src/librustc_typeck/collect.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
  13 # Collect phase
  14
  15 The collect phase of type check has the job of visiting all items,
  16 determining their type, and writing that type into the `tcx.tcache`
  17 table.  Despite its name, this table does not really operate as a
  18 *cache*, at least not for the types of items defined within the
  19 current crate: we assume that after the collect phase, the types of
  20 all local items will be present in the table.
  21
  22 Unlike most of the types that are present in Rust, the types computed
  23 for each item are in fact type schemes. This means that they are
  24 generic types that may have type parameters. TypeSchemes are
  25 represented by an instance of `ty::TypeScheme`.  This combines the
  26 core type along with a list of the bounds for each parameter. Type
  27 parameters themselves are represented as `ty_param()` instances.
  28
  29 The phasing of type conversion is somewhat complicated. There is no
  30 clear set of phases we can enforce (e.g., converting traits first,
  31 then types, or something like that) because the user can introduce
  32 arbitrary interdependencies. So instead we generally convert things
  33 lazilly and on demand, and include logic that checks for cycles.
  34 Demand is driven by calls to `AstConv::get_item_type_scheme` or
  35 `AstConv::lookup_trait_def`.
  36
  37 Currently, we "convert" types and traits in three phases (note that
  38 conversion only affects the types of items / enum variants / methods;
  39 it does not e.g. compute the types of individual expressions):
  40
  41 0. Intrinsics
  42 1. Trait definitions
  43 2. Type definitions
  44
  45 Conversion itself is done by simply walking each of the items in turn
  46 and invoking an appropriate function (e.g., `trait_def_of_item` or
  47 `convert_item`). However, it is possible that while converting an
  48 item, we may need to compute the *type scheme* or *trait definition*
  49 for other items.
  50
  51 There are some shortcomings in this design:
  52
  53 - Before walking the set of supertraits for a given trait, you must
  54   call `ensure_super_predicates` on that trait def-id. Otherwise,
  55   `lookup_super_predicates` will result in ICEs.
  56 - Because the type scheme includes defaults, cycles through type
  57   parameter defaults are illegal even if those defaults are never
  58   employed. This is not necessarily a bug.
  59 - The phasing of trait definitions before type definitions does not
  60   seem to be necessary, sufficient, or particularly helpful, given that
  61   processing a trait definition can trigger processing a type def and
  62   vice versa. However, if I remove it, I get ICEs, so some more work is
  63   needed in that area. -nmatsakis
  64
  65 */
  66
  67 use astconv::{self, AstConv, ty_of_arg, ast_ty_to_ty, ast_region_to_region};
  68 use middle::def;
  69 use middle::def_id::DefId;
  70 use constrained_type_params as ctp;
  71 use middle::lang_items::SizedTraitLangItem;
  72 use middle::free_region::FreeRegionMap;
  73 use middle::region;
  74 use middle::resolve_lifetime;
  75 use middle::const_eval::{self, ConstVal};
  76 use middle::const_eval::EvalHint::UncheckedExprHint;
  77 use middle::subst::{Substs, FnSpace, ParamSpace, SelfSpace, TypeSpace, VecPerParamSpace};
  78 use middle::ty::{ToPredicate, ImplContainer, ImplOrTraitItemContainer, TraitContainer};
  79 use middle::ty::{self, RegionEscape, ToPolyTraitRef, Ty, TypeScheme};
  80 use middle::ty::{VariantKind};
  81 use middle::ty::fold::{TypeFolder, TypeFoldable};
  82 use middle::ty::util::IntTypeExt;
  83 use middle::infer;
  84 use rscope::*;
  85 use rustc::front::map as hir_map;
  86 use util::common::{ErrorReported, memoized};
  87 use util::nodemap::{FnvHashMap, FnvHashSet};
  88 use write_ty_to_tcx;
  89
  90 use std::cell::{Cell, RefCell};
  91 use std::collections::HashSet;
  92 use std::rc::Rc;
  93
  94 use syntax::abi;
  95 use syntax::ast;
  96 use syntax::attr;
  97 use syntax::codemap::Span;
  98 use syntax::parse::token::special_idents;
  99 use syntax::ptr::P;
 100 use rustc_front::hir;
 101 use rustc_front::visit;
 102 use rustc_front::print::pprust;
 103
 104 ///////////////////////////////////////////////////////////////////////////
 105 // Main entry point
 106
 107 pub fn collect_item_types(tcx: &ty::ctxt) {
 108     let ccx = &CrateCtxt { tcx: tcx, stack: RefCell::new(Vec::new()) };
 109
 110     let mut visitor = CollectTraitDefVisitor{ ccx: ccx };
 111     visit::walk_crate(&mut visitor, ccx.tcx.map.krate());
 112
 113     let mut visitor = CollectItemTypesVisitor{ ccx: ccx };
 114     visit::walk_crate(&mut visitor, ccx.tcx.map.krate());
 115 }
 116
 117 ///////////////////////////////////////////////////////////////////////////
 118
 119 struct CrateCtxt<'a,'tcx:'a> {
 120     tcx: &'a ty::ctxt<'tcx>,
 121
 122     // This stack is used to identify cycles in the user's source.
 123     // Note that these cycles can cross multiple items.
 124     stack: RefCell<Vec<AstConvRequest>>,
 125 }
 126
 127 /// Context specific to some particular item. This is what implements
 128 /// AstConv. It has information about the predicates that are defined
 129 /// on the trait. Unfortunately, this predicate information is
 130 /// available in various different forms at various points in the
 131 /// process. So we can't just store a pointer to e.g. the AST or the
 132 /// parsed ty form, we have to be more flexible. To this end, the
 133 /// `ItemCtxt` is parameterized by a `GetTypeParameterBounds` object
 134 /// that it uses to satisfy `get_type_parameter_bounds` requests.
 135 /// This object might draw the information from the AST
 136 /// (`hir::Generics`) or it might draw from a `ty::GenericPredicates`
 137 /// or both (a tuple).
 138 struct ItemCtxt<'a,'tcx:'a> {
 139     ccx: &'a CrateCtxt<'a,'tcx>,
 140     param_bounds: &'a (GetTypeParameterBounds<'tcx>+'a),
 141 }
 142
 143 #[derive(Copy, Clone, PartialEq, Eq)]
 144 enum AstConvRequest {
 145     GetItemTypeScheme(DefId),
 146     GetTraitDef(DefId),
 147     EnsureSuperPredicates(DefId),
 148     GetTypeParameterBounds(ast::NodeId),
 149 }
 150
 151 ///////////////////////////////////////////////////////////////////////////
 152 // First phase: just collect *trait definitions* -- basically, the set
 153 // of type parameters and supertraits. This is information we need to
 154 // know later when parsing field defs.
 155
 156 struct CollectTraitDefVisitor<'a, 'tcx: 'a> {
 157     ccx: &'a CrateCtxt<'a, 'tcx>
 158 }
 159
 160 impl<'a, 'tcx, 'v> visit::Visitor<'v> for CollectTraitDefVisitor<'a, 'tcx> {
 161     fn visit_item(&mut self, i: &hir::Item) {
 162         match i.node {
 163             hir::ItemTrait(..) => {
 164                 // computing the trait def also fills in the table
 165                 let _ = trait_def_of_item(self.ccx, i);
 166             }
 167             _ => { }
 168         }
 169
 170         visit::walk_item(self, i);
 171     }
 172 }
 173
 174 ///////////////////////////////////////////////////////////////////////////
 175 // Second phase: collection proper.
 176
 177 struct CollectItemTypesVisitor<'a, 'tcx: 'a> {
 178     ccx: &'a CrateCtxt<'a, 'tcx>
 179 }
 180
 181 impl<'a, 'tcx, 'v> visit::Visitor<'v> for CollectItemTypesVisitor<'a, 'tcx> {
 182     fn visit_item(&mut self, i: &hir::Item) {
 183         convert_item(self.ccx, i);
 184         visit::walk_item(self, i);
 185     }
 186     fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
 187         convert_foreign_item(self.ccx, i);
 188         visit::walk_foreign_item(self, i);
 189     }
 190 }
 191
 192 ///////////////////////////////////////////////////////////////////////////
 193 // Utility types and common code for the above passes.
 194
 195 impl<'a,'tcx> CrateCtxt<'a,'tcx> {
 196     fn icx(&'a self, param_bounds: &'a GetTypeParameterBounds<'tcx>) -> ItemCtxt<'a,'tcx> {
 197         ItemCtxt { ccx: self, param_bounds: param_bounds }
 198     }
 199
 200     fn method_ty(&self, method_id: ast::NodeId) -> Rc<ty::Method<'tcx>> {
 201         let def_id = self.tcx.map.local_def_id(method_id);
 202         match *self.tcx.impl_or_trait_items.borrow().get(&def_id).unwrap() {
 203             ty::MethodTraitItem(ref mty) => mty.clone(),
 204             _ => {
 205                 self.tcx.sess.bug(&format!("method with id {} has the wrong type", method_id));
 206             }
 207         }
 208     }
 209
 210     fn cycle_check<F,R>(&self,
 211                         span: Span,
 212                         request: AstConvRequest,
 213                         code: F)
 214                         -> Result<R,ErrorReported>
 215         where F: FnOnce() -> Result<R,ErrorReported>
 216     {
 217         {
 218             let mut stack = self.stack.borrow_mut();
 219             match stack.iter().enumerate().rev().find(|&(_, r)| *r == request) {
 220                 None => { }
 221                 Some((i, _)) => {
 222                     let cycle = &stack[i..];
 223                     self.report_cycle(span, cycle);
 224                     return Err(ErrorReported);
 225                 }
 226             }
 227             stack.push(request);
 228         }
 229
 230         let result = code();
 231
 232         self.stack.borrow_mut().pop();
 233         result
 234     }
 235
 236     fn report_cycle(&self,
 237                     span: Span,
 238                     cycle: &[AstConvRequest])
 239     {
 240         assert!(!cycle.is_empty());
 241         let tcx = self.tcx;
 242
 243         span_err!(tcx.sess, span, E0391,
 244             "unsupported cyclic reference between types/traits detected");
 245
 246         match cycle[0] {
 247             AstConvRequest::GetItemTypeScheme(def_id) |
 248             AstConvRequest::GetTraitDef(def_id) => {
 249                 tcx.sess.note(
 250                     &format!("the cycle begins when processing `{}`...",
 251                              tcx.item_path_str(def_id)));
 252             }
 253             AstConvRequest::EnsureSuperPredicates(def_id) => {
 254                 tcx.sess.note(
 255                     &format!("the cycle begins when computing the supertraits of `{}`...",
 256                              tcx.item_path_str(def_id)));
 257             }
 258             AstConvRequest::GetTypeParameterBounds(id) => {
 259                 let def = tcx.type_parameter_def(id);
 260                 tcx.sess.note(
 261                     &format!("the cycle begins when computing the bounds \
 262                               for type parameter `{}`...",
 263                              def.name));
 264             }
 265         }
 266
 267         for request in &cycle[1..] {
 268             match *request {
 269                 AstConvRequest::GetItemTypeScheme(def_id) |
 270                 AstConvRequest::GetTraitDef(def_id) => {
 271                     tcx.sess.note(
 272                         &format!("...which then requires processing `{}`...",
 273                                  tcx.item_path_str(def_id)));
 274                 }
 275                 AstConvRequest::EnsureSuperPredicates(def_id) => {
 276                     tcx.sess.note(
 277                         &format!("...which then requires computing the supertraits of `{}`...",
 278                                  tcx.item_path_str(def_id)));
 279                 }
 280                 AstConvRequest::GetTypeParameterBounds(id) => {
 281                     let def = tcx.type_parameter_def(id);
 282                     tcx.sess.note(
 283                         &format!("...which then requires computing the bounds \
 284                                   for type parameter `{}`...",
 285                                  def.name));
 286                 }
 287             }
 288         }
 289
 290         match cycle[0] {
 291             AstConvRequest::GetItemTypeScheme(def_id) |
 292             AstConvRequest::GetTraitDef(def_id) => {
 293                 tcx.sess.note(
 294                     &format!("...which then again requires processing `{}`, completing the cycle.",
 295                              tcx.item_path_str(def_id)));
 296             }
 297             AstConvRequest::EnsureSuperPredicates(def_id) => {
 298                 tcx.sess.note(
 299                     &format!("...which then again requires computing the supertraits of `{}`, \
 300                               completing the cycle.",
 301                              tcx.item_path_str(def_id)));
 302             }
 303             AstConvRequest::GetTypeParameterBounds(id) => {
 304                 let def = tcx.type_parameter_def(id);
 305                 tcx.sess.note(
 306                     &format!("...which then again requires computing the bounds \
 307                               for type parameter `{}`, completing the cycle.",
 308                              def.name));
 309             }
 310         }
 311     }
 312
 313     /// Loads the trait def for a given trait, returning ErrorReported if a cycle arises.
 314     fn get_trait_def(&self, trait_id: DefId)
 315                      -> &'tcx ty::TraitDef<'tcx>
 316     {
 317         let tcx = self.tcx;
 318
 319         if let Some(trait_id) = tcx.map.as_local_node_id(trait_id) {
 320             let item = match tcx.map.get(trait_id) {
 321                 hir_map::NodeItem(item) => item,
 322                 _ => tcx.sess.bug(&format!("get_trait_def({:?}): not an item", trait_id))
 323             };
 324
 325             trait_def_of_item(self, &*item)
 326         } else {
 327             tcx.lookup_trait_def(trait_id)
 328         }
 329     }
 330
 331     /// Ensure that the (transitive) super predicates for
 332     /// `trait_def_id` are available. This will report a cycle error
 333     /// if a trait `X` (transitively) extends itself in some form.
 334     fn ensure_super_predicates(&self, span: Span, trait_def_id: DefId)
 335                                -> Result<(), ErrorReported>
 336     {
 337         self.cycle_check(span, AstConvRequest::EnsureSuperPredicates(trait_def_id), || {
 338             let def_ids = ensure_super_predicates_step(self, trait_def_id);
 339
 340             for def_id in def_ids {
 341                 try!(self.ensure_super_predicates(span, def_id));
 342             }
 343
 344             Ok(())
 345         })
 346     }
 347 }
 348
 349 impl<'a,'tcx> ItemCtxt<'a,'tcx> {
 350     fn to_ty<RS:RegionScope>(&self, rs: &RS, ast_ty: &hir::Ty) -> Ty<'tcx> {
 351         ast_ty_to_ty(self, rs, ast_ty)
 352     }
 353 }
 354
 355 impl<'a, 'tcx> AstConv<'tcx> for ItemCtxt<'a, 'tcx> {
 356     fn tcx(&self) -> &ty::ctxt<'tcx> { self.ccx.tcx }
 357
 358     fn get_item_type_scheme(&self, span: Span, id: DefId)
 359                             -> Result<ty::TypeScheme<'tcx>, ErrorReported>
 360     {
 361         self.ccx.cycle_check(span, AstConvRequest::GetItemTypeScheme(id), || {
 362             Ok(type_scheme_of_def_id(self.ccx, id))
 363         })
 364     }
 365
 366     fn get_trait_def(&self, span: Span, id: DefId)
 367                      -> Result<&'tcx ty::TraitDef<'tcx>, ErrorReported>
 368     {
 369         self.ccx.cycle_check(span, AstConvRequest::GetTraitDef(id), || {
 370             Ok(self.ccx.get_trait_def(id))
 371         })
 372     }
 373
 374     fn ensure_super_predicates(&self,
 375                                span: Span,
 376                                trait_def_id: DefId)
 377                                -> Result<(), ErrorReported>
 378     {
 379         debug!("ensure_super_predicates(trait_def_id={:?})",
 380                trait_def_id);
 381
 382         self.ccx.ensure_super_predicates(span, trait_def_id)
 383     }
 384
 385
 386     fn get_type_parameter_bounds(&self,
 387                                  span: Span,
 388                                  node_id: ast::NodeId)
 389                                  -> Result<Vec<ty::PolyTraitRef<'tcx>>, ErrorReported>
 390     {
 391         self.ccx.cycle_check(span, AstConvRequest::GetTypeParameterBounds(node_id), || {
 392             let v = self.param_bounds.get_type_parameter_bounds(self, span, node_id)
 393                                      .into_iter()
 394                                      .filter_map(|p| p.to_opt_poly_trait_ref())
 395                                      .collect();
 396             Ok(v)
 397         })
 398     }
 399
 400     fn trait_defines_associated_type_named(&self,
 401                                            trait_def_id: DefId,
 402                                            assoc_name: ast::Name)
 403                                            -> bool
 404     {
 405         if let Some(trait_id) = self.tcx().map.as_local_node_id(trait_def_id) {
 406             trait_defines_associated_type_named(self.ccx, trait_id, assoc_name)
 407         } else {
 408             let trait_def = self.tcx().lookup_trait_def(trait_def_id);
 409             trait_def.associated_type_names.contains(&assoc_name)
 410         }
 411     }
 412
 413         fn ty_infer(&self,
 414                     _ty_param_def: Option<ty::TypeParameterDef<'tcx>>,
 415                     _substs: Option<&mut Substs<'tcx>>,
 416                     _space: Option<ParamSpace>,
 417                     span: Span) -> Ty<'tcx> {
 418         span_err!(self.tcx().sess, span, E0121,
 419                   "the type placeholder `_` is not allowed within types on item signatures");
 420         self.tcx().types.err
 421     }
 422
 423     fn projected_ty(&self,
 424                     _span: Span,
 425                     trait_ref: ty::TraitRef<'tcx>,
 426                     item_name: ast::Name)
 427                     -> Ty<'tcx>
 428     {
 429         self.tcx().mk_projection(trait_ref, item_name)
 430     }
 431 }
 432
 433 /// Interface used to find the bounds on a type parameter from within
 434 /// an `ItemCtxt`. This allows us to use multiple kinds of sources.
 435 trait GetTypeParameterBounds<'tcx> {
 436     fn get_type_parameter_bounds(&self,
 437                                  astconv: &AstConv<'tcx>,
 438                                  span: Span,
 439                                  node_id: ast::NodeId)
 440                                  -> Vec<ty::Predicate<'tcx>>;
 441 }
 442
 443 /// Find bounds from both elements of the tuple.
 444 impl<'a,'b,'tcx,A,B> GetTypeParameterBounds<'tcx> for (&'a A,&'b B)
 445     where A : GetTypeParameterBounds<'tcx>, B : GetTypeParameterBounds<'tcx>
 446 {
 447     fn get_type_parameter_bounds(&self,
 448                                  astconv: &AstConv<'tcx>,
 449                                  span: Span,
 450                                  node_id: ast::NodeId)
 451                                  -> Vec<ty::Predicate<'tcx>>
 452     {
 453         let mut v = self.0.get_type_parameter_bounds(astconv, span, node_id);
 454         v.extend(self.1.get_type_parameter_bounds(astconv, span, node_id));
 455         v
 456     }
 457 }
 458
 459 /// Empty set of bounds.
 460 impl<'tcx> GetTypeParameterBounds<'tcx> for () {
 461     fn get_type_parameter_bounds(&self,
 462                                  _astconv: &AstConv<'tcx>,
 463                                  _span: Span,
 464                                  _node_id: ast::NodeId)
 465                                  -> Vec<ty::Predicate<'tcx>>
 466     {
 467         Vec::new()
 468     }
 469 }
 470
 471 /// Find bounds from the parsed and converted predicates.  This is
 472 /// used when converting methods, because by that time the predicates
 473 /// from the trait/impl have been fully converted.
 474 impl<'tcx> GetTypeParameterBounds<'tcx> for ty::GenericPredicates<'tcx> {
 475     fn get_type_parameter_bounds(&self,
 476                                  astconv: &AstConv<'tcx>,
 477                                  _span: Span,
 478                                  node_id: ast::NodeId)
 479                                  -> Vec<ty::Predicate<'tcx>>
 480     {
 481         let def = astconv.tcx().type_parameter_def(node_id);
 482
 483         self.predicates
 484             .iter()
 485             .filter(|predicate| {
 486                 match **predicate {
 487                     ty::Predicate::Trait(ref data) => {
 488                         data.skip_binder().self_ty().is_param(def.space, def.index)
 489                     }
 490                     ty::Predicate::TypeOutlives(ref data) => {
 491                         data.skip_binder().0.is_param(def.space, def.index)
 492                     }
 493                     ty::Predicate::Equate(..) |
 494                     ty::Predicate::RegionOutlives(..) |
 495                     ty::Predicate::WellFormed(..) |
 496                     ty::Predicate::ObjectSafe(..) |
 497                     ty::Predicate::Projection(..) => {
 498                         false
 499                     }
 500                 }
 501             })
 502             .cloned()
 503             .collect()
 504     }
 505 }
 506
 507 /// Find bounds from hir::Generics. This requires scanning through the
 508 /// AST. We do this to avoid having to convert *all* the bounds, which
 509 /// would create artificial cycles. Instead we can only convert the
 510 /// bounds for a type parameter `X` if `X::Foo` is used.
 511 impl<'tcx> GetTypeParameterBounds<'tcx> for hir::Generics {
 512     fn get_type_parameter_bounds(&self,
 513                                  astconv: &AstConv<'tcx>,
 514                                  _: Span,
 515                                  node_id: ast::NodeId)
 516                                  -> Vec<ty::Predicate<'tcx>>
 517     {
 518         // In the AST, bounds can derive from two places. Either
 519         // written inline like `<T:Foo>` or in a where clause like
 520         // `where T:Foo`.
 521
 522         let def = astconv.tcx().type_parameter_def(node_id);
 523         let ty = astconv.tcx().mk_param_from_def(&def);
 524
 525         let from_ty_params =
 526             self.ty_params
 527                 .iter()
 528                 .filter(|p| p.id == node_id)
 529                 .flat_map(|p| p.bounds.iter())
 530                 .flat_map(|b| predicates_from_bound(astconv, ty, b));
 531
 532         let from_where_clauses =
 533             self.where_clause
 534                 .predicates
 535                 .iter()
 536                 .filter_map(|wp| match *wp {
 537                     hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
 538                     _ => None
 539                 })
 540                 .filter(|bp| is_param(astconv.tcx(), &bp.bounded_ty, node_id))
 541                 .flat_map(|bp| bp.bounds.iter())
 542                 .flat_map(|b| predicates_from_bound(astconv, ty, b));
 543
 544         from_ty_params.chain(from_where_clauses).collect()
 545     }
 546 }
 547
 548 /// Tests whether this is the AST for a reference to the type
 549 /// parameter with id `param_id`. We use this so as to avoid running
 550 /// `ast_ty_to_ty`, because we want to avoid triggering an all-out
 551 /// conversion of the type to avoid inducing unnecessary cycles.
 552 fn is_param<'tcx>(tcx: &ty::ctxt<'tcx>,
 553                   ast_ty: &hir::Ty,
 554                   param_id: ast::NodeId)
 555                   -> bool
 556 {
 557     if let hir::TyPath(None, _) = ast_ty.node {
 558         let path_res = *tcx.def_map.borrow().get(&ast_ty.id).unwrap();
 559         match path_res.base_def {
 560             def::DefSelfTy(Some(def_id), None) => {
 561                 path_res.depth == 0 && def_id == tcx.map.local_def_id(param_id)
 562             }
 563             def::DefTyParam(_, _, def_id, _) => {
 564                 path_res.depth == 0 && def_id == tcx.map.local_def_id(param_id)
 565             }
 566             _ => {
 567                 false
 568             }
 569         }
 570     } else {
 571         false
 572     }
 573 }
 574
 575
 576 fn convert_method<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
 577                             container: ImplOrTraitItemContainer,
 578                             sig: &hir::MethodSig,
 579                             id: ast::NodeId,
 580                             name: ast::Name,
 581                             vis: hir::Visibility,
 582                             untransformed_rcvr_ty: Ty<'tcx>,
 583                             rcvr_ty_generics: &ty::Generics<'tcx>,
 584                             rcvr_ty_predicates: &ty::GenericPredicates<'tcx>) {
 585     let ty_generics = ty_generics_for_fn(ccx, &sig.generics, rcvr_ty_generics);
 586
 587     let ty_generic_predicates =
 588         ty_generic_predicates_for_fn(ccx, &sig.generics, rcvr_ty_predicates);
 589
 590     let (fty, explicit_self_category) =
 591         astconv::ty_of_method(&ccx.icx(&(rcvr_ty_predicates, &sig.generics)),
 592                               sig, untransformed_rcvr_ty);
 593
 594     let def_id = ccx.tcx.map.local_def_id(id);
 595     let ty_method = ty::Method::new(name,
 596                                     ty_generics,
 597                                     ty_generic_predicates,
 598                                     fty,
 599                                     explicit_self_category,
 600                                     vis,
 601                                     def_id,
 602                                     container);
 603
 604     let fty = ccx.tcx.mk_fn(Some(def_id),
 605                             ccx.tcx.mk_bare_fn(ty_method.fty.clone()));
 606     debug!("method {} (id {}) has type {:?}",
 607             name, id, fty);
 608     ccx.tcx.register_item_type(def_id, TypeScheme {
 609         generics: ty_method.generics.clone(),
 610         ty: fty
 611     });
 612     ccx.tcx.predicates.borrow_mut().insert(def_id, ty_method.predicates.clone());
 613
 614     write_ty_to_tcx(ccx.tcx, id, fty);
 615
 616     debug!("writing method type: def_id={:?} mty={:?}",
 617             def_id, ty_method);
 618
 619     ccx.tcx.impl_or_trait_items.borrow_mut().insert(def_id,
 620         ty::MethodTraitItem(Rc::new(ty_method)));
 621 }
 622
 623 fn convert_field<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
 624                            struct_generics: &ty::Generics<'tcx>,
 625                            struct_predicates: &ty::GenericPredicates<'tcx>,
 626                            v: &hir::StructField,
 627                            ty_f: ty::FieldDefMaster<'tcx>)
 628 {
 629     let tt = ccx.icx(struct_predicates).to_ty(&ExplicitRscope, &*v.node.ty);
 630     ty_f.fulfill_ty(tt);
 631     write_ty_to_tcx(ccx.tcx, v.node.id, tt);
 632
 633     /* add the field to the tcache */
 634     ccx.tcx.register_item_type(ccx.tcx.map.local_def_id(v.node.id),
 635                                ty::TypeScheme {
 636                                    generics: struct_generics.clone(),
 637                                    ty: tt
 638                                });
 639     ccx.tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(v.node.id),
 640                                            struct_predicates.clone());
 641 }
 642
 643 fn convert_associated_const<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
 644                                       container: ImplOrTraitItemContainer,
 645                                       name: ast::Name,
 646                                       id: ast::NodeId,
 647                                       vis: hir::Visibility,
 648                                       ty: ty::Ty<'tcx>,
 649                                       has_value: bool)
 650 {
 651     ccx.tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(id),
 652                                            ty::GenericPredicates::empty());
 653
 654     write_ty_to_tcx(ccx.tcx, id, ty);
 655
 656     let associated_const = Rc::new(ty::AssociatedConst {
 657         name: name,
 658         vis: vis,
 659         def_id: ccx.tcx.map.local_def_id(id),
 660         container: container,
 661         ty: ty,
 662         has_value: has_value
 663     });
 664     ccx.tcx.impl_or_trait_items.borrow_mut()
 665        .insert(ccx.tcx.map.local_def_id(id), ty::ConstTraitItem(associated_const));
 666 }
 667
 668 fn convert_associated_type<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
 669                                      container: ImplOrTraitItemContainer,
 670                                      name: ast::Name,
 671                                      id: ast::NodeId,
 672                                      vis: hir::Visibility,
 673                                      ty: Option<Ty<'tcx>>)
 674 {
 675     let associated_type = Rc::new(ty::AssociatedType {
 676         name: name,
 677         vis: vis,
 678         ty: ty,
 679         def_id: ccx.tcx.map.local_def_id(id),
 680         container: container
 681     });
 682     ccx.tcx.impl_or_trait_items.borrow_mut()
 683        .insert(ccx.tcx.map.local_def_id(id), ty::TypeTraitItem(associated_type));
 684 }
 685
 686 fn convert_methods<'a,'tcx,'i,I>(ccx: &CrateCtxt<'a, 'tcx>,
 687                                  container: ImplOrTraitItemContainer,
 688                                  methods: I,
 689                                  untransformed_rcvr_ty: Ty<'tcx>,
 690                                  rcvr_ty_generics: &ty::Generics<'tcx>,
 691                                  rcvr_ty_predicates: &ty::GenericPredicates<'tcx>)
 692     where I: Iterator<Item=(&'i hir::MethodSig, ast::NodeId, ast::Name, hir::Visibility, Span)>
 693 {
 694     debug!("convert_methods(untransformed_rcvr_ty={:?}, rcvr_ty_generics={:?}, \
 695                             rcvr_ty_predicates={:?})",
 696            untransformed_rcvr_ty,
 697            rcvr_ty_generics,
 698            rcvr_ty_predicates);
 699
 700     for (sig, id, name, vis, _span) in methods {
 701         convert_method(ccx,
 702                        container,
 703                        sig,
 704                        id,
 705                        name,
 706                        vis,
 707                        untransformed_rcvr_ty,
 708                        rcvr_ty_generics,
 709                        rcvr_ty_predicates);
 710     }
 711 }
 712
 713 fn ensure_no_ty_param_bounds(ccx: &CrateCtxt,
 714                                  span: Span,
 715                                  generics: &hir::Generics,
 716                                  thing: &'static str) {
 717     let mut warn = false;
 718
 719     for ty_param in generics.ty_params.iter() {
 720         for bound in ty_param.bounds.iter() {
 721             match *bound {
 722                 hir::TraitTyParamBound(..) => {
 723                     warn = true;
 724                 }
 725                 hir::RegionTyParamBound(..) => { }
 726             }
 727         }
 728     }
 729
 730     if warn {
 731         // According to accepted RFC #XXX, we should
 732         // eventually accept these, but it will not be
 733         // part of this PR. Still, convert to warning to
 734         // make bootstrapping easier.
 735         span_warn!(ccx.tcx.sess, span, E0122,
 736                    "trait bounds are not (yet) enforced \
 737                    in {} definitions",
 738                    thing);
 739     }
 740 }
 741
 742 fn convert_item(ccx: &CrateCtxt, it: &hir::Item) {
 743     let tcx = ccx.tcx;
 744     debug!("convert: item {} with id {}", it.name, it.id);
 745     match it.node {
 746         // These don't define types.
 747         hir::ItemExternCrate(_) | hir::ItemUse(_) |
 748         hir::ItemForeignMod(_) | hir::ItemMod(_) => {
 749         }
 750         hir::ItemEnum(ref enum_definition, _) => {
 751             let (scheme, predicates) = convert_typed_item(ccx, it);
 752             write_ty_to_tcx(tcx, it.id, scheme.ty);
 753             convert_enum_variant_types(ccx,
 754                                        tcx.lookup_adt_def_master(ccx.tcx.map.local_def_id(it.id)),
 755                                        scheme,
 756                                        predicates,
 757                                        &enum_definition.variants);
 758         },
 759         hir::ItemDefaultImpl(_, ref ast_trait_ref) => {
 760             let trait_ref =
 761                 astconv::instantiate_mono_trait_ref(&ccx.icx(&()),
 762                                                     &ExplicitRscope,
 763                                                     ast_trait_ref,
 764                                                     None);
 765
 766             tcx.record_trait_has_default_impl(trait_ref.def_id);
 767
 768             tcx.impl_trait_refs.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
 769                                                     Some(trait_ref));
 770         }
 771         hir::ItemImpl(_, _,
 772                       ref generics,
 773                       ref opt_trait_ref,
 774                       ref selfty,
 775                       ref impl_items) => {
 776             // Create generics from the generics specified in the impl head.
 777             debug!("convert: ast_generics={:?}", generics);
 778             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
 779             let ty_predicates = ty_generic_predicates_for_type_or_impl(ccx, generics);
 780
 781             debug!("convert: impl_bounds={:?}", ty_predicates);
 782
 783             let selfty = ccx.icx(&ty_predicates).to_ty(&ExplicitRscope, &**selfty);
 784             write_ty_to_tcx(tcx, it.id, selfty);
 785
 786             tcx.register_item_type(ccx.tcx.map.local_def_id(it.id),
 787                                    TypeScheme { generics: ty_generics.clone(),
 788                                                 ty: selfty });
 789             tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
 790                                                ty_predicates.clone());
 791             if let &Some(ref ast_trait_ref) = opt_trait_ref {
 792                 tcx.impl_trait_refs.borrow_mut().insert(
 793                     ccx.tcx.map.local_def_id(it.id),
 794                     Some(astconv::instantiate_mono_trait_ref(&ccx.icx(&ty_predicates),
 795                                                              &ExplicitRscope,
 796                                                              ast_trait_ref,
 797                                                              Some(selfty)))
 798                         );
 799             } else {
 800                 tcx.impl_trait_refs.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id), None);
 801             }
 802
 803
 804             // If there is a trait reference, treat the methods as always public.
 805             // This is to work around some incorrect behavior in privacy checking:
 806             // when the method belongs to a trait, it should acquire the privacy
 807             // from the trait, not the impl. Forcing the visibility to be public
 808             // makes things sorta work.
 809             let parent_visibility = if opt_trait_ref.is_some() {
 810                 hir::Public
 811             } else {
 812                 it.vis
 813             };
 814
 815             // Convert all the associated consts.
 816             // Also, check if there are any duplicate associated items
 817             let mut seen_type_items = FnvHashSet();
 818             let mut seen_value_items = FnvHashSet();
 819
 820             for impl_item in impl_items {
 821                 let seen_items = match impl_item.node {
 822                     hir::TypeImplItem(_) => &mut seen_type_items,
 823                     _                    => &mut seen_value_items,
 824                 };
 825                 if !seen_items.insert(impl_item.name) {
 826                     let desc = match impl_item.node {
 827                         hir::ConstImplItem(_, _) => "associated constant",
 828                         hir::TypeImplItem(_) => "associated type",
 829                         hir::MethodImplItem(ref sig, _) =>
 830                             match sig.explicit_self.node {
 831                                 hir::SelfStatic => "associated function",
 832                                 _ => "method",
 833                             },
 834                     };
 835
 836                     span_err!(tcx.sess, impl_item.span, E0201, "duplicate {}", desc);
 837                 }
 838
 839                 if let hir::ConstImplItem(ref ty, _) = impl_item.node {
 840                     let ty = ccx.icx(&ty_predicates)
 841                                 .to_ty(&ExplicitRscope, &*ty);
 842                     tcx.register_item_type(ccx.tcx.map.local_def_id(impl_item.id),
 843                                            TypeScheme {
 844                                                generics: ty_generics.clone(),
 845                                                ty: ty,
 846                                            });
 847                     convert_associated_const(ccx, ImplContainer(ccx.tcx.map.local_def_id(it.id)),
 848                                              impl_item.name, impl_item.id,
 849                                              impl_item.vis.inherit_from(parent_visibility),
 850                                              ty, true /* has_value */);
 851                 }
 852             }
 853
 854             // Convert all the associated types.
 855             for impl_item in impl_items {
 856                 if let hir::TypeImplItem(ref ty) = impl_item.node {
 857                     if opt_trait_ref.is_none() {
 858                         span_err!(tcx.sess, impl_item.span, E0202,
 859                                   "associated types are not allowed in inherent impls");
 860                     }
 861
 862                     let typ = ccx.icx(&ty_predicates).to_ty(&ExplicitRscope, ty);
 863
 864                     convert_associated_type(ccx, ImplContainer(ccx.tcx.map.local_def_id(it.id)),
 865                                             impl_item.name, impl_item.id, impl_item.vis,
 866                                             Some(typ));
 867                 }
 868             }
 869
 870             let methods = impl_items.iter().filter_map(|ii| {
 871                 if let hir::MethodImplItem(ref sig, _) = ii.node {
 872                     // if the method specifies a visibility, use that, otherwise
 873                     // inherit the visibility from the impl (so `foo` in `pub impl
 874                     // { fn foo(); }` is public, but private in `impl { fn
 875                     // foo(); }`).
 876                     let method_vis = ii.vis.inherit_from(parent_visibility);
 877                     Some((sig, ii.id, ii.name, method_vis, ii.span))
 878                 } else {
 879                     None
 880                 }
 881             });
 882             convert_methods(ccx,
 883                             ImplContainer(ccx.tcx.map.local_def_id(it.id)),
 884                             methods,
 885                             selfty,
 886                             &ty_generics,
 887                             &ty_predicates);
 888
 889             for impl_item in impl_items {
 890                 if let hir::MethodImplItem(ref sig, ref body) = impl_item.node {
 891                     let body_id = body.id;
 892                     check_method_self_type(ccx,
 893                                            &BindingRscope::new(),
 894                                            ccx.method_ty(impl_item.id),
 895                                            selfty,
 896                                            &sig.explicit_self,
 897                                            body_id);
 898                 }
 899             }
 900
 901             enforce_impl_params_are_constrained(tcx,
 902                                                 generics,
 903                                                 ccx.tcx.map.local_def_id(it.id),
 904                                                 impl_items);
 905         },
 906         hir::ItemTrait(_, _, _, ref trait_items) => {
 907             let trait_def = trait_def_of_item(ccx, it);
 908             let _: Result<(), ErrorReported> = // any error is already reported, can ignore
 909                 ccx.ensure_super_predicates(it.span, ccx.tcx.map.local_def_id(it.id));
 910             convert_trait_predicates(ccx, it);
 911             let trait_predicates = tcx.lookup_predicates(ccx.tcx.map.local_def_id(it.id));
 912
 913             debug!("convert: trait_bounds={:?}", trait_predicates);
 914
 915             // Convert all the associated types.
 916             for trait_item in trait_items {
 917                 match trait_item.node {
 918                     hir::ConstTraitItem(ref ty, ref default) => {
 919                         let ty = ccx.icx(&trait_predicates)
 920                                     .to_ty(&ExplicitRscope, ty);
 921                         tcx.register_item_type(ccx.tcx.map.local_def_id(trait_item.id),
 922                                                TypeScheme {
 923                                                    generics: trait_def.generics.clone(),
 924                                                    ty: ty,
 925                                                });
 926                         convert_associated_const(ccx,
 927                                                  TraitContainer(ccx.tcx.map.local_def_id(it.id)),
 928                                                  trait_item.name,
 929                                                  trait_item.id,
 930                                                  hir::Public,
 931                                                  ty,
 932                                                  default.is_some())
 933                     }
 934                     _ => {}
 935                 }
 936             };
 937
 938             // Convert all the associated types.
 939             for trait_item in trait_items {
 940                 match trait_item.node {
 941                     hir::TypeTraitItem(_, ref opt_ty) => {
 942                         let typ = opt_ty.as_ref().map({
 943                             |ty| ccx.icx(&trait_predicates).to_ty(&ExplicitRscope, &ty)
 944                         });
 945
 946                         convert_associated_type(ccx,
 947                                                 TraitContainer(ccx.tcx.map.local_def_id(it.id)),
 948                                                 trait_item.name,
 949                                                 trait_item.id,
 950                                                 hir::Public,
 951                                                 typ);
 952                     }
 953                     _ => {}
 954                 }
 955             };
 956
 957             let methods = trait_items.iter().filter_map(|ti| {
 958                 let sig = match ti.node {
 959                     hir::MethodTraitItem(ref sig, _) => sig,
 960                     _ => return None,
 961                 };
 962                 Some((sig, ti.id, ti.name, hir::Inherited, ti.span))
 963             });
 964
 965             // Run convert_methods on the trait methods.
 966             convert_methods(ccx,
 967                             TraitContainer(ccx.tcx.map.local_def_id(it.id)),
 968                             methods,
 969                             tcx.mk_self_type(),
 970                             &trait_def.generics,
 971                             &trait_predicates);
 972
 973             // Add an entry mapping
 974             let trait_item_def_ids = Rc::new(trait_items.iter().map(|trait_item| {
 975                 let def_id = ccx.tcx.map.local_def_id(trait_item.id);
 976                 match trait_item.node {
 977                     hir::ConstTraitItem(..) => {
 978                         ty::ConstTraitItemId(def_id)
 979                     }
 980                     hir::MethodTraitItem(..) => {
 981                         ty::MethodTraitItemId(def_id)
 982                     }
 983                     hir::TypeTraitItem(..) => {
 984                         ty::TypeTraitItemId(def_id)
 985                     }
 986                 }
 987             }).collect());
 988             tcx.trait_item_def_ids.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
 989                                                        trait_item_def_ids);
 990
 991             // This must be done after `collect_trait_methods` so that
 992             // we have a method type stored for every method.
 993             for trait_item in trait_items {
 994                 let sig = match trait_item.node {
 995                     hir::MethodTraitItem(ref sig, _) => sig,
 996                     _ => continue
 997                 };
 998                 check_method_self_type(ccx,
 999                                        &BindingRscope::new(),
1000                                        ccx.method_ty(trait_item.id),
1001                                        tcx.mk_self_type(),
1002                                        &sig.explicit_self,
1003                                        it.id)
1004             }
1005         },
1006         hir::ItemStruct(ref struct_def, _) => {
1007             let (scheme, predicates) = convert_typed_item(ccx, it);
1008             write_ty_to_tcx(tcx, it.id, scheme.ty);
1009
1010             let it_def_id = ccx.tcx.map.local_def_id(it.id);
1011             let variant = tcx.lookup_adt_def_master(it_def_id).struct_variant();
1012
1013             for (f, ty_f) in struct_def.fields.iter().zip(variant.fields.iter()) {
1014                 convert_field(ccx, &scheme.generics, &predicates, f, ty_f)
1015             }
1016
1017             if struct_def.kind != hir::VariantKind::Struct {
1018                 convert_variant_ctor(tcx, struct_def.id, variant, scheme, predicates);
1019             }
1020         },
1021         hir::ItemTy(_, ref generics) => {
1022             ensure_no_ty_param_bounds(ccx, it.span, generics, "type");
1023             let (scheme, _) = convert_typed_item(ccx, it);
1024             write_ty_to_tcx(tcx, it.id, scheme.ty);
1025         },
1026         _ => {
1027             // This call populates the type cache with the converted type
1028             // of the item in passing. All we have to do here is to write
1029             // it into the node type table.
1030             let (scheme, _) = convert_typed_item(ccx, it);
1031             write_ty_to_tcx(tcx, it.id, scheme.ty);
1032         },
1033     }
1034 }
1035
1036 fn convert_variant_ctor<'a, 'tcx>(tcx: &ty::ctxt<'tcx>,
1037                                   ctor_id: ast::NodeId,
1038                                   variant: ty::VariantDef<'tcx>,
1039                                   scheme: ty::TypeScheme<'tcx>,
1040                                   predicates: ty::GenericPredicates<'tcx>) {
1041     let ctor_ty = match variant.kind() {
1042         VariantKind::Unit | VariantKind::Struct => scheme.ty,
1043         VariantKind::Tuple => {
1044             let inputs: Vec<_> =
1045                 variant.fields
1046                 .iter()
1047                 .map(|field| field.unsubst_ty())
1048                 .collect();
1049             tcx.mk_ctor_fn(tcx.map.local_def_id(ctor_id),
1050                            &inputs[..],
1051                            scheme.ty)
1052         }
1053     };
1054     write_ty_to_tcx(tcx, ctor_id, ctor_ty);
1055     tcx.predicates.borrow_mut().insert(tcx.map.local_def_id(ctor_id), predicates);
1056     tcx.register_item_type(tcx.map.local_def_id(ctor_id),
1057                            TypeScheme {
1058                                generics: scheme.generics,
1059                                ty: ctor_ty
1060                            });
1061 }
1062
1063 fn convert_enum_variant_types<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1064                                         def: ty::AdtDefMaster<'tcx>,
1065                                         scheme: ty::TypeScheme<'tcx>,
1066                                         predicates: ty::GenericPredicates<'tcx>,
1067                                         variants: &[P<hir::Variant>]) {
1068     // fill the field types
1069     for (variant, ty_variant) in variants.iter().zip(def.variants.iter()) {
1070         for (f, ty_f) in variant.node.data.fields.iter().zip(ty_variant.fields.iter()) {
1071             convert_field(ccx, &scheme.generics, &predicates, f, ty_f)
1072         }
1073
1074         // Convert the ctor, if any. This also registers the variant as
1075         // an item.
1076         convert_variant_ctor(
1077             ccx.tcx,
1078             variant.node.data.id,
1079             ty_variant,
1080             scheme.clone(),
1081             predicates.clone()
1082         );
1083     }
1084 }
1085
1086 fn convert_struct_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
1087                                 did: DefId,
1088                                 name: ast::Name,
1089                                 disr_val: ty::Disr,
1090                                 def: &hir::VariantData) -> ty::VariantDefData<'tcx, 'tcx> {
1091     let mut seen_fields: FnvHashMap<ast::Name, Span> = FnvHashMap();
1092     let fields = def.fields.iter().map(|f| {
1093         let fid = tcx.map.local_def_id(f.node.id);
1094         match f.node.kind {
1095             hir::NamedField(name, vis) => {
1096                 let dup_span = seen_fields.get(&name).cloned();
1097                 if let Some(prev_span) = dup_span {
1098                     span_err!(tcx.sess, f.span, E0124,
1099                               "field `{}` is already declared",
1100                               name);
1101                     span_note!(tcx.sess, prev_span, "previously declared here");
1102                 } else {
1103                     seen_fields.insert(name, f.span);
1104                 }
1105
1106                 ty::FieldDefData::new(fid, name, vis)
1107             },
1108             hir::UnnamedField(vis) => {
1109                 ty::FieldDefData::new(fid, special_idents::unnamed_field.name, vis)
1110             }
1111         }
1112     }).collect();
1113     ty::VariantDefData {
1114         did: did,
1115         name: name,
1116         disr_val: disr_val,
1117         fields: fields
1118     }
1119 }
1120
1121 fn convert_struct_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1122                             it: &hir::Item,
1123                             def: &hir::VariantData)
1124                             -> ty::AdtDefMaster<'tcx>
1125 {
1126
1127     let did = tcx.map.local_def_id(it.id);
1128     let ctor_id = if def.kind != hir::VariantKind::Struct {
1129         tcx.map.local_def_id(def.id)
1130     } else {
1131         did
1132     };
1133     tcx.intern_adt_def(
1134         did,
1135         ty::AdtKind::Struct,
1136         vec![convert_struct_variant(tcx, ctor_id, it.name, 0, def)]
1137     )
1138 }
1139
1140 fn convert_enum_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1141                           it: &hir::Item,
1142                           def: &hir::EnumDef)
1143                           -> ty::AdtDefMaster<'tcx>
1144 {
1145     fn evaluate_disr_expr<'tcx>(tcx: &ty::ctxt<'tcx>,
1146                                 repr_ty: Ty<'tcx>,
1147                                 e: &hir::Expr) -> Option<ty::Disr> {
1148         debug!("disr expr, checking {}", pprust::expr_to_string(e));
1149
1150         let hint = UncheckedExprHint(repr_ty);
1151         match const_eval::eval_const_expr_partial(tcx, e, hint) {
1152             Ok(ConstVal::Int(val)) => Some(val as ty::Disr),
1153             Ok(ConstVal::Uint(val)) => Some(val as ty::Disr),
1154             Ok(_) => {
1155                 let sign_desc = if repr_ty.is_signed() {
1156                     "signed"
1157                 } else {
1158                     "unsigned"
1159                 };
1160                 span_err!(tcx.sess, e.span, E0079,
1161                           "expected {} integer constant",
1162                           sign_desc);
1163                 None
1164             },
1165             Err(err) => {
1166                 span_err!(tcx.sess, err.span, E0080,
1167                           "constant evaluation error: {}",
1168                           err.description());
1169                 if !e.span.contains(err.span) {
1170                     tcx.sess.span_note(e.span, "for enum discriminant here");
1171                 }
1172                 None
1173             }
1174         }
1175     }
1176
1177     fn report_discrim_overflow(tcx: &ty::ctxt,
1178                                variant_span: Span,
1179                                variant_name: &str,
1180                                repr_type: attr::IntType,
1181                                prev_val: ty::Disr) {
1182         let computed_value = repr_type.disr_wrap_incr(Some(prev_val));
1183         let computed_value = repr_type.disr_string(computed_value);
1184         let prev_val = repr_type.disr_string(prev_val);
1185         let repr_type = repr_type.to_ty(tcx);
1186         span_err!(tcx.sess, variant_span, E0370,
1187                   "enum discriminant overflowed on value after {}: {}; \
1188                    set explicitly via {} = {} if that is desired outcome",
1189                   prev_val, repr_type, variant_name, computed_value);
1190     }
1191
1192     fn next_disr(tcx: &ty::ctxt,
1193                  v: &hir::Variant,
1194                  repr_type: attr::IntType,
1195                  prev_disr_val: Option<ty::Disr>) -> Option<ty::Disr> {
1196         if let Some(prev_disr_val) = prev_disr_val {
1197             let result = repr_type.disr_incr(prev_disr_val);
1198             if let None = result {
1199                 report_discrim_overflow(tcx, v.span, &v.node.name.as_str(),
1200                                              repr_type, prev_disr_val);
1201             }
1202             result
1203         } else {
1204             Some(ty::INITIAL_DISCRIMINANT_VALUE)
1205         }
1206     }
1207     fn convert_enum_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
1208                                   v: &hir::Variant,
1209                                   disr: ty::Disr)
1210                                   -> ty::VariantDefData<'tcx, 'tcx>
1211     {
1212         let did = tcx.map.local_def_id(v.node.data.id);
1213         let name = v.node.name;
1214         convert_struct_variant(tcx, did, name, disr, &v.node.data, did)
1215     }
1216     let did = tcx.map.local_def_id(it.id);
1217     let repr_hints = tcx.lookup_repr_hints(did);
1218     let (repr_type, repr_type_ty) = tcx.enum_repr_type(repr_hints.get(0));
1219     let mut prev_disr = None;
1220     let variants = def.variants.iter().map(|v| {
1221         let disr = match v.node.disr_expr {
1222             Some(ref e) => evaluate_disr_expr(tcx, repr_type_ty, e),
1223             None => next_disr(tcx, v, repr_type, prev_disr)
1224         }.unwrap_or(repr_type.disr_wrap_incr(prev_disr));
1225
1226         let v = convert_enum_variant(tcx, v, disr);
1227         prev_disr = Some(disr);
1228         v
1229     }).collect();
1230     tcx.intern_adt_def(tcx.map.local_def_id(it.id), ty::AdtKind::Enum, variants)
1231 }
1232
1233 /// Ensures that the super-predicates of the trait with def-id
1234 /// trait_def_id are converted and stored. This does NOT ensure that
1235 /// the transitive super-predicates are converted; that is the job of
1236 /// the `ensure_super_predicates()` method in the `AstConv` impl
1237 /// above. Returns a list of trait def-ids that must be ensured as
1238 /// well to guarantee that the transitive superpredicates are
1239 /// converted.
1240 fn ensure_super_predicates_step(ccx: &CrateCtxt,
1241                                 trait_def_id: DefId)
1242                                 -> Vec<DefId>
1243 {
1244     let tcx = ccx.tcx;
1245
1246     debug!("ensure_super_predicates_step(trait_def_id={:?})", trait_def_id);
1247
1248     let trait_node_id = if let Some(n) = tcx.map.as_local_node_id(trait_def_id) {
1249         n
1250     } else {
1251         // If this trait comes from an external crate, then all of the
1252         // supertraits it may depend on also must come from external
1253         // crates, and hence all of them already have their
1254         // super-predicates "converted" (and available from crate
1255         // meta-data), so there is no need to transitively test them.
1256         return Vec::new();
1257     };
1258
1259     let superpredicates = tcx.super_predicates.borrow().get(&trait_def_id).cloned();
1260     let superpredicates = superpredicates.unwrap_or_else(|| {
1261         let item = match ccx.tcx.map.get(trait_node_id) {
1262             hir_map::NodeItem(item) => item,
1263             _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1264         };
1265
1266         let (generics, bounds) = match item.node {
1267             hir::ItemTrait(_, ref generics, ref supertraits, _) => (generics, supertraits),
1268             _ => tcx.sess.span_bug(item.span,
1269                                    "ensure_super_predicates_step invoked on non-trait"),
1270         };
1271
1272         // In-scope when converting the superbounds for `Trait` are
1273         // that `Self:Trait` as well as any bounds that appear on the
1274         // generic types:
1275         let trait_def = trait_def_of_item(ccx, item);
1276         let self_predicate = ty::GenericPredicates {
1277             predicates: VecPerParamSpace::new(vec![],
1278                                               vec![trait_def.trait_ref.to_predicate()],
1279                                               vec![])
1280         };
1281         let scope = &(generics, &self_predicate);
1282
1283         // Convert the bounds that follow the colon, e.g. `Bar+Zed` in `trait Foo : Bar+Zed`.
1284         let self_param_ty = tcx.mk_self_type();
1285         let superbounds1 = compute_bounds(&ccx.icx(scope),
1286                                     self_param_ty,
1287                                     bounds,
1288                                     SizedByDefault::No,
1289                                     item.span);
1290
1291         let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1292
1293         // Convert any explicit superbounds in the where clause,
1294         // e.g. `trait Foo where Self : Bar`:
1295         let superbounds2 = generics.get_type_parameter_bounds(&ccx.icx(scope), item.span, item.id);
1296
1297         // Combine the two lists to form the complete set of superbounds:
1298         let superbounds = superbounds1.into_iter().chain(superbounds2).collect();
1299         let superpredicates = ty::GenericPredicates {
1300             predicates: VecPerParamSpace::new(superbounds, vec![], vec![])
1301         };
1302         debug!("superpredicates for trait {:?} = {:?}",
1303                tcx.map.local_def_id(item.id),
1304                superpredicates);
1305
1306         tcx.super_predicates.borrow_mut().insert(trait_def_id, superpredicates.clone());
1307
1308         superpredicates
1309     });
1310
1311     let def_ids: Vec<_> = superpredicates.predicates
1312                                          .iter()
1313                                          .filter_map(|p| p.to_opt_poly_trait_ref())
1314                                          .map(|tr| tr.def_id())
1315                                          .collect();
1316
1317     debug!("ensure_super_predicates_step: def_ids={:?}", def_ids);
1318
1319     def_ids
1320 }
1321
1322 fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1323                                it: &hir::Item)
1324                                -> &'tcx ty::TraitDef<'tcx>
1325 {
1326     let def_id = ccx.tcx.map.local_def_id(it.id);
1327     let tcx = ccx.tcx;
1328
1329     if let Some(def) = tcx.trait_defs.borrow().get(&def_id) {
1330         return def.clone();
1331     }
1332
1333     let (unsafety, generics, items) = match it.node {
1334         hir::ItemTrait(unsafety, ref generics, _, ref items) => (unsafety, generics, items),
1335         _ => tcx.sess.span_bug(it.span, "trait_def_of_item invoked on non-trait"),
1336     };
1337
1338     let paren_sugar = tcx.has_attr(def_id, "rustc_paren_sugar");
1339     if paren_sugar && !ccx.tcx.sess.features.borrow().unboxed_closures {
1340         ccx.tcx.sess.span_err(
1341             it.span,
1342             "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1343              which traits can use parenthetical notation");
1344         fileline_help!(ccx.tcx.sess, it.span,
1345                    "add `#![feature(unboxed_closures)]` to \
1346                     the crate attributes to use it");
1347     }
1348
1349     let substs = ccx.tcx.mk_substs(mk_trait_substs(ccx, generics));
1350
1351     let ty_generics = ty_generics_for_trait(ccx, it.id, substs, generics);
1352
1353     let associated_type_names: Vec<_> = items.iter().filter_map(|trait_item| {
1354         match trait_item.node {
1355             hir::TypeTraitItem(..) => Some(trait_item.name),
1356             _ => None,
1357         }
1358     }).collect();
1359
1360     let trait_ref = ty::TraitRef {
1361         def_id: def_id,
1362         substs: substs,
1363     };
1364
1365     let trait_def = ty::TraitDef {
1366         paren_sugar: paren_sugar,
1367         unsafety: unsafety,
1368         generics: ty_generics,
1369         trait_ref: trait_ref,
1370         associated_type_names: associated_type_names,
1371         nonblanket_impls: RefCell::new(FnvHashMap()),
1372         blanket_impls: RefCell::new(vec![]),
1373         flags: Cell::new(ty::TraitFlags::NO_TRAIT_FLAGS)
1374     };
1375
1376     return tcx.intern_trait_def(trait_def);
1377
1378     fn mk_trait_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1379                                  generics: &hir::Generics)
1380                                  -> Substs<'tcx>
1381     {
1382         let tcx = ccx.tcx;
1383
1384         // Creates a no-op substitution for the trait's type parameters.
1385         let regions =
1386             generics.lifetimes
1387                     .iter()
1388                     .enumerate()
1389                     .map(|(i, def)| ty::ReEarlyBound(ty::EarlyBoundRegion {
1390                         def_id: tcx.map.local_def_id(def.lifetime.id),
1391                         space: TypeSpace,
1392                         index: i as u32,
1393                         name: def.lifetime.name
1394                     }))
1395                     .collect();
1396
1397         // Start with the generics in the type parameters...
1398         let types: Vec<_> =
1399             generics.ty_params
1400                     .iter()
1401                     .enumerate()
1402                     .map(|(i, def)| tcx.mk_param(TypeSpace,
1403                                                  i as u32, def.name))
1404                     .collect();
1405
1406         // ...and also create the `Self` parameter.
1407         let self_ty = tcx.mk_self_type();
1408
1409         Substs::new_trait(types, regions, self_ty)
1410     }
1411 }
1412
1413 fn trait_defines_associated_type_named(ccx: &CrateCtxt,
1414                                        trait_node_id: ast::NodeId,
1415                                        assoc_name: ast::Name)
1416                                        -> bool
1417 {
1418     let item = match ccx.tcx.map.get(trait_node_id) {
1419         hir_map::NodeItem(item) => item,
1420         _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1421     };
1422
1423     let trait_items = match item.node {
1424         hir::ItemTrait(_, _, _, ref trait_items) => trait_items,
1425         _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not a trait", trait_node_id))
1426     };
1427
1428     trait_items.iter().any(|trait_item| {
1429         match trait_item.node {
1430             hir::TypeTraitItem(..) => trait_item.name == assoc_name,
1431             _ => false,
1432         }
1433     })
1434 }
1435
1436 fn convert_trait_predicates<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>, it: &hir::Item) {
1437     let tcx = ccx.tcx;
1438     let trait_def = trait_def_of_item(ccx, it);
1439
1440     let def_id = ccx.tcx.map.local_def_id(it.id);
1441
1442     let (generics, items) = match it.node {
1443         hir::ItemTrait(_, ref generics, _, ref items) => (generics, items),
1444         ref s => {
1445             tcx.sess.span_bug(
1446                 it.span,
1447                 &format!("trait_def_of_item invoked on {:?}", s));
1448         }
1449     };
1450
1451     let super_predicates = ccx.tcx.lookup_super_predicates(def_id);
1452
1453     // `ty_generic_predicates` below will consider the bounds on the type
1454     // parameters (including `Self`) and the explicit where-clauses,
1455     // but to get the full set of predicates on a trait we need to add
1456     // in the supertrait bounds and anything declared on the
1457     // associated types.
1458     let mut base_predicates = super_predicates;
1459
1460     // Add in a predicate that `Self:Trait` (where `Trait` is the
1461     // current trait).  This is needed for builtin bounds.
1462     let self_predicate = trait_def.trait_ref.to_poly_trait_ref().to_predicate();
1463     base_predicates.predicates.push(SelfSpace, self_predicate);
1464
1465     // add in the explicit where-clauses
1466     let mut trait_predicates =
1467         ty_generic_predicates(ccx, TypeSpace, generics, &base_predicates);
1468
1469     let assoc_predicates = predicates_for_associated_types(ccx,
1470                                                            generics,
1471                                                            &trait_predicates,
1472                                                            trait_def.trait_ref,
1473                                                            items);
1474     trait_predicates.predicates.extend(TypeSpace, assoc_predicates.into_iter());
1475
1476     let prev_predicates = tcx.predicates.borrow_mut().insert(def_id, trait_predicates);
1477     assert!(prev_predicates.is_none());
1478
1479     return;
1480
1481     fn predicates_for_associated_types<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1482                                                  ast_generics: &hir::Generics,
1483                                                  trait_predicates: &ty::GenericPredicates<'tcx>,
1484                                                  self_trait_ref: ty::TraitRef<'tcx>,
1485                                                  trait_items: &[P<hir::TraitItem>])
1486                                                  -> Vec<ty::Predicate<'tcx>>
1487     {
1488         trait_items.iter().flat_map(|trait_item| {
1489             let bounds = match trait_item.node {
1490                 hir::TypeTraitItem(ref bounds, _) => bounds,
1491                 _ => {
1492                     return vec!().into_iter();
1493                 }
1494             };
1495
1496             let assoc_ty = ccx.tcx.mk_projection(self_trait_ref,
1497                                                  trait_item.name);
1498
1499             let bounds = compute_bounds(&ccx.icx(&(ast_generics, trait_predicates)),
1500                                         assoc_ty,
1501                                         bounds,
1502                                         SizedByDefault::Yes,
1503                                         trait_item.span);
1504
1505             bounds.predicates(ccx.tcx, assoc_ty).into_iter()
1506         }).collect()
1507     }
1508 }
1509
1510 fn type_scheme_of_def_id<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1511                                   def_id: DefId)
1512                                   -> ty::TypeScheme<'tcx>
1513 {
1514     if let Some(node_id) = ccx.tcx.map.as_local_node_id(def_id) {
1515         match ccx.tcx.map.find(node_id) {
1516             Some(hir_map::NodeItem(item)) => {
1517                 type_scheme_of_item(ccx, &*item)
1518             }
1519             Some(hir_map::NodeForeignItem(foreign_item)) => {
1520                 let abi = ccx.tcx.map.get_foreign_abi(node_id);
1521                 type_scheme_of_foreign_item(ccx, &*foreign_item, abi)
1522             }
1523             x => {
1524                 ccx.tcx.sess.bug(&format!("unexpected sort of node \
1525                                            in get_item_type_scheme(): {:?}",
1526                                           x));
1527             }
1528         }
1529     } else {
1530         ccx.tcx.lookup_item_type(def_id)
1531     }
1532 }
1533
1534 fn type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1535                                 it: &hir::Item)
1536                                 -> ty::TypeScheme<'tcx>
1537 {
1538     memoized(&ccx.tcx.tcache,
1539              ccx.tcx.map.local_def_id(it.id),
1540              |_| compute_type_scheme_of_item(ccx, it))
1541 }
1542
1543 fn compute_type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1544                                         it: &hir::Item)
1545                                         -> ty::TypeScheme<'tcx>
1546 {
1547     let tcx = ccx.tcx;
1548     match it.node {
1549         hir::ItemStatic(ref t, _, _) | hir::ItemConst(ref t, _) => {
1550             let ty = ccx.icx(&()).to_ty(&ExplicitRscope, &**t);
1551             ty::TypeScheme { ty: ty, generics: ty::Generics::empty() }
1552         }
1553         hir::ItemFn(ref decl, unsafety, _, abi, ref generics, _) => {
1554             let ty_generics = ty_generics_for_fn(ccx, generics, &ty::Generics::empty());
1555             let tofd = astconv::ty_of_bare_fn(&ccx.icx(generics), unsafety, abi, &**decl);
1556             let ty = tcx.mk_fn(Some(ccx.tcx.map.local_def_id(it.id)), tcx.mk_bare_fn(tofd));
1557             ty::TypeScheme { ty: ty, generics: ty_generics }
1558         }
1559         hir::ItemTy(ref t, ref generics) => {
1560             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1561             let ty = ccx.icx(generics).to_ty(&ExplicitRscope, &**t);
1562             ty::TypeScheme { ty: ty, generics: ty_generics }
1563         }
1564         hir::ItemEnum(ref ei, ref generics) => {
1565             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1566             let substs = mk_item_substs(ccx, &ty_generics);
1567             let def = convert_enum_def(tcx, it, ei);
1568             let t = tcx.mk_enum(def, tcx.mk_substs(substs));
1569             ty::TypeScheme { ty: t, generics: ty_generics }
1570         }
1571         hir::ItemStruct(ref si, ref generics) => {
1572             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1573             let substs = mk_item_substs(ccx, &ty_generics);
1574             let def = convert_struct_def(tcx, it, si);
1575             let t = tcx.mk_struct(def, tcx.mk_substs(substs));
1576             ty::TypeScheme { ty: t, generics: ty_generics }
1577         }
1578         hir::ItemDefaultImpl(..) |
1579         hir::ItemTrait(..) |
1580         hir::ItemImpl(..) |
1581         hir::ItemMod(..) |
1582         hir::ItemForeignMod(..) |
1583         hir::ItemExternCrate(..) |
1584         hir::ItemUse(..) => {
1585             tcx.sess.span_bug(
1586                 it.span,
1587                 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1588                          it.node));
1589         }
1590     }
1591 }
1592
1593 fn convert_typed_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1594                                 it: &hir::Item)
1595                                 -> (ty::TypeScheme<'tcx>, ty::GenericPredicates<'tcx>)
1596 {
1597     let tcx = ccx.tcx;
1598
1599     let tag = type_scheme_of_item(ccx, it);
1600     let scheme = TypeScheme { generics: tag.generics, ty: tag.ty };
1601     let predicates = match it.node {
1602         hir::ItemStatic(..) | hir::ItemConst(..) => {
1603             ty::GenericPredicates::empty()
1604         }
1605         hir::ItemFn(_, _, _, _, ref ast_generics, _) => {
1606             ty_generic_predicates_for_fn(ccx, ast_generics, &ty::GenericPredicates::empty())
1607         }
1608         hir::ItemTy(_, ref generics) => {
1609             ty_generic_predicates_for_type_or_impl(ccx, generics)
1610         }
1611         hir::ItemEnum(_, ref generics) => {
1612             ty_generic_predicates_for_type_or_impl(ccx, generics)
1613         }
1614         hir::ItemStruct(_, ref generics) => {
1615             ty_generic_predicates_for_type_or_impl(ccx, generics)
1616         }
1617         hir::ItemDefaultImpl(..) |
1618         hir::ItemTrait(..) |
1619         hir::ItemExternCrate(..) |
1620         hir::ItemUse(..) |
1621         hir::ItemImpl(..) |
1622         hir::ItemMod(..) |
1623         hir::ItemForeignMod(..) => {
1624             tcx.sess.span_bug(
1625                 it.span,
1626                 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1627                          it.node));
1628         }
1629     };
1630
1631     let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1632                                                              predicates.clone());
1633     assert!(prev_predicates.is_none());
1634
1635     // Debugging aid.
1636     if tcx.has_attr(ccx.tcx.map.local_def_id(it.id), "rustc_object_lifetime_default") {
1637         let object_lifetime_default_reprs: String =
1638             scheme.generics.types.iter()
1639                                  .map(|t| match t.object_lifetime_default {
1640                                      ty::ObjectLifetimeDefault::Specific(r) => r.to_string(),
1641                                      d => format!("{:?}", d),
1642                                  })
1643                                  .collect::<Vec<String>>()
1644                                  .join(",");
1645
1646         tcx.sess.span_err(it.span, &object_lifetime_default_reprs);
1647     }
1648
1649     return (scheme, predicates);
1650 }
1651
1652 fn type_scheme_of_foreign_item<'a, 'tcx>(
1653     ccx: &CrateCtxt<'a, 'tcx>,
1654     it: &hir::ForeignItem,
1655     abi: abi::Abi)
1656     -> ty::TypeScheme<'tcx>
1657 {
1658     memoized(&ccx.tcx.tcache,
1659              ccx.tcx.map.local_def_id(it.id),
1660              |_| compute_type_scheme_of_foreign_item(ccx, it, abi))
1661 }
1662
1663 fn compute_type_scheme_of_foreign_item<'a, 'tcx>(
1664     ccx: &CrateCtxt<'a, 'tcx>,
1665     it: &hir::ForeignItem,
1666     abi: abi::Abi)
1667     -> ty::TypeScheme<'tcx>
1668 {
1669     match it.node {
1670         hir::ForeignItemFn(ref fn_decl, ref generics) => {
1671             compute_type_scheme_of_foreign_fn_decl(ccx, fn_decl, generics, abi)
1672         }
1673         hir::ForeignItemStatic(ref t, _) => {
1674             ty::TypeScheme {
1675                 generics: ty::Generics::empty(),
1676                 ty: ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, t)
1677             }
1678         }
1679     }
1680 }
1681
1682 fn convert_foreign_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1683                                   it: &hir::ForeignItem)
1684 {
1685     // For reasons I cannot fully articulate, I do so hate the AST
1686     // map, and I regard each time that I use it as a personal and
1687     // moral failing, but at the moment it seems like the only
1688     // convenient way to extract the ABI. - ndm
1689     let tcx = ccx.tcx;
1690     let abi = tcx.map.get_foreign_abi(it.id);
1691
1692     let scheme = type_scheme_of_foreign_item(ccx, it, abi);
1693     write_ty_to_tcx(ccx.tcx, it.id, scheme.ty);
1694
1695     let predicates = match it.node {
1696         hir::ForeignItemFn(_, ref generics) => {
1697             ty_generic_predicates_for_fn(ccx, generics, &ty::GenericPredicates::empty())
1698         }
1699         hir::ForeignItemStatic(..) => {
1700             ty::GenericPredicates::empty()
1701         }
1702     };
1703
1704     let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1705                                                              predicates);
1706     assert!(prev_predicates.is_none());
1707 }
1708
1709 fn ty_generics_for_type_or_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1710                                           generics: &hir::Generics)
1711                                           -> ty::Generics<'tcx> {
1712     ty_generics(ccx, TypeSpace, generics, &ty::Generics::empty())
1713 }
1714
1715 fn ty_generic_predicates_for_type_or_impl<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1716                                                    generics: &hir::Generics)
1717                                                    -> ty::GenericPredicates<'tcx>
1718 {
1719     ty_generic_predicates(ccx, TypeSpace, generics, &ty::GenericPredicates::empty())
1720 }
1721
1722 fn ty_generics_for_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1723                                    trait_id: ast::NodeId,
1724                                    substs: &'tcx Substs<'tcx>,
1725                                    ast_generics: &hir::Generics)
1726                                    -> ty::Generics<'tcx>
1727 {
1728     debug!("ty_generics_for_trait(trait_id={:?}, substs={:?})",
1729            ccx.tcx.map.local_def_id(trait_id), substs);
1730
1731     let mut generics = ty_generics_for_type_or_impl(ccx, ast_generics);
1732
1733     // Add in the self type parameter.
1734     //
1735     // Something of a hack: use the node id for the trait, also as
1736     // the node id for the Self type parameter.
1737     let param_id = trait_id;
1738
1739     let parent = ccx.tcx.map.get_parent(param_id);
1740
1741     let def = ty::TypeParameterDef {
1742         space: SelfSpace,
1743         index: 0,
1744         name: special_idents::type_self.name,
1745         def_id: ccx.tcx.map.local_def_id(param_id),
1746         default_def_id: ccx.tcx.map.local_def_id(parent),
1747         default: None,
1748         object_lifetime_default: ty::ObjectLifetimeDefault::BaseDefault,
1749     };
1750
1751     ccx.tcx.ty_param_defs.borrow_mut().insert(param_id, def.clone());
1752
1753     generics.types.push(SelfSpace, def);
1754
1755     return generics;
1756 }
1757
1758 fn ty_generics_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1759                                generics: &hir::Generics,
1760                                base_generics: &ty::Generics<'tcx>)
1761                                -> ty::Generics<'tcx>
1762 {
1763     ty_generics(ccx, FnSpace, generics, base_generics)
1764 }
1765
1766 fn ty_generic_predicates_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1767                                          generics: &hir::Generics,
1768                                          base_predicates: &ty::GenericPredicates<'tcx>)
1769                                          -> ty::GenericPredicates<'tcx>
1770 {
1771     ty_generic_predicates(ccx, FnSpace, generics, base_predicates)
1772 }
1773
1774 // Add the Sized bound, unless the type parameter is marked as `?Sized`.
1775 fn add_unsized_bound<'tcx>(astconv: &AstConv<'tcx>,
1776                            bounds: &mut ty::BuiltinBounds,
1777                            ast_bounds: &[hir::TyParamBound],
1778                            span: Span)
1779 {
1780     let tcx = astconv.tcx();
1781
1782     // Try to find an unbound in bounds.
1783     let mut unbound = None;
1784     for ab in ast_bounds {
1785         if let &hir::TraitTyParamBound(ref ptr, hir::TraitBoundModifier::Maybe) = ab  {
1786             if unbound.is_none() {
1787                 assert!(ptr.bound_lifetimes.is_empty());
1788                 unbound = Some(ptr.trait_ref.clone());
1789             } else {
1790                 span_err!(tcx.sess, span, E0203,
1791                           "type parameter has more than one relaxed default \
1792                                                 bound, only one is supported");
1793             }
1794         }
1795     }
1796
1797     let kind_id = tcx.lang_items.require(SizedTraitLangItem);
1798     match unbound {
1799         Some(ref tpb) => {
1800             // FIXME(#8559) currently requires the unbound to be built-in.
1801             let trait_def_id = tcx.trait_ref_to_def_id(tpb);
1802             match kind_id {
1803                 Ok(kind_id) if trait_def_id != kind_id => {
1804                     tcx.sess.span_warn(span,
1805                                        "default bound relaxed for a type parameter, but \
1806                                        this does nothing because the given bound is not \
1807                                        a default. Only `?Sized` is supported");
1808                     tcx.try_add_builtin_trait(kind_id, bounds);
1809                 }
1810                 _ => {}
1811             }
1812         }
1813         _ if kind_id.is_ok() => {
1814             tcx.try_add_builtin_trait(kind_id.unwrap(), bounds);
1815         }
1816         // No lang item for Sized, so we can't add it as a bound.
1817         None => {}
1818     }
1819 }
1820
1821 /// Returns the early-bound lifetimes declared in this generics
1822 /// listing.  For anything other than fns/methods, this is just all
1823 /// the lifetimes that are declared. For fns or methods, we have to
1824 /// screen out those that do not appear in any where-clauses etc using
1825 /// `resolve_lifetime::early_bound_lifetimes`.
1826 fn early_bound_lifetimes_from_generics(space: ParamSpace,
1827                                        ast_generics: &hir::Generics)
1828                                        -> Vec<hir::LifetimeDef>
1829 {
1830     match space {
1831         SelfSpace | TypeSpace => ast_generics.lifetimes.to_vec(),
1832         FnSpace => resolve_lifetime::early_bound_lifetimes(ast_generics),
1833     }
1834 }
1835
1836 fn ty_generic_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1837                                   space: ParamSpace,
1838                                   ast_generics: &hir::Generics,
1839                                   base_predicates: &ty::GenericPredicates<'tcx>)
1840                                   -> ty::GenericPredicates<'tcx>
1841 {
1842     let tcx = ccx.tcx;
1843     let mut result = base_predicates.clone();
1844
1845     // Collect the predicates that were written inline by the user on each
1846     // type parameter (e.g., `<T:Foo>`).
1847     for (index, param) in ast_generics.ty_params.iter().enumerate() {
1848         let index = index as u32;
1849         let param_ty = ty::ParamTy::new(space, index, param.name).to_ty(ccx.tcx);
1850         let bounds = compute_bounds(&ccx.icx(&(base_predicates, ast_generics)),
1851                                     param_ty,
1852                                     &param.bounds,
1853                                     SizedByDefault::Yes,
1854                                     param.span);
1855         let predicates = bounds.predicates(ccx.tcx, param_ty);
1856         result.predicates.extend(space, predicates.into_iter());
1857     }
1858
1859     // Collect the region predicates that were declared inline as
1860     // well. In the case of parameters declared on a fn or method, we
1861     // have to be careful to only iterate over early-bound regions.
1862     let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1863     for (index, param) in early_lifetimes.iter().enumerate() {
1864         let index = index as u32;
1865         let def_id = tcx.map.local_def_id(param.lifetime.id);
1866         let region =
1867             ty::ReEarlyBound(ty::EarlyBoundRegion {
1868                 def_id: def_id,
1869                 space: space,
1870                 index: index,
1871                 name: param.lifetime.name
1872             });
1873         for bound in &param.bounds {
1874             let bound_region = ast_region_to_region(ccx.tcx, bound);
1875             let outlives = ty::Binder(ty::OutlivesPredicate(region, bound_region));
1876             result.predicates.push(space, outlives.to_predicate());
1877         }
1878     }
1879
1880     // Add in the bounds that appear in the where-clause
1881     let where_clause = &ast_generics.where_clause;
1882     for predicate in &where_clause.predicates {
1883         match predicate {
1884             &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
1885                 let ty = ast_ty_to_ty(&ccx.icx(&(base_predicates, ast_generics)),
1886                                       &ExplicitRscope,
1887                                       &*bound_pred.bounded_ty);
1888
1889                 for bound in bound_pred.bounds.iter() {
1890                     match bound {
1891                         &hir::TyParamBound::TraitTyParamBound(ref poly_trait_ref, _) => {
1892                             let mut projections = Vec::new();
1893
1894                             let trait_ref =
1895                                 conv_poly_trait_ref(&ccx.icx(&(base_predicates, ast_generics)),
1896                                                     ty,
1897                                                     poly_trait_ref,
1898                                                     &mut projections);
1899
1900                             result.predicates.push(space, trait_ref.to_predicate());
1901
1902                             for projection in &projections {
1903                                 result.predicates.push(space, projection.to_predicate());
1904                             }
1905                         }
1906
1907                         &hir::TyParamBound::RegionTyParamBound(ref lifetime) => {
1908                             let region = ast_region_to_region(tcx, lifetime);
1909                             let pred = ty::Binder(ty::OutlivesPredicate(ty, region));
1910                             result.predicates.push(space, ty::Predicate::TypeOutlives(pred))
1911                         }
1912                     }
1913                 }
1914             }
1915
1916             &hir::WherePredicate::RegionPredicate(ref region_pred) => {
1917                 let r1 = ast_region_to_region(tcx, &region_pred.lifetime);
1918                 for bound in &region_pred.bounds {
1919                     let r2 = ast_region_to_region(tcx, bound);
1920                     let pred = ty::Binder(ty::OutlivesPredicate(r1, r2));
1921                     result.predicates.push(space, ty::Predicate::RegionOutlives(pred))
1922                 }
1923             }
1924
1925             &hir::WherePredicate::EqPredicate(ref eq_pred) => {
1926                 // FIXME(#20041)
1927                 tcx.sess.span_bug(eq_pred.span,
1928                                     "Equality constraints are not yet \
1929                                         implemented (#20041)")
1930             }
1931         }
1932     }
1933
1934     return result;
1935 }
1936
1937 fn ty_generics<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1938                         space: ParamSpace,
1939                         ast_generics: &hir::Generics,
1940                         base_generics: &ty::Generics<'tcx>)
1941                         -> ty::Generics<'tcx>
1942 {
1943     let tcx = ccx.tcx;
1944     let mut result = base_generics.clone();
1945
1946     let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1947     for (i, l) in early_lifetimes.iter().enumerate() {
1948         let bounds = l.bounds.iter()
1949                              .map(|l| ast_region_to_region(tcx, l))
1950                              .collect();
1951         let def = ty::RegionParameterDef { name: l.lifetime.name,
1952                                            space: space,
1953                                            index: i as u32,
1954                                            def_id: ccx.tcx.map.local_def_id(l.lifetime.id),
1955                                            bounds: bounds };
1956         result.regions.push(space, def);
1957     }
1958
1959     assert!(result.types.is_empty_in(space));
1960
1961     // Now create the real type parameters.
1962     for i in 0..ast_generics.ty_params.len() {
1963         let def = get_or_create_type_parameter_def(ccx, ast_generics, space, i as u32);
1964         debug!("ty_generics: def for type param: {:?}, {:?}", def, space);
1965         result.types.push(space, def);
1966     }
1967
1968     result
1969 }
1970
1971 fn convert_default_type_parameter<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1972                                             path: &P<hir::Ty>,
1973                                             space: ParamSpace,
1974                                             index: u32)
1975                                             -> Ty<'tcx>
1976 {
1977     let ty = ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, &path);
1978
1979     for leaf_ty in ty.walk() {
1980         if let ty::TyParam(p) = leaf_ty.sty {
1981             if p.space == space && p.idx >= index {
1982                 span_err!(ccx.tcx.sess, path.span, E0128,
1983                           "type parameters with a default cannot use \
1984                            forward declared identifiers");
1985
1986                 return ccx.tcx.types.err
1987             }
1988         }
1989     }
1990
1991     ty
1992 }
1993
1994 fn get_or_create_type_parameter_def<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1995                                              ast_generics: &hir::Generics,
1996                                              space: ParamSpace,
1997                                              index: u32)
1998                                              -> ty::TypeParameterDef<'tcx>
1999 {
2000     let param = &ast_generics.ty_params[index as usize];
2001
2002     let tcx = ccx.tcx;
2003     match tcx.ty_param_defs.borrow().get(&param.id) {
2004         Some(d) => { return d.clone(); }
2005         None => { }
2006     }
2007
2008     let default = param.default.as_ref().map(
2009         |def| convert_default_type_parameter(ccx, def, space, index)
2010     );
2011
2012     let object_lifetime_default =
2013         compute_object_lifetime_default(ccx, param.id,
2014                                         &param.bounds, &ast_generics.where_clause);
2015
2016     let parent = tcx.map.get_parent(param.id);
2017
2018     let def = ty::TypeParameterDef {
2019         space: space,
2020         index: index,
2021         name: param.name,
2022         def_id: ccx.tcx.map.local_def_id(param.id),
2023         default_def_id: ccx.tcx.map.local_def_id(parent),
2024         default: default,
2025         object_lifetime_default: object_lifetime_default,
2026     };
2027
2028     tcx.ty_param_defs.borrow_mut().insert(param.id, def.clone());
2029
2030     def
2031 }
2032
2033 /// Scan the bounds and where-clauses on a parameter to extract bounds
2034 /// of the form `T:'a` so as to determine the `ObjectLifetimeDefault`.
2035 /// This runs as part of computing the minimal type scheme, so we
2036 /// intentionally avoid just asking astconv to convert all the where
2037 /// clauses into a `ty::Predicate`. This is because that could induce
2038 /// artificial cycles.
2039 fn compute_object_lifetime_default<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2040                                             param_id: ast::NodeId,
2041                                             param_bounds: &[hir::TyParamBound],
2042                                             where_clause: &hir::WhereClause)
2043                                             -> ty::ObjectLifetimeDefault
2044 {
2045     let inline_bounds = from_bounds(ccx, param_bounds);
2046     let where_bounds = from_predicates(ccx, param_id, &where_clause.predicates);
2047     let all_bounds: HashSet<_> = inline_bounds.into_iter()
2048                                               .chain(where_bounds)
2049                                               .collect();
2050     return if all_bounds.len() > 1 {
2051         ty::ObjectLifetimeDefault::Ambiguous
2052     } else if all_bounds.len() == 0 {
2053         ty::ObjectLifetimeDefault::BaseDefault
2054     } else {
2055         ty::ObjectLifetimeDefault::Specific(
2056             all_bounds.into_iter().next().unwrap())
2057     };
2058
2059     fn from_bounds<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2060                             bounds: &[hir::TyParamBound])
2061                             -> Vec<ty::Region>
2062     {
2063         bounds.iter()
2064               .filter_map(|bound| {
2065                   match *bound {
2066                       hir::TraitTyParamBound(..) =>
2067                           None,
2068                       hir::RegionTyParamBound(ref lifetime) =>
2069                           Some(astconv::ast_region_to_region(ccx.tcx, lifetime)),
2070                   }
2071               })
2072               .collect()
2073     }
2074
2075     fn from_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2076                                 param_id: ast::NodeId,
2077                                 predicates: &[hir::WherePredicate])
2078                                 -> Vec<ty::Region>
2079     {
2080         predicates.iter()
2081                   .flat_map(|predicate| {
2082                       match *predicate {
2083                           hir::WherePredicate::BoundPredicate(ref data) => {
2084                               if data.bound_lifetimes.is_empty() &&
2085                                   is_param(ccx.tcx, &data.bounded_ty, param_id)
2086                               {
2087                                   from_bounds(ccx, &data.bounds).into_iter()
2088                               } else {
2089                                   Vec::new().into_iter()
2090                               }
2091                           }
2092                           hir::WherePredicate::RegionPredicate(..) |
2093                           hir::WherePredicate::EqPredicate(..) => {
2094                               Vec::new().into_iter()
2095                           }
2096                       }
2097                   })
2098                   .collect()
2099     }
2100 }
2101
2102 enum SizedByDefault { Yes, No, }
2103
2104 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped Ty or
2105 /// a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2106 /// built-in trait (formerly known as kind): Send.
2107 fn compute_bounds<'tcx>(astconv: &AstConv<'tcx>,
2108                         param_ty: ty::Ty<'tcx>,
2109                         ast_bounds: &[hir::TyParamBound],
2110                         sized_by_default: SizedByDefault,
2111                         span: Span)
2112                         -> astconv::Bounds<'tcx>
2113 {
2114     let mut bounds =
2115         conv_param_bounds(astconv,
2116                           span,
2117                           param_ty,
2118                           ast_bounds);
2119
2120     if let SizedByDefault::Yes = sized_by_default {
2121         add_unsized_bound(astconv,
2122                           &mut bounds.builtin_bounds,
2123                           ast_bounds,
2124                           span);
2125     }
2126
2127     bounds.trait_bounds.sort_by(|a,b| a.def_id().cmp(&b.def_id()));
2128
2129     bounds
2130 }
2131
2132 /// Converts a specific TyParamBound from the AST into a set of
2133 /// predicates that apply to the self-type. A vector is returned
2134 /// because this can be anywhere from 0 predicates (`T:?Sized` adds no
2135 /// predicates) to 1 (`T:Foo`) to many (`T:Bar<X=i32>` adds `T:Bar`
2136 /// and `<T as Bar>::X == i32`).
2137 fn predicates_from_bound<'tcx>(astconv: &AstConv<'tcx>,
2138                                param_ty: Ty<'tcx>,
2139                                bound: &hir::TyParamBound)
2140                                -> Vec<ty::Predicate<'tcx>>
2141 {
2142     match *bound {
2143         hir::TraitTyParamBound(ref tr, hir::TraitBoundModifier::None) => {
2144             let mut projections = Vec::new();
2145             let pred = conv_poly_trait_ref(astconv, param_ty, tr, &mut projections);
2146             projections.into_iter()
2147                        .map(|p| p.to_predicate())
2148                        .chain(Some(pred.to_predicate()))
2149                        .collect()
2150         }
2151         hir::RegionTyParamBound(ref lifetime) => {
2152             let region = ast_region_to_region(astconv.tcx(), lifetime);
2153             let pred = ty::Binder(ty::OutlivesPredicate(param_ty, region));
2154             vec![ty::Predicate::TypeOutlives(pred)]
2155         }
2156         hir::TraitTyParamBound(_, hir::TraitBoundModifier::Maybe) => {
2157             Vec::new()
2158         }
2159     }
2160 }
2161
2162 fn conv_poly_trait_ref<'tcx>(astconv: &AstConv<'tcx>,
2163                              param_ty: Ty<'tcx>,
2164                              trait_ref: &hir::PolyTraitRef,
2165                              projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
2166                              -> ty::PolyTraitRef<'tcx>
2167 {
2168     astconv::instantiate_poly_trait_ref(astconv,
2169                                         &ExplicitRscope,
2170                                         trait_ref,
2171                                         Some(param_ty),
2172                                         projections)
2173 }
2174
2175 fn conv_param_bounds<'a,'tcx>(astconv: &AstConv<'tcx>,
2176                               span: Span,
2177                               param_ty: ty::Ty<'tcx>,
2178                               ast_bounds: &[hir::TyParamBound])
2179                               -> astconv::Bounds<'tcx>
2180 {
2181     let tcx = astconv.tcx();
2182     let astconv::PartitionedBounds {
2183         builtin_bounds,
2184         trait_bounds,
2185         region_bounds
2186     } = astconv::partition_bounds(tcx, span, &ast_bounds);
2187
2188     let mut projection_bounds = Vec::new();
2189
2190     let trait_bounds: Vec<ty::PolyTraitRef> =
2191         trait_bounds.iter()
2192                     .map(|bound| conv_poly_trait_ref(astconv,
2193                                                      param_ty,
2194                                                      *bound,
2195                                                      &mut projection_bounds))
2196                     .collect();
2197
2198     let region_bounds: Vec<ty::Region> =
2199         region_bounds.into_iter()
2200                      .map(|r| ast_region_to_region(tcx, r))
2201                      .collect();
2202
2203     astconv::Bounds {
2204         region_bounds: region_bounds,
2205         builtin_bounds: builtin_bounds,
2206         trait_bounds: trait_bounds,
2207         projection_bounds: projection_bounds,
2208     }
2209 }
2210
2211 fn compute_type_scheme_of_foreign_fn_decl<'a, 'tcx>(
2212     ccx: &CrateCtxt<'a, 'tcx>,
2213     decl: &hir::FnDecl,
2214     ast_generics: &hir::Generics,
2215     abi: abi::Abi)
2216     -> ty::TypeScheme<'tcx>
2217 {
2218     for i in &decl.inputs {
2219         match (*i).pat.node {
2220             hir::PatIdent(_, _, _) => (),
2221             hir::PatWild(hir::PatWildSingle) => (),
2222             _ => {
2223                 span_err!(ccx.tcx.sess, (*i).pat.span, E0130,
2224                           "patterns aren't allowed in foreign function declarations");
2225             }
2226         }
2227     }
2228
2229     let ty_generics = ty_generics_for_fn(ccx, ast_generics, &ty::Generics::empty());
2230
2231     let rb = BindingRscope::new();
2232     let input_tys = decl.inputs
2233                         .iter()
2234                         .map(|a| ty_of_arg(&ccx.icx(ast_generics), &rb, a, None))
2235                         .collect();
2236
2237     let output = match decl.output {
2238         hir::Return(ref ty) =>
2239             ty::FnConverging(ast_ty_to_ty(&ccx.icx(ast_generics), &rb, &**ty)),
2240         hir::DefaultReturn(..) =>
2241             ty::FnConverging(ccx.tcx.mk_nil()),
2242         hir::NoReturn(..) =>
2243             ty::FnDiverging
2244     };
2245
2246     let t_fn = ccx.tcx.mk_fn(None,
2247         ccx.tcx.mk_bare_fn(ty::BareFnTy {
2248             abi: abi,
2249             unsafety: hir::Unsafety::Unsafe,
2250             sig: ty::Binder(ty::FnSig {inputs: input_tys,
2251                                        output: output,
2252                                        variadic: decl.variadic}),
2253         }));
2254
2255     ty::TypeScheme {
2256         generics: ty_generics,
2257         ty: t_fn
2258     }
2259 }
2260
2261 fn mk_item_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
2262                             ty_generics: &ty::Generics<'tcx>)
2263                             -> Substs<'tcx>
2264 {
2265     let types =
2266         ty_generics.types.map(
2267             |def| ccx.tcx.mk_param_from_def(def));
2268
2269     let regions =
2270         ty_generics.regions.map(
2271             |def| def.to_early_bound_region());
2272
2273     Substs::new(types, regions)
2274 }
2275
2276 /// Verifies that the explicit self type of a method matches the impl
2277 /// or trait. This is a bit weird but basically because right now we
2278 /// don't handle the general case, but instead map it to one of
2279 /// several pre-defined options using various heuristics, this method
2280 /// comes back to check after the fact that explicit type the user
2281 /// wrote actually matches what the pre-defined option said.
2282 fn check_method_self_type<'a, 'tcx, RS:RegionScope>(
2283     ccx: &CrateCtxt<'a, 'tcx>,
2284     rs: &RS,
2285     method_type: Rc<ty::Method<'tcx>>,
2286     required_type: Ty<'tcx>,
2287     explicit_self: &hir::ExplicitSelf,
2288     body_id: ast::NodeId)
2289 {
2290     let tcx = ccx.tcx;
2291     if let hir::SelfExplicit(ref ast_type, _) = explicit_self.node {
2292         let typ = ccx.icx(&method_type.predicates).to_ty(rs, &**ast_type);
2293         let base_type = match typ.sty {
2294             ty::TyRef(_, tm) => tm.ty,
2295             ty::TyBox(typ) => typ,
2296             _ => typ,
2297         };
2298
2299         let body_scope = tcx.region_maps.item_extent(body_id);
2300
2301         // "Required type" comes from the trait definition. It may
2302         // contain late-bound regions from the method, but not the
2303         // trait (since traits only have early-bound region
2304         // parameters).
2305         assert!(!base_type.has_regions_escaping_depth(1));
2306         let required_type_free =
2307             liberate_early_bound_regions(
2308                 tcx, body_scope,
2309                 &tcx.liberate_late_bound_regions(body_scope, &ty::Binder(required_type)));
2310
2311         // The "base type" comes from the impl. It too may have late-bound
2312         // regions from the method.
2313         assert!(!base_type.has_regions_escaping_depth(1));
2314         let base_type_free =
2315             liberate_early_bound_regions(
2316                 tcx, body_scope,
2317                 &tcx.liberate_late_bound_regions(body_scope, &ty::Binder(base_type)));
2318
2319         debug!("required_type={:?} required_type_free={:?} \
2320                 base_type={:?} base_type_free={:?}",
2321                required_type,
2322                required_type_free,
2323                base_type,
2324                base_type_free);
2325
2326         let infcx = infer::new_infer_ctxt(tcx, &tcx.tables, None, false);
2327         drop(::require_same_types(tcx,
2328                                   Some(&infcx),
2329                                   false,
2330                                   explicit_self.span,
2331                                   base_type_free,
2332                                   required_type_free,
2333                                   || {
2334                 format!("mismatched self type: expected `{}`",
2335                          required_type)
2336         }));
2337
2338         // We could conceviably add more free-region relations here,
2339         // but since this code is just concerned with checking that
2340         // the `&Self` types etc match up, it's not really necessary.
2341         // It would just allow people to be more approximate in some
2342         // cases. In any case, we can do it later as we feel the need;
2343         // I'd like this function to go away eventually.
2344         let free_regions = FreeRegionMap::new();
2345
2346         infcx.resolve_regions_and_report_errors(&free_regions, body_id);
2347     }
2348
2349     fn liberate_early_bound_regions<'tcx,T>(
2350         tcx: &ty::ctxt<'tcx>,
2351         scope: region::CodeExtent,
2352         value: &T)
2353         -> T
2354         where T : TypeFoldable<'tcx>
2355     {
2356         /*!
2357          * Convert early-bound regions into free regions; normally this is done by
2358          * applying the `free_substs` from the `ParameterEnvironment`, but this particular
2359          * method-self-type check is kind of hacky and done very early in the process,
2360          * before we really have a `ParameterEnvironment` to check.
2361          */
2362
2363         tcx.fold_regions(value, &mut false, |region, _| {
2364             match region {
2365                 ty::ReEarlyBound(data) => {
2366                     ty::ReFree(ty::FreeRegion {
2367                         scope: scope,
2368                         bound_region: ty::BrNamed(data.def_id, data.name)
2369                     })
2370                 }
2371                 _ => region
2372             }
2373         })
2374     }
2375 }
2376
2377 /// Checks that all the type parameters on an impl
2378 fn enforce_impl_params_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
2379                                              ast_generics: &hir::Generics,
2380                                              impl_def_id: DefId,
2381                                              impl_items: &[P<hir::ImplItem>])
2382 {
2383     let impl_scheme = tcx.lookup_item_type(impl_def_id);
2384     let impl_predicates = tcx.lookup_predicates(impl_def_id);
2385     let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
2386
2387     // The trait reference is an input, so find all type parameters
2388     // reachable from there, to start (if this is an inherent impl,
2389     // then just examine the self type).
2390     let mut input_parameters: HashSet<_> =
2391         ctp::parameters_for_type(impl_scheme.ty).into_iter().collect();
2392     if let Some(ref trait_ref) = impl_trait_ref {
2393         input_parameters.extend(ctp::parameters_for_trait_ref(trait_ref));
2394     }
2395
2396     ctp::identify_constrained_type_params(tcx,
2397                                           impl_predicates.predicates.as_slice(),
2398                                           impl_trait_ref,
2399                                           &mut input_parameters);
2400
2401     for (index, ty_param) in ast_generics.ty_params.iter().enumerate() {
2402         let param_ty = ty::ParamTy { space: TypeSpace,
2403                                      idx: index as u32,
2404                                      name: ty_param.name };
2405         if !input_parameters.contains(&ctp::Parameter::Type(param_ty)) {
2406             report_unused_parameter(tcx, ty_param.span, "type", &param_ty.to_string());
2407         }
2408     }
2409
2410     // Every lifetime used in an associated type must be constrained.
2411
2412     let lifetimes_in_associated_types: HashSet<_> =
2413         impl_items.iter()
2414                   .map(|item| tcx.impl_or_trait_item(tcx.map.local_def_id(item.id)))
2415                   .filter_map(|item| match item {
2416                       ty::TypeTraitItem(ref assoc_ty) => assoc_ty.ty,
2417                       ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => None
2418                   })
2419                   .flat_map(|ty| ctp::parameters_for_type(ty))
2420                   .filter_map(|p| match p {
2421                       ctp::Parameter::Type(_) => None,
2422                       ctp::Parameter::Region(r) => Some(r),
2423                   })
2424                   .collect();
2425
2426     for (index, lifetime_def) in ast_generics.lifetimes.iter().enumerate() {
2427         let def_id = tcx.map.local_def_id(lifetime_def.lifetime.id);
2428         let region = ty::EarlyBoundRegion { def_id: def_id,
2429                                             space: TypeSpace,
2430                                             index: index as u32,
2431                                             name: lifetime_def.lifetime.name };
2432         if
2433             lifetimes_in_associated_types.contains(&region) && // (*)
2434             !input_parameters.contains(&ctp::Parameter::Region(region))
2435         {
2436             report_unused_parameter(tcx, lifetime_def.lifetime.span,
2437                                     "lifetime", &region.name.to_string());
2438         }
2439     }
2440
2441     // (*) This is a horrible concession to reality. I think it'd be
2442     // better to just ban unconstrianed lifetimes outright, but in
2443     // practice people do non-hygenic macros like:
2444     //
2445     // ```
2446     // macro_rules! __impl_slice_eq1 {
2447     //     ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
2448     //         impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
2449     //            ....
2450     //         }
2451     //     }
2452     // }
2453     // ```
2454     //
2455     // In a concession to backwards compatbility, we continue to
2456     // permit those, so long as the lifetimes aren't used in
2457     // associated types. I believe this is sound, because lifetimes
2458     // used elsewhere are not projected back out.
2459 }
2460
2461 fn report_unused_parameter(tcx: &ty::ctxt,
2462                            span: Span,
2463                            kind: &str,
2464                            name: &str)
2465 {
2466     span_err!(tcx.sess, span, E0207,
2467               "the {} parameter `{}` is not constrained by the \
2468                impl trait, self type, or predicates",
2469               kind, name);
2470 }