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.
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.
11 //! Conversion from AST representation of types to the ty.rs
12 //! representation. The main routine here is `ast_ty_to_ty()`: each use
13 //! is parameterized by an instance of `AstConv` and a `RegionScope`.
15 //! The parameterization of `ast_ty_to_ty()` is because it behaves
16 //! somewhat differently during the collect and check phases,
17 //! particularly with respect to looking up the types of top-level
18 //! items. In the collect phase, the crate context is used as the
19 //! `AstConv` instance; in this phase, the `get_item_type_scheme()`
20 //! function triggers a recursive call to `type_scheme_of_item()`
21 //! (note that `ast_ty_to_ty()` will detect recursive types and report
22 //! an error). In the check phase, when the FnCtxt is used as the
23 //! `AstConv`, `get_item_type_scheme()` just looks up the item type in
24 //! `tcx.tcache` (using `ty::lookup_item_type`).
26 //! The `RegionScope` trait controls what happens when the user does
27 //! not specify a region in some location where a region is required
28 //! (e.g., if the user writes `&Foo` as a type rather than `&'a Foo`).
29 //! See the `rscope` module for more details.
31 //! Unlike the `AstConv` trait, the region scope can change as we descend
32 //! the type. This is to accommodate the fact that (a) fn types are binding
33 //! scopes and (b) the default region may change. To understand case (a),
34 //! consider something like:
36 //! type foo = { x: &a.int, y: |&a.int| }
38 //! The type of `x` is an error because there is no region `a` in scope.
39 //! In the type of `y`, however, region `a` is considered a bound region
40 //! as it does not already appear in scope.
42 //! Case (b) says that if you have a type:
43 //! type foo<'a> = ...;
44 //! type bar = fn(&foo, &a.foo)
45 //! The fully expanded version of type bar is:
46 //! type bar = fn(&'foo &, &a.foo<'a>)
47 //! Note that the self region for the `foo` defaulted to `&` in the first
48 //! case but `&a` in the second. Basically, defaults that appear inside
49 //! an rptr (`&r.T`) use the region `r` that appears in the rptr.
51 use middle::astconv_util::{prim_ty_to_ty, check_path_args, NO_TPS, NO_REGIONS};
52 use middle::const_eval::{self, ConstVal};
53 use middle::const_eval::EvalHint::UncheckedExprHint;
55 use middle::implicator::object_region_bounds;
56 use middle::resolve_lifetime as rl;
57 use middle::privacy::{AllPublic, LastMod};
58 use middle::subst::{FnSpace, TypeSpace, SelfSpace, Subst, Substs, ParamSpace};
60 use middle::ty::{self, RegionEscape, Ty, ToPredicate, HasTypeFlags};
62 use require_c_abi_if_variadic;
63 use rscope::{self, UnelidableRscope, RegionScope, ElidableRscope, ExplicitRscope,
64 ObjectLifetimeDefaultRscope, ShiftedRscope, BindingRscope,
65 ElisionFailureInfo, ElidedLifetime};
66 use util::common::{ErrorReported, FN_OUTPUT_NAME};
67 use util::nodemap::FnvHashSet;
70 use syntax::{abi, ast, ast_util};
71 use syntax::codemap::{Span, Pos};
72 use syntax::parse::token;
73 use syntax::print::pprust;
75 pub trait AstConv<'tcx> {
76 fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx>;
78 /// Identify the type scheme for an item with a type, like a type
79 /// alias, fn, or struct. This allows you to figure out the set of
80 /// type parameters defined on the item.
81 fn get_item_type_scheme(&self, span: Span, id: ast::DefId)
82 -> Result<ty::TypeScheme<'tcx>, ErrorReported>;
84 /// Returns the `TraitDef` for a given trait. This allows you to
85 /// figure out the set of type parameters defined on the trait.
86 fn get_trait_def(&self, span: Span, id: ast::DefId)
87 -> Result<&'tcx ty::TraitDef<'tcx>, ErrorReported>;
89 /// Ensure that the super-predicates for the trait with the given
90 /// id are available and also for the transitive set of
92 fn ensure_super_predicates(&self, span: Span, id: ast::DefId)
93 -> Result<(), ErrorReported>;
95 /// Returns the set of bounds in scope for the type parameter with
97 fn get_type_parameter_bounds(&self, span: Span, def_id: ast::NodeId)
98 -> Result<Vec<ty::PolyTraitRef<'tcx>>, ErrorReported>;
100 /// Returns true if the trait with id `trait_def_id` defines an
101 /// associated type with the name `name`.
102 fn trait_defines_associated_type_named(&self, trait_def_id: ast::DefId, name: ast::Name)
105 /// Return an (optional) substitution to convert bound type parameters that
106 /// are in scope into free ones. This function should only return Some
107 /// within a fn body.
108 /// See ParameterEnvironment::free_substs for more information.
109 fn get_free_substs(&self) -> Option<&Substs<'tcx>> {
113 /// What type should we use when a type is omitted?
115 param_and_substs: Option<ty::TypeParameterDef<'tcx>>,
116 substs: Option<&mut Substs<'tcx>>,
117 space: Option<ParamSpace>,
118 span: Span) -> Ty<'tcx>;
120 /// Projecting an associated type from a (potentially)
121 /// higher-ranked trait reference is more complicated, because of
122 /// the possibility of late-bound regions appearing in the
123 /// associated type binding. This is not legal in function
124 /// signatures for that reason. In a function body, we can always
125 /// handle it because we can use inference variables to remove the
126 /// late-bound regions.
127 fn projected_ty_from_poly_trait_ref(&self,
129 poly_trait_ref: ty::PolyTraitRef<'tcx>,
130 item_name: ast::Name)
133 if let Some(trait_ref) = self.tcx().no_late_bound_regions(&poly_trait_ref) {
134 self.projected_ty(span, trait_ref, item_name)
136 // no late-bound regions, we can just ignore the binder
137 span_err!(self.tcx().sess, span, E0212,
138 "cannot extract an associated type from a higher-ranked trait bound \
144 /// Project an associated type from a non-higher-ranked trait reference.
145 /// This is fairly straightforward and can be accommodated in any context.
146 fn projected_ty(&self,
148 _trait_ref: ty::TraitRef<'tcx>,
149 _item_name: ast::Name)
153 pub fn ast_region_to_region(tcx: &ty::ctxt, lifetime: &ast::Lifetime)
155 let r = match tcx.named_region_map.get(&lifetime.id) {
157 // should have been recorded by the `resolve_lifetime` pass
158 tcx.sess.span_bug(lifetime.span, "unresolved lifetime");
161 Some(&rl::DefStaticRegion) => {
165 Some(&rl::DefLateBoundRegion(debruijn, id)) => {
166 ty::ReLateBound(debruijn, ty::BrNamed(ast_util::local_def(id), lifetime.name))
169 Some(&rl::DefEarlyBoundRegion(space, index, id)) => {
170 ty::ReEarlyBound(ty::EarlyBoundRegion {
178 Some(&rl::DefFreeRegion(scope, id)) => {
179 ty::ReFree(ty::FreeRegion {
181 bound_region: ty::BrNamed(ast_util::local_def(id),
187 debug!("ast_region_to_region(lifetime={:?} id={}) yields {:?}",
195 fn report_elision_failure(
198 params: Vec<ElisionFailureInfo>)
200 let mut m = String::new();
201 let len = params.len();
202 for (i, info) in params.into_iter().enumerate() {
203 let ElisionFailureInfo {
204 name, lifetime_count: n, have_bound_regions
207 let help_name = if name.is_empty() {
208 format!("argument {}", i + 1)
210 format!("`{}`", name)
213 m.push_str(&(if n == 1 {
216 format!("one of {}'s {} elided {}lifetimes", help_name, n,
217 if have_bound_regions { "free " } else { "" } )
220 if len == 2 && i == 0 {
222 } else if i + 2 == len {
224 } else if i + 1 != len {
229 fileline_help!(tcx.sess, default_span,
230 "this function's return type contains a borrowed value, but \
231 the signature does not say which {} it is borrowed from",
234 fileline_help!(tcx.sess, default_span,
235 "this function's return type contains a borrowed value, but \
236 there is no value for it to be borrowed from");
237 fileline_help!(tcx.sess, default_span,
238 "consider giving it a 'static lifetime");
240 fileline_help!(tcx.sess, default_span,
241 "this function's return type contains a borrowed value, but \
242 the signature does not say whether it is borrowed from {}",
247 pub fn opt_ast_region_to_region<'tcx>(
248 this: &AstConv<'tcx>,
249 rscope: &RegionScope,
251 opt_lifetime: &Option<ast::Lifetime>) -> ty::Region
253 let r = match *opt_lifetime {
254 Some(ref lifetime) => {
255 ast_region_to_region(this.tcx(), lifetime)
258 None => match rscope.anon_regions(default_span, 1) {
261 span_err!(this.tcx().sess, default_span, E0106,
262 "missing lifetime specifier");
263 if let Some(params) = params {
264 report_elision_failure(this.tcx(), default_span, params);
271 debug!("opt_ast_region_to_region(opt_lifetime={:?}) yields {:?}",
278 /// Given a path `path` that refers to an item `I` with the declared generics `decl_generics`,
279 /// returns an appropriate set of substitutions for this particular reference to `I`.
280 pub fn ast_path_substs_for_ty<'tcx>(
281 this: &AstConv<'tcx>,
282 rscope: &RegionScope,
284 param_mode: PathParamMode,
285 decl_generics: &ty::Generics<'tcx>,
286 item_segment: &ast::PathSegment)
289 let tcx = this.tcx();
291 // ast_path_substs() is only called to convert paths that are
292 // known to refer to traits, types, or structs. In these cases,
293 // all type parameters defined for the item being referenced will
294 // be in the TypeSpace or SelfSpace.
296 // Note: in the case of traits, the self parameter is also
297 // defined, but we don't currently create a `type_param_def` for
298 // `Self` because it is implicit.
299 assert!(decl_generics.regions.all(|d| d.space == TypeSpace));
300 assert!(decl_generics.types.all(|d| d.space != FnSpace));
302 let (regions, types, assoc_bindings) = match item_segment.parameters {
303 ast::AngleBracketedParameters(ref data) => {
304 convert_angle_bracketed_parameters(this, rscope, span, decl_generics, data)
306 ast::ParenthesizedParameters(..) => {
307 span_err!(tcx.sess, span, E0214,
308 "parenthesized parameters may only be used with a trait");
309 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
311 ty_param_defs.iter().map(|_| tcx.types.err).collect(),
316 prohibit_projections(this.tcx(), &assoc_bindings);
318 create_substs_for_ast_path(this,
327 #[derive(PartialEq, Eq)]
328 pub enum PathParamMode {
329 // Any path in a type context.
331 // The `module::Type` in `module::Type::method` in an expression.
335 fn create_region_substs<'tcx>(
336 this: &AstConv<'tcx>,
337 rscope: &RegionScope,
339 decl_generics: &ty::Generics<'tcx>,
340 regions_provided: Vec<ty::Region>)
343 let tcx = this.tcx();
345 // If the type is parameterized by the this region, then replace this
346 // region with the current anon region binding (in other words,
347 // whatever & would get replaced with).
348 let expected_num_region_params = decl_generics.regions.len(TypeSpace);
349 let supplied_num_region_params = regions_provided.len();
350 let regions = if expected_num_region_params == supplied_num_region_params {
354 rscope.anon_regions(span, expected_num_region_params);
356 if supplied_num_region_params != 0 || anon_regions.is_err() {
357 report_lifetime_number_error(tcx, span,
358 supplied_num_region_params,
359 expected_num_region_params);
363 Ok(anon_regions) => anon_regions,
364 Err(_) => (0..expected_num_region_params).map(|_| ty::ReStatic).collect()
367 Substs::new_type(vec![], regions)
370 /// Given the type/region arguments provided to some path (along with
371 /// an implicit Self, if this is a trait reference) returns the complete
372 /// set of substitutions. This may involve applying defaulted type parameters.
374 /// Note that the type listing given here is *exactly* what the user provided.
376 /// The `region_substs` should be the result of `create_region_substs`
377 /// -- that is, a substitution with no types but the correct number of
379 fn create_substs_for_ast_path<'tcx>(
380 this: &AstConv<'tcx>,
382 param_mode: PathParamMode,
383 decl_generics: &ty::Generics<'tcx>,
384 self_ty: Option<Ty<'tcx>>,
385 types_provided: Vec<Ty<'tcx>>,
386 region_substs: Substs<'tcx>)
389 let tcx = this.tcx();
391 debug!("create_substs_for_ast_path(decl_generics={:?}, self_ty={:?}, \
392 types_provided={:?}, region_substs={:?}",
393 decl_generics, self_ty, types_provided,
396 assert_eq!(region_substs.regions().len(TypeSpace), decl_generics.regions.len(TypeSpace));
397 assert!(region_substs.types.is_empty());
399 // Convert the type parameters supplied by the user.
400 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
401 let formal_ty_param_count = ty_param_defs.len();
402 let required_ty_param_count = ty_param_defs.iter()
403 .take_while(|x| x.default.is_none())
406 // Fill with `ty_infer` if no params were specified, as long as
407 // they were optional (e.g. paths inside expressions).
408 let mut type_substs = if param_mode == PathParamMode::Optional &&
409 types_provided.is_empty() {
410 let mut substs = region_substs.clone();
413 .map(|p| this.ty_infer(Some(p.clone()), Some(&mut substs), Some(TypeSpace), span))
419 let supplied_ty_param_count = type_substs.len();
420 check_type_argument_count(this.tcx(), span, supplied_ty_param_count,
421 required_ty_param_count, formal_ty_param_count);
423 if supplied_ty_param_count < required_ty_param_count {
424 while type_substs.len() < required_ty_param_count {
425 type_substs.push(tcx.types.err);
427 } else if supplied_ty_param_count > formal_ty_param_count {
428 type_substs.truncate(formal_ty_param_count);
430 assert!(type_substs.len() >= required_ty_param_count &&
431 type_substs.len() <= formal_ty_param_count);
433 let mut substs = region_substs;
434 substs.types.extend(TypeSpace, type_substs.into_iter());
438 // If no self-type is provided, it's still possible that
439 // one was declared, because this could be an object type.
442 // If a self-type is provided, one should have been
443 // "declared" (in other words, this should be a
445 assert!(decl_generics.types.get_self().is_some());
446 substs.types.push(SelfSpace, ty);
450 let actual_supplied_ty_param_count = substs.types.len(TypeSpace);
451 for param in &ty_param_defs[actual_supplied_ty_param_count..] {
452 if let Some(default) = param.default {
453 // If we are converting an object type, then the
454 // `Self` parameter is unknown. However, some of the
455 // other type parameters may reference `Self` in their
456 // defaults. This will lead to an ICE if we are not
458 if self_ty.is_none() && default.has_self_ty() {
459 span_err!(tcx.sess, span, E0393,
460 "the type parameter `{}` must be explicitly specified \
461 in an object type because its default value `{}` references \
465 substs.types.push(TypeSpace, tcx.types.err);
467 // This is a default type parameter.
468 let default = default.subst_spanned(tcx,
471 substs.types.push(TypeSpace, default);
474 tcx.sess.span_bug(span, "extra parameter without default");
481 struct ConvertedBinding<'tcx> {
482 item_name: ast::Name,
487 fn convert_angle_bracketed_parameters<'tcx>(this: &AstConv<'tcx>,
488 rscope: &RegionScope,
490 decl_generics: &ty::Generics<'tcx>,
491 data: &ast::AngleBracketedParameterData)
494 Vec<ConvertedBinding<'tcx>>)
496 let regions: Vec<_> =
497 data.lifetimes.iter()
498 .map(|l| ast_region_to_region(this.tcx(), l))
502 create_region_substs(this, rscope, span, decl_generics, regions);
507 .map(|(i,t)| ast_ty_arg_to_ty(this, rscope, decl_generics,
508 i, ®ion_substs, t))
511 let assoc_bindings: Vec<_> =
513 .map(|b| ConvertedBinding { item_name: b.ident.name,
514 ty: ast_ty_to_ty(this, rscope, &*b.ty),
518 (region_substs, types, assoc_bindings)
521 /// Returns the appropriate lifetime to use for any output lifetimes
522 /// (if one exists) and a vector of the (pattern, number of lifetimes)
523 /// corresponding to each input type/pattern.
524 fn find_implied_output_region<'tcx>(tcx: &ty::ctxt<'tcx>,
525 input_tys: &[Ty<'tcx>],
526 input_pats: Vec<String>) -> ElidedLifetime
528 let mut lifetimes_for_params = Vec::new();
529 let mut possible_implied_output_region = None;
531 for (input_type, input_pat) in input_tys.iter().zip(input_pats) {
532 let mut regions = FnvHashSet();
533 let have_bound_regions = ty_fold::collect_regions(tcx,
537 debug!("find_implied_output_regions: collected {:?} from {:?} \
538 have_bound_regions={:?}", ®ions, input_type, have_bound_regions);
540 if regions.len() == 1 {
541 // there's a chance that the unique lifetime of this
542 // iteration will be the appropriate lifetime for output
543 // parameters, so lets store it.
544 possible_implied_output_region = regions.iter().cloned().next();
547 lifetimes_for_params.push(ElisionFailureInfo {
549 lifetime_count: regions.len(),
550 have_bound_regions: have_bound_regions
554 if lifetimes_for_params.iter().map(|e| e.lifetime_count).sum::<usize>() == 1 {
555 Ok(possible_implied_output_region.unwrap())
557 Err(Some(lifetimes_for_params))
561 fn convert_ty_with_lifetime_elision<'tcx>(this: &AstConv<'tcx>,
562 elided_lifetime: ElidedLifetime,
566 match elided_lifetime {
567 Ok(implied_output_region) => {
568 let rb = ElidableRscope::new(implied_output_region);
569 ast_ty_to_ty(this, &rb, ty)
571 Err(param_lifetimes) => {
572 // All regions must be explicitly specified in the output
573 // if the lifetime elision rules do not apply. This saves
574 // the user from potentially-confusing errors.
575 let rb = UnelidableRscope::new(param_lifetimes);
576 ast_ty_to_ty(this, &rb, ty)
581 fn convert_parenthesized_parameters<'tcx>(this: &AstConv<'tcx>,
582 rscope: &RegionScope,
584 decl_generics: &ty::Generics<'tcx>,
585 data: &ast::ParenthesizedParameterData)
588 Vec<ConvertedBinding<'tcx>>)
591 create_region_substs(this, rscope, span, decl_generics, Vec::new());
593 let binding_rscope = BindingRscope::new();
596 .map(|a_t| ast_ty_arg_to_ty(this, &binding_rscope, decl_generics,
597 0, ®ion_substs, a_t))
598 .collect::<Vec<Ty<'tcx>>>();
600 let input_params = vec![String::new(); inputs.len()];
601 let implied_output_region = find_implied_output_region(this.tcx(), &inputs, input_params);
603 let input_ty = this.tcx().mk_tup(inputs);
605 let (output, output_span) = match data.output {
606 Some(ref output_ty) => {
607 (convert_ty_with_lifetime_elision(this,
608 implied_output_region,
613 (this.tcx().mk_nil(), data.span)
617 let output_binding = ConvertedBinding {
618 item_name: token::intern(FN_OUTPUT_NAME),
623 (region_substs, vec![input_ty], vec![output_binding])
626 pub fn instantiate_poly_trait_ref<'tcx>(
627 this: &AstConv<'tcx>,
628 rscope: &RegionScope,
629 ast_trait_ref: &ast::PolyTraitRef,
630 self_ty: Option<Ty<'tcx>>,
631 poly_projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
632 -> ty::PolyTraitRef<'tcx>
634 let trait_ref = &ast_trait_ref.trait_ref;
635 let trait_def_id = trait_def_id(this, trait_ref);
636 ast_path_to_poly_trait_ref(this,
639 PathParamMode::Explicit,
642 trait_ref.path.segments.last().unwrap(),
646 /// Instantiates the path for the given trait reference, assuming that it's
647 /// bound to a valid trait type. Returns the def_id for the defining trait.
648 /// Fails if the type is a type other than a trait type.
650 /// If the `projections` argument is `None`, then assoc type bindings like `Foo<T=X>`
651 /// are disallowed. Otherwise, they are pushed onto the vector given.
652 pub fn instantiate_mono_trait_ref<'tcx>(
653 this: &AstConv<'tcx>,
654 rscope: &RegionScope,
655 trait_ref: &ast::TraitRef,
656 self_ty: Option<Ty<'tcx>>)
657 -> ty::TraitRef<'tcx>
659 let trait_def_id = trait_def_id(this, trait_ref);
660 ast_path_to_mono_trait_ref(this,
663 PathParamMode::Explicit,
666 trait_ref.path.segments.last().unwrap())
669 fn trait_def_id<'tcx>(this: &AstConv<'tcx>, trait_ref: &ast::TraitRef) -> ast::DefId {
670 let path = &trait_ref.path;
671 match ::lookup_full_def(this.tcx(), path.span, trait_ref.ref_id) {
672 def::DefTrait(trait_def_id) => trait_def_id,
674 span_fatal!(this.tcx().sess, path.span, E0245, "`{}` is not a trait",
680 fn object_path_to_poly_trait_ref<'a,'tcx>(
681 this: &AstConv<'tcx>,
682 rscope: &RegionScope,
684 param_mode: PathParamMode,
685 trait_def_id: ast::DefId,
686 trait_segment: &ast::PathSegment,
687 mut projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
688 -> ty::PolyTraitRef<'tcx>
690 ast_path_to_poly_trait_ref(this,
700 fn ast_path_to_poly_trait_ref<'a,'tcx>(
701 this: &AstConv<'tcx>,
702 rscope: &RegionScope,
704 param_mode: PathParamMode,
705 trait_def_id: ast::DefId,
706 self_ty: Option<Ty<'tcx>>,
707 trait_segment: &ast::PathSegment,
708 poly_projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
709 -> ty::PolyTraitRef<'tcx>
711 // The trait reference introduces a binding level here, so
712 // we need to shift the `rscope`. It'd be nice if we could
713 // do away with this rscope stuff and work this knowledge
714 // into resolve_lifetimes, as we do with non-omitted
715 // lifetimes. Oh well, not there yet.
716 let shifted_rscope = &ShiftedRscope::new(rscope);
718 let (substs, assoc_bindings) =
719 create_substs_for_ast_trait_ref(this,
726 let poly_trait_ref = ty::Binder(ty::TraitRef::new(trait_def_id, substs));
729 let converted_bindings =
732 .filter_map(|binding| {
733 // specify type to assert that error was already reported in Err case:
734 let predicate: Result<_, ErrorReported> =
735 ast_type_binding_to_poly_projection_predicate(this,
736 poly_trait_ref.clone(),
739 predicate.ok() // ok to ignore Err() because ErrorReported (see above)
741 poly_projections.extend(converted_bindings);
747 fn ast_path_to_mono_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
748 rscope: &RegionScope,
750 param_mode: PathParamMode,
751 trait_def_id: ast::DefId,
752 self_ty: Option<Ty<'tcx>>,
753 trait_segment: &ast::PathSegment)
754 -> ty::TraitRef<'tcx>
756 let (substs, assoc_bindings) =
757 create_substs_for_ast_trait_ref(this,
764 prohibit_projections(this.tcx(), &assoc_bindings);
765 ty::TraitRef::new(trait_def_id, substs)
768 fn create_substs_for_ast_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
769 rscope: &RegionScope,
771 param_mode: PathParamMode,
772 trait_def_id: ast::DefId,
773 self_ty: Option<Ty<'tcx>>,
774 trait_segment: &ast::PathSegment)
775 -> (&'tcx Substs<'tcx>, Vec<ConvertedBinding<'tcx>>)
777 debug!("create_substs_for_ast_trait_ref(trait_segment={:?})",
780 let trait_def = match this.get_trait_def(span, trait_def_id) {
781 Ok(trait_def) => trait_def,
782 Err(ErrorReported) => {
783 // No convenient way to recover from a cycle here. Just bail. Sorry!
784 this.tcx().sess.abort_if_errors();
785 this.tcx().sess.bug("ErrorReported returned, but no errors reports?")
789 let (regions, types, assoc_bindings) = match trait_segment.parameters {
790 ast::AngleBracketedParameters(ref data) => {
791 // For now, require that parenthetical notation be used
792 // only with `Fn()` etc.
793 if !this.tcx().sess.features.borrow().unboxed_closures && trait_def.paren_sugar {
794 span_err!(this.tcx().sess, span, E0215,
795 "angle-bracket notation is not stable when \
796 used with the `Fn` family of traits, use parentheses");
797 fileline_help!(this.tcx().sess, span,
798 "add `#![feature(unboxed_closures)]` to \
799 the crate attributes to enable");
802 convert_angle_bracketed_parameters(this, rscope, span, &trait_def.generics, data)
804 ast::ParenthesizedParameters(ref data) => {
805 // For now, require that parenthetical notation be used
806 // only with `Fn()` etc.
807 if !this.tcx().sess.features.borrow().unboxed_closures && !trait_def.paren_sugar {
808 span_err!(this.tcx().sess, span, E0216,
809 "parenthetical notation is only stable when \
810 used with the `Fn` family of traits");
811 fileline_help!(this.tcx().sess, span,
812 "add `#![feature(unboxed_closures)]` to \
813 the crate attributes to enable");
816 convert_parenthesized_parameters(this, rscope, span, &trait_def.generics, data)
820 let substs = create_substs_for_ast_path(this,
828 (this.tcx().mk_substs(substs), assoc_bindings)
831 fn ast_type_binding_to_poly_projection_predicate<'tcx>(
832 this: &AstConv<'tcx>,
833 mut trait_ref: ty::PolyTraitRef<'tcx>,
834 self_ty: Option<Ty<'tcx>>,
835 binding: &ConvertedBinding<'tcx>)
836 -> Result<ty::PolyProjectionPredicate<'tcx>, ErrorReported>
838 let tcx = this.tcx();
840 // Given something like `U : SomeTrait<T=X>`, we want to produce a
841 // predicate like `<U as SomeTrait>::T = X`. This is somewhat
842 // subtle in the event that `T` is defined in a supertrait of
843 // `SomeTrait`, because in that case we need to upcast.
845 // That is, consider this case:
848 // trait SubTrait : SuperTrait<int> { }
849 // trait SuperTrait<A> { type T; }
851 // ... B : SubTrait<T=foo> ...
854 // We want to produce `<B as SuperTrait<int>>::T == foo`.
856 // Simple case: X is defined in the current trait.
857 if this.trait_defines_associated_type_named(trait_ref.def_id(), binding.item_name) {
858 return Ok(ty::Binder(ty::ProjectionPredicate { // <-------------------+
859 projection_ty: ty::ProjectionTy { // |
860 trait_ref: trait_ref.skip_binder().clone(), // Binder moved here --+
861 item_name: binding.item_name,
867 // Otherwise, we have to walk through the supertraits to find
868 // those that do. This is complicated by the fact that, for an
869 // object type, the `Self` type is not present in the
870 // substitutions (after all, it's being constructed right now),
871 // but the `supertraits` iterator really wants one. To handle
872 // this, we currently insert a dummy type and then remove it
875 let dummy_self_ty = tcx.mk_infer(ty::FreshTy(0));
876 if self_ty.is_none() { // if converting for an object type
877 let mut dummy_substs = trait_ref.skip_binder().substs.clone(); // binder moved here -+
878 assert!(dummy_substs.self_ty().is_none()); // |
879 dummy_substs.types.push(SelfSpace, dummy_self_ty); // |
880 trait_ref = ty::Binder(ty::TraitRef::new(trait_ref.def_id(), // <------------+
881 tcx.mk_substs(dummy_substs)));
884 try!(this.ensure_super_predicates(binding.span, trait_ref.def_id()));
886 let mut candidates: Vec<ty::PolyTraitRef> =
887 traits::supertraits(tcx, trait_ref.clone())
888 .filter(|r| this.trait_defines_associated_type_named(r.def_id(), binding.item_name))
891 // If converting for an object type, then remove the dummy-ty from `Self` now.
893 if self_ty.is_none() {
894 for candidate in &mut candidates {
895 let mut dummy_substs = candidate.0.substs.clone();
896 assert!(dummy_substs.self_ty() == Some(dummy_self_ty));
897 dummy_substs.types.pop(SelfSpace);
898 *candidate = ty::Binder(ty::TraitRef::new(candidate.def_id(),
899 tcx.mk_substs(dummy_substs)));
903 let candidate = try!(one_bound_for_assoc_type(tcx,
905 &trait_ref.to_string(),
906 &token::get_name(binding.item_name),
909 Ok(ty::Binder(ty::ProjectionPredicate { // <-------------------------+
910 projection_ty: ty::ProjectionTy { // |
911 trait_ref: candidate.skip_binder().clone(), // binder is moved up here --+
912 item_name: binding.item_name,
918 fn ast_path_to_ty<'tcx>(
919 this: &AstConv<'tcx>,
920 rscope: &RegionScope,
922 param_mode: PathParamMode,
924 item_segment: &ast::PathSegment)
927 let tcx = this.tcx();
928 let (generics, decl_ty) = match this.get_item_type_scheme(span, did) {
929 Ok(ty::TypeScheme { generics, ty: decl_ty }) => {
932 Err(ErrorReported) => {
933 return tcx.types.err;
937 let substs = ast_path_substs_for_ty(this,
944 // FIXME(#12938): This is a hack until we have full support for DST.
945 if Some(did) == this.tcx().lang_items.owned_box() {
946 assert_eq!(substs.types.len(TypeSpace), 1);
947 return this.tcx().mk_box(*substs.types.get(TypeSpace, 0));
950 decl_ty.subst(this.tcx(), &substs)
953 type TraitAndProjections<'tcx> = (ty::PolyTraitRef<'tcx>, Vec<ty::PolyProjectionPredicate<'tcx>>);
955 fn ast_ty_to_trait_ref<'tcx>(this: &AstConv<'tcx>,
956 rscope: &RegionScope,
958 bounds: &[ast::TyParamBound])
959 -> Result<TraitAndProjections<'tcx>, ErrorReported>
962 * In a type like `Foo + Send`, we want to wait to collect the
963 * full set of bounds before we make the object type, because we
964 * need them to infer a region bound. (For example, if we tried
965 * made a type from just `Foo`, then it wouldn't be enough to
966 * infer a 'static bound, and hence the user would get an error.)
967 * So this function is used when we're dealing with a sum type to
968 * convert the LHS. It only accepts a type that refers to a trait
969 * name, and reports an error otherwise.
973 ast::TyPath(None, ref path) => {
974 let def = match this.tcx().def_map.borrow().get(&ty.id) {
975 Some(&def::PathResolution { base_def, depth: 0, .. }) => Some(base_def),
979 Some(def::DefTrait(trait_def_id)) => {
980 let mut projection_bounds = Vec::new();
981 let trait_ref = object_path_to_poly_trait_ref(this,
984 PathParamMode::Explicit,
986 path.segments.last().unwrap(),
987 &mut projection_bounds);
988 Ok((trait_ref, projection_bounds))
991 span_err!(this.tcx().sess, ty.span, E0172, "expected a reference to a trait");
997 span_err!(this.tcx().sess, ty.span, E0178,
998 "expected a path on the left-hand side of `+`, not `{}`",
999 pprust::ty_to_string(ty));
1000 let hi = bounds.iter().map(|x| match *x {
1001 ast::TraitTyParamBound(ref tr, _) => tr.span.hi,
1002 ast::RegionTyParamBound(ref r) => r.span.hi,
1003 }).max_by(|x| x.to_usize());
1004 let full_span = hi.map(|hi| Span {
1007 expn_id: ty.span.expn_id,
1009 match (&ty.node, full_span) {
1010 (&ast::TyRptr(None, ref mut_ty), Some(full_span)) => {
1011 let mutbl_str = if mut_ty.mutbl == ast::MutMutable { "mut " } else { "" };
1013 .span_suggestion(full_span, "try adding parentheses (per RFC 438):",
1014 format!("&{}({} +{})",
1016 pprust::ty_to_string(&*mut_ty.ty),
1017 pprust::bounds_to_string(bounds)));
1019 (&ast::TyRptr(Some(ref lt), ref mut_ty), Some(full_span)) => {
1020 let mutbl_str = if mut_ty.mutbl == ast::MutMutable { "mut " } else { "" };
1022 .span_suggestion(full_span, "try adding parentheses (per RFC 438):",
1023 format!("&{} {}({} +{})",
1024 pprust::lifetime_to_string(lt),
1026 pprust::ty_to_string(&*mut_ty.ty),
1027 pprust::bounds_to_string(bounds)));
1031 fileline_help!(this.tcx().sess, ty.span,
1032 "perhaps you forgot parentheses? (per RFC 438)");
1040 fn trait_ref_to_object_type<'tcx>(this: &AstConv<'tcx>,
1041 rscope: &RegionScope,
1043 trait_ref: ty::PolyTraitRef<'tcx>,
1044 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
1045 bounds: &[ast::TyParamBound])
1048 let existential_bounds = conv_existential_bounds(this,
1055 let result = make_object_type(this, span, trait_ref, existential_bounds);
1056 debug!("trait_ref_to_object_type: result={:?}",
1062 fn make_object_type<'tcx>(this: &AstConv<'tcx>,
1064 principal: ty::PolyTraitRef<'tcx>,
1065 bounds: ty::ExistentialBounds<'tcx>)
1067 let tcx = this.tcx();
1068 let object = ty::TraitTy {
1069 principal: principal,
1072 let object_trait_ref =
1073 object.principal_trait_ref_with_self_ty(tcx, tcx.types.err);
1075 // ensure the super predicates and stop if we encountered an error
1076 if this.ensure_super_predicates(span, object.principal_def_id()).is_err() {
1077 return tcx.types.err;
1080 let mut associated_types: FnvHashSet<(ast::DefId, ast::Name)> =
1081 traits::supertraits(tcx, object_trait_ref)
1083 let trait_def = tcx.lookup_trait_def(tr.def_id());
1084 trait_def.associated_type_names
1087 .map(move |associated_type_name| (tr.def_id(), associated_type_name))
1091 for projection_bound in &object.bounds.projection_bounds {
1092 let pair = (projection_bound.0.projection_ty.trait_ref.def_id,
1093 projection_bound.0.projection_ty.item_name);
1094 associated_types.remove(&pair);
1097 for (trait_def_id, name) in associated_types {
1098 span_err!(tcx.sess, span, E0191,
1099 "the value of the associated type `{}` (from the trait `{}`) must be specified",
1101 tcx.item_path_str(trait_def_id));
1104 tcx.mk_trait(object.principal, object.bounds)
1107 fn report_ambiguous_associated_type(tcx: &ty::ctxt,
1112 span_err!(tcx.sess, span, E0223,
1113 "ambiguous associated type; specify the type using the syntax \
1115 type_str, trait_str, name);
1118 // Search for a bound on a type parameter which includes the associated item
1119 // given by assoc_name. ty_param_node_id is the node id for the type parameter
1120 // (which might be `Self`, but only if it is the `Self` of a trait, not an
1121 // impl). This function will fail if there are no suitable bounds or there is
1123 fn find_bound_for_assoc_item<'tcx>(this: &AstConv<'tcx>,
1124 ty_param_node_id: ast::NodeId,
1125 ty_param_name: ast::Name,
1126 assoc_name: ast::Name,
1128 -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
1130 let tcx = this.tcx();
1132 let bounds = match this.get_type_parameter_bounds(span, ty_param_node_id) {
1134 Err(ErrorReported) => {
1135 return Err(ErrorReported);
1139 // Ensure the super predicates and stop if we encountered an error.
1140 if bounds.iter().any(|b| this.ensure_super_predicates(span, b.def_id()).is_err()) {
1141 return Err(ErrorReported);
1144 // Check that there is exactly one way to find an associated type with the
1146 let suitable_bounds: Vec<_> =
1147 traits::transitive_bounds(tcx, &bounds)
1148 .filter(|b| this.trait_defines_associated_type_named(b.def_id(), assoc_name))
1151 one_bound_for_assoc_type(tcx,
1153 &token::get_name(ty_param_name),
1154 &token::get_name(assoc_name),
1159 // Checks that bounds contains exactly one element and reports appropriate
1160 // errors otherwise.
1161 fn one_bound_for_assoc_type<'tcx>(tcx: &ty::ctxt<'tcx>,
1162 bounds: Vec<ty::PolyTraitRef<'tcx>>,
1163 ty_param_name: &str,
1166 -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
1168 if bounds.is_empty() {
1169 span_err!(tcx.sess, span, E0220,
1170 "associated type `{}` not found for `{}`",
1173 return Err(ErrorReported);
1176 if bounds.len() > 1 {
1177 span_err!(tcx.sess, span, E0221,
1178 "ambiguous associated type `{}` in bounds of `{}`",
1182 for bound in &bounds {
1183 span_note!(tcx.sess, span,
1184 "associated type `{}` could derive from `{}`",
1190 Ok(bounds[0].clone())
1193 // Create a type from a a path to an associated type.
1194 // For a path A::B::C::D, ty and ty_path_def are the type and def for A::B::C
1195 // and item_segment is the path segment for D. We return a type and a def for
1197 // Will fail except for T::A and Self::A; i.e., if ty/ty_path_def are not a type
1198 // parameter or Self.
1199 fn associated_path_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1202 ty_path_def: def::Def,
1203 item_segment: &ast::PathSegment)
1204 -> (Ty<'tcx>, def::Def)
1206 let tcx = this.tcx();
1207 let assoc_name = item_segment.identifier.name;
1209 debug!("associated_path_def_to_ty: {:?}::{}", ty, assoc_name);
1211 check_path_args(tcx, slice::ref_slice(item_segment), NO_TPS | NO_REGIONS);
1213 // Find the type of the associated item, and the trait where the associated
1214 // item is declared.
1215 let bound = match (&ty.sty, ty_path_def) {
1216 (_, def::DefSelfTy(Some(trait_did), Some((impl_id, _)))) => {
1217 // `Self` in an impl of a trait - we have a concrete self type and a
1219 match tcx.map.expect_item(impl_id).node {
1220 ast::ItemImpl(_, _, _, Some(ref trait_ref), _, _) => {
1221 if this.ensure_super_predicates(span, trait_did).is_err() {
1222 return (tcx.types.err, ty_path_def);
1225 let trait_segment = &trait_ref.path.segments.last().unwrap();
1226 let trait_ref = ast_path_to_mono_trait_ref(this,
1229 PathParamMode::Explicit,
1234 let candidates: Vec<ty::PolyTraitRef> =
1235 traits::supertraits(tcx, ty::Binder(trait_ref.clone()))
1236 .filter(|r| this.trait_defines_associated_type_named(r.def_id(),
1240 match one_bound_for_assoc_type(tcx,
1243 &token::get_name(assoc_name),
1246 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1252 (&ty::TyParam(_), def::DefSelfTy(Some(trait_did), None)) => {
1253 assert_eq!(trait_did.krate, ast::LOCAL_CRATE);
1254 match find_bound_for_assoc_item(this,
1256 token::special_idents::type_self.name,
1260 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1263 (&ty::TyParam(_), def::DefTyParam(_, _, param_did, param_name)) => {
1264 assert_eq!(param_did.krate, ast::LOCAL_CRATE);
1265 match find_bound_for_assoc_item(this,
1271 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1275 report_ambiguous_associated_type(tcx,
1279 &token::get_name(assoc_name));
1280 return (tcx.types.err, ty_path_def);
1284 let trait_did = bound.0.def_id;
1285 let ty = this.projected_ty_from_poly_trait_ref(span, bound, assoc_name);
1287 let item_did = if trait_did.krate == ast::LOCAL_CRATE {
1288 // `ty::trait_items` used below requires information generated
1289 // by type collection, which may be in progress at this point.
1290 match tcx.map.expect_item(trait_did.node).node {
1291 ast::ItemTrait(_, _, _, ref trait_items) => {
1292 let item = trait_items.iter()
1293 .find(|i| i.ident.name == assoc_name)
1294 .expect("missing associated type");
1295 ast_util::local_def(item.id)
1300 let trait_items = tcx.trait_items(trait_did);
1301 let item = trait_items.iter().find(|i| i.name() == assoc_name);
1302 item.expect("missing associated type").def_id()
1305 (ty, def::DefAssociatedTy(trait_did, item_did))
1308 fn qpath_to_ty<'tcx>(this: &AstConv<'tcx>,
1309 rscope: &RegionScope,
1311 param_mode: PathParamMode,
1312 opt_self_ty: Option<Ty<'tcx>>,
1313 trait_def_id: ast::DefId,
1314 trait_segment: &ast::PathSegment,
1315 item_segment: &ast::PathSegment)
1318 let tcx = this.tcx();
1320 check_path_args(tcx, slice::ref_slice(item_segment), NO_TPS | NO_REGIONS);
1322 let self_ty = if let Some(ty) = opt_self_ty {
1325 let path_str = tcx.item_path_str(trait_def_id);
1326 report_ambiguous_associated_type(tcx,
1330 &token::get_ident(item_segment.identifier));
1331 return tcx.types.err;
1334 debug!("qpath_to_ty: self_type={:?}", self_ty);
1336 let trait_ref = ast_path_to_mono_trait_ref(this,
1344 debug!("qpath_to_ty: trait_ref={:?}", trait_ref);
1346 this.projected_ty(span, trait_ref, item_segment.identifier.name)
1349 /// Convert a type supplied as value for a type argument from AST into our
1350 /// our internal representation. This is the same as `ast_ty_to_ty` but that
1351 /// it applies the object lifetime default.
1355 /// * `this`, `rscope`: the surrounding context
1356 /// * `decl_generics`: the generics of the struct/enum/trait declaration being
1358 /// * `index`: the index of the type parameter being instantiated from the list
1359 /// (we assume it is in the `TypeSpace`)
1360 /// * `region_substs`: a partial substitution consisting of
1361 /// only the region type parameters being supplied to this type.
1362 /// * `ast_ty`: the ast representation of the type being supplied
1363 pub fn ast_ty_arg_to_ty<'tcx>(this: &AstConv<'tcx>,
1364 rscope: &RegionScope,
1365 decl_generics: &ty::Generics<'tcx>,
1367 region_substs: &Substs<'tcx>,
1371 let tcx = this.tcx();
1373 if let Some(def) = decl_generics.types.opt_get(TypeSpace, index) {
1374 let object_lifetime_default = def.object_lifetime_default.subst(tcx, region_substs);
1375 let rscope1 = &ObjectLifetimeDefaultRscope::new(rscope, object_lifetime_default);
1376 ast_ty_to_ty(this, rscope1, ast_ty)
1378 ast_ty_to_ty(this, rscope, ast_ty)
1382 // Check the base def in a PathResolution and convert it to a Ty. If there are
1383 // associated types in the PathResolution, these will need to be separately
1385 fn base_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1386 rscope: &RegionScope,
1388 param_mode: PathParamMode,
1390 opt_self_ty: Option<Ty<'tcx>>,
1391 base_segments: &[ast::PathSegment])
1393 let tcx = this.tcx();
1396 def::DefTrait(trait_def_id) => {
1397 // N.B. this case overlaps somewhat with
1398 // TyObjectSum, see that fn for details
1399 let mut projection_bounds = Vec::new();
1401 let trait_ref = object_path_to_poly_trait_ref(this,
1406 base_segments.last().unwrap(),
1407 &mut projection_bounds);
1409 check_path_args(tcx, base_segments.split_last().unwrap().1, NO_TPS | NO_REGIONS);
1410 trait_ref_to_object_type(this,
1417 def::DefTy(did, _) | def::DefStruct(did) => {
1418 check_path_args(tcx, base_segments.split_last().unwrap().1, NO_TPS | NO_REGIONS);
1419 ast_path_to_ty(this,
1424 base_segments.last().unwrap())
1426 def::DefTyParam(space, index, _, name) => {
1427 check_path_args(tcx, base_segments, NO_TPS | NO_REGIONS);
1428 tcx.mk_param(space, index, name)
1430 def::DefSelfTy(_, Some((_, self_ty_id))) => {
1431 // Self in impl (we know the concrete type).
1432 check_path_args(tcx, base_segments, NO_TPS | NO_REGIONS);
1433 if let Some(&ty) = tcx.ast_ty_to_ty_cache.borrow().get(&self_ty_id) {
1434 if let Some(free_substs) = this.get_free_substs() {
1435 ty.subst(tcx, free_substs)
1440 tcx.sess.span_bug(span, "self type has not been fully resolved")
1443 def::DefSelfTy(Some(_), None) => {
1445 check_path_args(tcx, base_segments, NO_TPS | NO_REGIONS);
1448 def::DefAssociatedTy(trait_did, _) => {
1449 check_path_args(tcx, &base_segments[..base_segments.len()-2], NO_TPS | NO_REGIONS);
1456 &base_segments[base_segments.len()-2],
1457 base_segments.last().unwrap())
1459 def::DefMod(id) => {
1460 // Used as sentinel by callers to indicate the `<T>::A::B::C` form.
1461 // FIXME(#22519) This part of the resolution logic should be
1462 // avoided entirely for that form, once we stop needed a Def
1463 // for `associated_path_def_to_ty`.
1464 // Fixing this will also let use resolve <Self>::Foo the same way we
1465 // resolve Self::Foo, at the moment we can't resolve the former because
1466 // we don't have the trait information around, which is just sad.
1468 if !base_segments.is_empty() {
1472 "found module name used as a type: {}",
1473 tcx.map.node_to_string(id.node));
1474 return this.tcx().types.err;
1477 opt_self_ty.expect("missing T in <T>::a::b::c")
1479 def::DefPrimTy(prim_ty) => {
1480 prim_ty_to_ty(tcx, base_segments, prim_ty)
1483 let node = def.def_id().node;
1484 span_err!(tcx.sess, span, E0248,
1485 "found value `{}` used as a type",
1486 tcx.map.path_to_string(node));
1487 return this.tcx().types.err;
1492 // Note that both base_segments and assoc_segments may be empty, although not at
1494 pub fn finish_resolving_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1495 rscope: &RegionScope,
1497 param_mode: PathParamMode,
1499 opt_self_ty: Option<Ty<'tcx>>,
1500 base_segments: &[ast::PathSegment],
1501 assoc_segments: &[ast::PathSegment])
1503 let mut ty = base_def_to_ty(this,
1511 // If any associated type segments remain, attempt to resolve them.
1512 for segment in assoc_segments {
1513 if ty.sty == ty::TyError {
1516 // This is pretty bad (it will fail except for T::A and Self::A).
1517 let (a_ty, a_def) = associated_path_def_to_ty(this,
1528 /// Parses the programmer's textual representation of a type into our
1529 /// internal notion of a type.
1530 pub fn ast_ty_to_ty<'tcx>(this: &AstConv<'tcx>,
1531 rscope: &RegionScope,
1535 debug!("ast_ty_to_ty(ast_ty={:?})",
1538 let tcx = this.tcx();
1540 if let Some(&ty) = tcx.ast_ty_to_ty_cache.borrow().get(&ast_ty.id) {
1544 let typ = match ast_ty.node {
1545 ast::TyVec(ref ty) => {
1546 tcx.mk_slice(ast_ty_to_ty(this, rscope, &**ty))
1548 ast::TyObjectSum(ref ty, ref bounds) => {
1549 match ast_ty_to_trait_ref(this, rscope, &**ty, bounds) {
1550 Ok((trait_ref, projection_bounds)) => {
1551 trait_ref_to_object_type(this,
1558 Err(ErrorReported) => {
1559 this.tcx().types.err
1563 ast::TyPtr(ref mt) => {
1564 tcx.mk_ptr(ty::TypeAndMut {
1565 ty: ast_ty_to_ty(this, rscope, &*mt.ty),
1569 ast::TyRptr(ref region, ref mt) => {
1570 let r = opt_ast_region_to_region(this, rscope, ast_ty.span, region);
1571 debug!("TyRef r={:?}", r);
1573 &ObjectLifetimeDefaultRscope::new(
1575 ty::ObjectLifetimeDefault::Specific(r));
1576 let t = ast_ty_to_ty(this, rscope1, &*mt.ty);
1577 tcx.mk_ref(tcx.mk_region(r), ty::TypeAndMut {ty: t, mutbl: mt.mutbl})
1579 ast::TyTup(ref fields) => {
1580 let flds = fields.iter()
1581 .map(|t| ast_ty_to_ty(this, rscope, &**t))
1585 ast::TyParen(ref typ) => ast_ty_to_ty(this, rscope, &**typ),
1586 ast::TyBareFn(ref bf) => {
1587 require_c_abi_if_variadic(tcx, &bf.decl, bf.abi, ast_ty.span);
1588 let bare_fn = ty_of_bare_fn(this, bf.unsafety, bf.abi, &*bf.decl);
1589 tcx.mk_fn(None, tcx.mk_bare_fn(bare_fn))
1591 ast::TyPolyTraitRef(ref bounds) => {
1592 conv_ty_poly_trait_ref(this, rscope, ast_ty.span, bounds)
1594 ast::TyPath(ref maybe_qself, ref path) => {
1595 let path_res = if let Some(&d) = tcx.def_map.borrow().get(&ast_ty.id) {
1597 } else if let Some(ast::QSelf { position: 0, .. }) = *maybe_qself {
1598 // Create some fake resolution that can't possibly be a type.
1599 def::PathResolution {
1600 base_def: def::DefMod(ast_util::local_def(ast::CRATE_NODE_ID)),
1601 last_private: LastMod(AllPublic),
1602 depth: path.segments.len()
1605 tcx.sess.span_bug(ast_ty.span, &format!("unbound path {:?}", ast_ty))
1607 let def = path_res.base_def;
1608 let base_ty_end = path.segments.len() - path_res.depth;
1609 let opt_self_ty = maybe_qself.as_ref().map(|qself| {
1610 ast_ty_to_ty(this, rscope, &qself.ty)
1612 let ty = finish_resolving_def_to_ty(this,
1615 PathParamMode::Explicit,
1618 &path.segments[..base_ty_end],
1619 &path.segments[base_ty_end..]);
1621 if path_res.depth != 0 && ty.sty != ty::TyError {
1622 // Write back the new resolution.
1623 tcx.def_map.borrow_mut().insert(ast_ty.id, def::PathResolution {
1625 last_private: path_res.last_private,
1632 ast::TyFixedLengthVec(ref ty, ref e) => {
1633 let hint = UncheckedExprHint(tcx.types.usize);
1634 match const_eval::eval_const_expr_partial(tcx, &e, hint) {
1638 tcx.mk_array(ast_ty_to_ty(this, rscope, &**ty),
1640 ConstVal::Uint(i) =>
1641 tcx.mk_array(ast_ty_to_ty(this, rscope, &**ty),
1644 span_err!(tcx.sess, ast_ty.span, E0249,
1645 "expected constant integer expression \
1647 this.tcx().types.err
1653 ast_ty.span.lo <= r.span.lo && r.span.hi <= ast_ty.span.hi;
1654 span_err!(tcx.sess, r.span, E0250,
1655 "array length constant evaluation error: {}",
1658 span_note!(tcx.sess, ast_ty.span, "for array length here")
1660 this.tcx().types.err
1664 ast::TyTypeof(ref _e) => {
1665 tcx.sess.span_bug(ast_ty.span, "typeof is reserved but unimplemented");
1668 // TyInfer also appears as the type of arguments or return
1669 // values in a ExprClosure, or as
1670 // the type of local variables. Both of these cases are
1671 // handled specially and will not descend into this routine.
1672 this.ty_infer(None, None, None, ast_ty.span)
1676 tcx.ast_ty_to_ty_cache.borrow_mut().insert(ast_ty.id, typ);
1680 pub fn ty_of_arg<'tcx>(this: &AstConv<'tcx>,
1681 rscope: &RegionScope,
1683 expected_ty: Option<Ty<'tcx>>)
1687 ast::TyInfer if expected_ty.is_some() => expected_ty.unwrap(),
1688 ast::TyInfer => this.ty_infer(None, None, None, a.ty.span),
1689 _ => ast_ty_to_ty(this, rscope, &*a.ty),
1693 struct SelfInfo<'a, 'tcx> {
1694 untransformed_self_ty: Ty<'tcx>,
1695 explicit_self: &'a ast::ExplicitSelf,
1698 pub fn ty_of_method<'tcx>(this: &AstConv<'tcx>,
1699 sig: &ast::MethodSig,
1700 untransformed_self_ty: Ty<'tcx>)
1701 -> (ty::BareFnTy<'tcx>, ty::ExplicitSelfCategory) {
1702 let self_info = Some(SelfInfo {
1703 untransformed_self_ty: untransformed_self_ty,
1704 explicit_self: &sig.explicit_self,
1706 let (bare_fn_ty, optional_explicit_self_category) =
1707 ty_of_method_or_bare_fn(this,
1712 (bare_fn_ty, optional_explicit_self_category.unwrap())
1715 pub fn ty_of_bare_fn<'tcx>(this: &AstConv<'tcx>, unsafety: ast::Unsafety, abi: abi::Abi,
1716 decl: &ast::FnDecl) -> ty::BareFnTy<'tcx> {
1717 let (bare_fn_ty, _) = ty_of_method_or_bare_fn(this, unsafety, abi, None, decl);
1721 fn ty_of_method_or_bare_fn<'a, 'tcx>(this: &AstConv<'tcx>,
1722 unsafety: ast::Unsafety,
1724 opt_self_info: Option<SelfInfo<'a, 'tcx>>,
1726 -> (ty::BareFnTy<'tcx>, Option<ty::ExplicitSelfCategory>)
1728 debug!("ty_of_method_or_bare_fn");
1730 // New region names that appear inside of the arguments of the function
1731 // declaration are bound to that function type.
1732 let rb = rscope::BindingRscope::new();
1734 // `implied_output_region` is the region that will be assumed for any
1735 // region parameters in the return type. In accordance with the rules for
1736 // lifetime elision, we can determine it in two ways. First (determined
1737 // here), if self is by-reference, then the implied output region is the
1738 // region of the self parameter.
1739 let mut explicit_self_category_result = None;
1740 let (self_ty, implied_output_region) = match opt_self_info {
1741 None => (None, None),
1742 Some(self_info) => {
1743 // This type comes from an impl or trait; no late-bound
1744 // regions should be present.
1745 assert!(!self_info.untransformed_self_ty.has_escaping_regions());
1747 // Figure out and record the explicit self category.
1748 let explicit_self_category =
1749 determine_explicit_self_category(this, &rb, &self_info);
1750 explicit_self_category_result = Some(explicit_self_category);
1751 match explicit_self_category {
1752 ty::StaticExplicitSelfCategory => {
1755 ty::ByValueExplicitSelfCategory => {
1756 (Some(self_info.untransformed_self_ty), None)
1758 ty::ByReferenceExplicitSelfCategory(region, mutability) => {
1759 (Some(this.tcx().mk_ref(
1760 this.tcx().mk_region(region),
1762 ty: self_info.untransformed_self_ty,
1767 ty::ByBoxExplicitSelfCategory => {
1768 (Some(this.tcx().mk_box(self_info.untransformed_self_ty)), None)
1774 // HACK(eddyb) replace the fake self type in the AST with the actual type.
1775 let input_params = if self_ty.is_some() {
1780 let input_tys = input_params.iter().map(|a| ty_of_arg(this, &rb, a, None));
1781 let input_pats: Vec<String> = input_params.iter()
1782 .map(|a| pprust::pat_to_string(&*a.pat))
1784 let self_and_input_tys: Vec<Ty> =
1785 self_ty.into_iter().chain(input_tys).collect();
1788 // Second, if there was exactly one lifetime (either a substitution or a
1789 // reference) in the arguments, then any anonymous regions in the output
1790 // have that lifetime.
1791 let implied_output_region = match implied_output_region {
1794 let input_tys = if self_ty.is_some() {
1795 // Skip the first argument if `self` is present.
1796 &self_and_input_tys[1..]
1798 &self_and_input_tys[..]
1801 find_implied_output_region(this.tcx(), input_tys, input_pats)
1805 let output_ty = match decl.output {
1806 ast::Return(ref output) if output.node == ast::TyInfer =>
1807 ty::FnConverging(this.ty_infer(None, None, None, output.span)),
1808 ast::Return(ref output) =>
1809 ty::FnConverging(convert_ty_with_lifetime_elision(this,
1810 implied_output_region,
1812 ast::DefaultReturn(..) => ty::FnConverging(this.tcx().mk_nil()),
1813 ast::NoReturn(..) => ty::FnDiverging
1819 sig: ty::Binder(ty::FnSig {
1820 inputs: self_and_input_tys,
1822 variadic: decl.variadic
1824 }, explicit_self_category_result)
1827 fn determine_explicit_self_category<'a, 'tcx>(this: &AstConv<'tcx>,
1828 rscope: &RegionScope,
1829 self_info: &SelfInfo<'a, 'tcx>)
1830 -> ty::ExplicitSelfCategory
1832 return match self_info.explicit_self.node {
1833 ast::SelfStatic => ty::StaticExplicitSelfCategory,
1834 ast::SelfValue(_) => ty::ByValueExplicitSelfCategory,
1835 ast::SelfRegion(ref lifetime, mutability, _) => {
1837 opt_ast_region_to_region(this,
1839 self_info.explicit_self.span,
1841 ty::ByReferenceExplicitSelfCategory(region, mutability)
1843 ast::SelfExplicit(ref ast_type, _) => {
1844 let explicit_type = ast_ty_to_ty(this, rscope, &**ast_type);
1846 // We wish to (for now) categorize an explicit self
1847 // declaration like `self: SomeType` into either `self`,
1848 // `&self`, `&mut self`, or `Box<self>`. We do this here
1849 // by some simple pattern matching. A more precise check
1850 // is done later in `check_method_self_type()`.
1855 // impl Foo for &T {
1856 // // Legal declarations:
1857 // fn method1(self: &&T); // ByReferenceExplicitSelfCategory
1858 // fn method2(self: &T); // ByValueExplicitSelfCategory
1859 // fn method3(self: Box<&T>); // ByBoxExplicitSelfCategory
1861 // // Invalid cases will be caught later by `check_method_self_type`:
1862 // fn method_err1(self: &mut T); // ByReferenceExplicitSelfCategory
1866 // To do the check we just count the number of "modifiers"
1867 // on each type and compare them. If they are the same or
1868 // the impl has more, we call it "by value". Otherwise, we
1869 // look at the outermost modifier on the method decl and
1870 // call it by-ref, by-box as appropriate. For method1, for
1871 // example, the impl type has one modifier, but the method
1872 // type has two, so we end up with
1873 // ByReferenceExplicitSelfCategory.
1875 let impl_modifiers = count_modifiers(self_info.untransformed_self_ty);
1876 let method_modifiers = count_modifiers(explicit_type);
1878 debug!("determine_explicit_self_category(self_info.untransformed_self_ty={:?} \
1879 explicit_type={:?} \
1881 self_info.untransformed_self_ty,
1886 if impl_modifiers >= method_modifiers {
1887 ty::ByValueExplicitSelfCategory
1889 match explicit_type.sty {
1890 ty::TyRef(r, mt) => ty::ByReferenceExplicitSelfCategory(*r, mt.mutbl),
1891 ty::TyBox(_) => ty::ByBoxExplicitSelfCategory,
1892 _ => ty::ByValueExplicitSelfCategory,
1898 fn count_modifiers(ty: Ty) -> usize {
1900 ty::TyRef(_, mt) => count_modifiers(mt.ty) + 1,
1901 ty::TyBox(t) => count_modifiers(t) + 1,
1907 pub fn ty_of_closure<'tcx>(
1908 this: &AstConv<'tcx>,
1909 unsafety: ast::Unsafety,
1912 expected_sig: Option<ty::FnSig<'tcx>>)
1913 -> ty::ClosureTy<'tcx>
1915 debug!("ty_of_closure(expected_sig={:?})",
1918 // new region names that appear inside of the fn decl are bound to
1919 // that function type
1920 let rb = rscope::BindingRscope::new();
1922 let input_tys: Vec<_> = decl.inputs.iter().enumerate().map(|(i, a)| {
1923 let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
1924 // no guarantee that the correct number of expected args
1926 if i < e.inputs.len() {
1932 ty_of_arg(this, &rb, a, expected_arg_ty)
1935 let expected_ret_ty = expected_sig.map(|e| e.output);
1937 let is_infer = match decl.output {
1938 ast::Return(ref output) if output.node == ast::TyInfer => true,
1939 ast::DefaultReturn(..) => true,
1943 let output_ty = match decl.output {
1944 _ if is_infer && expected_ret_ty.is_some() =>
1945 expected_ret_ty.unwrap(),
1947 ty::FnConverging(this.ty_infer(None, None, None, decl.output.span())),
1948 ast::Return(ref output) =>
1949 ty::FnConverging(ast_ty_to_ty(this, &rb, &**output)),
1950 ast::DefaultReturn(..) => unreachable!(),
1951 ast::NoReturn(..) => ty::FnDiverging
1954 debug!("ty_of_closure: input_tys={:?}", input_tys);
1955 debug!("ty_of_closure: output_ty={:?}", output_ty);
1960 sig: ty::Binder(ty::FnSig {inputs: input_tys,
1962 variadic: decl.variadic}),
1966 /// Given an existential type like `Foo+'a+Bar`, this routine converts the `'a` and `Bar` intos an
1967 /// `ExistentialBounds` struct. The `main_trait_refs` argument specifies the `Foo` -- it is absent
1968 /// for closures. Eventually this should all be normalized, I think, so that there is no "main
1969 /// trait ref" and instead we just have a flat list of bounds as the existential type.
1970 fn conv_existential_bounds<'tcx>(
1971 this: &AstConv<'tcx>,
1972 rscope: &RegionScope,
1974 principal_trait_ref: ty::PolyTraitRef<'tcx>,
1975 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
1976 ast_bounds: &[ast::TyParamBound])
1977 -> ty::ExistentialBounds<'tcx>
1979 let partitioned_bounds =
1980 partition_bounds(this.tcx(), span, ast_bounds);
1982 conv_existential_bounds_from_partitioned_bounds(
1983 this, rscope, span, principal_trait_ref, projection_bounds, partitioned_bounds)
1986 fn conv_ty_poly_trait_ref<'tcx>(
1987 this: &AstConv<'tcx>,
1988 rscope: &RegionScope,
1990 ast_bounds: &[ast::TyParamBound])
1993 let mut partitioned_bounds = partition_bounds(this.tcx(), span, &ast_bounds[..]);
1995 let mut projection_bounds = Vec::new();
1996 let main_trait_bound = if !partitioned_bounds.trait_bounds.is_empty() {
1997 let trait_bound = partitioned_bounds.trait_bounds.remove(0);
1998 instantiate_poly_trait_ref(this,
2002 &mut projection_bounds)
2004 span_err!(this.tcx().sess, span, E0224,
2005 "at least one non-builtin trait is required for an object type");
2006 return this.tcx().types.err;
2010 conv_existential_bounds_from_partitioned_bounds(this,
2013 main_trait_bound.clone(),
2015 partitioned_bounds);
2017 make_object_type(this, span, main_trait_bound, bounds)
2020 pub fn conv_existential_bounds_from_partitioned_bounds<'tcx>(
2021 this: &AstConv<'tcx>,
2022 rscope: &RegionScope,
2024 principal_trait_ref: ty::PolyTraitRef<'tcx>,
2025 mut projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>, // Empty for boxed closures
2026 partitioned_bounds: PartitionedBounds)
2027 -> ty::ExistentialBounds<'tcx>
2029 let PartitionedBounds { builtin_bounds,
2034 if !trait_bounds.is_empty() {
2035 let b = &trait_bounds[0];
2036 span_err!(this.tcx().sess, b.trait_ref.path.span, E0225,
2037 "only the builtin traits can be used as closure or object bounds");
2041 compute_object_lifetime_bound(this,
2044 principal_trait_ref,
2047 let region_bound = match region_bound {
2050 match rscope.object_lifetime_default(span) {
2053 span_err!(this.tcx().sess, span, E0228,
2054 "the lifetime bound for this object type cannot be deduced \
2055 from context; please supply an explicit bound");
2062 debug!("region_bound: {:?}", region_bound);
2064 ty::sort_bounds_list(&mut projection_bounds);
2066 ty::ExistentialBounds {
2067 region_bound: region_bound,
2068 builtin_bounds: builtin_bounds,
2069 projection_bounds: projection_bounds,
2073 /// Given the bounds on an object, determines what single region bound
2074 /// (if any) we can use to summarize this type. The basic idea is that we will use the bound the
2075 /// user provided, if they provided one, and otherwise search the supertypes of trait bounds for
2076 /// region bounds. It may be that we can derive no bound at all, in which case we return `None`.
2077 fn compute_object_lifetime_bound<'tcx>(
2078 this: &AstConv<'tcx>,
2080 explicit_region_bounds: &[&ast::Lifetime],
2081 principal_trait_ref: ty::PolyTraitRef<'tcx>,
2082 builtin_bounds: ty::BuiltinBounds)
2083 -> Option<ty::Region> // if None, use the default
2085 let tcx = this.tcx();
2087 debug!("compute_opt_region_bound(explicit_region_bounds={:?}, \
2088 principal_trait_ref={:?}, builtin_bounds={:?})",
2089 explicit_region_bounds,
2090 principal_trait_ref,
2093 if explicit_region_bounds.len() > 1 {
2094 span_err!(tcx.sess, explicit_region_bounds[1].span, E0226,
2095 "only a single explicit lifetime bound is permitted");
2098 if !explicit_region_bounds.is_empty() {
2099 // Explicitly specified region bound. Use that.
2100 let r = explicit_region_bounds[0];
2101 return Some(ast_region_to_region(tcx, r));
2104 if let Err(ErrorReported) = this.ensure_super_predicates(span,principal_trait_ref.def_id()) {
2105 return Some(ty::ReStatic);
2108 // No explicit region bound specified. Therefore, examine trait
2109 // bounds and see if we can derive region bounds from those.
2110 let derived_region_bounds =
2111 object_region_bounds(tcx, &principal_trait_ref, builtin_bounds);
2113 // If there are no derived region bounds, then report back that we
2114 // can find no region bound. The caller will use the default.
2115 if derived_region_bounds.is_empty() {
2119 // If any of the derived region bounds are 'static, that is always
2121 if derived_region_bounds.iter().any(|r| ty::ReStatic == *r) {
2122 return Some(ty::ReStatic);
2125 // Determine whether there is exactly one unique region in the set
2126 // of derived region bounds. If so, use that. Otherwise, report an
2128 let r = derived_region_bounds[0];
2129 if derived_region_bounds[1..].iter().any(|r1| r != *r1) {
2130 span_err!(tcx.sess, span, E0227,
2131 "ambiguous lifetime bound, explicit lifetime bound required");
2136 pub struct PartitionedBounds<'a> {
2137 pub builtin_bounds: ty::BuiltinBounds,
2138 pub trait_bounds: Vec<&'a ast::PolyTraitRef>,
2139 pub region_bounds: Vec<&'a ast::Lifetime>,
2142 /// Divides a list of bounds from the AST into three groups: builtin bounds (Copy, Sized etc),
2143 /// general trait bounds, and region bounds.
2144 pub fn partition_bounds<'a>(tcx: &ty::ctxt,
2146 ast_bounds: &'a [ast::TyParamBound])
2147 -> PartitionedBounds<'a>
2149 let mut builtin_bounds = ty::BuiltinBounds::empty();
2150 let mut region_bounds = Vec::new();
2151 let mut trait_bounds = Vec::new();
2152 for ast_bound in ast_bounds {
2154 ast::TraitTyParamBound(ref b, ast::TraitBoundModifier::None) => {
2155 match ::lookup_full_def(tcx, b.trait_ref.path.span, b.trait_ref.ref_id) {
2156 def::DefTrait(trait_did) => {
2157 if tcx.try_add_builtin_trait(trait_did,
2158 &mut builtin_bounds) {
2159 let segments = &b.trait_ref.path.segments;
2160 let parameters = &segments[segments.len() - 1].parameters;
2161 if !parameters.types().is_empty() {
2162 check_type_argument_count(tcx, b.trait_ref.path.span,
2163 parameters.types().len(), 0, 0);
2165 if !parameters.lifetimes().is_empty() {
2166 report_lifetime_number_error(tcx, b.trait_ref.path.span,
2167 parameters.lifetimes().len(), 0);
2169 continue; // success
2173 // Not a trait? that's an error, but it'll get
2177 trait_bounds.push(b);
2179 ast::TraitTyParamBound(_, ast::TraitBoundModifier::Maybe) => {}
2180 ast::RegionTyParamBound(ref l) => {
2181 region_bounds.push(l);
2187 builtin_bounds: builtin_bounds,
2188 trait_bounds: trait_bounds,
2189 region_bounds: region_bounds,
2193 fn prohibit_projections<'tcx>(tcx: &ty::ctxt<'tcx>,
2194 bindings: &[ConvertedBinding<'tcx>])
2196 for binding in bindings.iter().take(1) {
2197 span_err!(tcx.sess, binding.span, E0229,
2198 "associated type bindings are not allowed here");
2202 fn check_type_argument_count(tcx: &ty::ctxt, span: Span, supplied: usize,
2203 required: usize, accepted: usize) {
2204 if supplied < required {
2205 let expected = if required < accepted {
2210 span_err!(tcx.sess, span, E0243,
2211 "wrong number of type arguments: {} {}, found {}",
2212 expected, required, supplied);
2213 } else if supplied > accepted {
2214 let expected = if required < accepted {
2219 span_err!(tcx.sess, span, E0244,
2220 "wrong number of type arguments: {} {}, found {}",
2227 fn report_lifetime_number_error(tcx: &ty::ctxt, span: Span, number: usize, expected: usize) {
2228 span_err!(tcx.sess, span, E0107,
2229 "wrong number of lifetime parameters: expected {}, found {}",
2233 // A helper struct for conveniently grouping a set of bounds which we pass to
2234 // and return from functions in multiple places.
2235 #[derive(PartialEq, Eq, Clone, Debug)]
2236 pub struct Bounds<'tcx> {
2237 pub region_bounds: Vec<ty::Region>,
2238 pub builtin_bounds: ty::BuiltinBounds,
2239 pub trait_bounds: Vec<ty::PolyTraitRef<'tcx>>,
2240 pub projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
2243 impl<'tcx> Bounds<'tcx> {
2244 pub fn predicates(&self,
2245 tcx: &ty::ctxt<'tcx>,
2247 -> Vec<ty::Predicate<'tcx>>
2249 let mut vec = Vec::new();
2251 for builtin_bound in &self.builtin_bounds {
2252 match traits::trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty) {
2253 Ok(trait_ref) => { vec.push(trait_ref.to_predicate()); }
2254 Err(ErrorReported) => { }
2258 for ®ion_bound in &self.region_bounds {
2259 // account for the binder being introduced below; no need to shift `param_ty`
2260 // because, at present at least, it can only refer to early-bound regions
2261 let region_bound = ty_fold::shift_region(region_bound, 1);
2262 vec.push(ty::Binder(ty::OutlivesPredicate(param_ty, region_bound)).to_predicate());
2265 for bound_trait_ref in &self.trait_bounds {
2266 vec.push(bound_trait_ref.to_predicate());
2269 for projection in &self.projection_bounds {
2270 vec.push(projection.to_predicate());