src/librustc/middle/typeck/astconv.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 /*!
  12  * Conversion from AST representation of types to the ty.rs
  13  * representation.  The main routine here is `ast_ty_to_ty()`: each use
  14  * is parameterized by an instance of `AstConv` and a `RegionScope`.
  15  *
  16  * The parameterization of `ast_ty_to_ty()` is because it behaves
  17  * somewhat differently during the collect and check phases,
  18  * particularly with respect to looking up the types of top-level
  19  * items.  In the collect phase, the crate context is used as the
  20  * `AstConv` instance; in this phase, the `get_item_ty()` function
  21  * triggers a recursive call to `ty_of_item()`  (note that
  22  * `ast_ty_to_ty()` will detect recursive types and report an error).
  23  * In the check phase, when the @FnCtxt is used as the `AstConv`,
  24  * `get_item_ty()` just looks up the item type in `tcx.tcache`.
  25  *
  26  * The `RegionScope` trait controls what happens when the user does
  27  * not specify a region in some location where a region is required
  28  * (e.g., if the user writes `&Foo` as a type rather than `&'a Foo`).
  29  * See the `rscope` module for more details.
  30  *
  31  * Unlike the `AstConv` trait, the region scope can change as we descend
  32  * the type.  This is to accommodate the fact that (a) fn types are binding
  33  * scopes and (b) the default region may change.  To understand case (a),
  34  * consider something like:
  35  *
  36  *   type foo = { x: &a.int, y: |&a.int| }
  37  *
  38  * The type of `x` is an error because there is no region `a` in scope.
  39  * In the type of `y`, however, region `a` is considered a bound region
  40  * as it does not already appear in scope.
  41  *
  42  * Case (b) says that if you have a type:
  43  *   type foo<'a> = ...;
  44  *   type bar = fn(&foo, &a.foo)
  45  * The fully expanded version of type bar is:
  46  *   type bar = fn(&'foo &, &a.foo<'a>)
  47  * Note that the self region for the `foo` defaulted to `&` in the first
  48  * case but `&a` in the second.  Basically, defaults that appear inside
  49  * an rptr (`&r.T`) use the region `r` that appears in the rptr.
  50  */
  51
  52
  53 use middle::const_eval;
  54 use middle::subst::Subst;
  55 use middle::ty::{substs};
  56 use middle::ty::{ty_param_substs_and_ty};
  57 use middle::ty;
  58 use middle::typeck::rscope;
  59 use middle::typeck::rscope::{RegionScope};
  60 use middle::typeck::lookup_def_tcx;
  61 use util::ppaux::Repr;
  62
  63 use std::vec;
  64 use syntax::abi::AbiSet;
  65 use syntax::{ast, ast_util};
  66 use syntax::codemap::Span;
  67 use syntax::opt_vec::OptVec;
  68 use syntax::opt_vec;
  69 use syntax::print::pprust::{lifetime_to_str, path_to_str};
  70
  71 pub trait AstConv {
  72     fn tcx(&self) -> ty::ctxt;
  73     fn get_item_ty(&self, id: ast::DefId) -> ty::ty_param_bounds_and_ty;
  74     fn get_trait_def(&self, id: ast::DefId) -> @ty::TraitDef;
  75
  76     // what type should we use when a type is omitted?
  77     fn ty_infer(&self, span: Span) -> ty::t;
  78 }
  79
  80 pub fn ast_region_to_region(tcx: ty::ctxt, lifetime: &ast::Lifetime)
  81                             -> ty::Region {
  82     let named_region_map = tcx.named_region_map.borrow();
  83     let r = match named_region_map.get().find(&lifetime.id) {
  84         None => {
  85             // should have been recorded by the `resolve_lifetime` pass
  86             tcx.sess.span_bug(lifetime.span, "unresolved lifetime");
  87         }
  88
  89         Some(&ast::DefStaticRegion) => {
  90             ty::ReStatic
  91         }
  92
  93         Some(&ast::DefLateBoundRegion(binder_id, _, id)) => {
  94             ty::ReLateBound(binder_id, ty::BrNamed(ast_util::local_def(id),
  95                                                    lifetime.ident))
  96         }
  97
  98         Some(&ast::DefEarlyBoundRegion(index, id)) => {
  99             ty::ReEarlyBound(id, index, lifetime.ident)
 100         }
 101
 102         Some(&ast::DefFreeRegion(scope_id, id)) => {
 103             ty::ReFree(ty::FreeRegion {
 104                     scope_id: scope_id,
 105                     bound_region: ty::BrNamed(ast_util::local_def(id),
 106                                               lifetime.ident)
 107                 })
 108         }
 109     };
 110
 111     debug!("ast_region_to_region(lifetime={} id={}) yields {}",
 112             lifetime_to_str(lifetime),
 113             lifetime.id, r.repr(tcx));
 114
 115     r
 116 }
 117
 118 fn opt_ast_region_to_region<AC:AstConv,RS:RegionScope>(
 119     this: &AC,
 120     rscope: &RS,
 121     default_span: Span,
 122     opt_lifetime: &Option<ast::Lifetime>) -> ty::Region
 123 {
 124     let r = match *opt_lifetime {
 125         Some(ref lifetime) => {
 126             ast_region_to_region(this.tcx(), lifetime)
 127         }
 128
 129         None => {
 130             match rscope.anon_regions(default_span, 1) {
 131                 Err(()) => {
 132                     debug!("optional region in illegal location");
 133                     this.tcx().sess.span_err(
 134                         default_span, "missing lifetime specifier");
 135                     ty::ReStatic
 136                 }
 137
 138                 Ok(rs) => {
 139                     rs[0]
 140                 }
 141             }
 142         }
 143     };
 144
 145     debug!("opt_ast_region_to_region(opt_lifetime={:?}) yields {}",
 146             opt_lifetime.as_ref().map(|e| lifetime_to_str(e)),
 147             r.repr(this.tcx()));
 148
 149     r
 150 }
 151
 152 fn ast_path_substs<AC:AstConv,RS:RegionScope>(
 153     this: &AC,
 154     rscope: &RS,
 155     decl_generics: &ty::Generics,
 156     self_ty: Option<ty::t>,
 157     path: &ast::Path) -> ty::substs
 158 {
 159     /*!
 160      * Given a path `path` that refers to an item `I` with the
 161      * declared generics `decl_generics`, returns an appropriate
 162      * set of substitutions for this particular reference to `I`.
 163      */
 164
 165     let tcx = this.tcx();
 166
 167     // If the type is parameterized by the this region, then replace this
 168     // region with the current anon region binding (in other words,
 169     // whatever & would get replaced with).
 170     let expected_num_region_params = decl_generics.region_param_defs().len();
 171     let supplied_num_region_params = path.segments.last().unwrap().lifetimes.len();
 172     let regions = if expected_num_region_params == supplied_num_region_params {
 173         path.segments.last().unwrap().lifetimes.map(
 174             |l| ast_region_to_region(this.tcx(), l))
 175     } else {
 176         let anon_regions =
 177             rscope.anon_regions(path.span, expected_num_region_params);
 178
 179         if supplied_num_region_params != 0 || anon_regions.is_err() {
 180             tcx.sess.span_err(
 181                 path.span,
 182                 format!("wrong number of lifetime parameters: \
 183                         expected {} but found {}",
 184                         expected_num_region_params,
 185                         supplied_num_region_params));
 186         }
 187
 188         match anon_regions {
 189             Ok(v) => opt_vec::from(v),
 190             Err(()) => opt_vec::from(vec::from_fn(expected_num_region_params,
 191                                                   |_| ty::ReStatic)) // hokey
 192         }
 193     };
 194
 195     // Convert the type parameters supplied by the user.
 196     let supplied_ty_param_count = path.segments.iter().flat_map(|s| s.types.iter()).len();
 197     let formal_ty_param_count = decl_generics.type_param_defs().len();
 198     let required_ty_param_count = decl_generics.type_param_defs().iter()
 199                                                .take_while(|x| x.default.is_none())
 200                                                .len();
 201     if supplied_ty_param_count < required_ty_param_count {
 202         let expected = if required_ty_param_count < formal_ty_param_count {
 203             "expected at least"
 204         } else {
 205             "expected"
 206         };
 207         this.tcx().sess.span_fatal(path.span,
 208             format!("wrong number of type arguments: {} {} but found {}",
 209                 expected, required_ty_param_count, supplied_ty_param_count));
 210     } else if supplied_ty_param_count > formal_ty_param_count {
 211         let expected = if required_ty_param_count < formal_ty_param_count {
 212             "expected at most"
 213         } else {
 214             "expected"
 215         };
 216         this.tcx().sess.span_fatal(path.span,
 217             format!("wrong number of type arguments: {} {} but found {}",
 218                 expected, formal_ty_param_count, supplied_ty_param_count));
 219     }
 220
 221     if supplied_ty_param_count > required_ty_param_count
 222         && !this.tcx().sess.features.default_type_params.get() {
 223         this.tcx().sess.span_err(path.span, "default type parameters are \
 224                                              experimental and possibly buggy");
 225         this.tcx().sess.span_note(path.span, "add #[feature(default_type_params)] \
 226                                               to the crate attributes to enable");
 227     }
 228
 229     let tps = path.segments.iter().flat_map(|s| s.types.iter())
 230                             .map(|&a_t| ast_ty_to_ty(this, rscope, a_t))
 231                             .collect();
 232
 233     let mut substs = substs {
 234         regions: ty::NonerasedRegions(regions),
 235         self_ty: self_ty,
 236         tps: tps
 237     };
 238
 239     for param in decl_generics.type_param_defs()
 240                               .slice_from(supplied_ty_param_count).iter() {
 241         let ty = param.default.unwrap().subst_spanned(tcx, &substs, Some(path.span));
 242         substs.tps.push(ty);
 243     }
 244
 245     substs
 246 }
 247
 248 pub fn ast_path_to_substs_and_ty<AC:AstConv,
 249                                  RS:RegionScope>(
 250                                  this: &AC,
 251                                  rscope: &RS,
 252                                  did: ast::DefId,
 253                                  path: &ast::Path)
 254                                  -> ty_param_substs_and_ty {
 255     let tcx = this.tcx();
 256     let ty::ty_param_bounds_and_ty {
 257         generics: generics,
 258         ty: decl_ty
 259     } = this.get_item_ty(did);
 260
 261     let substs = ast_path_substs(this, rscope, &generics, None, path);
 262     let ty = ty::subst(tcx, &substs, decl_ty);
 263     ty_param_substs_and_ty { substs: substs, ty: ty }
 264 }
 265
 266 pub fn ast_path_to_trait_ref<AC:AstConv,RS:RegionScope>(
 267     this: &AC,
 268     rscope: &RS,
 269     trait_def_id: ast::DefId,
 270     self_ty: Option<ty::t>,
 271     path: &ast::Path) -> @ty::TraitRef
 272 {
 273     let trait_def =
 274         this.get_trait_def(trait_def_id);
 275     let substs =
 276         ast_path_substs(
 277             this,
 278             rscope,
 279             &trait_def.generics,
 280             self_ty,
 281             path);
 282     let trait_ref =
 283         @ty::TraitRef {def_id: trait_def_id,
 284                        substs: substs};
 285     return trait_ref;
 286 }
 287
 288 pub fn ast_path_to_ty<AC:AstConv,RS:RegionScope>(
 289         this: &AC,
 290         rscope: &RS,
 291         did: ast::DefId,
 292         path: &ast::Path)
 293      -> ty_param_substs_and_ty
 294 {
 295     // Look up the polytype of the item and then substitute the provided types
 296     // for any type/region parameters.
 297     let ty::ty_param_substs_and_ty {
 298         substs: substs,
 299         ty: ty
 300     } = ast_path_to_substs_and_ty(this, rscope, did, path);
 301     ty_param_substs_and_ty { substs: substs, ty: ty }
 302 }
 303
 304 pub static NO_REGIONS: uint = 1;
 305 pub static NO_TPS: uint = 2;
 306
 307 fn check_path_args(tcx: ty::ctxt,
 308                    path: &ast::Path,
 309                    flags: uint) {
 310     if (flags & NO_TPS) != 0u {
 311         if !path.segments.iter().all(|s| s.types.is_empty()) {
 312             tcx.sess.span_err(
 313                 path.span,
 314                 "type parameters are not allowed on this type");
 315         }
 316     }
 317
 318     if (flags & NO_REGIONS) != 0u {
 319         if !path.segments.last().unwrap().lifetimes.is_empty() {
 320             tcx.sess.span_err(
 321                 path.span,
 322                 "region parameters are not allowed on this type");
 323         }
 324     }
 325 }
 326
 327 pub fn ast_ty_to_prim_ty(tcx: ty::ctxt, ast_ty: &ast::Ty) -> Option<ty::t> {
 328     match ast_ty.node {
 329         ast::TyPath(ref path, _, id) => {
 330             let def_map = tcx.def_map.borrow();
 331             let a_def = match def_map.get().find(&id) {
 332                 None => tcx.sess.span_fatal(
 333                     ast_ty.span, format!("unbound path {}", path_to_str(path))),
 334                 Some(&d) => d
 335             };
 336             match a_def {
 337                 ast::DefPrimTy(nty) => {
 338                     match nty {
 339                         ast::TyBool => {
 340                             check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 341                             Some(ty::mk_bool())
 342                         }
 343                         ast::TyChar => {
 344                             check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 345                             Some(ty::mk_char())
 346                         }
 347                         ast::TyInt(it) => {
 348                             check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 349                             Some(ty::mk_mach_int(it))
 350                         }
 351                         ast::TyUint(uit) => {
 352                             check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 353                             Some(ty::mk_mach_uint(uit))
 354                         }
 355                         ast::TyFloat(ft) => {
 356                             check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 357                             Some(ty::mk_mach_float(ft))
 358                         }
 359                         ast::TyStr => {
 360                             tcx.sess.span_err(ast_ty.span,
 361                                               "bare `str` is not a type");
 362                             // return /something/ so they can at least get more errors
 363                             Some(ty::mk_str(tcx, ty::vstore_uniq))
 364                         }
 365                     }
 366                 }
 367                 _ => None
 368             }
 369         }
 370         _ => None
 371     }
 372 }
 373
 374 // Parses the programmer's textual representation of a type into our
 375 // internal notion of a type.
 376 pub fn ast_ty_to_ty<AC:AstConv, RS:RegionScope>(
 377     this: &AC, rscope: &RS, ast_ty: &ast::Ty) -> ty::t {
 378
 379     fn ast_ty_to_mt<AC:AstConv, RS:RegionScope>(
 380         this: &AC, rscope: &RS, ty: &ast::Ty) -> ty::mt {
 381
 382         ty::mt {ty: ast_ty_to_ty(this, rscope, ty), mutbl: ast::MutImmutable}
 383     }
 384
 385     fn ast_mt_to_mt<AC:AstConv, RS:RegionScope>(
 386         this: &AC, rscope: &RS, mt: &ast::MutTy) -> ty::mt {
 387
 388         ty::mt {ty: ast_ty_to_ty(this, rscope, mt.ty), mutbl: mt.mutbl}
 389     }
 390
 391     enum PointerTy {
 392         Box,
 393         VStore(ty::vstore)
 394     }
 395     impl PointerTy {
 396         fn expect_vstore(&self, tcx: ty::ctxt, span: Span, ty: &str) -> ty::vstore {
 397             match *self {
 398                 Box => {
 399                     tcx.sess.span_err(span, format!("managed {} are not supported", ty));
 400                     // everything can be ~, so this is a worth substitute
 401                     ty::vstore_uniq
 402                 }
 403                 VStore(vst) => vst
 404             }
 405         }
 406     }
 407
 408     // Handle ~, and & being able to mean strs and vecs.
 409     // If a_seq_ty is a str or a vec, make it a str/vec.
 410     // Also handle first-class trait types.
 411     fn mk_pointer<AC:AstConv,
 412                   RS:RegionScope>(
 413                   this: &AC,
 414                   rscope: &RS,
 415                   a_seq_ty: &ast::MutTy,
 416                   ptr_ty: PointerTy,
 417                   constr: |ty::mt| -> ty::t)
 418                   -> ty::t {
 419         let tcx = this.tcx();
 420         debug!("mk_pointer(ptr_ty={:?})", ptr_ty);
 421
 422         match a_seq_ty.ty.node {
 423             ast::TyVec(ty) => {
 424                 let vst = ptr_ty.expect_vstore(tcx, a_seq_ty.ty.span, "vectors");
 425                 let mut mt = ast_ty_to_mt(this, rscope, ty);
 426                 if a_seq_ty.mutbl == ast::MutMutable {
 427                     mt.mutbl = ast::MutMutable;
 428                 }
 429                 debug!("&[]: vst={:?}", vst);
 430                 return ty::mk_vec(tcx, mt, vst);
 431             }
 432             ast::TyPath(ref path, ref bounds, id) => {
 433                 // Note that the "bounds must be empty if path is not a trait"
 434                 // restriction is enforced in the below case for ty_path, which
 435                 // will run after this as long as the path isn't a trait.
 436                 let def_map = tcx.def_map.borrow();
 437                 match def_map.get().find(&id) {
 438                     Some(&ast::DefPrimTy(ast::TyStr)) if
 439                             a_seq_ty.mutbl == ast::MutImmutable => {
 440                         check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 441                         let vst = ptr_ty.expect_vstore(tcx, path.span, "strings");
 442                         return ty::mk_str(tcx, vst);
 443                     }
 444                     Some(&ast::DefTrait(trait_def_id)) => {
 445                         let result = ast_path_to_trait_ref(
 446                             this, rscope, trait_def_id, None, path);
 447                         let trait_store = match ptr_ty {
 448                             VStore(ty::vstore_uniq) => ty::UniqTraitStore,
 449                             VStore(ty::vstore_slice(r)) => {
 450                                 ty::RegionTraitStore(r)
 451                             }
 452                             _ => {
 453                                 tcx.sess.span_err(
 454                                     path.span,
 455                                     "~trait or &trait are the only supported \
 456                                      forms of casting-to-trait");
 457                                 return ty::mk_err();
 458                             }
 459                         };
 460                         let bounds = conv_builtin_bounds(this.tcx(), bounds, trait_store);
 461                         return ty::mk_trait(tcx,
 462                                             result.def_id,
 463                                             result.substs.clone(),
 464                                             trait_store,
 465                                             a_seq_ty.mutbl,
 466                                             bounds);
 467                     }
 468                     _ => {}
 469                 }
 470             }
 471             _ => {}
 472         }
 473
 474         let seq_ty = ast_mt_to_mt(this, rscope, a_seq_ty);
 475         return constr(seq_ty);
 476     }
 477
 478     let tcx = this.tcx();
 479
 480     {
 481         let mut ast_ty_to_ty_cache = tcx.ast_ty_to_ty_cache.borrow_mut();
 482         match ast_ty_to_ty_cache.get().find(&ast_ty.id) {
 483             Some(&ty::atttce_resolved(ty)) => return ty,
 484             Some(&ty::atttce_unresolved) => {
 485                 tcx.sess.span_fatal(ast_ty.span,
 486                                     "illegal recursive type; insert an enum \
 487                                      or struct in the cycle, if this is \
 488                                      desired");
 489             }
 490             None => { /* go on */ }
 491         }
 492         ast_ty_to_ty_cache.get().insert(ast_ty.id, ty::atttce_unresolved);
 493     }
 494
 495     let typ = ast_ty_to_prim_ty(tcx, ast_ty).unwrap_or_else(|| match ast_ty.node {
 496             ast::TyNil => ty::mk_nil(),
 497             ast::TyBot => ty::mk_bot(),
 498             ast::TyBox(ty) => {
 499                 let mt = ast::MutTy { ty: ty, mutbl: ast::MutImmutable };
 500                 mk_pointer(this, rscope, &mt, Box, |tmt| ty::mk_box(tcx, tmt.ty))
 501             }
 502             ast::TyUniq(ty) => {
 503                 let mt = ast::MutTy { ty: ty, mutbl: ast::MutImmutable };
 504                 mk_pointer(this, rscope, &mt, VStore(ty::vstore_uniq),
 505                            |tmt| ty::mk_uniq(tcx, tmt.ty))
 506             }
 507             ast::TyVec(ty) => {
 508                 tcx.sess.span_err(ast_ty.span, "bare `[]` is not a type");
 509                 // return /something/ so they can at least get more errors
 510                 ty::mk_vec(tcx, ast_ty_to_mt(this, rscope, ty), ty::vstore_uniq)
 511             }
 512             ast::TyPtr(ref mt) => {
 513                 ty::mk_ptr(tcx, ast_mt_to_mt(this, rscope, mt))
 514             }
 515             ast::TyRptr(ref region, ref mt) => {
 516                 let r = opt_ast_region_to_region(this, rscope, ast_ty.span, region);
 517                 debug!("ty_rptr r={}", r.repr(this.tcx()));
 518                 mk_pointer(this, rscope, mt, VStore(ty::vstore_slice(r)),
 519                            |tmt| ty::mk_rptr(tcx, r, tmt))
 520             }
 521             ast::TyTup(ref fields) => {
 522                 let flds = fields.map(|&t| ast_ty_to_ty(this, rscope, t));
 523                 ty::mk_tup(tcx, flds)
 524             }
 525             ast::TyBareFn(ref bf) => {
 526                 if bf.decl.variadic && !bf.abis.is_c() {
 527                     tcx.sess.span_err(ast_ty.span,
 528                                       "variadic function must have C calling convention");
 529                 }
 530                 ty::mk_bare_fn(tcx, ty_of_bare_fn(this, ast_ty.id, bf.purity,
 531                                                   bf.abis, bf.decl))
 532             }
 533             ast::TyClosure(ref f) => {
 534                 if f.sigil == ast::ManagedSigil {
 535                     tcx.sess.span_err(ast_ty.span,
 536                                       "managed closures are not supported");
 537                 }
 538
 539                 let bounds = conv_builtin_bounds(this.tcx(), &f.bounds, match f.sigil {
 540                         // Use corresponding trait store to figure out default bounds
 541                         // if none were specified.
 542                         ast::BorrowedSigil => ty::RegionTraitStore(ty::ReEmpty), // dummy region
 543                         ast::OwnedSigil    => ty::UniqTraitStore,
 544                         ast::ManagedSigil  => return ty::mk_err()
 545                     });
 546                 let fn_decl = ty_of_closure(this,
 547                                             rscope,
 548                                             ast_ty.id,
 549                                             f.sigil,
 550                                             f.purity,
 551                                             f.onceness,
 552                                             bounds,
 553                                             &f.region,
 554                                             f.decl,
 555                                             None,
 556                                             ast_ty.span);
 557                 ty::mk_closure(tcx, fn_decl)
 558             }
 559             ast::TyPath(ref path, ref bounds, id) => {
 560                 let def_map = tcx.def_map.borrow();
 561                 let a_def = match def_map.get().find(&id) {
 562                     None => tcx.sess.span_fatal(
 563                         ast_ty.span, format!("unbound path {}", path_to_str(path))),
 564                     Some(&d) => d
 565                 };
 566                 // Kind bounds on path types are only supported for traits.
 567                 match a_def {
 568                     // But don't emit the error if the user meant to do a trait anyway.
 569                     ast::DefTrait(..) => { },
 570                     _ if bounds.is_some() =>
 571                         tcx.sess.span_err(ast_ty.span,
 572                                           "kind bounds can only be used on trait types"),
 573                     _ => { },
 574                 }
 575                 match a_def {
 576                     ast::DefTrait(_) => {
 577                         let path_str = path_to_str(path);
 578                         tcx.sess.span_err(
 579                             ast_ty.span,
 580                             format!("reference to trait `{}` where a type is expected; \
 581                                     try `@{}`, `~{}`, or `&{}`",
 582                                     path_str, path_str, path_str, path_str));
 583                         ty::mk_err()
 584                     }
 585                     ast::DefTy(did) | ast::DefStruct(did) => {
 586                         ast_path_to_ty(this, rscope, did, path).ty
 587                     }
 588                     ast::DefTyParam(id, n) => {
 589                         check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 590                         ty::mk_param(tcx, n, id)
 591                     }
 592                     ast::DefSelfTy(id) => {
 593                         // n.b.: resolve guarantees that the this type only appears in a
 594                         // trait, which we rely upon in various places when creating
 595                         // substs
 596                         check_path_args(tcx, path, NO_TPS | NO_REGIONS);
 597                         let did = ast_util::local_def(id);
 598                         ty::mk_self(tcx, did)
 599                     }
 600                     ast::DefMod(id) => {
 601                         tcx.sess.span_fatal(ast_ty.span,
 602                             format!("found module name used as a type: {}",
 603                                     tcx.map.node_to_str(id.node)));
 604                     }
 605                     ast::DefPrimTy(_) => {
 606                         fail!("DefPrimTy arm missed in previous ast_ty_to_prim_ty call");
 607                     }
 608                     _ => {
 609                         tcx.sess.span_fatal(ast_ty.span,
 610                             format!("found value name used as a type: {:?}", a_def));
 611                     }
 612                 }
 613             }
 614             ast::TyFixedLengthVec(ty, e) => {
 615                 match const_eval::eval_const_expr_partial(&tcx, e) {
 616                     Ok(ref r) => {
 617                         match *r {
 618                             const_eval::const_int(i) =>
 619                                 ty::mk_vec(tcx, ast_ty_to_mt(this, rscope, ty),
 620                                            ty::vstore_fixed(i as uint)),
 621                             const_eval::const_uint(i) =>
 622                                 ty::mk_vec(tcx, ast_ty_to_mt(this, rscope, ty),
 623                                            ty::vstore_fixed(i as uint)),
 624                             _ => {
 625                                 tcx.sess.span_fatal(
 626                                     ast_ty.span, "expected constant expr for vector length");
 627                             }
 628                         }
 629                     }
 630                     Err(ref r) => {
 631                         tcx.sess.span_fatal(
 632                             ast_ty.span,
 633                             format!("expected constant expr for vector length: {}", *r));
 634                     }
 635                 }
 636             }
 637             ast::TyTypeof(_e) => {
 638                 tcx.sess.span_bug(ast_ty.span, "typeof is reserved but unimplemented");
 639             }
 640             ast::TyInfer => {
 641                 // ty_infer should only appear as the type of arguments or return
 642                 // values in a fn_expr, or as the type of local variables.  Both of
 643                 // these cases are handled specially and should not descend into this
 644                 // routine.
 645                 this.tcx().sess.span_bug(
 646                     ast_ty.span,
 647                     "found `ty_infer` in unexpected place");
 648             }
 649         });
 650
 651     let mut ast_ty_to_ty_cache = tcx.ast_ty_to_ty_cache.borrow_mut();
 652     ast_ty_to_ty_cache.get().insert(ast_ty.id, ty::atttce_resolved(typ));
 653     return typ;
 654 }
 655
 656 pub fn ty_of_arg<AC: AstConv, RS: RegionScope>(this: &AC, rscope: &RS, a: &ast::Arg,
 657                                                expected_ty: Option<ty::t>) -> ty::t {
 658     match a.ty.node {
 659         ast::TyInfer if expected_ty.is_some() => expected_ty.unwrap(),
 660         ast::TyInfer => this.ty_infer(a.ty.span),
 661         _ => ast_ty_to_ty(this, rscope, a.ty),
 662     }
 663 }
 664
 665 struct SelfInfo {
 666     untransformed_self_ty: ty::t,
 667     explicit_self: ast::ExplicitSelf
 668 }
 669
 670 pub fn ty_of_method<AC:AstConv>(
 671     this: &AC,
 672     id: ast::NodeId,
 673     purity: ast::Purity,
 674     untransformed_self_ty: ty::t,
 675     explicit_self: ast::ExplicitSelf,
 676     decl: &ast::FnDecl) -> ty::BareFnTy {
 677     ty_of_method_or_bare_fn(this, id, purity, AbiSet::Rust(), Some(SelfInfo {
 678         untransformed_self_ty: untransformed_self_ty,
 679         explicit_self: explicit_self
 680     }), decl)
 681 }
 682
 683 pub fn ty_of_bare_fn<AC:AstConv>(this: &AC, id: ast::NodeId,
 684                                  purity: ast::Purity, abi: AbiSet,
 685                                  decl: &ast::FnDecl) -> ty::BareFnTy {
 686     ty_of_method_or_bare_fn(this, id, purity, abi, None, decl)
 687 }
 688
 689 fn ty_of_method_or_bare_fn<AC:AstConv>(this: &AC, id: ast::NodeId,
 690                                        purity: ast::Purity, abi: AbiSet,
 691                                        opt_self_info: Option<SelfInfo>,
 692                                        decl: &ast::FnDecl) -> ty::BareFnTy {
 693     debug!("ty_of_method_or_bare_fn");
 694
 695     // new region names that appear inside of the fn decl are bound to
 696     // that function type
 697     let rb = rscope::BindingRscope::new(id);
 698
 699     let self_ty = opt_self_info.and_then(|self_info| {
 700         match self_info.explicit_self.node {
 701             ast::SelfStatic => None,
 702             ast::SelfValue => {
 703                 Some(self_info.untransformed_self_ty)
 704             }
 705             ast::SelfRegion(ref lifetime, mutability) => {
 706                 let region =
 707                     opt_ast_region_to_region(this, &rb,
 708                                              self_info.explicit_self.span,
 709                                              lifetime);
 710                 Some(ty::mk_rptr(this.tcx(), region,
 711                                  ty::mt {ty: self_info.untransformed_self_ty,
 712                                          mutbl: mutability}))
 713             }
 714             ast::SelfUniq => {
 715                 Some(ty::mk_uniq(this.tcx(), self_info.untransformed_self_ty))
 716             }
 717         }
 718     });
 719
 720     // HACK(eddyb) replace the fake self type in the AST with the actual type.
 721     let input_tys = if self_ty.is_some() {
 722         decl.inputs.slice_from(1)
 723     } else {
 724         decl.inputs.as_slice()
 725     };
 726     let input_tys = input_tys.iter().map(|a| ty_of_arg(this, &rb, a, None));
 727
 728     let self_and_input_tys = self_ty.move_iter().chain(input_tys).collect();
 729
 730     let output_ty = match decl.output.node {
 731         ast::TyInfer => this.ty_infer(decl.output.span),
 732         _ => ast_ty_to_ty(this, &rb, decl.output)
 733     };
 734
 735     return ty::BareFnTy {
 736         purity: purity,
 737         abis: abi,
 738         sig: ty::FnSig {
 739             binder_id: id,
 740             inputs: self_and_input_tys,
 741             output: output_ty,
 742             variadic: decl.variadic
 743         }
 744     };
 745 }
 746
 747 pub fn ty_of_closure<AC:AstConv,RS:RegionScope>(
 748     this: &AC,
 749     rscope: &RS,
 750     id: ast::NodeId,
 751     sigil: ast::Sigil,
 752     purity: ast::Purity,
 753     onceness: ast::Onceness,
 754     bounds: ty::BuiltinBounds,
 755     opt_lifetime: &Option<ast::Lifetime>,
 756     decl: &ast::FnDecl,
 757     expected_sig: Option<ty::FnSig>,
 758     span: Span)
 759     -> ty::ClosureTy
 760 {
 761     debug!("ty_of_fn_decl");
 762
 763     // resolve the function bound region in the original region
 764     // scope `rscope`, not the scope of the function parameters
 765     let bound_region = match opt_lifetime {
 766         &Some(ref lifetime) => {
 767             ast_region_to_region(this.tcx(), lifetime)
 768         }
 769         &None => {
 770             match sigil {
 771                 ast::OwnedSigil | ast::ManagedSigil => {
 772                     // @fn(), ~fn() default to static as the bound
 773                     // on their upvars:
 774                     ty::ReStatic
 775                 }
 776                 ast::BorrowedSigil => {
 777                     // || defaults as normal for an omitted lifetime:
 778                     opt_ast_region_to_region(this, rscope, span, opt_lifetime)
 779                 }
 780             }
 781         }
 782     };
 783
 784     // new region names that appear inside of the fn decl are bound to
 785     // that function type
 786     let rb = rscope::BindingRscope::new(id);
 787
 788     let input_tys = decl.inputs.iter().enumerate().map(|(i, a)| {
 789         let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
 790             // no guarantee that the correct number of expected args
 791             // were supplied
 792             if i < e.inputs.len() {Some(e.inputs[i])} else {None}
 793         });
 794         ty_of_arg(this, &rb, a, expected_arg_ty)
 795     }).collect();
 796
 797     let expected_ret_ty = expected_sig.map(|e| e.output);
 798     let output_ty = match decl.output.node {
 799         ast::TyInfer if expected_ret_ty.is_some() => expected_ret_ty.unwrap(),
 800         ast::TyInfer => this.ty_infer(decl.output.span),
 801         _ => ast_ty_to_ty(this, &rb, decl.output)
 802     };
 803
 804     ty::ClosureTy {
 805         purity: purity,
 806         sigil: sigil,
 807         onceness: onceness,
 808         region: bound_region,
 809         bounds: bounds,
 810         sig: ty::FnSig {binder_id: id,
 811                         inputs: input_tys,
 812                         output: output_ty,
 813                         variadic: decl.variadic}
 814     }
 815 }
 816
 817 fn conv_builtin_bounds(tcx: ty::ctxt, ast_bounds: &Option<OptVec<ast::TyParamBound>>,
 818                        store: ty::TraitStore)
 819                        -> ty::BuiltinBounds {
 820     //! Converts a list of bounds from the AST into a `BuiltinBounds`
 821     //! struct. Reports an error if any of the bounds that appear
 822     //! in the AST refer to general traits and not the built-in traits
 823     //! like `Send`. Used to translate the bounds that
 824     //! appear in closure and trait types, where only builtin bounds are
 825     //! legal.
 826     //! If no bounds were specified, we choose a "default" bound based on
 827     //! the allocation type of the fn/trait, as per issue #7264. The user can
 828     //! override this with an empty bounds list, e.g. "~fn:()" or "~Trait:".
 829
 830     match (ast_bounds, store) {
 831         (&Some(ref bound_vec), _) => {
 832             let mut builtin_bounds = ty::EmptyBuiltinBounds();
 833             for ast_bound in bound_vec.iter() {
 834                 match *ast_bound {
 835                     ast::TraitTyParamBound(ref b) => {
 836                         match lookup_def_tcx(tcx, b.path.span, b.ref_id) {
 837                             ast::DefTrait(trait_did) => {
 838                                 if ty::try_add_builtin_trait(tcx, trait_did,
 839                                                              &mut builtin_bounds) {
 840                                     continue; // success
 841                                 }
 842                             }
 843                             _ => { }
 844                         }
 845                         tcx.sess.span_fatal(
 846                             b.path.span,
 847                             format!("only the builtin traits can be used \
 848                                   as closure or object bounds"));
 849                     }
 850                     ast::RegionTyParamBound => {
 851                         builtin_bounds.add(ty::BoundStatic);
 852                     }
 853                 }
 854             }
 855             builtin_bounds
 856         },
 857         // ~Trait is sugar for ~Trait:Send.
 858         (&None, ty::UniqTraitStore) => {
 859             let mut set = ty::EmptyBuiltinBounds(); set.add(ty::BoundSend); set
 860         }
 861         // &'static Trait is sugar for &'static Trait:'static.
 862         (&None, ty::RegionTraitStore(ty::ReStatic)) => {
 863             let mut set = ty::EmptyBuiltinBounds(); set.add(ty::BoundStatic); set
 864         }
 865         // &'r Trait is sugar for &'r Trait:<no-bounds>.
 866         (&None, ty::RegionTraitStore(..)) => ty::EmptyBuiltinBounds(),
 867     }
 868 }