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 those 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 let Some(ctor_id) = struct_def.ctor_id {
1018                 convert_variant_ctor(tcx, ctor_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::Dict => 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     let tcx = ccx.tcx;
1069     let icx = ccx.icx(&predicates);
1070
1071     // fill the field types
1072     for (variant, ty_variant) in variants.iter().zip(def.variants.iter()) {
1073         match variant.node.kind {
1074             hir::TupleVariantKind(ref args) => {
1075                 let rs = ExplicitRscope;
1076                 let input_tys: Vec<_> = args.iter().map(|va| icx.to_ty(&rs, &*va.ty)).collect();
1077                 for (field, &ty) in ty_variant.fields.iter().zip(input_tys.iter()) {
1078                     field.fulfill_ty(ty);
1079                 }
1080             }
1081
1082             hir::StructVariantKind(ref struct_def) => {
1083                 for (f, ty_f) in struct_def.fields.iter().zip(ty_variant.fields.iter()) {
1084                     convert_field(ccx, &scheme.generics, &predicates, f, ty_f)
1085                 }
1086             }
1087         };
1088
1089         // Convert the ctor, if any. This also registers the variant as
1090         // an item.
1091         convert_variant_ctor(
1092             tcx,
1093             variant.node.id,
1094             ty_variant,
1095             scheme.clone(),
1096             predicates.clone()
1097         );
1098     }
1099 }
1100
1101 fn convert_struct_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
1102                                 did: DefId,
1103                                 name: ast::Name,
1104                                 disr_val: ty::Disr,
1105                                 def: &hir::StructDef) -> ty::VariantDefData<'tcx, 'tcx> {
1106     let mut seen_fields: FnvHashMap<ast::Name, Span> = FnvHashMap();
1107     let fields = def.fields.iter().map(|f| {
1108         let fid = tcx.map.local_def_id(f.node.id);
1109         match f.node.kind {
1110             hir::NamedField(name, vis) => {
1111                 let dup_span = seen_fields.get(&name).cloned();
1112                 if let Some(prev_span) = dup_span {
1113                     span_err!(tcx.sess, f.span, E0124,
1114                               "field `{}` is already declared",
1115                               name);
1116                     span_note!(tcx.sess, prev_span, "previously declared here");
1117                 } else {
1118                     seen_fields.insert(name, f.span);
1119                 }
1120
1121                 ty::FieldDefData::new(fid, name, vis)
1122             },
1123             hir::UnnamedField(vis) => {
1124                 ty::FieldDefData::new(fid, special_idents::unnamed_field.name, vis)
1125             }
1126         }
1127     }).collect();
1128     ty::VariantDefData {
1129         did: did,
1130         name: name,
1131         disr_val: disr_val,
1132         fields: fields
1133     }
1134 }
1135
1136 fn convert_struct_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1137                             it: &hir::Item,
1138                             def: &hir::StructDef)
1139                             -> ty::AdtDefMaster<'tcx>
1140 {
1141
1142     let did = tcx.map.local_def_id(it.id);
1143     tcx.intern_adt_def(
1144         did,
1145         ty::AdtKind::Struct,
1146         vec![convert_struct_variant(tcx, did, it.name, 0, def)]
1147     )
1148 }
1149
1150 fn convert_enum_def<'tcx>(tcx: &ty::ctxt<'tcx>,
1151                           it: &hir::Item,
1152                           def: &hir::EnumDef)
1153                           -> ty::AdtDefMaster<'tcx>
1154 {
1155     fn evaluate_disr_expr<'tcx>(tcx: &ty::ctxt<'tcx>,
1156                                 repr_ty: Ty<'tcx>,
1157                                 e: &hir::Expr) -> Option<ty::Disr> {
1158         debug!("disr expr, checking {}", pprust::expr_to_string(e));
1159
1160         let hint = UncheckedExprHint(repr_ty);
1161         match const_eval::eval_const_expr_partial(tcx, e, hint) {
1162             Ok(ConstVal::Int(val)) => Some(val as ty::Disr),
1163             Ok(ConstVal::Uint(val)) => Some(val as ty::Disr),
1164             Ok(_) => {
1165                 let sign_desc = if repr_ty.is_signed() {
1166                     "signed"
1167                 } else {
1168                     "unsigned"
1169                 };
1170                 span_err!(tcx.sess, e.span, E0079,
1171                           "expected {} integer constant",
1172                           sign_desc);
1173                 None
1174             },
1175             Err(err) => {
1176               span_err!(tcx.sess, err.span, E0080,
1177                         "constant evaluation error: {}",
1178                         err.description());
1179                 None
1180             }
1181         }
1182     }
1183
1184     fn report_discrim_overflow(tcx: &ty::ctxt,
1185                                variant_span: Span,
1186                                variant_name: &str,
1187                                repr_type: attr::IntType,
1188                                prev_val: ty::Disr) {
1189         let computed_value = repr_type.disr_wrap_incr(Some(prev_val));
1190         let computed_value = repr_type.disr_string(computed_value);
1191         let prev_val = repr_type.disr_string(prev_val);
1192         let repr_type = repr_type.to_ty(tcx);
1193         span_err!(tcx.sess, variant_span, E0370,
1194                   "enum discriminant overflowed on value after {}: {}; \
1195                    set explicitly via {} = {} if that is desired outcome",
1196                   prev_val, repr_type, variant_name, computed_value);
1197     }
1198
1199     fn next_disr(tcx: &ty::ctxt,
1200                  v: &hir::Variant,
1201                  repr_type: attr::IntType,
1202                  prev_disr_val: Option<ty::Disr>) -> Option<ty::Disr> {
1203         if let Some(prev_disr_val) = prev_disr_val {
1204             let result = repr_type.disr_incr(prev_disr_val);
1205             if let None = result {
1206                 report_discrim_overflow(tcx, v.span, &v.node.name.as_str(),
1207                                              repr_type, prev_disr_val);
1208             }
1209             result
1210         } else {
1211             Some(ty::INITIAL_DISCRIMINANT_VALUE)
1212         }
1213     }
1214     fn convert_enum_variant<'tcx>(tcx: &ty::ctxt<'tcx>,
1215                                   v: &hir::Variant,
1216                                   disr: ty::Disr)
1217                                   -> ty::VariantDefData<'tcx, 'tcx>
1218     {
1219         let did = tcx.map.local_def_id(v.node.id);
1220         let name = v.node.name;
1221         match v.node.kind {
1222             hir::TupleVariantKind(ref va) => {
1223                 ty::VariantDefData {
1224                     did: did,
1225                     name: name,
1226                     disr_val: disr,
1227                     fields: va.iter().map(|&hir::VariantArg { id, .. }| {
1228                         ty::FieldDefData::new(
1229                             tcx.map.local_def_id(id),
1230                             special_idents::unnamed_field.name,
1231                             hir::Visibility::Public
1232                         )
1233                     }).collect()
1234                 }
1235             }
1236             hir::StructVariantKind(ref def) => {
1237                 convert_struct_variant(tcx, did, name, disr, &def)
1238             }
1239         }
1240     }
1241     let did = tcx.map.local_def_id(it.id);
1242     let repr_hints = tcx.lookup_repr_hints(did);
1243     let (repr_type, repr_type_ty) = tcx.enum_repr_type(repr_hints.get(0));
1244     let mut prev_disr = None;
1245     let variants = def.variants.iter().map(|v| {
1246         let disr = match v.node.disr_expr {
1247             Some(ref e) => evaluate_disr_expr(tcx, repr_type_ty, e),
1248             None => next_disr(tcx, v, repr_type, prev_disr)
1249         }.unwrap_or(repr_type.disr_wrap_incr(prev_disr));
1250
1251         let v = convert_enum_variant(tcx, v, disr);
1252         prev_disr = Some(disr);
1253         v
1254     }).collect();
1255     tcx.intern_adt_def(tcx.map.local_def_id(it.id), ty::AdtKind::Enum, variants)
1256 }
1257
1258 /// Ensures that the super-predicates of the trait with def-id
1259 /// trait_def_id are converted and stored. This does NOT ensure that
1260 /// the transitive super-predicates are converted; that is the job of
1261 /// the `ensure_super_predicates()` method in the `AstConv` impl
1262 /// above. Returns a list of trait def-ids that must be ensured as
1263 /// well to guarantee that the transitive superpredicates are
1264 /// converted.
1265 fn ensure_super_predicates_step(ccx: &CrateCtxt,
1266                                 trait_def_id: DefId)
1267                                 -> Vec<DefId>
1268 {
1269     let tcx = ccx.tcx;
1270
1271     debug!("ensure_super_predicates_step(trait_def_id={:?})", trait_def_id);
1272
1273     let trait_node_id = if let Some(n) = tcx.map.as_local_node_id(trait_def_id) {
1274         n
1275     } else {
1276         // If this trait comes from an external crate, then all of the
1277         // supertraits it may depend on also must come from external
1278         // crates, and hence all of them already have their
1279         // super-predicates "converted" (and available from crate
1280         // meta-data), so there is no need to transitively test them.
1281         return Vec::new();
1282     };
1283
1284     let superpredicates = tcx.super_predicates.borrow().get(&trait_def_id).cloned();
1285     let superpredicates = superpredicates.unwrap_or_else(|| {
1286         let item = match ccx.tcx.map.get(trait_node_id) {
1287             hir_map::NodeItem(item) => item,
1288             _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1289         };
1290
1291         let (generics, bounds) = match item.node {
1292             hir::ItemTrait(_, ref generics, ref supertraits, _) => (generics, supertraits),
1293             _ => tcx.sess.span_bug(item.span,
1294                                    "ensure_super_predicates_step invoked on non-trait"),
1295         };
1296
1297         // In-scope when converting the superbounds for `Trait` are
1298         // that `Self:Trait` as well as any bounds that appear on the
1299         // generic types:
1300         let trait_def = trait_def_of_item(ccx, item);
1301         let self_predicate = ty::GenericPredicates {
1302             predicates: VecPerParamSpace::new(vec![],
1303                                               vec![trait_def.trait_ref.to_predicate()],
1304                                               vec![])
1305         };
1306         let scope = &(generics, &self_predicate);
1307
1308         // Convert the bounds that follow the colon, e.g. `Bar+Zed` in `trait Foo : Bar+Zed`.
1309         let self_param_ty = tcx.mk_self_type();
1310         let superbounds1 = compute_bounds(&ccx.icx(scope),
1311                                     self_param_ty,
1312                                     bounds,
1313                                     SizedByDefault::No,
1314                                     item.span);
1315
1316         let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
1317
1318         // Convert any explicit superbounds in the where clause,
1319         // e.g. `trait Foo where Self : Bar`:
1320         let superbounds2 = generics.get_type_parameter_bounds(&ccx.icx(scope), item.span, item.id);
1321
1322         // Combine the two lists to form the complete set of superbounds:
1323         let superbounds = superbounds1.into_iter().chain(superbounds2).collect();
1324         let superpredicates = ty::GenericPredicates {
1325             predicates: VecPerParamSpace::new(superbounds, vec![], vec![])
1326         };
1327         debug!("superpredicates for trait {:?} = {:?}",
1328                tcx.map.local_def_id(item.id),
1329                superpredicates);
1330
1331         tcx.super_predicates.borrow_mut().insert(trait_def_id, superpredicates.clone());
1332
1333         superpredicates
1334     });
1335
1336     let def_ids: Vec<_> = superpredicates.predicates
1337                                          .iter()
1338                                          .filter_map(|p| p.to_opt_poly_trait_ref())
1339                                          .map(|tr| tr.def_id())
1340                                          .collect();
1341
1342     debug!("ensure_super_predicates_step: def_ids={:?}", def_ids);
1343
1344     def_ids
1345 }
1346
1347 fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1348                                it: &hir::Item)
1349                                -> &'tcx ty::TraitDef<'tcx>
1350 {
1351     let def_id = ccx.tcx.map.local_def_id(it.id);
1352     let tcx = ccx.tcx;
1353
1354     if let Some(def) = tcx.trait_defs.borrow().get(&def_id) {
1355         return def.clone();
1356     }
1357
1358     let (unsafety, generics, items) = match it.node {
1359         hir::ItemTrait(unsafety, ref generics, _, ref items) => (unsafety, generics, items),
1360         _ => tcx.sess.span_bug(it.span, "trait_def_of_item invoked on non-trait"),
1361     };
1362
1363     let paren_sugar = tcx.has_attr(def_id, "rustc_paren_sugar");
1364     if paren_sugar && !ccx.tcx.sess.features.borrow().unboxed_closures {
1365         ccx.tcx.sess.span_err(
1366             it.span,
1367             "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
1368              which traits can use parenthetical notation");
1369         fileline_help!(ccx.tcx.sess, it.span,
1370                    "add `#![feature(unboxed_closures)]` to \
1371                     the crate attributes to use it");
1372     }
1373
1374     let substs = ccx.tcx.mk_substs(mk_trait_substs(ccx, generics));
1375
1376     let ty_generics = ty_generics_for_trait(ccx, it.id, substs, generics);
1377
1378     let associated_type_names: Vec<_> = items.iter().filter_map(|trait_item| {
1379         match trait_item.node {
1380             hir::TypeTraitItem(..) => Some(trait_item.name),
1381             _ => None,
1382         }
1383     }).collect();
1384
1385     let trait_ref = ty::TraitRef {
1386         def_id: def_id,
1387         substs: substs,
1388     };
1389
1390     let trait_def = ty::TraitDef {
1391         paren_sugar: paren_sugar,
1392         unsafety: unsafety,
1393         generics: ty_generics,
1394         trait_ref: trait_ref,
1395         associated_type_names: associated_type_names,
1396         nonblanket_impls: RefCell::new(FnvHashMap()),
1397         blanket_impls: RefCell::new(vec![]),
1398         flags: Cell::new(ty::TraitFlags::NO_TRAIT_FLAGS)
1399     };
1400
1401     return tcx.intern_trait_def(trait_def);
1402
1403     fn mk_trait_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1404                                  generics: &hir::Generics)
1405                                  -> Substs<'tcx>
1406     {
1407         let tcx = ccx.tcx;
1408
1409         // Creates a no-op substitution for the trait's type parameters.
1410         let regions =
1411             generics.lifetimes
1412                     .iter()
1413                     .enumerate()
1414                     .map(|(i, def)| ty::ReEarlyBound(ty::EarlyBoundRegion {
1415                         def_id: tcx.map.local_def_id(def.lifetime.id),
1416                         space: TypeSpace,
1417                         index: i as u32,
1418                         name: def.lifetime.name
1419                     }))
1420                     .collect();
1421
1422         // Start with the generics in the type parameters...
1423         let types: Vec<_> =
1424             generics.ty_params
1425                     .iter()
1426                     .enumerate()
1427                     .map(|(i, def)| tcx.mk_param(TypeSpace,
1428                                                  i as u32, def.name))
1429                     .collect();
1430
1431         // ...and also create the `Self` parameter.
1432         let self_ty = tcx.mk_self_type();
1433
1434         Substs::new_trait(types, regions, self_ty)
1435     }
1436 }
1437
1438 fn trait_defines_associated_type_named(ccx: &CrateCtxt,
1439                                        trait_node_id: ast::NodeId,
1440                                        assoc_name: ast::Name)
1441                                        -> bool
1442 {
1443     let item = match ccx.tcx.map.get(trait_node_id) {
1444         hir_map::NodeItem(item) => item,
1445         _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not an item", trait_node_id))
1446     };
1447
1448     let trait_items = match item.node {
1449         hir::ItemTrait(_, _, _, ref trait_items) => trait_items,
1450         _ => ccx.tcx.sess.bug(&format!("trait_node_id {} is not a trait", trait_node_id))
1451     };
1452
1453     trait_items.iter().any(|trait_item| {
1454         match trait_item.node {
1455             hir::TypeTraitItem(..) => trait_item.name == assoc_name,
1456             _ => false,
1457         }
1458     })
1459 }
1460
1461 fn convert_trait_predicates<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>, it: &hir::Item) {
1462     let tcx = ccx.tcx;
1463     let trait_def = trait_def_of_item(ccx, it);
1464
1465     let def_id = ccx.tcx.map.local_def_id(it.id);
1466
1467     let (generics, items) = match it.node {
1468         hir::ItemTrait(_, ref generics, _, ref items) => (generics, items),
1469         ref s => {
1470             tcx.sess.span_bug(
1471                 it.span,
1472                 &format!("trait_def_of_item invoked on {:?}", s));
1473         }
1474     };
1475
1476     let super_predicates = ccx.tcx.lookup_super_predicates(def_id);
1477
1478     // `ty_generic_predicates` below will consider the bounds on the type
1479     // parameters (including `Self`) and the explicit where-clauses,
1480     // but to get the full set of predicates on a trait we need to add
1481     // in the supertrait bounds and anything declared on the
1482     // associated types.
1483     let mut base_predicates = super_predicates;
1484
1485     // Add in a predicate that `Self:Trait` (where `Trait` is the
1486     // current trait).  This is needed for builtin bounds.
1487     let self_predicate = trait_def.trait_ref.to_poly_trait_ref().to_predicate();
1488     base_predicates.predicates.push(SelfSpace, self_predicate);
1489
1490     // add in the explicit where-clauses
1491     let mut trait_predicates =
1492         ty_generic_predicates(ccx, TypeSpace, generics, &base_predicates);
1493
1494     let assoc_predicates = predicates_for_associated_types(ccx,
1495                                                            generics,
1496                                                            &trait_predicates,
1497                                                            trait_def.trait_ref,
1498                                                            items);
1499     trait_predicates.predicates.extend(TypeSpace, assoc_predicates.into_iter());
1500
1501     let prev_predicates = tcx.predicates.borrow_mut().insert(def_id, trait_predicates);
1502     assert!(prev_predicates.is_none());
1503
1504     return;
1505
1506     fn predicates_for_associated_types<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1507                                                  ast_generics: &hir::Generics,
1508                                                  trait_predicates: &ty::GenericPredicates<'tcx>,
1509                                                  self_trait_ref: ty::TraitRef<'tcx>,
1510                                                  trait_items: &[P<hir::TraitItem>])
1511                                                  -> Vec<ty::Predicate<'tcx>>
1512     {
1513         trait_items.iter().flat_map(|trait_item| {
1514             let bounds = match trait_item.node {
1515                 hir::TypeTraitItem(ref bounds, _) => bounds,
1516                 _ => {
1517                     return vec!().into_iter();
1518                 }
1519             };
1520
1521             let assoc_ty = ccx.tcx.mk_projection(self_trait_ref,
1522                                                  trait_item.name);
1523
1524             let bounds = compute_bounds(&ccx.icx(&(ast_generics, trait_predicates)),
1525                                         assoc_ty,
1526                                         bounds,
1527                                         SizedByDefault::Yes,
1528                                         trait_item.span);
1529
1530             bounds.predicates(ccx.tcx, assoc_ty).into_iter()
1531         }).collect()
1532     }
1533 }
1534
1535 fn type_scheme_of_def_id<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1536                                   def_id: DefId)
1537                                   -> ty::TypeScheme<'tcx>
1538 {
1539     if let Some(node_id) = ccx.tcx.map.as_local_node_id(def_id) {
1540         match ccx.tcx.map.find(node_id) {
1541             Some(hir_map::NodeItem(item)) => {
1542                 type_scheme_of_item(ccx, &*item)
1543             }
1544             Some(hir_map::NodeForeignItem(foreign_item)) => {
1545                 let abi = ccx.tcx.map.get_foreign_abi(node_id);
1546                 type_scheme_of_foreign_item(ccx, &*foreign_item, abi)
1547             }
1548             x => {
1549                 ccx.tcx.sess.bug(&format!("unexpected sort of node \
1550                                            in get_item_type_scheme(): {:?}",
1551                                           x));
1552             }
1553         }
1554     } else {
1555         ccx.tcx.lookup_item_type(def_id)
1556     }
1557 }
1558
1559 fn type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1560                                 it: &hir::Item)
1561                                 -> ty::TypeScheme<'tcx>
1562 {
1563     memoized(&ccx.tcx.tcache,
1564              ccx.tcx.map.local_def_id(it.id),
1565              |_| compute_type_scheme_of_item(ccx, it))
1566 }
1567
1568 fn compute_type_scheme_of_item<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1569                                         it: &hir::Item)
1570                                         -> ty::TypeScheme<'tcx>
1571 {
1572     let tcx = ccx.tcx;
1573     match it.node {
1574         hir::ItemStatic(ref t, _, _) | hir::ItemConst(ref t, _) => {
1575             let ty = ccx.icx(&()).to_ty(&ExplicitRscope, &**t);
1576             ty::TypeScheme { ty: ty, generics: ty::Generics::empty() }
1577         }
1578         hir::ItemFn(ref decl, unsafety, _, abi, ref generics, _) => {
1579             let ty_generics = ty_generics_for_fn(ccx, generics, &ty::Generics::empty());
1580             let tofd = astconv::ty_of_bare_fn(&ccx.icx(generics), unsafety, abi, &**decl);
1581             let ty = tcx.mk_fn(Some(ccx.tcx.map.local_def_id(it.id)), tcx.mk_bare_fn(tofd));
1582             ty::TypeScheme { ty: ty, generics: ty_generics }
1583         }
1584         hir::ItemTy(ref t, ref generics) => {
1585             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1586             let ty = ccx.icx(generics).to_ty(&ExplicitRscope, &**t);
1587             ty::TypeScheme { ty: ty, generics: ty_generics }
1588         }
1589         hir::ItemEnum(ref ei, ref generics) => {
1590             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1591             let substs = mk_item_substs(ccx, &ty_generics);
1592             let def = convert_enum_def(tcx, it, ei);
1593             let t = tcx.mk_enum(def, tcx.mk_substs(substs));
1594             ty::TypeScheme { ty: t, generics: ty_generics }
1595         }
1596         hir::ItemStruct(ref si, ref generics) => {
1597             let ty_generics = ty_generics_for_type_or_impl(ccx, generics);
1598             let substs = mk_item_substs(ccx, &ty_generics);
1599             let def = convert_struct_def(tcx, it, si);
1600             let t = tcx.mk_struct(def, tcx.mk_substs(substs));
1601             ty::TypeScheme { ty: t, generics: ty_generics }
1602         }
1603         hir::ItemDefaultImpl(..) |
1604         hir::ItemTrait(..) |
1605         hir::ItemImpl(..) |
1606         hir::ItemMod(..) |
1607         hir::ItemForeignMod(..) |
1608         hir::ItemExternCrate(..) |
1609         hir::ItemUse(..) => {
1610             tcx.sess.span_bug(
1611                 it.span,
1612                 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1613                          it.node));
1614         }
1615     }
1616 }
1617
1618 fn convert_typed_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1619                                 it: &hir::Item)
1620                                 -> (ty::TypeScheme<'tcx>, ty::GenericPredicates<'tcx>)
1621 {
1622     let tcx = ccx.tcx;
1623
1624     let tag = type_scheme_of_item(ccx, it);
1625     let scheme = TypeScheme { generics: tag.generics, ty: tag.ty };
1626     let predicates = match it.node {
1627         hir::ItemStatic(..) | hir::ItemConst(..) => {
1628             ty::GenericPredicates::empty()
1629         }
1630         hir::ItemFn(_, _, _, _, ref ast_generics, _) => {
1631             ty_generic_predicates_for_fn(ccx, ast_generics, &ty::GenericPredicates::empty())
1632         }
1633         hir::ItemTy(_, ref generics) => {
1634             ty_generic_predicates_for_type_or_impl(ccx, generics)
1635         }
1636         hir::ItemEnum(_, ref generics) => {
1637             ty_generic_predicates_for_type_or_impl(ccx, generics)
1638         }
1639         hir::ItemStruct(_, ref generics) => {
1640             ty_generic_predicates_for_type_or_impl(ccx, generics)
1641         }
1642         hir::ItemDefaultImpl(..) |
1643         hir::ItemTrait(..) |
1644         hir::ItemExternCrate(..) |
1645         hir::ItemUse(..) |
1646         hir::ItemImpl(..) |
1647         hir::ItemMod(..) |
1648         hir::ItemForeignMod(..) => {
1649             tcx.sess.span_bug(
1650                 it.span,
1651                 &format!("compute_type_scheme_of_item: unexpected item type: {:?}",
1652                          it.node));
1653         }
1654     };
1655
1656     let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1657                                                              predicates.clone());
1658     assert!(prev_predicates.is_none());
1659
1660     // Debugging aid.
1661     if tcx.has_attr(ccx.tcx.map.local_def_id(it.id), "rustc_object_lifetime_default") {
1662         let object_lifetime_default_reprs: String =
1663             scheme.generics.types.iter()
1664                                  .map(|t| match t.object_lifetime_default {
1665                                      ty::ObjectLifetimeDefault::Specific(r) => r.to_string(),
1666                                      d => format!("{:?}", d),
1667                                  })
1668                                  .collect::<Vec<String>>()
1669                                  .join(",");
1670
1671         tcx.sess.span_err(it.span, &object_lifetime_default_reprs);
1672     }
1673
1674     return (scheme, predicates);
1675 }
1676
1677 fn type_scheme_of_foreign_item<'a, 'tcx>(
1678     ccx: &CrateCtxt<'a, 'tcx>,
1679     it: &hir::ForeignItem,
1680     abi: abi::Abi)
1681     -> ty::TypeScheme<'tcx>
1682 {
1683     memoized(&ccx.tcx.tcache,
1684              ccx.tcx.map.local_def_id(it.id),
1685              |_| compute_type_scheme_of_foreign_item(ccx, it, abi))
1686 }
1687
1688 fn compute_type_scheme_of_foreign_item<'a, 'tcx>(
1689     ccx: &CrateCtxt<'a, 'tcx>,
1690     it: &hir::ForeignItem,
1691     abi: abi::Abi)
1692     -> ty::TypeScheme<'tcx>
1693 {
1694     match it.node {
1695         hir::ForeignItemFn(ref fn_decl, ref generics) => {
1696             compute_type_scheme_of_foreign_fn_decl(ccx, fn_decl, generics, abi)
1697         }
1698         hir::ForeignItemStatic(ref t, _) => {
1699             ty::TypeScheme {
1700                 generics: ty::Generics::empty(),
1701                 ty: ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, t)
1702             }
1703         }
1704     }
1705 }
1706
1707 fn convert_foreign_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1708                                   it: &hir::ForeignItem)
1709 {
1710     // For reasons I cannot fully articulate, I do so hate the AST
1711     // map, and I regard each time that I use it as a personal and
1712     // moral failing, but at the moment it seems like the only
1713     // convenient way to extract the ABI. - ndm
1714     let tcx = ccx.tcx;
1715     let abi = tcx.map.get_foreign_abi(it.id);
1716
1717     let scheme = type_scheme_of_foreign_item(ccx, it, abi);
1718     write_ty_to_tcx(ccx.tcx, it.id, scheme.ty);
1719
1720     let predicates = match it.node {
1721         hir::ForeignItemFn(_, ref generics) => {
1722             ty_generic_predicates_for_fn(ccx, generics, &ty::GenericPredicates::empty())
1723         }
1724         hir::ForeignItemStatic(..) => {
1725             ty::GenericPredicates::empty()
1726         }
1727     };
1728
1729     let prev_predicates = tcx.predicates.borrow_mut().insert(ccx.tcx.map.local_def_id(it.id),
1730                                                              predicates);
1731     assert!(prev_predicates.is_none());
1732 }
1733
1734 fn ty_generics_for_type_or_impl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1735                                           generics: &hir::Generics)
1736                                           -> ty::Generics<'tcx> {
1737     ty_generics(ccx, TypeSpace, generics, &ty::Generics::empty())
1738 }
1739
1740 fn ty_generic_predicates_for_type_or_impl<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1741                                                    generics: &hir::Generics)
1742                                                    -> ty::GenericPredicates<'tcx>
1743 {
1744     ty_generic_predicates(ccx, TypeSpace, generics, &ty::GenericPredicates::empty())
1745 }
1746
1747 fn ty_generics_for_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1748                                    trait_id: ast::NodeId,
1749                                    substs: &'tcx Substs<'tcx>,
1750                                    ast_generics: &hir::Generics)
1751                                    -> ty::Generics<'tcx>
1752 {
1753     debug!("ty_generics_for_trait(trait_id={:?}, substs={:?})",
1754            ccx.tcx.map.local_def_id(trait_id), substs);
1755
1756     let mut generics = ty_generics_for_type_or_impl(ccx, ast_generics);
1757
1758     // Add in the self type parameter.
1759     //
1760     // Something of a hack: use the node id for the trait, also as
1761     // the node id for the Self type parameter.
1762     let param_id = trait_id;
1763
1764     let parent = ccx.tcx.map.get_parent(param_id);
1765
1766     let def = ty::TypeParameterDef {
1767         space: SelfSpace,
1768         index: 0,
1769         name: special_idents::type_self.name,
1770         def_id: ccx.tcx.map.local_def_id(param_id),
1771         default_def_id: ccx.tcx.map.local_def_id(parent),
1772         default: None,
1773         object_lifetime_default: ty::ObjectLifetimeDefault::BaseDefault,
1774     };
1775
1776     ccx.tcx.ty_param_defs.borrow_mut().insert(param_id, def.clone());
1777
1778     generics.types.push(SelfSpace, def);
1779
1780     return generics;
1781 }
1782
1783 fn ty_generics_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1784                                generics: &hir::Generics,
1785                                base_generics: &ty::Generics<'tcx>)
1786                                -> ty::Generics<'tcx>
1787 {
1788     ty_generics(ccx, FnSpace, generics, base_generics)
1789 }
1790
1791 fn ty_generic_predicates_for_fn<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1792                                          generics: &hir::Generics,
1793                                          base_predicates: &ty::GenericPredicates<'tcx>)
1794                                          -> ty::GenericPredicates<'tcx>
1795 {
1796     ty_generic_predicates(ccx, FnSpace, generics, base_predicates)
1797 }
1798
1799 // Add the Sized bound, unless the type parameter is marked as `?Sized`.
1800 fn add_unsized_bound<'tcx>(astconv: &AstConv<'tcx>,
1801                            bounds: &mut ty::BuiltinBounds,
1802                            ast_bounds: &[hir::TyParamBound],
1803                            span: Span)
1804 {
1805     let tcx = astconv.tcx();
1806
1807     // Try to find an unbound in bounds.
1808     let mut unbound = None;
1809     for ab in ast_bounds {
1810         if let &hir::TraitTyParamBound(ref ptr, hir::TraitBoundModifier::Maybe) = ab  {
1811             if unbound.is_none() {
1812                 assert!(ptr.bound_lifetimes.is_empty());
1813                 unbound = Some(ptr.trait_ref.clone());
1814             } else {
1815                 span_err!(tcx.sess, span, E0203,
1816                           "type parameter has more than one relaxed default \
1817                                                 bound, only one is supported");
1818             }
1819         }
1820     }
1821
1822     let kind_id = tcx.lang_items.require(SizedTraitLangItem);
1823     match unbound {
1824         Some(ref tpb) => {
1825             // FIXME(#8559) currently requires the unbound to be built-in.
1826             let trait_def_id = tcx.trait_ref_to_def_id(tpb);
1827             match kind_id {
1828                 Ok(kind_id) if trait_def_id != kind_id => {
1829                     tcx.sess.span_warn(span,
1830                                        "default bound relaxed for a type parameter, but \
1831                                        this does nothing because the given bound is not \
1832                                        a default. Only `?Sized` is supported");
1833                     tcx.try_add_builtin_trait(kind_id, bounds);
1834                 }
1835                 _ => {}
1836             }
1837         }
1838         _ if kind_id.is_ok() => {
1839             tcx.try_add_builtin_trait(kind_id.unwrap(), bounds);
1840         }
1841         // No lang item for Sized, so we can't add it as a bound.
1842         None => {}
1843     }
1844 }
1845
1846 /// Returns the early-bound lifetimes declared in this generics
1847 /// listing.  For anything other than fns/methods, this is just all
1848 /// the lifetimes that are declared. For fns or methods, we have to
1849 /// screen out those that do not appear in any where-clauses etc using
1850 /// `resolve_lifetime::early_bound_lifetimes`.
1851 fn early_bound_lifetimes_from_generics(space: ParamSpace,
1852                                        ast_generics: &hir::Generics)
1853                                        -> Vec<hir::LifetimeDef>
1854 {
1855     match space {
1856         SelfSpace | TypeSpace => ast_generics.lifetimes.to_vec(),
1857         FnSpace => resolve_lifetime::early_bound_lifetimes(ast_generics),
1858     }
1859 }
1860
1861 fn ty_generic_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1862                                   space: ParamSpace,
1863                                   ast_generics: &hir::Generics,
1864                                   base_predicates: &ty::GenericPredicates<'tcx>)
1865                                   -> ty::GenericPredicates<'tcx>
1866 {
1867     let tcx = ccx.tcx;
1868     let mut result = base_predicates.clone();
1869
1870     // Collect the predicates that were written inline by the user on each
1871     // type parameter (e.g., `<T:Foo>`).
1872     for (index, param) in ast_generics.ty_params.iter().enumerate() {
1873         let index = index as u32;
1874         let param_ty = ty::ParamTy::new(space, index, param.name).to_ty(ccx.tcx);
1875         let bounds = compute_bounds(&ccx.icx(&(base_predicates, ast_generics)),
1876                                     param_ty,
1877                                     &param.bounds,
1878                                     SizedByDefault::Yes,
1879                                     param.span);
1880         let predicates = bounds.predicates(ccx.tcx, param_ty);
1881         result.predicates.extend(space, predicates.into_iter());
1882     }
1883
1884     // Collect the region predicates that were declared inline as
1885     // well. In the case of parameters declared on a fn or method, we
1886     // have to be careful to only iterate over early-bound regions.
1887     let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1888     for (index, param) in early_lifetimes.iter().enumerate() {
1889         let index = index as u32;
1890         let def_id = tcx.map.local_def_id(param.lifetime.id);
1891         let region =
1892             ty::ReEarlyBound(ty::EarlyBoundRegion {
1893                 def_id: def_id,
1894                 space: space,
1895                 index: index,
1896                 name: param.lifetime.name
1897             });
1898         for bound in &param.bounds {
1899             let bound_region = ast_region_to_region(ccx.tcx, bound);
1900             let outlives = ty::Binder(ty::OutlivesPredicate(region, bound_region));
1901             result.predicates.push(space, outlives.to_predicate());
1902         }
1903     }
1904
1905     // Add in the bounds that appear in the where-clause
1906     let where_clause = &ast_generics.where_clause;
1907     for predicate in &where_clause.predicates {
1908         match predicate {
1909             &hir::WherePredicate::BoundPredicate(ref bound_pred) => {
1910                 let ty = ast_ty_to_ty(&ccx.icx(&(base_predicates, ast_generics)),
1911                                       &ExplicitRscope,
1912                                       &*bound_pred.bounded_ty);
1913
1914                 for bound in bound_pred.bounds.iter() {
1915                     match bound {
1916                         &hir::TyParamBound::TraitTyParamBound(ref poly_trait_ref, _) => {
1917                             let mut projections = Vec::new();
1918
1919                             let trait_ref =
1920                                 conv_poly_trait_ref(&ccx.icx(&(base_predicates, ast_generics)),
1921                                                     ty,
1922                                                     poly_trait_ref,
1923                                                     &mut projections);
1924
1925                             result.predicates.push(space, trait_ref.to_predicate());
1926
1927                             for projection in &projections {
1928                                 result.predicates.push(space, projection.to_predicate());
1929                             }
1930                         }
1931
1932                         &hir::TyParamBound::RegionTyParamBound(ref lifetime) => {
1933                             let region = ast_region_to_region(tcx, lifetime);
1934                             let pred = ty::Binder(ty::OutlivesPredicate(ty, region));
1935                             result.predicates.push(space, ty::Predicate::TypeOutlives(pred))
1936                         }
1937                     }
1938                 }
1939             }
1940
1941             &hir::WherePredicate::RegionPredicate(ref region_pred) => {
1942                 let r1 = ast_region_to_region(tcx, &region_pred.lifetime);
1943                 for bound in &region_pred.bounds {
1944                     let r2 = ast_region_to_region(tcx, bound);
1945                     let pred = ty::Binder(ty::OutlivesPredicate(r1, r2));
1946                     result.predicates.push(space, ty::Predicate::RegionOutlives(pred))
1947                 }
1948             }
1949
1950             &hir::WherePredicate::EqPredicate(ref eq_pred) => {
1951                 // FIXME(#20041)
1952                 tcx.sess.span_bug(eq_pred.span,
1953                                     "Equality constraints are not yet \
1954                                         implemented (#20041)")
1955             }
1956         }
1957     }
1958
1959     return result;
1960 }
1961
1962 fn ty_generics<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
1963                         space: ParamSpace,
1964                         ast_generics: &hir::Generics,
1965                         base_generics: &ty::Generics<'tcx>)
1966                         -> ty::Generics<'tcx>
1967 {
1968     let tcx = ccx.tcx;
1969     let mut result = base_generics.clone();
1970
1971     let early_lifetimes = early_bound_lifetimes_from_generics(space, ast_generics);
1972     for (i, l) in early_lifetimes.iter().enumerate() {
1973         let bounds = l.bounds.iter()
1974                              .map(|l| ast_region_to_region(tcx, l))
1975                              .collect();
1976         let def = ty::RegionParameterDef { name: l.lifetime.name,
1977                                            space: space,
1978                                            index: i as u32,
1979                                            def_id: ccx.tcx.map.local_def_id(l.lifetime.id),
1980                                            bounds: bounds };
1981         result.regions.push(space, def);
1982     }
1983
1984     assert!(result.types.is_empty_in(space));
1985
1986     // Now create the real type parameters.
1987     for i in 0..ast_generics.ty_params.len() {
1988         let def = get_or_create_type_parameter_def(ccx, ast_generics, space, i as u32);
1989         debug!("ty_generics: def for type param: {:?}, {:?}", def, space);
1990         result.types.push(space, def);
1991     }
1992
1993     result
1994 }
1995
1996 fn convert_default_type_parameter<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
1997                                             path: &P<hir::Ty>,
1998                                             space: ParamSpace,
1999                                             index: u32)
2000                                             -> Ty<'tcx>
2001 {
2002     let ty = ast_ty_to_ty(&ccx.icx(&()), &ExplicitRscope, &path);
2003
2004     for leaf_ty in ty.walk() {
2005         if let ty::TyParam(p) = leaf_ty.sty {
2006             if p.space == space && p.idx >= index {
2007                 span_err!(ccx.tcx.sess, path.span, E0128,
2008                           "type parameters with a default cannot use \
2009                            forward declared identifiers");
2010
2011                 return ccx.tcx.types.err
2012             }
2013         }
2014     }
2015
2016     ty
2017 }
2018
2019 fn get_or_create_type_parameter_def<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2020                                              ast_generics: &hir::Generics,
2021                                              space: ParamSpace,
2022                                              index: u32)
2023                                              -> ty::TypeParameterDef<'tcx>
2024 {
2025     let param = &ast_generics.ty_params[index as usize];
2026
2027     let tcx = ccx.tcx;
2028     match tcx.ty_param_defs.borrow().get(&param.id) {
2029         Some(d) => { return d.clone(); }
2030         None => { }
2031     }
2032
2033     let default = param.default.as_ref().map(
2034         |def| convert_default_type_parameter(ccx, def, space, index)
2035     );
2036
2037     let object_lifetime_default =
2038         compute_object_lifetime_default(ccx, param.id,
2039                                         &param.bounds, &ast_generics.where_clause);
2040
2041     let parent = tcx.map.get_parent(param.id);
2042
2043     let def = ty::TypeParameterDef {
2044         space: space,
2045         index: index,
2046         name: param.name,
2047         def_id: ccx.tcx.map.local_def_id(param.id),
2048         default_def_id: ccx.tcx.map.local_def_id(parent),
2049         default: default,
2050         object_lifetime_default: object_lifetime_default,
2051     };
2052
2053     tcx.ty_param_defs.borrow_mut().insert(param.id, def.clone());
2054
2055     def
2056 }
2057
2058 /// Scan the bounds and where-clauses on a parameter to extract bounds
2059 /// of the form `T:'a` so as to determine the `ObjectLifetimeDefault`.
2060 /// This runs as part of computing the minimal type scheme, so we
2061 /// intentionally avoid just asking astconv to convert all the where
2062 /// clauses into a `ty::Predicate`. This is because that could induce
2063 /// artificial cycles.
2064 fn compute_object_lifetime_default<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2065                                             param_id: ast::NodeId,
2066                                             param_bounds: &[hir::TyParamBound],
2067                                             where_clause: &hir::WhereClause)
2068                                             -> ty::ObjectLifetimeDefault
2069 {
2070     let inline_bounds = from_bounds(ccx, param_bounds);
2071     let where_bounds = from_predicates(ccx, param_id, &where_clause.predicates);
2072     let all_bounds: HashSet<_> = inline_bounds.into_iter()
2073                                               .chain(where_bounds)
2074                                               .collect();
2075     return if all_bounds.len() > 1 {
2076         ty::ObjectLifetimeDefault::Ambiguous
2077     } else if all_bounds.len() == 0 {
2078         ty::ObjectLifetimeDefault::BaseDefault
2079     } else {
2080         ty::ObjectLifetimeDefault::Specific(
2081             all_bounds.into_iter().next().unwrap())
2082     };
2083
2084     fn from_bounds<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2085                             bounds: &[hir::TyParamBound])
2086                             -> Vec<ty::Region>
2087     {
2088         bounds.iter()
2089               .filter_map(|bound| {
2090                   match *bound {
2091                       hir::TraitTyParamBound(..) =>
2092                           None,
2093                       hir::RegionTyParamBound(ref lifetime) =>
2094                           Some(astconv::ast_region_to_region(ccx.tcx, lifetime)),
2095                   }
2096               })
2097               .collect()
2098     }
2099
2100     fn from_predicates<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
2101                                 param_id: ast::NodeId,
2102                                 predicates: &[hir::WherePredicate])
2103                                 -> Vec<ty::Region>
2104     {
2105         predicates.iter()
2106                   .flat_map(|predicate| {
2107                       match *predicate {
2108                           hir::WherePredicate::BoundPredicate(ref data) => {
2109                               if data.bound_lifetimes.is_empty() &&
2110                                   is_param(ccx.tcx, &data.bounded_ty, param_id)
2111                               {
2112                                   from_bounds(ccx, &data.bounds).into_iter()
2113                               } else {
2114                                   Vec::new().into_iter()
2115                               }
2116                           }
2117                           hir::WherePredicate::RegionPredicate(..) |
2118                           hir::WherePredicate::EqPredicate(..) => {
2119                               Vec::new().into_iter()
2120                           }
2121                       }
2122                   })
2123                   .collect()
2124     }
2125 }
2126
2127 enum SizedByDefault { Yes, No, }
2128
2129 /// Translate the AST's notion of ty param bounds (which are an enum consisting of a newtyped Ty or
2130 /// a region) to ty's notion of ty param bounds, which can either be user-defined traits, or the
2131 /// built-in trait (formerly known as kind): Send.
2132 fn compute_bounds<'tcx>(astconv: &AstConv<'tcx>,
2133                         param_ty: ty::Ty<'tcx>,
2134                         ast_bounds: &[hir::TyParamBound],
2135                         sized_by_default: SizedByDefault,
2136                         span: Span)
2137                         -> astconv::Bounds<'tcx>
2138 {
2139     let mut bounds =
2140         conv_param_bounds(astconv,
2141                           span,
2142                           param_ty,
2143                           ast_bounds);
2144
2145     if let SizedByDefault::Yes = sized_by_default {
2146         add_unsized_bound(astconv,
2147                           &mut bounds.builtin_bounds,
2148                           ast_bounds,
2149                           span);
2150     }
2151
2152     bounds.trait_bounds.sort_by(|a,b| a.def_id().cmp(&b.def_id()));
2153
2154     bounds
2155 }
2156
2157 /// Converts a specific TyParamBound from the AST into a set of
2158 /// predicates that apply to the self-type. A vector is returned
2159 /// because this can be anywhere from 0 predicates (`T:?Sized` adds no
2160 /// predicates) to 1 (`T:Foo`) to many (`T:Bar<X=i32>` adds `T:Bar`
2161 /// and `<T as Bar>::X == i32`).
2162 fn predicates_from_bound<'tcx>(astconv: &AstConv<'tcx>,
2163                                param_ty: Ty<'tcx>,
2164                                bound: &hir::TyParamBound)
2165                                -> Vec<ty::Predicate<'tcx>>
2166 {
2167     match *bound {
2168         hir::TraitTyParamBound(ref tr, hir::TraitBoundModifier::None) => {
2169             let mut projections = Vec::new();
2170             let pred = conv_poly_trait_ref(astconv, param_ty, tr, &mut projections);
2171             projections.into_iter()
2172                        .map(|p| p.to_predicate())
2173                        .chain(Some(pred.to_predicate()))
2174                        .collect()
2175         }
2176         hir::RegionTyParamBound(ref lifetime) => {
2177             let region = ast_region_to_region(astconv.tcx(), lifetime);
2178             let pred = ty::Binder(ty::OutlivesPredicate(param_ty, region));
2179             vec![ty::Predicate::TypeOutlives(pred)]
2180         }
2181         hir::TraitTyParamBound(_, hir::TraitBoundModifier::Maybe) => {
2182             Vec::new()
2183         }
2184     }
2185 }
2186
2187 fn conv_poly_trait_ref<'tcx>(astconv: &AstConv<'tcx>,
2188                              param_ty: Ty<'tcx>,
2189                              trait_ref: &hir::PolyTraitRef,
2190                              projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
2191                              -> ty::PolyTraitRef<'tcx>
2192 {
2193     astconv::instantiate_poly_trait_ref(astconv,
2194                                         &ExplicitRscope,
2195                                         trait_ref,
2196                                         Some(param_ty),
2197                                         projections)
2198 }
2199
2200 fn conv_param_bounds<'a,'tcx>(astconv: &AstConv<'tcx>,
2201                               span: Span,
2202                               param_ty: ty::Ty<'tcx>,
2203                               ast_bounds: &[hir::TyParamBound])
2204                               -> astconv::Bounds<'tcx>
2205 {
2206     let tcx = astconv.tcx();
2207     let astconv::PartitionedBounds {
2208         builtin_bounds,
2209         trait_bounds,
2210         region_bounds
2211     } = astconv::partition_bounds(tcx, span, &ast_bounds);
2212
2213     let mut projection_bounds = Vec::new();
2214
2215     let trait_bounds: Vec<ty::PolyTraitRef> =
2216         trait_bounds.iter()
2217                     .map(|bound| conv_poly_trait_ref(astconv,
2218                                                      param_ty,
2219                                                      *bound,
2220                                                      &mut projection_bounds))
2221                     .collect();
2222
2223     let region_bounds: Vec<ty::Region> =
2224         region_bounds.into_iter()
2225                      .map(|r| ast_region_to_region(tcx, r))
2226                      .collect();
2227
2228     astconv::Bounds {
2229         region_bounds: region_bounds,
2230         builtin_bounds: builtin_bounds,
2231         trait_bounds: trait_bounds,
2232         projection_bounds: projection_bounds,
2233     }
2234 }
2235
2236 fn compute_type_scheme_of_foreign_fn_decl<'a, 'tcx>(
2237     ccx: &CrateCtxt<'a, 'tcx>,
2238     decl: &hir::FnDecl,
2239     ast_generics: &hir::Generics,
2240     abi: abi::Abi)
2241     -> ty::TypeScheme<'tcx>
2242 {
2243     for i in &decl.inputs {
2244         match (*i).pat.node {
2245             hir::PatIdent(_, _, _) => (),
2246             hir::PatWild(hir::PatWildSingle) => (),
2247             _ => {
2248                 span_err!(ccx.tcx.sess, (*i).pat.span, E0130,
2249                           "patterns aren't allowed in foreign function declarations");
2250             }
2251         }
2252     }
2253
2254     let ty_generics = ty_generics_for_fn(ccx, ast_generics, &ty::Generics::empty());
2255
2256     let rb = BindingRscope::new();
2257     let input_tys = decl.inputs
2258                         .iter()
2259                         .map(|a| ty_of_arg(&ccx.icx(ast_generics), &rb, a, None))
2260                         .collect();
2261
2262     let output = match decl.output {
2263         hir::Return(ref ty) =>
2264             ty::FnConverging(ast_ty_to_ty(&ccx.icx(ast_generics), &rb, &**ty)),
2265         hir::DefaultReturn(..) =>
2266             ty::FnConverging(ccx.tcx.mk_nil()),
2267         hir::NoReturn(..) =>
2268             ty::FnDiverging
2269     };
2270
2271     let t_fn = ccx.tcx.mk_fn(None,
2272         ccx.tcx.mk_bare_fn(ty::BareFnTy {
2273             abi: abi,
2274             unsafety: hir::Unsafety::Unsafe,
2275             sig: ty::Binder(ty::FnSig {inputs: input_tys,
2276                                        output: output,
2277                                        variadic: decl.variadic}),
2278         }));
2279
2280     ty::TypeScheme {
2281         generics: ty_generics,
2282         ty: t_fn
2283     }
2284 }
2285
2286 fn mk_item_substs<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
2287                             ty_generics: &ty::Generics<'tcx>)
2288                             -> Substs<'tcx>
2289 {
2290     let types =
2291         ty_generics.types.map(
2292             |def| ccx.tcx.mk_param_from_def(def));
2293
2294     let regions =
2295         ty_generics.regions.map(
2296             |def| def.to_early_bound_region());
2297
2298     Substs::new(types, regions)
2299 }
2300
2301 /// Verifies that the explicit self type of a method matches the impl
2302 /// or trait. This is a bit weird but basically because right now we
2303 /// don't handle the general case, but instead map it to one of
2304 /// several pre-defined options using various heuristics, this method
2305 /// comes back to check after the fact that explicit type the user
2306 /// wrote actually matches what the pre-defined option said.
2307 fn check_method_self_type<'a, 'tcx, RS:RegionScope>(
2308     ccx: &CrateCtxt<'a, 'tcx>,
2309     rs: &RS,
2310     method_type: Rc<ty::Method<'tcx>>,
2311     required_type: Ty<'tcx>,
2312     explicit_self: &hir::ExplicitSelf,
2313     body_id: ast::NodeId)
2314 {
2315     let tcx = ccx.tcx;
2316     if let hir::SelfExplicit(ref ast_type, _) = explicit_self.node {
2317         let typ = ccx.icx(&method_type.predicates).to_ty(rs, &**ast_type);
2318         let base_type = match typ.sty {
2319             ty::TyRef(_, tm) => tm.ty,
2320             ty::TyBox(typ) => typ,
2321             _ => typ,
2322         };
2323
2324         let body_scope = tcx.region_maps.item_extent(body_id);
2325
2326         // "Required type" comes from the trait definition. It may
2327         // contain late-bound regions from the method, but not the
2328         // trait (since traits only have early-bound region
2329         // parameters).
2330         assert!(!base_type.has_regions_escaping_depth(1));
2331         let required_type_free =
2332             liberate_early_bound_regions(
2333                 tcx, body_scope,
2334                 &tcx.liberate_late_bound_regions(body_scope, &ty::Binder(required_type)));
2335
2336         // The "base type" comes from the impl. It too may have late-bound
2337         // regions from the method.
2338         assert!(!base_type.has_regions_escaping_depth(1));
2339         let base_type_free =
2340             liberate_early_bound_regions(
2341                 tcx, body_scope,
2342                 &tcx.liberate_late_bound_regions(body_scope, &ty::Binder(base_type)));
2343
2344         debug!("required_type={:?} required_type_free={:?} \
2345                 base_type={:?} base_type_free={:?}",
2346                required_type,
2347                required_type_free,
2348                base_type,
2349                base_type_free);
2350
2351         let infcx = infer::new_infer_ctxt(tcx, &tcx.tables, None, false);
2352         drop(::require_same_types(tcx,
2353                                   Some(&infcx),
2354                                   false,
2355                                   explicit_self.span,
2356                                   base_type_free,
2357                                   required_type_free,
2358                                   || {
2359                 format!("mismatched self type: expected `{}`",
2360                          required_type)
2361         }));
2362
2363         // We could conceviably add more free-region relations here,
2364         // but since this code is just concerned with checking that
2365         // the `&Self` types etc match up, it's not really necessary.
2366         // It would just allow people to be more approximate in some
2367         // cases. In any case, we can do it later as we feel the need;
2368         // I'd like this function to go away eventually.
2369         let free_regions = FreeRegionMap::new();
2370
2371         infcx.resolve_regions_and_report_errors(&free_regions, body_id);
2372     }
2373
2374     fn liberate_early_bound_regions<'tcx,T>(
2375         tcx: &ty::ctxt<'tcx>,
2376         scope: region::CodeExtent,
2377         value: &T)
2378         -> T
2379         where T : TypeFoldable<'tcx>
2380     {
2381         /*!
2382          * Convert early-bound regions into free regions; normally this is done by
2383          * applying the `free_substs` from the `ParameterEnvironment`, but this particular
2384          * method-self-type check is kind of hacky and done very early in the process,
2385          * before we really have a `ParameterEnvironment` to check.
2386          */
2387
2388         tcx.fold_regions(value, &mut false, |region, _| {
2389             match region {
2390                 ty::ReEarlyBound(data) => {
2391                     ty::ReFree(ty::FreeRegion {
2392                         scope: scope,
2393                         bound_region: ty::BrNamed(data.def_id, data.name)
2394                     })
2395                 }
2396                 _ => region
2397             }
2398         })
2399     }
2400 }
2401
2402 /// Checks that all the type parameters on an impl
2403 fn enforce_impl_params_are_constrained<'tcx>(tcx: &ty::ctxt<'tcx>,
2404                                              ast_generics: &hir::Generics,
2405                                              impl_def_id: DefId,
2406                                              impl_items: &[P<hir::ImplItem>])
2407 {
2408     let impl_scheme = tcx.lookup_item_type(impl_def_id);
2409     let impl_predicates = tcx.lookup_predicates(impl_def_id);
2410     let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
2411
2412     // The trait reference is an input, so find all type parameters
2413     // reachable from there, to start (if this is an inherent impl,
2414     // then just examine the self type).
2415     let mut input_parameters: HashSet<_> =
2416         ctp::parameters_for_type(impl_scheme.ty).into_iter().collect();
2417     if let Some(ref trait_ref) = impl_trait_ref {
2418         input_parameters.extend(ctp::parameters_for_trait_ref(trait_ref));
2419     }
2420
2421     ctp::identify_constrained_type_params(tcx,
2422                                           impl_predicates.predicates.as_slice(),
2423                                           impl_trait_ref,
2424                                           &mut input_parameters);
2425
2426     for (index, ty_param) in ast_generics.ty_params.iter().enumerate() {
2427         let param_ty = ty::ParamTy { space: TypeSpace,
2428                                      idx: index as u32,
2429                                      name: ty_param.name };
2430         if !input_parameters.contains(&ctp::Parameter::Type(param_ty)) {
2431             report_unused_parameter(tcx, ty_param.span, "type", &param_ty.to_string());
2432         }
2433     }
2434
2435     // Every lifetime used in an associated type must be constrained.
2436
2437     let lifetimes_in_associated_types: HashSet<_> =
2438         impl_items.iter()
2439                   .map(|item| tcx.impl_or_trait_item(tcx.map.local_def_id(item.id)))
2440                   .filter_map(|item| match item {
2441                       ty::TypeTraitItem(ref assoc_ty) => assoc_ty.ty,
2442                       ty::ConstTraitItem(..) | ty::MethodTraitItem(..) => None
2443                   })
2444                   .flat_map(|ty| ctp::parameters_for_type(ty))
2445                   .filter_map(|p| match p {
2446                       ctp::Parameter::Type(_) => None,
2447                       ctp::Parameter::Region(r) => Some(r),
2448                   })
2449                   .collect();
2450
2451     for (index, lifetime_def) in ast_generics.lifetimes.iter().enumerate() {
2452         let def_id = tcx.map.local_def_id(lifetime_def.lifetime.id);
2453         let region = ty::EarlyBoundRegion { def_id: def_id,
2454                                             space: TypeSpace,
2455                                             index: index as u32,
2456                                             name: lifetime_def.lifetime.name };
2457         if
2458             lifetimes_in_associated_types.contains(&region) && // (*)
2459             !input_parameters.contains(&ctp::Parameter::Region(region))
2460         {
2461             report_unused_parameter(tcx, lifetime_def.lifetime.span,
2462                                     "lifetime", &region.name.to_string());
2463         }
2464     }
2465
2466     // (*) This is a horrible concession to reality. I think it'd be
2467     // better to just ban unconstrianed lifetimes outright, but in
2468     // practice people do non-hygenic macros like:
2469     //
2470     // ```
2471     // macro_rules! __impl_slice_eq1 {
2472     //     ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
2473     //         impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
2474     //            ....
2475     //         }
2476     //     }
2477     // }
2478     // ```
2479     //
2480     // In a concession to backwards compatbility, we continue to
2481     // permit those, so long as the lifetimes aren't used in
2482     // associated types. I believe this is sound, because lifetimes
2483     // used elsewhere are not projected back out.
2484 }
2485
2486 fn report_unused_parameter(tcx: &ty::ctxt,
2487                            span: Span,
2488                            kind: &str,
2489                            name: &str)
2490 {
2491     span_err!(tcx.sess, span, E0207,
2492               "the {} parameter `{}` is not constrained by the \
2493                impl trait, self type, or predicates",
2494               kind, name);
2495 }