp256k1::Error" if !is_ref => Some("crate::c_types::Secp256k1Error::from_rust("),
 552                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice::from_slice(&"),
 553                         "bitcoin::blockdata::script::Script" if !is_ref => Some(""),
 554                         "bitcoin::blockdata::transaction::Transaction" => Some("crate::c_types::Transaction::from_vec(local_"),
 555                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut::from_rust("),
 556                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some("&local_"),
 557                         "bitcoin::blockdata::block::Block" if is_ref => Some("crate::c_types::u8slice::from_slice(&local_"),
 558
 559                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 560
 561                         // Newtypes that we just expose in their original form.
 562                         "bitcoin::hash_types::Txid" if is_ref => Some(""),
 563                         "bitcoin::hash_types::BlockHash" if is_ref => Some(""),
 564                         "bitcoin::hash_types::BlockHash" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 565                         "ln::channelmanager::PaymentHash" if is_ref => Some("&"),
 566                         "ln::channelmanager::PaymentHash" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 567                         "ln::channelmanager::PaymentPreimage" if is_ref => Some("&"),
 568                         "ln::channelmanager::PaymentPreimage" => Some("crate::c_types::ThirtyTwoBytes { data: "),
 569                         "ln::channelmanager::PaymentSecret" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 570
 571                         // Override the default since Records contain an fmt with a lifetime:
 572                         "util::logger::Record" => Some("local_"),
 573
 574                         // List of structs we map (possibly during processing of other files):
 575                         "ln::features::InitFeatures" if is_ref && ptr_for_ref => Some("crate::ln::features::InitFeatures { inner: &mut "),
 576                         "ln::features::InitFeatures" if is_ref => Some("Box::into_raw(Box::new(crate::ln::features::InitFeatures { inner: &mut "),
 577                         "ln::features::InitFeatures" if !is_ref => Some("crate::ln::features::InitFeatures { inner: Box::into_raw(Box::new("),
 578
 579                         _ => {
 580                                 eprintln!("    Type {} (is_ref: {}) unconvertable to C", full_path, is_ref);
 581                                 None
 582                         },
 583                 }.map(|s| s.to_owned())
 584         }
 585         fn to_c_conversion_inline_suffix_from_path(&self, full_path: &str, is_ref: bool, ptr_for_ref: bool) -> Option<String> {
 586                 if self.is_primitive(full_path) {
 587                         return Some("".to_owned());
 588                 }
 589                 match full_path {
 590                         "Result" if !is_ref => Some(""),
 591                         "Vec" if !is_ref => Some(".into()"),
 592                         "Option" => Some(""),
 593
 594                         "[u8; 32]" if !is_ref => Some(" }"),
 595                         "[u8; 32]" if is_ref => Some(""),
 596                         "[u8; 16]" if !is_ref => Some(" }"),
 597                         "[u8; 10]" if !is_ref => Some(" }"),
 598                         "[u8; 4]" if !is_ref => Some(" }"),
 599                         "[u8; 3]" if is_ref => Some(""),
 600
 601                         "[u8]" if is_ref => Some(""),
 602                         "[usize]" if is_ref => Some(""),
 603
 604                         "str" if is_ref => Some(".into()"),
 605                         "String" if !is_ref => Some(".into_bytes().into()"),
 606                         "String" if is_ref => Some(".as_str().into()"),
 607
 608                         "std::time::Duration" => Some(".as_secs()"),
 609
 610                         "bitcoin::secp256k1::key::PublicKey" => Some(")"),
 611                         "bitcoin::secp256k1::Signature" => Some(")"),
 612                         "bitcoin::secp256k1::key::SecretKey" if !is_ref => Some(")"),
 613                         "bitcoin::secp256k1::key::SecretKey" if is_ref => Some(".as_ref()"),
 614                         "bitcoin::secp256k1::Error" if !is_ref => Some(")"),
 615                         "bitcoin::blockdata::script::Script" if is_ref => Some("[..])"),
 616                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_bytes().into()"),
 617                         "bitcoin::blockdata::transaction::Transaction" => Some(")"),
 618                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(")"),
 619                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(""),
 620                         "bitcoin::blockdata::block::Block" if is_ref => Some(")"),
 621
 622                         "bitcoin::hash_types::Txid" if !is_ref => Some(".into_inner() }"),
 623
 624                         // Newtypes that we just expose in their original form.
 625                         "bitcoin::hash_types::Txid" if is_ref => Some(".as_inner()"),
 626                         "bitcoin::hash_types::BlockHash" if is_ref => Some(".as_inner()"),
 627                         "bitcoin::hash_types::BlockHash" => Some(".into_inner() }"),
 628                         "ln::channelmanager::PaymentHash" if is_ref => Some(".0"),
 629                         "ln::channelmanager::PaymentHash" => Some(".0 }"),
 630                         "ln::channelmanager::PaymentPreimage" if is_ref => Some(".0"),
 631                         "ln::channelmanager::PaymentPreimage" => Some(".0 }"),
 632                         "ln::channelmanager::PaymentSecret" if !is_ref => Some(".0 }"),
 633
 634                         // Override the default since Records contain an fmt with a lifetime:
 635                         "util::logger::Record" => Some(".as_ptr()"),
 636
 637                         // List of structs we map (possibly during processing of other files):
 638                         "ln::features::InitFeatures" if is_ref && ptr_for_ref => Some(", is_owned: false }"),
 639                         "ln::features::InitFeatures" if is_ref => Some(", is_owned: false }))"),
 640                         "ln::features::InitFeatures" => Some(")), is_owned: true }"),
 641
 642                         _ => {
 643                                 eprintln!("    Type {} unconvertable to C", full_path);
 644                                 None
 645                         },
 646                 }.map(|s| s.to_owned())
 647         }
 648
 649         fn empty_val_check_suffix_from_path(&self, full_path: &str) -> Option<&str> {
 650                 match full_path {
 651                         "ln::channelmanager::PaymentSecret" => Some(".data == [0; 32]"),
 652                         "bitcoin::secp256k1::key::PublicKey" => Some(".is_null()"),
 653                         "bitcoin::secp256k1::Signature" => Some(".is_null()"),
 654                         _ => None
 655                 }
 656         }
 657
 658         // ****************************
 659         // *** Container Processing ***
 660         // ****************************
 661
 662         /// Returns the module path in the generated mapping crate to the containers which we generate
 663         /// when writing to CrateTypes::template_file.
 664         fn generated_container_path() -> &'static str {
 665                 "crate::c_types::derived"
 666         }
 667         /// Returns the module path in the generated mapping crate to the container templates, which
 668         /// are then concretized and put in the generated container path/template_file.
 669         fn container_templ_path() -> &'static str {
 670                 "crate::c_types"
 671         }
 672
 673         /// Returns true if this is a "transparent" container, ie an Option or a container which does
 674         /// not require a generated continer class.
 675         fn is_transparent_container(&self, full_path: &str, _is_ref: bool) -> bool {
 676                 full_path == "Option"
 677         }
 678         /// Returns true if this is a known, supported, non-transparent container.
 679         fn is_known_container(&self, full_path: &str, is_ref: bool) -> bool {
 680                 (full_path == "Result" && !is_ref) || (full_path == "Vec" && !is_ref) || full_path.ends_with("Tuple")
 681         }
 682         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)
 683                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
 684                         // expecting one element in the vec per generic type, each of which is inline-converted
 685                         -> Option<(&'b str, Vec<(String, String)>, &'b str)> {
 686                 match full_path {
 687                         "Result" if !is_ref => {
 688                                 Some(("match ",
 689                                                 vec![(" { Ok(mut o) => crate::c_types::CResultTempl::ok(".to_string(), "o".to_string()),
 690                                                         ("), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
 691                                                 ") }"))
 692                         },
 693                         "Vec" if !is_ref => {
 694                                 Some(("Vec::new(); for item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 695                         },
 696                         "Slice" => {
 697                                 Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "**item".to_string())], "); }"))
 698                         },
 699                         "Option" => {
 700                                 if let Some(syn::Type::Path(p)) = single_contained {
 701                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
 702                                                 if is_ref {
 703                                                         return Some(("if ", vec![
 704                                                                 (".is_none() { std::ptr::null() } else { ".to_owned(), format!("({}.as_ref().unwrap())", var_access))
 705                                                                 ], " }"));
 706                                                 } else {
 707                                                         return Some(("if ", vec![
 708                                                                 (".is_none() { std::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
 709                                                                 ], " }"));
 710                                                 }
 711                                         }
 712                                 }
 713                                 if let Some(t) = single_contained {
 714                                         let mut v = Vec::new();
 715                                         self.write_empty_rust_val(generics, &mut v, t);
 716                                         let s = String::from_utf8(v).unwrap();
 717                                         return Some(("if ", vec![
 718                                                 (format!(".is_none() {{ {} }} else {{ ", s), format!("({}.unwrap())", var_access))
 719                                                 ], " }"));
 720                                 } else { unreachable!(); }
 721                         },
 722                         _ => None,
 723                 }
 724         }
 725
 726         /// only_contained_has_inner implies that there is only one contained element in the container
 727         /// and it has an inner field (ie is an "opaque" type we've defined).
 728         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)
 729                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
 730                         // expecting one element in the vec per generic type, each of which is inline-converted
 731                         -> Option<(&'b str, Vec<(String, String)>, &'b str)> {
 732                 match full_path {
 733                         "Result" if !is_ref => {
 734                                 Some(("match ",
 735                                                 vec![(".result_ok { true => Ok(".to_string(), format!("(*unsafe {{ Box::from_raw({}.contents.result.take_ptr()) }})", var_name)),
 736                                                      ("), false => Err(".to_string(), format!("(*unsafe {{ Box::from_raw({}.contents.err.take_ptr()) }})", var_name))],
 737                                                 ")}"))
 738                         },
 739                         "Vec"|"Slice" if !is_ref => {
 740                                 Some(("Vec::new(); for mut item in ", vec![(format!(".into_rust().drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 741                         },
 742                         "Slice" if is_ref => {
 743                                 Some(("Vec::new(); for mut item in ", vec![(format!(".as_slice().iter() {{ local_{}.push(", var_name), "item".to_string())], "); }"))
 744                         },
 745                         "Option" => {
 746                                 if let Some(syn::Type::Path(p)) = single_contained {
 747                                         if self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)) {
 748                                                 if is_ref {
 749                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some((*".to_string(), format!("{}", var_name))], ").clone()) }"))
 750                                                 } else {
 751                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some(".to_string(), format!("{}", var_name))], ") }"));
 752                                                 }
 753                                         }
 754                                 }
 755
 756                                 if let Some(t) = single_contained {
 757                                         let mut v = Vec::new();
 758                                         let (needs_deref, ret_ref) = self.write_empty_rust_val_check_suffix(generics, &mut v, t);
 759                                         let s = String::from_utf8(v).unwrap();
 760                                         if needs_deref && ret_ref {
 761                                                 return Some(("if ", vec![
 762                                                         (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ &mut *{} }}", var_access))
 763                                                 ], ") }"));
 764                                         } else if needs_deref {
 765                                                 return Some(("if ", vec![
 766                                                         (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ *Box::from_raw({}) }}", var_access))
 767                                                 ], ") }"));
 768                                         } else {
 769                                                 return Some(("if ", vec![
 770                                                         (format!("{} {{ None }} else {{ Some(", s), format!("{}", var_access))
 771                                                 ], ") }"));
 772                                         }
 773                                 } else { unreachable!(); }
 774                         },
 775                         _ => None,
 776                 }
 777         }
 778
 779         // *************************************************
 780         // *** Type definition during main.rs processing ***
 781         // *************************************************
 782
 783         fn process_use_intern<W: std::io::Write>(&mut self, w: &mut W, u: &syn::UseTree, partial_path: &str) {
 784                 match u {
 785                         syn::UseTree::Path(p) => {
 786                                 let new_path = format!("{}::{}", partial_path, p.ident);
 787                                 self.process_use_intern(w, &p.tree, &new_path);
 788                         },
 789                         syn::UseTree::Name(n) => {
 790                                 let full_path = format!("{}::{}", partial_path, n.ident);
 791                                 self.imports.insert(n.ident.clone(), full_path);
 792                         },
 793                         syn::UseTree::Group(g) => {
 794                                 for i in g.items.iter() {
 795                                         self.process_use_intern(w, i, partial_path);
 796                                 }
 797                         },
 798                         syn::UseTree::Rename(r) => {
 799                                 let full_path = format!("{}::{}", partial_path, r.ident);
 800                                 self.imports.insert(r.rename.clone(), full_path);
 801                         },
 802                         syn::UseTree::Glob(_) => {
 803                                 eprintln!("Ignoring * use for {} - this may result in resolution failures", partial_path);
 804                         },
 805                 }
 806         }
 807         pub fn process_use<W: std::io::Write>(&mut self, w: &mut W, u: &syn::ItemUse) {
 808                 if let syn::Visibility::Public(_) = u.vis {
 809                         // We actually only use these for #[cfg(fuzztarget)]
 810                         eprintln!("Ignoring pub(use) tree!");
 811                         return;
 812                 }
 813                 match &u.tree {
 814                         syn::UseTree::Path(p) => {
 815                                 let new_path = format!("{}", p.ident);
 816                                 self.process_use_intern(w, &p.tree, &new_path);
 817                         },
 818                         syn::UseTree::Name(n) => {
 819                                 let full_path = format!("{}", n.ident);
 820                                 self.imports.insert(n.ident.clone(), full_path);
 821                         },
 822                         _ => unimplemented!(),
 823                 }
 824                 if u.leading_colon.is_some() { unimplemented!() }
 825         }
 826
 827         pub fn mirrored_enum_declared(&mut self, ident: &syn::Ident) {
 828                 eprintln!("{} mirrored", ident);
 829                 self.declared.insert(ident.clone(), DeclType::MirroredEnum);
 830         }
 831         pub fn enum_ignored(&mut self, ident: &'c syn::Ident) {
 832                 self.declared.insert(ident.clone(), DeclType::EnumIgnored);
 833         }
 834         pub fn struct_imported(&mut self, ident: &'c syn::Ident, named: String) {
 835                 eprintln!("Imported {} as {}", ident, named);
 836                 self.declared.insert(ident.clone(), DeclType::StructImported);
 837         }
 838         pub fn struct_ignored(&mut self, ident: &syn::Ident) {
 839                 eprintln!("Not importing {}", ident);
 840                 self.declared.insert(ident.clone(), DeclType::StructIgnored);
 841         }
 842         pub fn trait_declared(&mut self, ident: &syn::Ident, t: &'c syn::ItemTrait) {
 843                 eprintln!("Trait {} created", ident);
 844                 self.declared.insert(ident.clone(), DeclType::Trait(t));
 845         }
 846         pub fn get_declared_type(&'a self, ident: &syn::Ident) -> Option<&'a DeclType<'c>> {
 847                 self.declared.get(ident)
 848         }
 849         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
 850         fn c_type_has_inner_from_path(&self, full_path: &str) -> bool{
 851                 self.crate_types.opaques.get(full_path).is_some()
 852         }
 853
 854         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
 855                 if let Some(imp) = self.imports.get(id) {
 856                         Some(imp.clone())
 857                 } else if self.declared.get(id).is_some() {
 858                         Some(self.module_path.to_string() + "::" + &format!("{}", id))
 859                 } else { None }
 860         }
 861
 862         pub fn maybe_resolve_non_ignored_ident(&self, id: &syn::Ident) -> Option<String> {
 863                 if let Some(imp) = self.imports.get(id) {
 864                         Some(imp.clone())
 865                 } else if let Some(decl_type) = self.declared.get(id) {
 866                         match decl_type {
 867                                 DeclType::StructIgnored => None,
 868                                 _ => Some(self.module_path.to_string() + "::" + &format!("{}", id)),
 869                         }
 870                 } else { None }
 871         }
 872
 873         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
 874                 let p = if let Some(gen_types) = generics {
 875                         if let Some((_, synpath)) = gen_types.maybe_resolve_path(p_arg) {
 876                                 synpath
 877                         } else { p_arg }
 878                 } else { p_arg };
 879
 880                 if p.leading_colon.is_some() {
 881                         // At some point we may need this, but for now, its unused, so just fail.
 882                         return None;
 883                 } else if let Some(id) = p.get_ident() {
 884                         self.maybe_resolve_ident(id)
 885                 } else {
 886                         if p.segments.len() == 1 {
 887                                 let seg = p.segments.iter().next().unwrap();
 888                                 return self.maybe_resolve_ident(&seg.ident);
 889                         }
 890                         let mut seg_iter = p.segments.iter();
 891                         let first_seg = seg_iter.next().unwrap();
 892                         let remaining: String = seg_iter.map(|seg| {
 893                                 if let syn::PathArguments::None = seg.arguments {
 894                                         format!("{}", seg.ident)
 895                                 } else {
 896                                         format!("{}", seg.ident)
 897                                 }
 898                         }).collect();
 899                         if let Some(imp) = self.imports.get(&first_seg.ident) {
 900                                 if remaining != "" {
 901                                         Some(imp.clone() + "::" + &remaining)
 902                                 } else {
 903                                         Some(imp.clone())
 904                                 }
 905                         } else { None }
 906                 }
 907         }
 908         pub fn resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> String {
 909                 self.maybe_resolve_path(p, generics).unwrap()
 910         }
 911
 912         // ***********************************
 913         // *** Original Rust Type Printing ***
 914         // ***********************************
 915
 916         fn write_rust_path<W: std::io::Write>(&self, w: &mut W, path: &syn::Path) {
 917                 if let Some(resolved) = self.maybe_resolve_path(&path, None) {
 918                         if self.is_primitive(&resolved) {
 919                                 write!(w, "{}", path.get_ident().unwrap()).unwrap();
 920                         } else {
 921                                 if resolved.starts_with("ln::") || resolved.starts_with("chain::") || resolved.starts_with("util::") {
 922                                         write!(w, "lightning::{}", resolved).unwrap();
 923                                 } else {
 924                                         write!(w, "{}", resolved).unwrap(); // XXX: Probably doens't work, get_ident().unwrap()
 925                                 }
 926                         }
 927                         if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().last().unwrap().arguments {
 928                                 self.write_rust_generic_arg(w, args.args.iter());
 929                         }
 930                 } else {
 931                         if path.leading_colon.is_some() {
 932                                 write!(w, "::").unwrap();
 933                         }
 934                         for (idx, seg) in path.segments.iter().enumerate() {
 935                                 if idx != 0 { write!(w, "::").unwrap(); }
 936                                 write!(w, "{}", seg.ident).unwrap();
 937                                 if let syn::PathArguments::AngleBracketed(args) = &seg.arguments {
 938                                         self.write_rust_generic_arg(w, args.args.iter());
 939                                 }
 940                         }
 941                 }
 942         }
 943         pub fn write_rust_generic_param<'b, W: std::io::Write>(&self, w: &mut W, generics: impl Iterator<Item=&'b syn::GenericParam>) {
 944                 let mut had_params = false;
 945                 for (idx, arg) in generics.enumerate() {
 946                         if idx != 0 { write!(w, ", ").unwrap(); } else { write!(w, "<").unwrap(); }
 947                         had_params = true;
 948                         match arg {
 949                                 syn::GenericParam::Lifetime(lt) => write!(w, "'{}", lt.lifetime.ident).unwrap(),
 950                                 syn::GenericParam::Type(t) => {
 951                                         write!(w, "{}", t.ident).unwrap();
 952                                         if t.colon_token.is_some() { write!(w, ":").unwrap(); }
 953                                         for (idx, bound) in t.bounds.iter().enumerate() {
 954                                                 if idx != 0 { write!(w, " + ").unwrap(); }
 955                                                 match bound {
 956                                                         syn::TypeParamBound::Trait(tb) => {
 957                                                                 if tb.paren_token.is_some() || tb.lifetimes.is_some() { unimplemented!(); }
 958                                                                 self.write_rust_path(w, &tb.path);
 959                                                         },
 960                                                         _ => unimplemented!(),
 961                                                 }
 962                                         }
 963                                         if t.eq_token.is_some() || t.default.is_some() { unimplemented!(); }
 964                                 },
 965                                 _ => unimplemented!(),
 966                         }
 967                 }
 968                 if had_params { write!(w, ">").unwrap(); }
 969         }
 970
 971         pub fn write_rust_generic_arg<'b, W: std::io::Write>(&self, w: &mut W, generics: impl Iterator<Item=&'b syn::GenericArgument>) {
 972                 write!(w, "<").unwrap();
 973                 for (idx, arg) in generics.enumerate() {
 974                         if idx != 0 { write!(w, ", ").unwrap(); }
 975                         match arg {
 976                                 syn::GenericArgument::Type(t) => self.write_rust_type(w, t),
 977                                 _ => unimplemented!(),
 978                         }
 979                 }
 980                 write!(w, ">").unwrap();
 981         }
 982         pub fn write_rust_type<W: std::io::Write>(&self, w: &mut W, t: &syn::Type) {
 983                 match t {
 984                         syn::Type::Path(p) => {
 985                                 if p.qself.is_some() || p.path.leading_colon.is_some() {
 986                                         unimplemented!();
 987                                 }
 988                                 self.write_rust_path(w, &p.path);
 989                         },
 990                         syn::Type::Reference(r) => {
 991                                 write!(w, "&").unwrap();
 992                                 if let Some(lft) = &r.lifetime {
 993                                         write!(w, "'{} ", lft.ident).unwrap();
 994                                 }
 995                                 if r.mutability.is_some() {
 996                                         write!(w, "mut ").unwrap();
 997                                 }
 998                                 self.write_rust_type(w, &*r.elem);
 999                         },
1000                         syn::Type::Array(a) => {
1001                                 write!(w, "[").unwrap();
1002                                 self.write_rust_type(w, &a.elem);
1003                                 if let syn::Expr::Lit(l) = &a.len {
1004                                         if let syn::Lit::Int(i) = &l.lit {
1005                                                 write!(w, "; {}]", i).unwrap();
1006                                         } else { unimplemented!(); }
1007                                 } else { unimplemented!(); }
1008                         }
1009                         syn::Type::Slice(s) => {
1010                                 write!(w, "[").unwrap();
1011                                 self.write_rust_type(w, &s.elem);
1012                                 write!(w, "]").unwrap();
1013                         },
1014                         syn::Type::Tuple(s) => {
1015                                 write!(w, "(").unwrap();
1016                                 for (idx, t) in s.elems.iter().enumerate() {
1017                                         if idx != 0 { write!(w, ", ").unwrap(); }
1018                                         self.write_rust_type(w, &t);
1019                                 }
1020                                 write!(w, ")").unwrap();
1021                         },
1022                         _ => unimplemented!(),
1023                 }
1024         }
1025
1026         /// Prints a constructor for something which is "uninitialized" (but obviously not actually
1027         /// unint'd memory).
1028         pub fn write_empty_rust_val<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) {
1029                 match t {
1030                         syn::Type::Path(p) => {
1031                                 let resolved = self.resolve_path(&p.path, generics);
1032                                 if self.crate_types.opaques.get(&resolved).is_some() {
1033                                         write!(w, "crate::{} {{ inner: std::ptr::null_mut(), is_owned: true }}", resolved).unwrap();
1034                                 } else {
1035                                         // Assume its a manually-mapped C type, where we can just define an null() fn
1036                                         write!(w, "{}::null()", self.c_type_from_path(&resolved, false, false).unwrap()).unwrap();
1037                                 }
1038                         },
1039                         syn::Type::Array(a) => {
1040                                 if let syn::Expr::Lit(l) = &a.len {
1041                                         if let syn::Lit::Int(i) = &l.lit {
1042                                                 if i.base10_digits().parse::<usize>().unwrap() < 32 {
1043                                                         // Blindly assume that if we're trying to create an empty value for an
1044                                                         // array < 32 entries that all-0s may be a valid state.
1045                                                         unimplemented!();
1046                                                 }
1047                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1048                                                 write!(w, "{}", self.to_c_conversion_inline_prefix_from_path(&arrty, false, false).unwrap()).unwrap();
1049                                                 write!(w, "[0; {}]", i.base10_digits()).unwrap();
1050                                                 write!(w, "{}", self.to_c_conversion_inline_suffix_from_path(&arrty, false, false).unwrap()).unwrap();
1051                                         } else { unimplemented!(); }
1052                                 } else { unimplemented!(); }
1053                         }
1054                         _ => unimplemented!(),
1055                 }
1056         }
1057
1058         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val),
1059         /// returning whether we need to dereference the inner value before using it (ie it is a
1060         /// pointer).
1061         pub fn write_empty_rust_val_check_suffix<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) -> (bool, bool) {
1062                 match t {
1063                         syn::Type::Path(p) => {
1064                                 let resolved = self.resolve_path(&p.path, generics);
1065                                 if self.crate_types.opaques.get(&resolved).is_some() {
1066                                         write!(w, ".inner.is_null()").unwrap();
1067                                         (false, false)
1068                                 } else {
1069                                         if let Some(suffix) = self.empty_val_check_suffix_from_path(&resolved) {
1070                                                 write!(w, "{}", suffix).unwrap();
1071                                                 (false, false) // We may eventually need to allow empty_val_check_suffix_from_path to specify if we need a deref or not
1072                                         } else {
1073                                                 write!(w, " == std::ptr::null_mut()").unwrap();
1074                                                 (true, false)
1075                                         }
1076                                 }
1077                         },
1078                         syn::Type::Array(a) => {
1079                                 if let syn::Expr::Lit(l) = &a.len {
1080                                         if let syn::Lit::Int(i) = &l.lit {
1081                                                 write!(w, " == [0; {}]", i.base10_digits()).unwrap();
1082                                                 (false, false)
1083                                         } else { unimplemented!(); }
1084                                 } else { unimplemented!(); }
1085                         },
1086                         syn::Type::Slice(_) => {
1087                                 // Option<[]> always implies that we want to treat len() == 0 differently from
1088                                 // None, so we always map an Option<[]> into a pointer.
1089                                 write!(w, " == std::ptr::null_mut()").unwrap();
1090                                 (true, true)
1091                         },
1092                         _ => unimplemented!(),
1093                 }
1094         }
1095
1096         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1097         pub fn write_empty_rust_val_check<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type, var_access: &str) {
1098                 match t {
1099                         syn::Type::Path(_) => {
1100                                 write!(w, "{}", var_access).unwrap();
1101                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1102                         },
1103                         syn::Type::Array(a) => {
1104                                 if let syn::Expr::Lit(l) = &a.len {
1105                                         if let syn::Lit::Int(i) = &l.lit {
1106                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1107                                                 // We don't (yet) support a new-var conversion here.
1108                                                 assert!(self.from_c_conversion_new_var_from_path(&arrty, false).is_none());
1109                                                 write!(w, "{}{}{}",
1110                                                         self.from_c_conversion_prefix_from_path(&arrty, false).unwrap(),
1111                                                         var_access,
1112                                                         self.from_c_conversion_suffix_from_path(&arrty, false).unwrap()).unwrap();
1113                                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1114                                         } else { unimplemented!(); }
1115                                 } else { unimplemented!(); }
1116                         }
1117                         _ => unimplemented!(),
1118                 }
1119         }
1120
1121         // ********************************
1122         // *** Type conversion printing ***
1123         // ********************************
1124
1125         /// Returns true we if can just skip passing this to C entirely
1126         pub fn skip_arg(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
1127                 match t {
1128                         syn::Type::Path(p) => {
1129                                 if p.qself.is_some() { unimplemented!(); }
1130                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1131                                         self.skip_path(&full_path)
1132                                 } else { false }
1133                         },
1134                         syn::Type::Reference(r) => {
1135                                 self.skip_arg(&*r.elem, generics)
1136                         },
1137                         _ => false,
1138                 }
1139         }
1140         pub fn no_arg_to_rust<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1141                 match t {
1142                         syn::Type::Path(p) => {
1143                                 if p.qself.is_some() { unimplemented!(); }
1144                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1145                                         write!(w, "{}", self.no_arg_path_to_rust(&full_path)).unwrap();
1146                                 }
1147                         },
1148                         syn::Type::Reference(r) => {
1149                                 self.no_arg_to_rust(w, &*r.elem, generics);
1150                         },
1151                         _ => {},
1152                 }
1153         }
1154
1155         fn write_conversion_inline_intern<W: std::io::Write,
1156                         LP: Fn(&str, bool, bool) -> Option<String>, DL: Fn(&mut W, &DeclType, &str, bool, bool), SC: Fn(bool) -> &'static str>
1157                         (&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool,
1158                          tupleconv: &str, prefix: bool, sliceconv: SC, path_lookup: LP, decl_lookup: DL) {
1159                 match t {
1160                         syn::Type::Reference(r) => {
1161                                 self.write_conversion_inline_intern(w, &*r.elem, generics, true, r.mutability.is_some(),
1162                                         ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1163                         },
1164                         syn::Type::Path(p) => {
1165                                 if p.qself.is_some() || p.path.leading_colon.is_some() {
1166                                         unimplemented!();
1167                                 }
1168
1169                                 let resolved_path = self.resolve_path(&p.path, generics);
1170                                 if let Some(c_type) = path_lookup(&resolved_path, is_ref, ptr_for_ref) {
1171                                         write!(w, "{}", c_type).unwrap();
1172                                 } else if self.crate_types.opaques.get(&resolved_path).is_some() {
1173                                         decl_lookup(w, &DeclType::StructImported, &resolved_path, is_ref, is_mut);
1174                                 } else if self.crate_types.mirrored_enums.get(&resolved_path).is_some() {
1175                                         decl_lookup(w, &DeclType::MirroredEnum, &resolved_path, is_ref, is_mut);
1176                                 } else if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
1177                                         if let Some(t) = self.crate_types.traits.get(&resolved_path) {
1178                                                 decl_lookup(w, &DeclType::Trait(t), &resolved_path, is_ref, is_mut);
1179                                                 return;
1180                                         } else if let Some(_) = self.imports.get(ident) {
1181                                                 // crate_types lookup has to have succeeded:
1182                                                 panic!("Failed to print inline conversion for {}", ident);
1183                                         } else if let Some(decl_type) = self.declared.get(ident) {
1184                                                 decl_lookup(w, decl_type, &self.maybe_resolve_ident(ident).unwrap(), is_ref, is_mut);
1185                                         } else { unimplemented!(); }
1186                                 }
1187                         },
1188                         syn::Type::Array(a) => {
1189                                 // We assume all arrays contain only [int_literal; X]s.
1190                                 // This may result in some outputs not compiling.
1191                                 if let syn::Expr::Lit(l) = &a.len {
1192                                         if let syn::Lit::Int(i) = &l.lit {
1193                                                 write!(w, "{}", path_lookup(&format!("[u8; {}]", i.base10_digits()), is_ref, ptr_for_ref).unwrap()).unwrap();
1194                                         } else { unimplemented!(); }
1195                                 } else { unimplemented!(); }
1196                         },
1197                         syn::Type::Slice(s) => {
1198                                 // We assume all slices contain only literals or references.
1199                                 // This may result in some outputs not compiling.
1200                                 if let syn::Type::Path(p) = &*s.elem {
1201                                         let resolved = self.resolve_path(&p.path, generics);
1202                                         assert!(self.is_primitive(&resolved));
1203                                         write!(w, "{}", path_lookup("[u8]", is_ref, ptr_for_ref).unwrap()).unwrap();
1204                                 } else if let syn::Type::Reference(r) = &*s.elem {
1205                                         if let syn::Type::Path(p) = &*r.elem {
1206                                                 write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)))).unwrap();
1207                                         } else { unimplemented!(); }
1208                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1209                                         assert!(!t.elems.is_empty());
1210                                         if prefix {
1211                                                 write!(w, "&local_").unwrap();
1212                                         } else {
1213                                                 let mut needs_map = false;
1214                                                 for e in t.elems.iter() {
1215                                                         if let syn::Type::Reference(_) = e {
1216                                                                 needs_map = true;
1217                                                         }
1218                                                 }
1219                                                 if needs_map {
1220                                                         write!(w, ".iter().map(|(").unwrap();
1221                                                         for i in 0..t.elems.len() {
1222                                                                 write!(w, "{}{}", if i != 0 { ", " } else { "" }, ('a' as u8 + i as u8) as char).unwrap();
1223                                                         }
1224                                                         write!(w, ")| (").unwrap();
1225                                                         for (idx, e) in t.elems.iter().enumerate() {
1226                                                                 if let syn::Type::Reference(_) = e {
1227                                                                         write!(w, "{}{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1228                                                                 } else if let syn::Type::Path(_) = e {
1229                                                                         write!(w, "{}*{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1230                                                                 } else { unimplemented!(); }
1231                                                         }
1232                                                         write!(w, ")).collect::<Vec<_>>()[..]").unwrap();
1233                                                 }
1234                                         }
1235                                 } else { unimplemented!(); }
1236                         },
1237                         syn::Type::Tuple(t) => {
1238                                 if t.elems.is_empty() {
1239                                         // cbindgen has poor support for (), see, eg https://github.com/eqrion/cbindgen/issues/527
1240                                         // so work around it by just pretending its a 0u8
1241                                         write!(w, "{}", tupleconv).unwrap();
1242                                 } else {
1243                                         if prefix { write!(w, "local_").unwrap(); }
1244                                 }
1245                         },
1246                         _ => unimplemented!(),
1247                 }
1248         }
1249
1250         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) {
1251                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "0u8 /*", true, |_| "local_",
1252                                 |a, b, c| self.to_c_conversion_inline_prefix_from_path(a, b, c),
1253                                 |w, decl_type, decl_path, is_ref, _is_mut| {
1254                                         match decl_type {
1255                                                 DeclType::MirroredEnum if is_ref && ptr_for_ref => write!(w, "crate::{}::from_native(&", decl_path).unwrap(),
1256                                                 DeclType::MirroredEnum if is_ref => write!(w, "&crate::{}::from_native(&", decl_path).unwrap(),
1257                                                 DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
1258                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1259                                                         write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1260                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1261                                                         write!(w, "crate::{} {{ inner: unsafe {{ ( (&(", decl_path).unwrap(),
1262                                                 DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1263                                                         write!(w, "&crate::{} {{ inner: unsafe {{ (", decl_path).unwrap(),
1264                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1265                                                         write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
1266                                                 DeclType::EnumIgnored|DeclType::StructImported if !is_ref =>
1267                                                         write!(w, "crate::{} {{ inner: Box::into_raw(Box::new(", decl_path).unwrap(),
1268                                                 DeclType::Trait(_) if is_ref => write!(w, "&").unwrap(),
1269                                                 _ => panic!("{:?}", decl_path),
1270                                         }
1271                                 });
1272         }
1273         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) {
1274                 self.write_to_c_conversion_inline_prefix_inner(w, t, generics, false, ptr_for_ref, false);
1275         }
1276         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) {
1277                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "*/", false, |_| ".into()",
1278                                 |a, b, c| self.to_c_conversion_inline_suffix_from_path(a, b, c),
1279                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1280                                         DeclType::MirroredEnum => write!(w, ")").unwrap(),
1281                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref && from_ptr =>
1282                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1283                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref && ptr_for_ref =>
1284                                                 write!(w, ") as *const _) as *mut _) }}, is_owned: false }}").unwrap(),
1285                                         DeclType::EnumIgnored|DeclType::StructImported if is_ref =>
1286                                                 write!(w, " as *const _) as *mut _ }}, is_owned: false }}").unwrap(),
1287                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref && from_ptr =>
1288                                                 write!(w, ", is_owned: true }}").unwrap(),
1289                                         DeclType::EnumIgnored|DeclType::StructImported if !is_ref => write!(w, ")), is_owned: true }}").unwrap(),
1290                                         DeclType::Trait(_) if is_ref => {},
1291                                         _ => unimplemented!(),
1292                                 });
1293         }
1294         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) {
1295                 self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
1296         }
1297
1298         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) {
1299                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_| "&local_",
1300                                 |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
1301                                 |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
1302                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, "unsafe {{ &*(*").unwrap(),
1303                                         DeclType::StructImported if is_mut && is_ref => write!(w, "unsafe {{ &mut *").unwrap(),
1304                                         DeclType::StructImported if is_ref => write!(w, "unsafe {{ &*").unwrap(),
1305                                         DeclType::StructImported if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
1306                                         DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
1307                                         DeclType::MirroredEnum => {},
1308                                         DeclType::Trait(_) => {},
1309                                         _ => unimplemented!(),
1310                                 });
1311         }
1312         pub fn write_from_c_conversion_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1313                 self.write_from_c_conversion_prefix_inner(w, t, generics, false, false);
1314         }
1315         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) {
1316                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "*/", false,
1317                                 |has_inner| match has_inner {
1318                                         false => ".iter().collect::<Vec<_>>()[..]",
1319                                         true => "[..]",
1320                                 },
1321                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1322                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1323                                         DeclType::StructImported if is_ref && ptr_for_ref => write!(w, ").inner }}").unwrap(),
1324                                         DeclType::StructImported if is_ref => write!(w, ".inner }}").unwrap(),
1325                                         DeclType::StructImported if !is_ref => write!(w, ".take_ptr()) }}").unwrap(),
1326                                         DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
1327                                         DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
1328                                         DeclType::Trait(_) => {},
1329                                         _ => unimplemented!(),
1330                                 });
1331         }
1332         pub fn write_from_c_conversion_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1333                 self.write_from_c_conversion_suffix_inner(w, t, generics, false, false);
1334         }
1335         // Note that compared to the above conversion functions, the following two are generally
1336         // significantly undertested:
1337         pub fn write_from_c_conversion_to_ref_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1338                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "() /*", true, |_| "&local_",
1339                                 |a, b, _c| {
1340                                         if let Some(conv) = self.from_c_conversion_prefix_from_path(a, b) {
1341                                                 Some(format!("&{}", conv))
1342                                         } else { None }
1343                                 },
1344                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1345                                         DeclType::StructImported if !is_ref => write!(w, "unsafe {{ &*").unwrap(),
1346                                         _ => unimplemented!(),
1347                                 });
1348         }
1349         pub fn write_from_c_conversion_to_ref_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1350                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "*/", false,
1351                                 |has_inner| match has_inner {
1352                                         false => ".iter().collect::<Vec<_>>()[..]",
1353                                         true => "[..]",
1354                                 },
1355                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
1356                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
1357                                         DeclType::StructImported if !is_ref => write!(w, ".inner }}").unwrap(),
1358                                         _ => unimplemented!(),
1359                                 });
1360         }
1361
1362         fn write_conversion_new_var_intern<'b, W: std::io::Write,
1363                 LP: Fn(&str, bool) -> Option<(&str, &str)>,
1364                 LC: Fn(&str, bool, Option<&syn::Type>, &syn::Ident, &str) ->  Option<(&'b str, Vec<(String, String)>, &'b str)>,
1365                 VP: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool),
1366                 VS: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool)>
1367                         (&self, w: &mut W, ident: &syn::Ident, var: &str, t: &syn::Type, generics: Option<&GenericTypes>,
1368                          mut is_ref: bool, mut ptr_for_ref: bool, to_c: bool,
1369                          path_lookup: &LP, container_lookup: &LC, var_prefix: &VP, var_suffix: &VS) -> bool {
1370
1371                 macro_rules! convert_container {
1372                         ($container_type: expr, $args_len: expr, $args_iter: expr) => { {
1373                                 // For slices (and Options), we refuse to directly map them as is_ref when they
1374                                 // aren't opaque types containing an inner pointer. This is due to the fact that,
1375                                 // in both cases, the actual higher-level type is non-is_ref.
1376                                 let ty_has_inner = if self.is_transparent_container(&$container_type, is_ref) || $container_type == "Slice" {
1377                                         let ty = $args_iter().next().unwrap();
1378                                         if $container_type == "Slice" && to_c {
1379                                                 // "To C ptr_for_ref" means "return the regular object with is_owned
1380                                                 // set to false", which is totally what we want in a slice if we're about to
1381                                                 // set ty_has_inner.
1382                                                 ptr_for_ref = true;
1383                                         }
1384                                         if let syn::Type::Reference(t) = ty {
1385                                                 if let syn::Type::Path(p) = &*t.elem {
1386                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1387                                                 } else { false }
1388                                         } else if let syn::Type::Path(p) = ty {
1389                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1390                                         } else { false }
1391                                 } else { true };
1392
1393                                 // Options get a bunch of special handling, since in general we map Option<>al
1394                                 // types into the same C type as non-Option-wrapped types. This ends up being
1395                                 // pretty manual here and most of the below special-cases are for Options.
1396                                 let mut needs_ref_map = false;
1397                                 let mut only_contained_type = None;
1398                                 let mut only_contained_has_inner = false;
1399                                 let mut contains_slice = false;
1400                                 if $args_len == 1 && self.is_transparent_container(&$container_type, is_ref) {
1401                                         only_contained_has_inner = ty_has_inner;
1402                                         let arg = $args_iter().next().unwrap();
1403                                         if let syn::Type::Reference(t) = arg {
1404                                                 only_contained_type = Some(&*t.elem);
1405                                                 if let syn::Type::Path(_) = &*t.elem {
1406                                                         is_ref = true;
1407                                                 } else if let syn::Type::Slice(_) = &*t.elem {
1408                                                         contains_slice = true;
1409                                                 } else { return false; }
1410                                                 needs_ref_map = true;
1411                                         } else if let syn::Type::Path(_) = arg {
1412                                                 only_contained_type = Some(&arg);
1413                                         } else { unimplemented!(); }
1414                                 }
1415
1416                                 if let Some((prefix, conversions, suffix)) = container_lookup(&$container_type, is_ref && ty_has_inner, only_contained_type, ident, var) {
1417                                         assert_eq!(conversions.len(), $args_len);
1418                                         write!(w, "let mut local_{}{} = ", ident, if !to_c && needs_ref_map {"_base"} else { "" }).unwrap();
1419                                         if only_contained_has_inner && to_c {
1420                                                 var_prefix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1421                                         }
1422                                         write!(w, "{}{}", prefix, var).unwrap();
1423
1424                                         for ((pfx, var_name), (idx, ty)) in conversions.iter().zip($args_iter().enumerate()) {
1425                                                 let mut var = std::io::Cursor::new(Vec::new());
1426                                                 write!(&mut var, "{}", var_name).unwrap();
1427                                                 let var_access = String::from_utf8(var.into_inner()).unwrap();
1428
1429                                                 let conv_ty = if needs_ref_map { only_contained_type.as_ref().unwrap() } else { ty };
1430
1431                                                 write!(w, "{} {{ ", pfx).unwrap();
1432                                                 let new_var_name = format!("{}_{}", ident, idx);
1433                                                 let new_var = self.write_conversion_new_var_intern(w, &syn::Ident::new(&new_var_name, Span::call_site()),
1434                                                                 &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);
1435                                                 if new_var { write!(w, " ").unwrap(); }
1436                                                 if (!only_contained_has_inner || !to_c) && !contains_slice {
1437                                                         var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1438                                                 }
1439
1440                                                 if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1441                                                         write!(w, "Box::into_raw(Box::new(").unwrap();
1442                                                 }
1443                                                 write!(w, "{}{}", if contains_slice { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
1444                                                 if (!only_contained_has_inner || !to_c) && !contains_slice {
1445                                                         var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1446                                                 }
1447                                                 if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
1448                                                         write!(w, "))").unwrap();
1449                                                 }
1450                                                 write!(w, " }}").unwrap();
1451                                         }
1452                                         write!(w, "{}", suffix).unwrap();
1453                                         if only_contained_has_inner && to_c {
1454                                                 var_suffix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
1455                                         }
1456                                         write!(w, ";").unwrap();
1457                                         if !to_c && needs_ref_map {
1458                                                 write!(w, " let mut local_{} = local_{}_base.as_ref()", ident, ident).unwrap();
1459                                                 if contains_slice {
1460                                                         write!(w, ".map(|a| &a[..])").unwrap();
1461                                                 }
1462                                                 write!(w, ";").unwrap();
1463                                         }
1464                                         return true;
1465                                 }
1466                         } }
1467                 }
1468
1469                 match t {
1470                         syn::Type::Reference(r) => {
1471                                 if let syn::Type::Slice(_) = &*r.elem {
1472                                         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)
1473                                 } else {
1474                                         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)
1475                                 }
1476                         },
1477                         syn::Type::Path(p) => {
1478                                 if p.qself.is_some() || p.path.leading_colon.is_some() {
1479                                         unimplemented!();
1480                                 }
1481                                 let resolved_path = self.resolve_path(&p.path, generics);
1482                                 if self.is_known_container(&resolved_path, is_ref) || self.is_transparent_container(&resolved_path, is_ref) {
1483                                         if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
1484                                                 convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
1485                                                         if let syn::GenericArgument::Type(ty) = arg {
1486                                                                 ty
1487                                                         } else { unimplemented!(); }
1488                                                 }));
1489                                         } else { unimplemented!(); }
1490                                 }
1491                                 if self.is_primitive(&resolved_path) {
1492                                         false
1493                                 } else if let Some(ty_ident) = single_ident_generic_path_to_ident(&p.path) {
1494                                         if let Some((prefix, suffix)) = path_lookup(&resolved_path, is_ref) {
1495                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1496                                                 true
1497                                         } else if self.declared.get(ty_ident).is_some() {
1498                                                 false
1499                                         } else { false }
1500                                 } else { false }
1501                         },
1502                         syn::Type::Array(_) => {
1503                                 // We assume all arrays contain only primitive types.
1504                                 // This may result in some outputs not compiling.
1505                                 false
1506                         },
1507                         syn::Type::Slice(s) => {
1508                                 if let syn::Type::Path(p) = &*s.elem {
1509                                         let resolved = self.resolve_path(&p.path, generics);
1510                                         assert!(self.is_primitive(&resolved));
1511                                         let slice_path = format!("[{}]", resolved);
1512                                         if let Some((prefix, suffix)) = path_lookup(&slice_path, true) {
1513                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
1514                                                 true
1515                                         } else { false }
1516                                 } else if let syn::Type::Reference(ty) = &*s.elem {
1517                                         let tyref = [&*ty.elem];
1518                                         is_ref = true;
1519                                         convert_container!("Slice", 1, || tyref.iter());
1520                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1521                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1522                                         // When mapping into a temporary new var, we need to own all the underlying objects.
1523                                         // Thus, we drop any references inside the tuple and convert with non-reference types.
1524                                         let mut elems = syn::punctuated::Punctuated::new();
1525                                         for elem in t.elems.iter() {
1526                                                 if let syn::Type::Reference(r) = elem {
1527                                                         elems.push((*r.elem).clone());
1528                                                 } else {
1529                                                         elems.push(elem.clone());
1530                                                 }
1531                                         }
1532                                         let ty = [syn::Type::Tuple(syn::TypeTuple {
1533                                                 paren_token: t.paren_token, elems
1534                                         })];
1535                                         is_ref = false;
1536                                         ptr_for_ref = true;
1537                                         convert_container!("Slice", 1, || ty.iter());
1538                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
1539                                 } else { unimplemented!() }
1540                         },
1541                         syn::Type::Tuple(t) => {
1542                                 if !t.elems.is_empty() {
1543                                         // We don't (yet) support tuple elements which cannot be converted inline
1544                                         write!(w, "let (").unwrap();
1545                                         for idx in 0..t.elems.len() {
1546                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1547                                                 write!(w, "{} orig_{}_{}", if is_ref { "ref" } else { "mut" }, ident, idx).unwrap();
1548                                         }
1549                                         write!(w, ") = {}{}; ", var, if !to_c { ".to_rust()" } else { "" }).unwrap();
1550                                         // Like other template types, tuples are always mapped as their non-ref
1551                                         // versions for types which have different ref mappings. Thus, we convert to
1552                                         // non-ref versions and handle opaque types with inner pointers manually.
1553                                         for (idx, elem) in t.elems.iter().enumerate() {
1554                                                 if let syn::Type::Path(p) = elem {
1555                                                         let v_name = format!("orig_{}_{}", ident, idx);
1556                                                         let tuple_elem_ident = syn::Ident::new(&v_name, Span::call_site());
1557                                                         if self.write_conversion_new_var_intern(w, &tuple_elem_ident, &v_name, elem, generics,
1558                                                                         false, ptr_for_ref, to_c,
1559                                                                         path_lookup, container_lookup, var_prefix, var_suffix) {
1560                                                                 write!(w, " ").unwrap();
1561                                                                 // Opaque types with inner pointers shouldn't ever create new stack
1562                                                                 // variables, so we don't handle it and just assert that it doesn't
1563                                                                 // here.
1564                                                                 assert!(!self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)));
1565                                                         }
1566                                                 }
1567                                         }
1568                                         write!(w, "let mut local_{} = (", ident).unwrap();
1569                                         for (idx, elem) in t.elems.iter().enumerate() {
1570                                                 let ty_has_inner = {
1571                                                                 if to_c {
1572                                                                         // "To C ptr_for_ref" means "return the regular object with
1573                                                                         // is_owned set to false", which is totally what we want
1574                                                                         // if we're about to set ty_has_inner.
1575                                                                         ptr_for_ref = true;
1576                                                                 }
1577                                                                 if let syn::Type::Reference(t) = elem {
1578                                                                         if let syn::Type::Path(p) = &*t.elem {
1579                                                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1580                                                                         } else { false }
1581                                                                 } else if let syn::Type::Path(p) = elem {
1582                                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
1583                                                                 } else { false }
1584                                                         };
1585                                                 if idx != 0 { write!(w, ", ").unwrap(); }
1586                                                 var_prefix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1587                                                 if is_ref && ty_has_inner {
1588                                                         // For ty_has_inner, the regular var_prefix mapping will take a
1589                                                         // reference, so deref once here to make sure we keep the original ref.
1590                                                         write!(w, "*").unwrap();
1591                                                 }
1592                                                 write!(w, "orig_{}_{}", ident, idx).unwrap();
1593                                                 if is_ref && !ty_has_inner {
1594                                                         // If we don't have an inner variable's reference to maintain, just
1595                                                         // hope the type is Clonable and use that.
1596                                                         write!(w, ".clone()").unwrap();
1597                                                 }
1598                                                 var_suffix(w, elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
1599                                         }
1600                                         write!(w, "){};", if to_c { ".into()" } else { "" }).unwrap();
1601                                         true
1602                                 } else { false }
1603                         },
1604                         _ => unimplemented!(),
1605                 }
1606         }
1607
1608         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 {
1609                 self.write_conversion_new_var_intern(w, ident, var_access, t, generics, false, ptr_for_ref, true,
1610                         &|a, b| self.to_c_conversion_new_var_from_path(a, b),
1611                         &|a, b, c, d, e| self.to_c_conversion_container_new_var(generics, a, b, c, d, e),
1612                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1613                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_prefix_inner(a, b, c, d, e, f),
1614                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_suffix_inner(a, b, c, d, e, f))
1615         }
1616         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 {
1617                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, ptr_for_ref)
1618         }
1619         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 {
1620                 self.write_conversion_new_var_intern(w, ident, &format!("{}", ident), t, generics, false, false, false,
1621                         &|a, b| self.from_c_conversion_new_var_from_path(a, b),
1622                         &|a, b, c, d, e| self.from_c_conversion_container_new_var(generics, a, b, c, d, e),
1623                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
1624                         &|a, b, c, d, e, _f| self.write_from_c_conversion_prefix_inner(a, b, c, d, e),
1625                         &|a, b, c, d, e, _f| self.write_from_c_conversion_suffix_inner(a, b, c, d, e))
1626         }
1627
1628         // ******************************************************
1629         // *** C Container Type Equivalent and alias Printing ***
1630         // ******************************************************
1631
1632         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) {
1633                 if container_type == "Result" {
1634                         assert_eq!(args.len(), 2);
1635                         macro_rules! write_fn {
1636                                 ($call: expr) => { {
1637                                         writeln!(w, "#[no_mangle]\npub extern \"C\" fn {}_{}() -> {} {{", mangled_container, $call, mangled_container).unwrap();
1638                                         writeln!(w, "\t{}::CResultTempl::{}(0)\n}}\n", Self::container_templ_path(), $call).unwrap();
1639                                 } }
1640                         }
1641                         macro_rules! write_alias {
1642                                 ($call: expr, $item: expr) => { {
1643                                         write!(w, "#[no_mangle]\npub static {}_{}: extern \"C\" fn (", mangled_container, $call).unwrap();
1644                                         if let syn::Type::Path(syn::TypePath { path, .. }) = $item {
1645                                                 let resolved = self.resolve_path(path, generics);
1646                                                 if self.is_known_container(&resolved, is_ref) || self.is_transparent_container(&resolved, is_ref) {
1647                                                         self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(path), generics,
1648                                                                 &format!("{}", single_ident_generic_path_to_ident(path).unwrap()), is_ref, false, false, false);
1649                                                 } else {
1650                                                         self.write_template_generics(w, &mut [$item].iter().map(|t| *t), is_ref, true);
1651                                                 }
1652                                         } else if let syn::Type::Tuple(syn::TypeTuple { elems, .. }) = $item {
1653                                                 self.write_c_mangled_container_path_intern(w, elems.iter().collect(), generics,
1654                                                         &format!("{}Tuple", elems.len()), is_ref, false, false, false);
1655                                         } else { unimplemented!(); }
1656                                         write!(w, ") -> {} =\n\t{}::CResultTempl::<", mangled_container, Self::container_templ_path()).unwrap();
1657                                         self.write_template_generics(w, &mut args.iter().map(|t| *t), is_ref, true);
1658                                         writeln!(w, ">::{};\n", $call).unwrap();
1659                                 } }
1660                         }
1661                         match args[0] {
1662                                 syn::Type::Tuple(t) if t.elems.is_empty() => write_fn!("ok"),
1663                                 _ => write_alias!("ok", args[0]),
1664                         }
1665                         match args[1] {
1666                                 syn::Type::Tuple(t) if t.elems.is_empty() => write_fn!("err"),
1667                                 _ => write_alias!("err", args[1]),
1668                         }
1669                 } else if container_type.ends_with("Tuple") {
1670                         write!(w, "#[no_mangle]\npub extern \"C\" fn {}_new(", mangled_container).unwrap();
1671                         for (idx, gen) in args.iter().enumerate() {
1672                                 write!(w, "{}{}: ", if idx != 0 { ", " } else { "" }, ('a' as u8 + idx as u8) as char).unwrap();
1673                                 self.write_c_type_intern(w, gen, None, false, false, false);
1674                         }
1675                         writeln!(w, ") -> {} {{", mangled_container).unwrap();
1676                         writeln!(w, "\t{} {{", mangled_container).unwrap();
1677                         for idx in 0..args.len() {
1678                                 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();
1679                         }
1680                         writeln!(w, "\t}}\n}}\n").unwrap();
1681                 } else {
1682                         writeln!(w, "").unwrap();
1683                 }
1684         }
1685
1686         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) {
1687                 for (idx, t) in args.enumerate() {
1688                         if idx != 0 {
1689                                 write!(w, ", ").unwrap();
1690                         }
1691                         if let syn::Type::Tuple(tup) = t {
1692                                 if tup.elems.is_empty() {
1693                                         write!(w, "u8").unwrap();
1694                                 } else {
1695                                         write!(w, "{}::C{}TupleTempl<", Self::container_templ_path(), tup.elems.len()).unwrap();
1696                                         self.write_template_generics(w, &mut tup.elems.iter(), is_ref, in_crate);
1697                                         write!(w, ">").unwrap();
1698                                 }
1699                         } else if let syn::Type::Path(p_arg) = t {
1700                                 let resolved_generic = self.resolve_path(&p_arg.path, None);
1701                                 if self.is_primitive(&resolved_generic) {
1702                                         write!(w, "{}", resolved_generic).unwrap();
1703                                 } else if let Some(c_type) = self.c_type_from_path(&resolved_generic, is_ref, false) {
1704                                         if self.is_known_container(&resolved_generic, is_ref) {
1705                                                         write!(w, "{}::C{}Templ<", Self::container_templ_path(), single_ident_generic_path_to_ident(&p_arg.path).unwrap()).unwrap();
1706                                                 assert_eq!(p_arg.path.segments.len(), 1);
1707                                                 if let syn::PathArguments::AngleBracketed(args) = &p_arg.path.segments.iter().next().unwrap().arguments {
1708                                                         self.write_template_generics(w, &mut args.args.iter().map(|gen|
1709                                                                 if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }),
1710                                                                 is_ref, in_crate);
1711                                                 } else { unimplemented!(); }
1712                                                 write!(w, ">").unwrap();
1713                                         } else if resolved_generic == "Option" {
1714                                                 if let syn::PathArguments::AngleBracketed(args) = &p_arg.path.segments.iter().next().unwrap().arguments {
1715                                                         self.write_template_generics(w, &mut args.args.iter().map(|gen|
1716                                                                 if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }),
1717                                                                 is_ref, in_crate);
1718                                                 } else { unimplemented!(); }
1719                                         } else if in_crate {
1720                                                 write!(w, "{}", c_type).unwrap();
1721                                         } else {
1722                                                 self.write_rust_type(w, &t);
1723                                         }
1724                                 } else {
1725                                         // If we just write out resolved_generic, it may mostly work, however for
1726                                         // original types which are generic, we need the template args. We could
1727                                         // figure them out and write them out, too, but its much easier to just
1728                                         // reference the native{} type alias which exists at least for opaque types.
1729                                         if in_crate {
1730                                                 write!(w, "crate::{}", resolved_generic).unwrap();
1731                                         } else {
1732                                                 let path_name: Vec<&str> = resolved_generic.rsplitn(2, "::").collect();
1733                                                 if path_name.len() > 1 {
1734                                                         write!(w, "crate::{}::native{}", path_name[1], path_name[0]).unwrap();
1735                                                 } else {
1736                                                         write!(w, "crate::native{}", path_name[0]).unwrap();
1737                                                 }
1738                                         }
1739                                 }
1740                         } else if let syn::Type::Reference(r_arg) = t {
1741                                 if let syn::Type::Path(p_arg) = &*r_arg.elem {
1742                                         let resolved = self.resolve_path(&p_arg.path, None);
1743                                         if single_ident_generic_path_to_ident(&p_arg.path).is_some() {
1744                                                 if self.crate_types.opaques.get(&resolved).is_some() {
1745                                                         write!(w, "crate::{}", resolved).unwrap();
1746                                                 } else {
1747                                                         let cty = self.c_type_from_path(&resolved, true, true).expect("Template generics should be opaque or have a predefined mapping");
1748                                                         w.write(cty.as_bytes()).unwrap();
1749                                                 }
1750                                         } else { unimplemented!(); }
1751                                 } else { unimplemented!(); }
1752                         } else if let syn::Type::Array(a_arg) = t {
1753                                 if let syn::Type::Path(p_arg) = &*a_arg.elem {
1754                                         let resolved = self.resolve_path(&p_arg.path, None);
1755                                         assert!(self.is_primitive(&resolved));
1756                                         if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a_arg.len {
1757                                                 write!(w, "{}",
1758                                                         self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, false).unwrap()).unwrap();
1759                                         }
1760                                 }
1761                         }
1762                 }
1763         }
1764         fn check_create_container(&mut self, mangled_container: String, container_type: &str, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) {
1765                 if !self.crate_types.templates_defined.get(&mangled_container).is_some() {
1766                         self.crate_types.templates_defined.insert(mangled_container.clone(), true);
1767                         let mut created_container: Vec<u8> = Vec::new();
1768
1769                         write!(&mut created_container, "#[no_mangle]\npub type {} = ", mangled_container).unwrap();
1770                         write!(&mut created_container, "{}::C{}Templ<", Self::container_templ_path(), container_type).unwrap();
1771                         self.write_template_generics(&mut created_container, &mut args.iter().map(|t| *t), is_ref, true);
1772                         writeln!(&mut created_container, ">;").unwrap();
1773
1774                         write!(&mut created_container, "#[no_mangle]\npub static {}_free: extern \"C\" fn({}) = ", mangled_container, mangled_container).unwrap();
1775                         write!(&mut created_container, "{}::C{}Templ_free::<", Self::container_templ_path(), container_type).unwrap();
1776                         self.write_template_generics(&mut created_container, &mut args.iter().map(|t| *t), is_ref, true);
1777                         writeln!(&mut created_container, ">;").unwrap();
1778
1779                         self.write_template_constructor(&mut created_container, container_type, &mangled_container, &args, generics, is_ref);
1780
1781                         self.crate_types.template_file.write(&created_container).unwrap();
1782                 }
1783         }
1784         fn path_to_generic_args(path: &syn::Path) -> Vec<&syn::Type> {
1785                 if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().next().unwrap().arguments {
1786                         args.args.iter().map(|gen| if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }).collect()
1787                 } else { unimplemented!(); }
1788         }
1789         fn write_c_mangled_container_path_intern<W: std::io::Write>
1790                         (&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 {
1791                 let mut mangled_type: Vec<u8> = Vec::new();
1792                 if !self.is_transparent_container(ident, is_ref) {
1793                         write!(w, "C{}_", ident).unwrap();
1794                         write!(mangled_type, "C{}_", ident).unwrap();
1795                 } else { assert_eq!(args.len(), 1); }
1796                 for arg in args.iter() {
1797                         macro_rules! write_path {
1798                                 ($p_arg: expr, $extra_write: expr) => {
1799                                         let subtype = self.resolve_path(&$p_arg.path, generics);
1800                                         if self.is_transparent_container(ident, is_ref) {
1801                                                 // We dont (yet) support primitives or containers inside transparent
1802                                                 // containers, so check for that first:
1803                                                 if self.is_primitive(&subtype) { return false; }
1804                                                 if self.is_known_container(&subtype, is_ref) { return false; }
1805                                                 if !in_type {
1806                                                         if self.c_type_has_inner_from_path(&subtype) {
1807                                                                 if !self.write_c_path_intern(w, &$p_arg.path, generics, is_ref, is_mut, ptr_for_ref) { return false; }
1808                                                         } else {
1809                                                                 // Option<T> needs to be converted to a *mut T, ie mut ptr-for-ref
1810                                                                 if !self.write_c_path_intern(w, &$p_arg.path, generics, true, true, true) { return false; }
1811                                                         }
1812                                                 } else {
1813                                                         if $p_arg.path.segments.len() == 1 {
1814                                                                 write!(w, "{}", $p_arg.path.segments.iter().next().unwrap().ident).unwrap();
1815                                                         } else {
1816                                                                 return false;
1817                                                         }
1818                                                 }
1819                                         } else if self.is_known_container(&subtype, is_ref) || self.is_transparent_container(&subtype, is_ref) {
1820                                                 if !self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(&$p_arg.path), generics,
1821                                                                 &subtype, is_ref, is_mut, ptr_for_ref, true) {
1822                                                         return false;
1823                                                 }
1824                                                 self.write_c_mangled_container_path_intern(&mut mangled_type, Self::path_to_generic_args(&$p_arg.path),
1825                                                         generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1826                                                 if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1827                                                         self.write_c_mangled_container_path_intern(w2, Self::path_to_generic_args(&$p_arg.path),
1828                                                                 generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
1829                                                 }
1830                                         } else if let Some(id) = single_ident_generic_path_to_ident(&$p_arg.path) {
1831                                                 write!(w, "{}", id).unwrap();
1832                                                 write!(mangled_type, "{}", id).unwrap();
1833                                                 if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
1834                                                         write!(w2, "{}", id).unwrap();
1835                                                 }
1836                                         } else { return false; }
1837                                 }
1838                         }
1839                         if let syn::Type::Tuple(tuple) = arg {
1840                                 if tuple.elems.len() == 0 {
1841                                         write!(w, "None").unwrap();
1842                                         write!(mangled_type, "None").unwrap();
1843                                 } else {
1844                                         let mut mangled_tuple_type: Vec<u8> = Vec::new();
1845
1846                                         // Figure out what the mangled type should look like. To disambiguate
1847                                         // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
1848                                         // them with a Z. Ideally we wouldn't use Z, but not many special chars are
1849                                         // available for use in type names.
1850                                         write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
1851                                         write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
1852                                         write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
1853                                         for elem in tuple.elems.iter() {
1854                                                 if let syn::Type::Path(p) = elem {
1855                                                         write_path!(p, Some(&mut mangled_tuple_type));
1856                                                 } else if let syn::Type::Reference(refelem) = elem {
1857                                                         if let syn::Type::Path(p) = &*refelem.elem {
1858                                                                 write_path!(p, Some(&mut mangled_tuple_type));
1859                                                         } else { return false; }
1860                                                 } else { return false; }
1861                                         }
1862                                         write!(w, "Z").unwrap();
1863                                         write!(mangled_type, "Z").unwrap();
1864                                         write!(mangled_tuple_type, "Z").unwrap();
1865                                         self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
1866                                                 &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref);
1867                                 }
1868                         } else if let syn::Type::Path(p_arg) = arg {
1869                                 write_path!(p_arg, None);
1870                         } else if let syn::Type::Reference(refty) = arg {
1871                                 if args.len() != 1 { return false; }
1872                                 if let syn::Type::Path(p_arg) = &*refty.elem {
1873                                         write_path!(p_arg, None);
1874                                 } else if let syn::Type::Slice(_) = &*refty.elem {
1875                                         // write_c_type will actually do exactly what we want here, we just need to
1876                                         // make it a pointer so that its an option. Note that we cannot always convert
1877                                         // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
1878                                         // to edit it, hence we use *mut here instead of *const.
1879                                         write!(w, "*mut ").unwrap();
1880                                         self.write_c_type(w, arg, None, true);
1881                                 } else { return false; }
1882                         } else if let syn::Type::Array(a) = arg {
1883                                 if let syn::Type::Path(p_arg) = &*a.elem {
1884                                         let resolved = self.resolve_path(&p_arg.path, generics);
1885                                         if !self.is_primitive(&resolved) { return false; }
1886                                         if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
1887                                                 if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
1888                                                 write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
1889                                                 write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
1890                                         } else { return false; }
1891                                 } else { return false; }
1892                         } else { return false; }
1893                 }
1894                 if self.is_transparent_container(ident, is_ref) { return true; }
1895                 // Push the "end of type" Z
1896                 write!(w, "Z").unwrap();
1897                 write!(mangled_type, "Z").unwrap();
1898
1899                 // Make sure the type is actually defined:
1900                 self.check_create_container(String::from_utf8(mangled_type).unwrap(), ident, args, generics, is_ref);
1901                 true
1902         }
1903         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 {
1904                 if !self.is_transparent_container(ident, is_ref) {
1905                         write!(w, "{}::", Self::generated_container_path()).unwrap();
1906                 }
1907                 self.write_c_mangled_container_path_intern(w, args, generics, ident, is_ref, is_mut, ptr_for_ref, false)
1908         }
1909
1910         // **********************************
1911         // *** C Type Equivalent Printing ***
1912         // **********************************
1913
1914         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 {
1915                 let full_path = match self.maybe_resolve_path(&path, generics) {
1916                         Some(path) => path, None => return false };
1917                 if let Some(c_type) = self.c_type_from_path(&full_path, is_ref, ptr_for_ref) {
1918                         write!(w, "{}", c_type).unwrap();
1919                         true
1920                 } else if self.crate_types.traits.get(&full_path).is_some() {
1921                         if is_ref && ptr_for_ref {
1922                                 write!(w, "*{} crate::{}", if is_mut { "mut" } else { "const" }, full_path).unwrap();
1923                         } else if is_ref {
1924                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
1925                         } else {
1926                                 write!(w, "crate::{}", full_path).unwrap();
1927                         }
1928                         true
1929                 } else if self.crate_types.opaques.get(&full_path).is_some() || self.crate_types.mirrored_enums.get(&full_path).is_some() {
1930                         if is_ref && ptr_for_ref {
1931                                 // ptr_for_ref implies we're returning the object, which we can't really do for
1932                                 // opaque or mirrored types without box'ing them, which is quite a waste, so return
1933                                 // the actual object itself (for opaque types we'll set the pointer to the actual
1934                                 // type and note that its a reference).
1935                                 write!(w, "crate::{}", full_path).unwrap();
1936                         } else if is_ref {
1937                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
1938                         } else {
1939                                 write!(w, "crate::{}", full_path).unwrap();
1940                         }
1941                         true
1942                 } else {
1943                         false
1944                 }
1945         }
1946         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 {
1947                 match t {
1948                         syn::Type::Path(p) => {
1949                                 if p.qself.is_some() || p.path.leading_colon.is_some() {
1950                                         return false;
1951                                 }
1952                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1953                                         if self.is_known_container(&full_path, is_ref) || self.is_transparent_container(&full_path, is_ref) {
1954                                                 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);
1955                                         }
1956                                 }
1957                                 if p.path.leading_colon.is_some() { return false; }
1958                                 self.write_c_path_intern(w, &p.path, generics, is_ref, is_mut, ptr_for_ref)
1959                         },
1960                         syn::Type::Reference(r) => {
1961                                 if let Some(lft) = &r.lifetime {
1962                                         if format!("{}", lft.ident) != "static" { return false; }
1963                                 }
1964                                 self.write_c_type_intern(w, &*r.elem, generics, true, r.mutability.is_some(), ptr_for_ref)
1965                         },
1966                         syn::Type::Array(a) => {
1967                                 if is_ref && is_mut {
1968                                         write!(w, "*mut [").unwrap();
1969                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
1970                                 } else if is_ref {
1971                                         write!(w, "*const [").unwrap();
1972                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref) { return false; }
1973                                 } else {
1974                                         let mut typecheck = Vec::new();
1975                                         if !self.write_c_type_intern(&mut typecheck, &a.elem, generics, false, false, ptr_for_ref) { return false; }
1976                                         if typecheck[..] != ['u' as u8, '8' as u8] { return false; }
1977                                 }
1978                                 if let syn::Expr::Lit(l) = &a.len {
1979                                         if let syn::Lit::Int(i) = &l.lit {
1980                                                 if !is_ref {
1981                                                         if let Some(ty) = self.c_type_from_path(&format!("[u8; {}]", i.base10_digits()), false, ptr_for_ref) {
1982                                                                 write!(w, "{}", ty).unwrap();
1983                                                                 true
1984                                                         } else { false }
1985                                                 } else {
1986                                                         write!(w, "; {}]", i).unwrap();
1987                                                         true
1988                                                 }
1989                                         } else { false }
1990                                 } else { false }
1991                         }
1992                         syn::Type::Slice(s) => {
1993                                 if !is_ref || is_mut { return false; }
1994                                 if let syn::Type::Path(p) = &*s.elem {
1995                                         let resolved = self.resolve_path(&p.path, generics);
1996                                         if self.is_primitive(&resolved) {
1997                                                 write!(w, "{}::{}slice", Self::container_templ_path(), resolved).unwrap();
1998                                                 true
1999                                         } else { false }
2000                                 } else if let syn::Type::Reference(r) = &*s.elem {
2001                                         if let syn::Type::Path(p) = &*r.elem {
2002                                                 // Slices with "real types" inside are mapped as the equivalent non-ref Vec
2003                                                 let resolved = self.resolve_path(&p.path, generics);
2004                                                 let mangled_container = if let Some(ident) = self.crate_types.opaques.get(&resolved) {
2005                                                         format!("CVec_{}Z", ident)
2006                                                 } else if let Some(en) = self.crate_types.mirrored_enums.get(&resolved) {
2007                                                         format!("CVec_{}Z", en.ident)
2008                                                 } else if let Some(id) = p.path.get_ident() {
2009                                                         format!("CVec_{}Z", id)
2010                                                 } else { return false; };
2011                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2012                                                 self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false);
2013                                                 true
2014                                         } else { false }
2015                                 } else if let syn::Type::Tuple(_) = &*s.elem {
2016                                         let mut args = syn::punctuated::Punctuated::new();
2017                                         args.push(syn::GenericArgument::Type((*s.elem).clone()));
2018                                         let mut segments = syn::punctuated::Punctuated::new();
2019                                         segments.push(syn::PathSegment {
2020                                                 ident: syn::Ident::new("Vec", Span::call_site()),
2021                                                 arguments: syn::PathArguments::AngleBracketed(syn::AngleBracketedGenericArguments {
2022                                                         colon2_token: None, lt_token: syn::Token![<](Span::call_site()), args, gt_token: syn::Token![>](Span::call_site()),
2023                                                 })
2024                                         });
2025                                         self.write_c_type_intern(w, &syn::Type::Path(syn::TypePath { qself: None, path: syn::Path { leading_colon: None, segments } }), generics, false, is_mut, ptr_for_ref)
2026                                 } else { false }
2027                         },
2028                         syn::Type::Tuple(t) => {
2029                                 if t.elems.len() == 0 {
2030                                         true
2031                                 } else {
2032                                         self.write_c_mangled_container_path(w, t.elems.iter().collect(), generics,
2033                                                 &format!("{}Tuple", t.elems.len()), is_ref, is_mut, ptr_for_ref)
2034                                 }
2035                         },
2036                         _ => false,
2037                 }
2038         }
2039         pub fn write_c_type<W: std::io::Write>(&mut self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2040                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref));
2041         }
2042         pub fn understood_c_path(&mut self, p: &syn::Path) -> bool {
2043                 if p.leading_colon.is_some() { return false; }
2044                 self.write_c_path_intern(&mut std::io::sink(), p, None, false, false, false)
2045         }
2046         pub fn understood_c_type(&mut self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2047                 self.write_c_type_intern(&mut std::io::sink(), t, generics, false, false, false)
2048         }
2049 }