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};
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?
114 fn ty_infer(&self, default: Option<Ty<'tcx>>, span: Span) -> Ty<'tcx>;
116 /// Projecting an associated type from a (potentially)
117 /// higher-ranked trait reference is more complicated, because of
118 /// the possibility of late-bound regions appearing in the
119 /// associated type binding. This is not legal in function
120 /// signatures for that reason. In a function body, we can always
121 /// handle it because we can use inference variables to remove the
122 /// late-bound regions.
123 fn projected_ty_from_poly_trait_ref(&self,
125 poly_trait_ref: ty::PolyTraitRef<'tcx>,
126 item_name: ast::Name)
129 if let Some(trait_ref) = self.tcx().no_late_bound_regions(&poly_trait_ref) {
130 self.projected_ty(span, trait_ref, item_name)
132 // no late-bound regions, we can just ignore the binder
133 span_err!(self.tcx().sess, span, E0212,
134 "cannot extract an associated type from a higher-ranked trait bound \
140 /// Project an associated type from a non-higher-ranked trait reference.
141 /// This is fairly straightforward and can be accommodated in any context.
142 fn projected_ty(&self,
144 _trait_ref: ty::TraitRef<'tcx>,
145 _item_name: ast::Name)
149 pub fn ast_region_to_region(tcx: &ty::ctxt, lifetime: &ast::Lifetime)
151 let r = match tcx.named_region_map.get(&lifetime.id) {
153 // should have been recorded by the `resolve_lifetime` pass
154 tcx.sess.span_bug(lifetime.span, "unresolved lifetime");
157 Some(&rl::DefStaticRegion) => {
161 Some(&rl::DefLateBoundRegion(debruijn, id)) => {
162 ty::ReLateBound(debruijn, ty::BrNamed(ast_util::local_def(id), lifetime.name))
165 Some(&rl::DefEarlyBoundRegion(space, index, id)) => {
166 ty::ReEarlyBound(ty::EarlyBoundRegion {
174 Some(&rl::DefFreeRegion(scope, id)) => {
175 ty::ReFree(ty::FreeRegion {
177 bound_region: ty::BrNamed(ast_util::local_def(id),
183 debug!("ast_region_to_region(lifetime={:?} id={}) yields {:?}",
191 fn report_elision_failure(
194 params: Vec<ElisionFailureInfo>)
196 let mut m = String::new();
197 let len = params.len();
198 for (i, info) in params.into_iter().enumerate() {
199 let ElisionFailureInfo {
200 name, lifetime_count: n, have_bound_regions
203 let help_name = if name.is_empty() {
204 format!("argument {}", i + 1)
206 format!("`{}`", name)
209 m.push_str(&(if n == 1 {
212 format!("one of {}'s {} elided {}lifetimes", help_name, n,
213 if have_bound_regions { "free " } else { "" } )
216 if len == 2 && i == 0 {
218 } else if i + 2 == len {
220 } else if i + 1 != len {
225 fileline_help!(tcx.sess, default_span,
226 "this function's return type contains a borrowed value, but \
227 the signature does not say which {} it is borrowed from",
230 fileline_help!(tcx.sess, default_span,
231 "this function's return type contains a borrowed value, but \
232 there is no value for it to be borrowed from");
233 fileline_help!(tcx.sess, default_span,
234 "consider giving it a 'static lifetime");
236 fileline_help!(tcx.sess, default_span,
237 "this function's return type contains a borrowed value, but \
238 the signature does not say whether it is borrowed from {}",
243 pub fn opt_ast_region_to_region<'tcx>(
244 this: &AstConv<'tcx>,
245 rscope: &RegionScope,
247 opt_lifetime: &Option<ast::Lifetime>) -> ty::Region
249 let r = match *opt_lifetime {
250 Some(ref lifetime) => {
251 ast_region_to_region(this.tcx(), lifetime)
254 None => match rscope.anon_regions(default_span, 1) {
257 span_err!(this.tcx().sess, default_span, E0106,
258 "missing lifetime specifier");
259 if let Some(params) = params {
260 report_elision_failure(this.tcx(), default_span, params);
267 debug!("opt_ast_region_to_region(opt_lifetime={:?}) yields {:?}",
274 /// Given a path `path` that refers to an item `I` with the declared generics `decl_generics`,
275 /// returns an appropriate set of substitutions for this particular reference to `I`.
276 pub fn ast_path_substs_for_ty<'tcx>(
277 this: &AstConv<'tcx>,
278 rscope: &RegionScope,
280 param_mode: PathParamMode,
281 decl_generics: &ty::Generics<'tcx>,
282 item_segment: &ast::PathSegment)
285 let tcx = this.tcx();
287 // ast_path_substs() is only called to convert paths that are
288 // known to refer to traits, types, or structs. In these cases,
289 // all type parameters defined for the item being referenced will
290 // be in the TypeSpace or SelfSpace.
292 // Note: in the case of traits, the self parameter is also
293 // defined, but we don't currently create a `type_param_def` for
294 // `Self` because it is implicit.
295 assert!(decl_generics.regions.all(|d| d.space == TypeSpace));
296 assert!(decl_generics.types.all(|d| d.space != FnSpace));
298 let (regions, types, assoc_bindings) = match item_segment.parameters {
299 ast::AngleBracketedParameters(ref data) => {
300 convert_angle_bracketed_parameters(this, rscope, span, decl_generics, data)
302 ast::ParenthesizedParameters(..) => {
303 span_err!(tcx.sess, span, E0214,
304 "parenthesized parameters may only be used with a trait");
305 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
307 ty_param_defs.iter().map(|_| tcx.types.err).collect(),
312 prohibit_projections(this.tcx(), &assoc_bindings);
314 create_substs_for_ast_path(this,
323 #[derive(PartialEq, Eq)]
324 pub enum PathParamMode {
325 // Any path in a type context.
327 // The `module::Type` in `module::Type::method` in an expression.
331 fn create_region_substs<'tcx>(
332 this: &AstConv<'tcx>,
333 rscope: &RegionScope,
335 decl_generics: &ty::Generics<'tcx>,
336 regions_provided: Vec<ty::Region>)
339 let tcx = this.tcx();
341 // If the type is parameterized by the this region, then replace this
342 // region with the current anon region binding (in other words,
343 // whatever & would get replaced with).
344 let expected_num_region_params = decl_generics.regions.len(TypeSpace);
345 let supplied_num_region_params = regions_provided.len();
346 let regions = if expected_num_region_params == supplied_num_region_params {
350 rscope.anon_regions(span, expected_num_region_params);
352 if supplied_num_region_params != 0 || anon_regions.is_err() {
353 report_lifetime_number_error(tcx, span,
354 supplied_num_region_params,
355 expected_num_region_params);
359 Ok(anon_regions) => anon_regions,
360 Err(_) => (0..expected_num_region_params).map(|_| ty::ReStatic).collect()
363 Substs::new_type(vec![], regions)
366 /// Given the type/region arguments provided to some path (along with
367 /// an implicit Self, if this is a trait reference) returns the complete
368 /// set of substitutions. This may involve applying defaulted type parameters.
370 /// Note that the type listing given here is *exactly* what the user provided.
372 /// The `region_substs` should be the result of `create_region_substs`
373 /// -- that is, a substitution with no types but the correct number of
375 fn create_substs_for_ast_path<'tcx>(
376 this: &AstConv<'tcx>,
378 param_mode: PathParamMode,
379 decl_generics: &ty::Generics<'tcx>,
380 self_ty: Option<Ty<'tcx>>,
381 types_provided: Vec<Ty<'tcx>>,
382 region_substs: Substs<'tcx>)
385 let tcx = this.tcx();
387 debug!("create_substs_for_ast_path(decl_generics={:?}, self_ty={:?}, \
388 types_provided={:?}, region_substs={:?}",
389 decl_generics, self_ty, types_provided,
392 assert_eq!(region_substs.regions().len(TypeSpace), decl_generics.regions.len(TypeSpace));
393 assert!(region_substs.types.is_empty());
395 // Convert the type parameters supplied by the user.
396 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
397 let formal_ty_param_count = ty_param_defs.len();
398 let required_ty_param_count = ty_param_defs.iter()
399 .take_while(|x| x.default.is_none())
402 // Fill with `ty_infer` if no params were specified, as long as
403 // they were optional (e.g. paths inside expressions).
404 let mut type_substs = if param_mode == PathParamMode::Optional &&
405 types_provided.is_empty() {
406 ty_param_defs.iter().map(|p| this.ty_infer(p.default, span)).collect()
411 let supplied_ty_param_count = type_substs.len();
412 check_type_argument_count(this.tcx(), span, supplied_ty_param_count,
413 required_ty_param_count, formal_ty_param_count);
415 if supplied_ty_param_count < required_ty_param_count {
416 while type_substs.len() < required_ty_param_count {
417 type_substs.push(tcx.types.err);
419 } else if supplied_ty_param_count > formal_ty_param_count {
420 type_substs.truncate(formal_ty_param_count);
422 assert!(type_substs.len() >= required_ty_param_count &&
423 type_substs.len() <= formal_ty_param_count);
425 let mut substs = region_substs;
426 substs.types.extend(TypeSpace, type_substs.into_iter());
430 // If no self-type is provided, it's still possible that
431 // one was declared, because this could be an object type.
434 // If a self-type is provided, one should have been
435 // "declared" (in other words, this should be a
437 assert!(decl_generics.types.get_self().is_some());
438 substs.types.push(SelfSpace, ty);
442 let actual_supplied_ty_param_count = substs.types.len(TypeSpace);
443 for param in &ty_param_defs[actual_supplied_ty_param_count..] {
444 if let Some(default) = param.default {
445 // If we are converting an object type, then the
446 // `Self` parameter is unknown. However, some of the
447 // other type parameters may reference `Self` in their
448 // defaults. This will lead to an ICE if we are not
450 if self_ty.is_none() && default.has_self_ty() {
451 span_err!(tcx.sess, span, E0393,
452 "the type parameter `{}` must be explicitly specified \
453 in an object type because its default value `{}` references \
457 substs.types.push(TypeSpace, tcx.types.err);
459 // This is a default type parameter.
460 let default = default.subst_spanned(tcx,
463 substs.types.push(TypeSpace, default);
466 tcx.sess.span_bug(span, "extra parameter without default");
473 struct ConvertedBinding<'tcx> {
474 item_name: ast::Name,
479 fn convert_angle_bracketed_parameters<'tcx>(this: &AstConv<'tcx>,
480 rscope: &RegionScope,
482 decl_generics: &ty::Generics<'tcx>,
483 data: &ast::AngleBracketedParameterData)
486 Vec<ConvertedBinding<'tcx>>)
488 let regions: Vec<_> =
489 data.lifetimes.iter()
490 .map(|l| ast_region_to_region(this.tcx(), l))
494 create_region_substs(this, rscope, span, decl_generics, regions);
499 .map(|(i,t)| ast_ty_arg_to_ty(this, rscope, decl_generics,
500 i, ®ion_substs, t))
503 let assoc_bindings: Vec<_> =
505 .map(|b| ConvertedBinding { item_name: b.ident.name,
506 ty: ast_ty_to_ty(this, rscope, &*b.ty),
510 (region_substs, types, assoc_bindings)
513 /// Returns the appropriate lifetime to use for any output lifetimes
514 /// (if one exists) and a vector of the (pattern, number of lifetimes)
515 /// corresponding to each input type/pattern.
516 fn find_implied_output_region<'tcx>(tcx: &ty::ctxt<'tcx>,
517 input_tys: &[Ty<'tcx>],
518 input_pats: Vec<String>) -> ElidedLifetime
520 let mut lifetimes_for_params = Vec::new();
521 let mut possible_implied_output_region = None;
523 for (input_type, input_pat) in input_tys.iter().zip(input_pats) {
524 let mut regions = FnvHashSet();
525 let have_bound_regions = ty_fold::collect_regions(tcx,
529 debug!("find_implied_output_regions: collected {:?} from {:?} \
530 have_bound_regions={:?}", ®ions, input_type, have_bound_regions);
532 if regions.len() == 1 {
533 // there's a chance that the unique lifetime of this
534 // iteration will be the appropriate lifetime for output
535 // parameters, so lets store it.
536 possible_implied_output_region = regions.iter().cloned().next();
539 lifetimes_for_params.push(ElisionFailureInfo {
541 lifetime_count: regions.len(),
542 have_bound_regions: have_bound_regions
546 if lifetimes_for_params.iter().map(|e| e.lifetime_count).sum::<usize>() == 1 {
547 Ok(possible_implied_output_region.unwrap())
549 Err(Some(lifetimes_for_params))
553 fn convert_ty_with_lifetime_elision<'tcx>(this: &AstConv<'tcx>,
554 elided_lifetime: ElidedLifetime,
558 match elided_lifetime {
559 Ok(implied_output_region) => {
560 let rb = ElidableRscope::new(implied_output_region);
561 ast_ty_to_ty(this, &rb, ty)
563 Err(param_lifetimes) => {
564 // All regions must be explicitly specified in the output
565 // if the lifetime elision rules do not apply. This saves
566 // the user from potentially-confusing errors.
567 let rb = UnelidableRscope::new(param_lifetimes);
568 ast_ty_to_ty(this, &rb, ty)
573 fn convert_parenthesized_parameters<'tcx>(this: &AstConv<'tcx>,
574 rscope: &RegionScope,
576 decl_generics: &ty::Generics<'tcx>,
577 data: &ast::ParenthesizedParameterData)
580 Vec<ConvertedBinding<'tcx>>)
583 create_region_substs(this, rscope, span, decl_generics, Vec::new());
585 let binding_rscope = BindingRscope::new();
588 .map(|a_t| ast_ty_arg_to_ty(this, &binding_rscope, decl_generics,
589 0, ®ion_substs, a_t))
590 .collect::<Vec<Ty<'tcx>>>();
592 let input_params = vec![String::new(); inputs.len()];
593 let implied_output_region = find_implied_output_region(this.tcx(), &inputs, input_params);
595 let input_ty = this.tcx().mk_tup(inputs);
597 let (output, output_span) = match data.output {
598 Some(ref output_ty) => {
599 (convert_ty_with_lifetime_elision(this,
600 implied_output_region,
605 (this.tcx().mk_nil(), data.span)
609 let output_binding = ConvertedBinding {
610 item_name: token::intern(FN_OUTPUT_NAME),
615 (region_substs, vec![input_ty], vec![output_binding])
618 pub fn instantiate_poly_trait_ref<'tcx>(
619 this: &AstConv<'tcx>,
620 rscope: &RegionScope,
621 ast_trait_ref: &ast::PolyTraitRef,
622 self_ty: Option<Ty<'tcx>>,
623 poly_projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
624 -> ty::PolyTraitRef<'tcx>
626 let trait_ref = &ast_trait_ref.trait_ref;
627 let trait_def_id = trait_def_id(this, trait_ref);
628 ast_path_to_poly_trait_ref(this,
631 PathParamMode::Explicit,
634 trait_ref.path.segments.last().unwrap(),
638 /// Instantiates the path for the given trait reference, assuming that it's
639 /// bound to a valid trait type. Returns the def_id for the defining trait.
640 /// Fails if the type is a type other than a trait type.
642 /// If the `projections` argument is `None`, then assoc type bindings like `Foo<T=X>`
643 /// are disallowed. Otherwise, they are pushed onto the vector given.
644 pub fn instantiate_mono_trait_ref<'tcx>(
645 this: &AstConv<'tcx>,
646 rscope: &RegionScope,
647 trait_ref: &ast::TraitRef,
648 self_ty: Option<Ty<'tcx>>)
649 -> ty::TraitRef<'tcx>
651 let trait_def_id = trait_def_id(this, trait_ref);
652 ast_path_to_mono_trait_ref(this,
655 PathParamMode::Explicit,
658 trait_ref.path.segments.last().unwrap())
661 fn trait_def_id<'tcx>(this: &AstConv<'tcx>, trait_ref: &ast::TraitRef) -> ast::DefId {
662 let path = &trait_ref.path;
663 match ::lookup_full_def(this.tcx(), path.span, trait_ref.ref_id) {
664 def::DefTrait(trait_def_id) => trait_def_id,
666 span_fatal!(this.tcx().sess, path.span, E0245, "`{}` is not a trait",
672 fn object_path_to_poly_trait_ref<'a,'tcx>(
673 this: &AstConv<'tcx>,
674 rscope: &RegionScope,
676 param_mode: PathParamMode,
677 trait_def_id: ast::DefId,
678 trait_segment: &ast::PathSegment,
679 mut projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
680 -> ty::PolyTraitRef<'tcx>
682 ast_path_to_poly_trait_ref(this,
692 fn ast_path_to_poly_trait_ref<'a,'tcx>(
693 this: &AstConv<'tcx>,
694 rscope: &RegionScope,
696 param_mode: PathParamMode,
697 trait_def_id: ast::DefId,
698 self_ty: Option<Ty<'tcx>>,
699 trait_segment: &ast::PathSegment,
700 poly_projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
701 -> ty::PolyTraitRef<'tcx>
703 // The trait reference introduces a binding level here, so
704 // we need to shift the `rscope`. It'd be nice if we could
705 // do away with this rscope stuff and work this knowledge
706 // into resolve_lifetimes, as we do with non-omitted
707 // lifetimes. Oh well, not there yet.
708 let shifted_rscope = &ShiftedRscope::new(rscope);
710 let (substs, assoc_bindings) =
711 create_substs_for_ast_trait_ref(this,
718 let poly_trait_ref = ty::Binder(ty::TraitRef::new(trait_def_id, substs));
721 let converted_bindings =
724 .filter_map(|binding| {
725 // specify type to assert that error was already reported in Err case:
726 let predicate: Result<_, ErrorReported> =
727 ast_type_binding_to_poly_projection_predicate(this,
728 poly_trait_ref.clone(),
731 predicate.ok() // ok to ignore Err() because ErrorReported (see above)
733 poly_projections.extend(converted_bindings);
739 fn ast_path_to_mono_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
740 rscope: &RegionScope,
742 param_mode: PathParamMode,
743 trait_def_id: ast::DefId,
744 self_ty: Option<Ty<'tcx>>,
745 trait_segment: &ast::PathSegment)
746 -> ty::TraitRef<'tcx>
748 let (substs, assoc_bindings) =
749 create_substs_for_ast_trait_ref(this,
756 prohibit_projections(this.tcx(), &assoc_bindings);
757 ty::TraitRef::new(trait_def_id, substs)
760 fn create_substs_for_ast_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
761 rscope: &RegionScope,
763 param_mode: PathParamMode,
764 trait_def_id: ast::DefId,
765 self_ty: Option<Ty<'tcx>>,
766 trait_segment: &ast::PathSegment)
767 -> (&'tcx Substs<'tcx>, Vec<ConvertedBinding<'tcx>>)
769 debug!("create_substs_for_ast_trait_ref(trait_segment={:?})",
772 let trait_def = match this.get_trait_def(span, trait_def_id) {
773 Ok(trait_def) => trait_def,
774 Err(ErrorReported) => {
775 // No convenient way to recover from a cycle here. Just bail. Sorry!
776 this.tcx().sess.abort_if_errors();
777 this.tcx().sess.bug("ErrorReported returned, but no errors reports?")
781 let (regions, types, assoc_bindings) = match trait_segment.parameters {
782 ast::AngleBracketedParameters(ref data) => {
783 // For now, require that parenthetical notation be used
784 // only with `Fn()` etc.
785 if !this.tcx().sess.features.borrow().unboxed_closures && trait_def.paren_sugar {
786 span_err!(this.tcx().sess, span, E0215,
787 "angle-bracket notation is not stable when \
788 used with the `Fn` family of traits, use parentheses");
789 fileline_help!(this.tcx().sess, span,
790 "add `#![feature(unboxed_closures)]` to \
791 the crate attributes to enable");
794 convert_angle_bracketed_parameters(this, rscope, span, &trait_def.generics, data)
796 ast::ParenthesizedParameters(ref data) => {
797 // For now, require that parenthetical notation be used
798 // only with `Fn()` etc.
799 if !this.tcx().sess.features.borrow().unboxed_closures && !trait_def.paren_sugar {
800 span_err!(this.tcx().sess, span, E0216,
801 "parenthetical notation is only stable when \
802 used with the `Fn` family of traits");
803 fileline_help!(this.tcx().sess, span,
804 "add `#![feature(unboxed_closures)]` to \
805 the crate attributes to enable");
808 convert_parenthesized_parameters(this, rscope, span, &trait_def.generics, data)
812 let substs = create_substs_for_ast_path(this,
820 (this.tcx().mk_substs(substs), assoc_bindings)
823 fn ast_type_binding_to_poly_projection_predicate<'tcx>(
824 this: &AstConv<'tcx>,
825 mut trait_ref: ty::PolyTraitRef<'tcx>,
826 self_ty: Option<Ty<'tcx>>,
827 binding: &ConvertedBinding<'tcx>)
828 -> Result<ty::PolyProjectionPredicate<'tcx>, ErrorReported>
830 let tcx = this.tcx();
832 // Given something like `U : SomeTrait<T=X>`, we want to produce a
833 // predicate like `<U as SomeTrait>::T = X`. This is somewhat
834 // subtle in the event that `T` is defined in a supertrait of
835 // `SomeTrait`, because in that case we need to upcast.
837 // That is, consider this case:
840 // trait SubTrait : SuperTrait<int> { }
841 // trait SuperTrait<A> { type T; }
843 // ... B : SubTrait<T=foo> ...
846 // We want to produce `<B as SuperTrait<int>>::T == foo`.
848 // Simple case: X is defined in the current trait.
849 if this.trait_defines_associated_type_named(trait_ref.def_id(), binding.item_name) {
850 return Ok(ty::Binder(ty::ProjectionPredicate { // <-------------------+
851 projection_ty: ty::ProjectionTy { // |
852 trait_ref: trait_ref.skip_binder().clone(), // Binder moved here --+
853 item_name: binding.item_name,
859 // Otherwise, we have to walk through the supertraits to find
860 // those that do. This is complicated by the fact that, for an
861 // object type, the `Self` type is not present in the
862 // substitutions (after all, it's being constructed right now),
863 // but the `supertraits` iterator really wants one. To handle
864 // this, we currently insert a dummy type and then remove it
867 let dummy_self_ty = tcx.mk_infer(ty::FreshTy(0));
868 if self_ty.is_none() { // if converting for an object type
869 let mut dummy_substs = trait_ref.skip_binder().substs.clone(); // binder moved here -+
870 assert!(dummy_substs.self_ty().is_none()); // |
871 dummy_substs.types.push(SelfSpace, dummy_self_ty); // |
872 trait_ref = ty::Binder(ty::TraitRef::new(trait_ref.def_id(), // <------------+
873 tcx.mk_substs(dummy_substs)));
876 try!(this.ensure_super_predicates(binding.span, trait_ref.def_id()));
878 let mut candidates: Vec<ty::PolyTraitRef> =
879 traits::supertraits(tcx, trait_ref.clone())
880 .filter(|r| this.trait_defines_associated_type_named(r.def_id(), binding.item_name))
883 // If converting for an object type, then remove the dummy-ty from `Self` now.
885 if self_ty.is_none() {
886 for candidate in &mut candidates {
887 let mut dummy_substs = candidate.0.substs.clone();
888 assert!(dummy_substs.self_ty() == Some(dummy_self_ty));
889 dummy_substs.types.pop(SelfSpace);
890 *candidate = ty::Binder(ty::TraitRef::new(candidate.def_id(),
891 tcx.mk_substs(dummy_substs)));
895 let candidate = try!(one_bound_for_assoc_type(tcx,
897 &trait_ref.to_string(),
898 &token::get_name(binding.item_name),
901 Ok(ty::Binder(ty::ProjectionPredicate { // <-------------------------+
902 projection_ty: ty::ProjectionTy { // |
903 trait_ref: candidate.skip_binder().clone(), // binder is moved up here --+
904 item_name: binding.item_name,
910 fn ast_path_to_ty<'tcx>(
911 this: &AstConv<'tcx>,
912 rscope: &RegionScope,
914 param_mode: PathParamMode,
916 item_segment: &ast::PathSegment)
919 let tcx = this.tcx();
920 let (generics, decl_ty) = match this.get_item_type_scheme(span, did) {
921 Ok(ty::TypeScheme { generics, ty: decl_ty }) => {
924 Err(ErrorReported) => {
925 return tcx.types.err;
929 let substs = ast_path_substs_for_ty(this,
936 // FIXME(#12938): This is a hack until we have full support for DST.
937 if Some(did) == this.tcx().lang_items.owned_box() {
938 assert_eq!(substs.types.len(TypeSpace), 1);
939 return this.tcx().mk_box(*substs.types.get(TypeSpace, 0));
942 decl_ty.subst(this.tcx(), &substs)
945 type TraitAndProjections<'tcx> = (ty::PolyTraitRef<'tcx>, Vec<ty::PolyProjectionPredicate<'tcx>>);
947 fn ast_ty_to_trait_ref<'tcx>(this: &AstConv<'tcx>,
948 rscope: &RegionScope,
950 bounds: &[ast::TyParamBound])
951 -> Result<TraitAndProjections<'tcx>, ErrorReported>
954 * In a type like `Foo + Send`, we want to wait to collect the
955 * full set of bounds before we make the object type, because we
956 * need them to infer a region bound. (For example, if we tried
957 * made a type from just `Foo`, then it wouldn't be enough to
958 * infer a 'static bound, and hence the user would get an error.)
959 * So this function is used when we're dealing with a sum type to
960 * convert the LHS. It only accepts a type that refers to a trait
961 * name, and reports an error otherwise.
965 ast::TyPath(None, ref path) => {
966 let def = match this.tcx().def_map.borrow().get(&ty.id) {
967 Some(&def::PathResolution { base_def, depth: 0, .. }) => Some(base_def),
971 Some(def::DefTrait(trait_def_id)) => {
972 let mut projection_bounds = Vec::new();
973 let trait_ref = object_path_to_poly_trait_ref(this,
976 PathParamMode::Explicit,
978 path.segments.last().unwrap(),
979 &mut projection_bounds);
980 Ok((trait_ref, projection_bounds))
983 span_err!(this.tcx().sess, ty.span, E0172, "expected a reference to a trait");
989 span_err!(this.tcx().sess, ty.span, E0178,
990 "expected a path on the left-hand side of `+`, not `{}`",
991 pprust::ty_to_string(ty));
992 let hi = bounds.iter().map(|x| match *x {
993 ast::TraitTyParamBound(ref tr, _) => tr.span.hi,
994 ast::RegionTyParamBound(ref r) => r.span.hi,
995 }).max_by(|x| x.to_usize());
996 let full_span = hi.map(|hi| Span {
999 expn_id: ty.span.expn_id,
1001 match (&ty.node, full_span) {
1002 (&ast::TyRptr(None, ref mut_ty), Some(full_span)) => {
1003 let mutbl_str = if mut_ty.mutbl == ast::MutMutable { "mut " } else { "" };
1005 .span_suggestion(full_span, "try adding parentheses (per RFC 438):",
1006 format!("&{}({} +{})",
1008 pprust::ty_to_string(&*mut_ty.ty),
1009 pprust::bounds_to_string(bounds)));
1011 (&ast::TyRptr(Some(ref lt), ref mut_ty), Some(full_span)) => {
1012 let mutbl_str = if mut_ty.mutbl == ast::MutMutable { "mut " } else { "" };
1014 .span_suggestion(full_span, "try adding parentheses (per RFC 438):",
1015 format!("&{} {}({} +{})",
1016 pprust::lifetime_to_string(lt),
1018 pprust::ty_to_string(&*mut_ty.ty),
1019 pprust::bounds_to_string(bounds)));
1023 fileline_help!(this.tcx().sess, ty.span,
1024 "perhaps you forgot parentheses? (per RFC 438)");
1032 fn trait_ref_to_object_type<'tcx>(this: &AstConv<'tcx>,
1033 rscope: &RegionScope,
1035 trait_ref: ty::PolyTraitRef<'tcx>,
1036 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
1037 bounds: &[ast::TyParamBound])
1040 let existential_bounds = conv_existential_bounds(this,
1047 let result = make_object_type(this, span, trait_ref, existential_bounds);
1048 debug!("trait_ref_to_object_type: result={:?}",
1054 fn make_object_type<'tcx>(this: &AstConv<'tcx>,
1056 principal: ty::PolyTraitRef<'tcx>,
1057 bounds: ty::ExistentialBounds<'tcx>)
1059 let tcx = this.tcx();
1060 let object = ty::TraitTy {
1061 principal: principal,
1064 let object_trait_ref =
1065 object.principal_trait_ref_with_self_ty(tcx, tcx.types.err);
1067 // ensure the super predicates and stop if we encountered an error
1068 if this.ensure_super_predicates(span, object.principal_def_id()).is_err() {
1069 return tcx.types.err;
1072 let mut associated_types: FnvHashSet<(ast::DefId, ast::Name)> =
1073 traits::supertraits(tcx, object_trait_ref)
1075 let trait_def = tcx.lookup_trait_def(tr.def_id());
1076 trait_def.associated_type_names
1079 .map(move |associated_type_name| (tr.def_id(), associated_type_name))
1083 for projection_bound in &object.bounds.projection_bounds {
1084 let pair = (projection_bound.0.projection_ty.trait_ref.def_id,
1085 projection_bound.0.projection_ty.item_name);
1086 associated_types.remove(&pair);
1089 for (trait_def_id, name) in associated_types {
1090 span_err!(tcx.sess, span, E0191,
1091 "the value of the associated type `{}` (from the trait `{}`) must be specified",
1093 tcx.item_path_str(trait_def_id));
1096 tcx.mk_trait(object.principal, object.bounds)
1099 fn report_ambiguous_associated_type(tcx: &ty::ctxt,
1104 span_err!(tcx.sess, span, E0223,
1105 "ambiguous associated type; specify the type using the syntax \
1107 type_str, trait_str, name);
1110 // Search for a bound on a type parameter which includes the associated item
1111 // given by assoc_name. ty_param_node_id is the node id for the type parameter
1112 // (which might be `Self`, but only if it is the `Self` of a trait, not an
1113 // impl). This function will fail if there are no suitable bounds or there is
1115 fn find_bound_for_assoc_item<'tcx>(this: &AstConv<'tcx>,
1116 ty_param_node_id: ast::NodeId,
1117 ty_param_name: ast::Name,
1118 assoc_name: ast::Name,
1120 -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
1122 let tcx = this.tcx();
1124 let bounds = match this.get_type_parameter_bounds(span, ty_param_node_id) {
1126 Err(ErrorReported) => {
1127 return Err(ErrorReported);
1131 // Ensure the super predicates and stop if we encountered an error.
1132 if bounds.iter().any(|b| this.ensure_super_predicates(span, b.def_id()).is_err()) {
1133 return Err(ErrorReported);
1136 // Check that there is exactly one way to find an associated type with the
1138 let suitable_bounds: Vec<_> =
1139 traits::transitive_bounds(tcx, &bounds)
1140 .filter(|b| this.trait_defines_associated_type_named(b.def_id(), assoc_name))
1143 one_bound_for_assoc_type(tcx,
1145 &token::get_name(ty_param_name),
1146 &token::get_name(assoc_name),
1151 // Checks that bounds contains exactly one element and reports appropriate
1152 // errors otherwise.
1153 fn one_bound_for_assoc_type<'tcx>(tcx: &ty::ctxt<'tcx>,
1154 bounds: Vec<ty::PolyTraitRef<'tcx>>,
1155 ty_param_name: &str,
1158 -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
1160 if bounds.is_empty() {
1161 span_err!(tcx.sess, span, E0220,
1162 "associated type `{}` not found for `{}`",
1165 return Err(ErrorReported);
1168 if bounds.len() > 1 {
1169 span_err!(tcx.sess, span, E0221,
1170 "ambiguous associated type `{}` in bounds of `{}`",
1174 for bound in &bounds {
1175 span_note!(tcx.sess, span,
1176 "associated type `{}` could derive from `{}`",
1182 Ok(bounds[0].clone())
1185 // Create a type from a a path to an associated type.
1186 // For a path A::B::C::D, ty and ty_path_def are the type and def for A::B::C
1187 // and item_segment is the path segment for D. We return a type and a def for
1189 // Will fail except for T::A and Self::A; i.e., if ty/ty_path_def are not a type
1190 // parameter or Self.
1191 fn associated_path_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1194 ty_path_def: def::Def,
1195 item_segment: &ast::PathSegment)
1196 -> (Ty<'tcx>, def::Def)
1198 let tcx = this.tcx();
1199 let assoc_name = item_segment.identifier.name;
1201 debug!("associated_path_def_to_ty: {:?}::{}", ty, assoc_name);
1203 check_path_args(tcx, slice::ref_slice(item_segment), NO_TPS | NO_REGIONS);
1205 // Find the type of the associated item, and the trait where the associated
1206 // item is declared.
1207 let bound = match (&ty.sty, ty_path_def) {
1208 (_, def::DefSelfTy(Some(trait_did), Some((impl_id, _)))) => {
1209 // `Self` in an impl of a trait - we have a concrete self type and a
1211 match tcx.map.expect_item(impl_id).node {
1212 ast::ItemImpl(_, _, _, Some(ref trait_ref), _, _) => {
1213 if this.ensure_super_predicates(span, trait_did).is_err() {
1214 return (tcx.types.err, ty_path_def);
1217 let trait_segment = &trait_ref.path.segments.last().unwrap();
1218 let trait_ref = ast_path_to_mono_trait_ref(this,
1221 PathParamMode::Explicit,
1226 let candidates: Vec<ty::PolyTraitRef> =
1227 traits::supertraits(tcx, ty::Binder(trait_ref.clone()))
1228 .filter(|r| this.trait_defines_associated_type_named(r.def_id(),
1232 match one_bound_for_assoc_type(tcx,
1235 &token::get_name(assoc_name),
1238 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1244 (&ty::TyParam(_), def::DefSelfTy(Some(trait_did), None)) => {
1245 assert_eq!(trait_did.krate, ast::LOCAL_CRATE);
1246 match find_bound_for_assoc_item(this,
1248 token::special_idents::type_self.name,
1252 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1255 (&ty::TyParam(_), def::DefTyParam(_, _, param_did, param_name)) => {
1256 assert_eq!(param_did.krate, ast::LOCAL_CRATE);
1257 match find_bound_for_assoc_item(this,
1263 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1267 report_ambiguous_associated_type(tcx,
1271 &token::get_name(assoc_name));
1272 return (tcx.types.err, ty_path_def);
1276 let trait_did = bound.0.def_id;
1277 let ty = this.projected_ty_from_poly_trait_ref(span, bound, assoc_name);
1279 let item_did = if trait_did.krate == ast::LOCAL_CRATE {
1280 // `ty::trait_items` used below requires information generated
1281 // by type collection, which may be in progress at this point.
1282 match tcx.map.expect_item(trait_did.node).node {
1283 ast::ItemTrait(_, _, _, ref trait_items) => {
1284 let item = trait_items.iter()
1285 .find(|i| i.ident.name == assoc_name)
1286 .expect("missing associated type");
1287 ast_util::local_def(item.id)
1292 let trait_items = tcx.trait_items(trait_did);
1293 let item = trait_items.iter().find(|i| i.name() == assoc_name);
1294 item.expect("missing associated type").def_id()
1297 (ty, def::DefAssociatedTy(trait_did, item_did))
1300 fn qpath_to_ty<'tcx>(this: &AstConv<'tcx>,
1301 rscope: &RegionScope,
1303 param_mode: PathParamMode,
1304 opt_self_ty: Option<Ty<'tcx>>,
1305 trait_def_id: ast::DefId,
1306 trait_segment: &ast::PathSegment,
1307 item_segment: &ast::PathSegment)
1310 let tcx = this.tcx();
1312 check_path_args(tcx, slice::ref_slice(item_segment), NO_TPS | NO_REGIONS);
1314 let self_ty = if let Some(ty) = opt_self_ty {
1317 let path_str = tcx.item_path_str(trait_def_id);
1318 report_ambiguous_associated_type(tcx,
1322 &token::get_ident(item_segment.identifier));
1323 return tcx.types.err;
1326 debug!("qpath_to_ty: self_type={:?}", self_ty);
1328 let trait_ref = ast_path_to_mono_trait_ref(this,
1336 debug!("qpath_to_ty: trait_ref={:?}", trait_ref);
1338 this.projected_ty(span, trait_ref, item_segment.identifier.name)
1341 /// Convert a type supplied as value for a type argument from AST into our
1342 /// our internal representation. This is the same as `ast_ty_to_ty` but that
1343 /// it applies the object lifetime default.
1347 /// * `this`, `rscope`: the surrounding context
1348 /// * `decl_generics`: the generics of the struct/enum/trait declaration being
1350 /// * `index`: the index of the type parameter being instantiated from the list
1351 /// (we assume it is in the `TypeSpace`)
1352 /// * `region_substs`: a partial substitution consisting of
1353 /// only the region type parameters being supplied to this type.
1354 /// * `ast_ty`: the ast representation of the type being supplied
1355 pub fn ast_ty_arg_to_ty<'tcx>(this: &AstConv<'tcx>,
1356 rscope: &RegionScope,
1357 decl_generics: &ty::Generics<'tcx>,
1359 region_substs: &Substs<'tcx>,
1363 let tcx = this.tcx();
1365 if let Some(def) = decl_generics.types.opt_get(TypeSpace, index) {
1366 let object_lifetime_default = def.object_lifetime_default.subst(tcx, region_substs);
1367 let rscope1 = &ObjectLifetimeDefaultRscope::new(rscope, object_lifetime_default);
1368 ast_ty_to_ty(this, rscope1, ast_ty)
1370 ast_ty_to_ty(this, rscope, ast_ty)
1374 // Check the base def in a PathResolution and convert it to a Ty. If there are
1375 // associated types in the PathResolution, these will need to be separately
1377 fn base_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1378 rscope: &RegionScope,
1380 param_mode: PathParamMode,
1382 opt_self_ty: Option<Ty<'tcx>>,
1383 base_segments: &[ast::PathSegment])
1385 let tcx = this.tcx();
1388 def::DefTrait(trait_def_id) => {
1389 // N.B. this case overlaps somewhat with
1390 // TyObjectSum, see that fn for details
1391 let mut projection_bounds = Vec::new();
1393 let trait_ref = object_path_to_poly_trait_ref(this,
1398 base_segments.last().unwrap(),
1399 &mut projection_bounds);
1401 check_path_args(tcx, base_segments.split_last().unwrap().1, NO_TPS | NO_REGIONS);
1402 trait_ref_to_object_type(this,
1409 def::DefTy(did, _) | def::DefStruct(did) => {
1410 check_path_args(tcx, base_segments.split_last().unwrap().1, NO_TPS | NO_REGIONS);
1411 ast_path_to_ty(this,
1416 base_segments.last().unwrap())
1418 def::DefTyParam(space, index, _, name) => {
1419 check_path_args(tcx, base_segments, NO_TPS | NO_REGIONS);
1420 tcx.mk_param(space, index, name)
1422 def::DefSelfTy(_, Some((_, self_ty_id))) => {
1423 // Self in impl (we know the concrete type).
1424 check_path_args(tcx, base_segments, NO_TPS | NO_REGIONS);
1425 if let Some(&ty) = tcx.ast_ty_to_ty_cache.borrow().get(&self_ty_id) {
1426 if let Some(free_substs) = this.get_free_substs() {
1427 ty.subst(tcx, free_substs)
1432 tcx.sess.span_bug(span, "self type has not been fully resolved")
1435 def::DefSelfTy(Some(_), None) => {
1437 check_path_args(tcx, base_segments, NO_TPS | NO_REGIONS);
1440 def::DefAssociatedTy(trait_did, _) => {
1441 check_path_args(tcx, &base_segments[..base_segments.len()-2], NO_TPS | NO_REGIONS);
1448 &base_segments[base_segments.len()-2],
1449 base_segments.last().unwrap())
1451 def::DefMod(id) => {
1452 // Used as sentinel by callers to indicate the `<T>::A::B::C` form.
1453 // FIXME(#22519) This part of the resolution logic should be
1454 // avoided entirely for that form, once we stop needed a Def
1455 // for `associated_path_def_to_ty`.
1456 // Fixing this will also let use resolve <Self>::Foo the same way we
1457 // resolve Self::Foo, at the moment we can't resolve the former because
1458 // we don't have the trait information around, which is just sad.
1460 if !base_segments.is_empty() {
1464 "found module name used as a type: {}",
1465 tcx.map.node_to_string(id.node));
1466 return this.tcx().types.err;
1469 opt_self_ty.expect("missing T in <T>::a::b::c")
1471 def::DefPrimTy(prim_ty) => {
1472 prim_ty_to_ty(tcx, base_segments, prim_ty)
1475 let node = def.def_id().node;
1476 span_err!(tcx.sess, span, E0248,
1477 "found value `{}` used as a type",
1478 tcx.map.path_to_string(node));
1479 return this.tcx().types.err;
1484 // Note that both base_segments and assoc_segments may be empty, although not at
1486 pub fn finish_resolving_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1487 rscope: &RegionScope,
1489 param_mode: PathParamMode,
1491 opt_self_ty: Option<Ty<'tcx>>,
1492 base_segments: &[ast::PathSegment],
1493 assoc_segments: &[ast::PathSegment])
1495 let mut ty = base_def_to_ty(this,
1503 // If any associated type segments remain, attempt to resolve them.
1504 for segment in assoc_segments {
1505 if ty.sty == ty::TyError {
1508 // This is pretty bad (it will fail except for T::A and Self::A).
1509 let (a_ty, a_def) = associated_path_def_to_ty(this,
1520 /// Parses the programmer's textual representation of a type into our
1521 /// internal notion of a type.
1522 pub fn ast_ty_to_ty<'tcx>(this: &AstConv<'tcx>,
1523 rscope: &RegionScope,
1527 debug!("ast_ty_to_ty(ast_ty={:?})",
1530 let tcx = this.tcx();
1532 if let Some(&ty) = tcx.ast_ty_to_ty_cache.borrow().get(&ast_ty.id) {
1536 let typ = match ast_ty.node {
1537 ast::TyVec(ref ty) => {
1538 tcx.mk_slice(ast_ty_to_ty(this, rscope, &**ty))
1540 ast::TyObjectSum(ref ty, ref bounds) => {
1541 match ast_ty_to_trait_ref(this, rscope, &**ty, bounds) {
1542 Ok((trait_ref, projection_bounds)) => {
1543 trait_ref_to_object_type(this,
1550 Err(ErrorReported) => {
1551 this.tcx().types.err
1555 ast::TyPtr(ref mt) => {
1556 tcx.mk_ptr(ty::TypeAndMut {
1557 ty: ast_ty_to_ty(this, rscope, &*mt.ty),
1561 ast::TyRptr(ref region, ref mt) => {
1562 let r = opt_ast_region_to_region(this, rscope, ast_ty.span, region);
1563 debug!("TyRef r={:?}", r);
1565 &ObjectLifetimeDefaultRscope::new(
1567 ty::ObjectLifetimeDefault::Specific(r));
1568 let t = ast_ty_to_ty(this, rscope1, &*mt.ty);
1569 tcx.mk_ref(tcx.mk_region(r), ty::TypeAndMut {ty: t, mutbl: mt.mutbl})
1571 ast::TyTup(ref fields) => {
1572 let flds = fields.iter()
1573 .map(|t| ast_ty_to_ty(this, rscope, &**t))
1577 ast::TyParen(ref typ) => ast_ty_to_ty(this, rscope, &**typ),
1578 ast::TyBareFn(ref bf) => {
1579 require_c_abi_if_variadic(tcx, &bf.decl, bf.abi, ast_ty.span);
1580 let bare_fn = ty_of_bare_fn(this, bf.unsafety, bf.abi, &*bf.decl);
1581 tcx.mk_fn(None, tcx.mk_bare_fn(bare_fn))
1583 ast::TyPolyTraitRef(ref bounds) => {
1584 conv_ty_poly_trait_ref(this, rscope, ast_ty.span, bounds)
1586 ast::TyPath(ref maybe_qself, ref path) => {
1587 let path_res = if let Some(&d) = tcx.def_map.borrow().get(&ast_ty.id) {
1589 } else if let Some(ast::QSelf { position: 0, .. }) = *maybe_qself {
1590 // Create some fake resolution that can't possibly be a type.
1591 def::PathResolution {
1592 base_def: def::DefMod(ast_util::local_def(ast::CRATE_NODE_ID)),
1593 last_private: LastMod(AllPublic),
1594 depth: path.segments.len()
1597 tcx.sess.span_bug(ast_ty.span, &format!("unbound path {:?}", ast_ty))
1599 let def = path_res.base_def;
1600 let base_ty_end = path.segments.len() - path_res.depth;
1601 let opt_self_ty = maybe_qself.as_ref().map(|qself| {
1602 ast_ty_to_ty(this, rscope, &qself.ty)
1604 let ty = finish_resolving_def_to_ty(this,
1607 PathParamMode::Explicit,
1610 &path.segments[..base_ty_end],
1611 &path.segments[base_ty_end..]);
1613 if path_res.depth != 0 && ty.sty != ty::TyError {
1614 // Write back the new resolution.
1615 tcx.def_map.borrow_mut().insert(ast_ty.id, def::PathResolution {
1617 last_private: path_res.last_private,
1624 ast::TyFixedLengthVec(ref ty, ref e) => {
1625 let hint = UncheckedExprHint(tcx.types.usize);
1626 match const_eval::eval_const_expr_partial(tcx, &e, hint) {
1630 tcx.mk_array(ast_ty_to_ty(this, rscope, &**ty),
1632 ConstVal::Uint(i) =>
1633 tcx.mk_array(ast_ty_to_ty(this, rscope, &**ty),
1636 span_err!(tcx.sess, ast_ty.span, E0249,
1637 "expected constant integer expression \
1639 this.tcx().types.err
1645 ast_ty.span.lo <= r.span.lo && r.span.hi <= ast_ty.span.hi;
1646 span_err!(tcx.sess, r.span, E0250,
1647 "array length constant evaluation error: {}",
1650 span_note!(tcx.sess, ast_ty.span, "for array length here")
1652 this.tcx().types.err
1656 ast::TyTypeof(ref _e) => {
1657 tcx.sess.span_bug(ast_ty.span, "typeof is reserved but unimplemented");
1660 // TyInfer also appears as the type of arguments or return
1661 // values in a ExprClosure, or as
1662 // the type of local variables. Both of these cases are
1663 // handled specially and will not descend into this routine.
1664 this.ty_infer(None, ast_ty.span)
1668 tcx.ast_ty_to_ty_cache.borrow_mut().insert(ast_ty.id, typ);
1672 pub fn ty_of_arg<'tcx>(this: &AstConv<'tcx>,
1673 rscope: &RegionScope,
1675 expected_ty: Option<Ty<'tcx>>)
1679 ast::TyInfer if expected_ty.is_some() => expected_ty.unwrap(),
1680 ast::TyInfer => this.ty_infer(None, a.ty.span),
1681 _ => ast_ty_to_ty(this, rscope, &*a.ty),
1685 struct SelfInfo<'a, 'tcx> {
1686 untransformed_self_ty: Ty<'tcx>,
1687 explicit_self: &'a ast::ExplicitSelf,
1690 pub fn ty_of_method<'tcx>(this: &AstConv<'tcx>,
1691 sig: &ast::MethodSig,
1692 untransformed_self_ty: Ty<'tcx>)
1693 -> (ty::BareFnTy<'tcx>, ty::ExplicitSelfCategory) {
1694 let self_info = Some(SelfInfo {
1695 untransformed_self_ty: untransformed_self_ty,
1696 explicit_self: &sig.explicit_self,
1698 let (bare_fn_ty, optional_explicit_self_category) =
1699 ty_of_method_or_bare_fn(this,
1704 (bare_fn_ty, optional_explicit_self_category.unwrap())
1707 pub fn ty_of_bare_fn<'tcx>(this: &AstConv<'tcx>, unsafety: ast::Unsafety, abi: abi::Abi,
1708 decl: &ast::FnDecl) -> ty::BareFnTy<'tcx> {
1709 let (bare_fn_ty, _) = ty_of_method_or_bare_fn(this, unsafety, abi, None, decl);
1713 fn ty_of_method_or_bare_fn<'a, 'tcx>(this: &AstConv<'tcx>,
1714 unsafety: ast::Unsafety,
1716 opt_self_info: Option<SelfInfo<'a, 'tcx>>,
1718 -> (ty::BareFnTy<'tcx>, Option<ty::ExplicitSelfCategory>)
1720 debug!("ty_of_method_or_bare_fn");
1722 // New region names that appear inside of the arguments of the function
1723 // declaration are bound to that function type.
1724 let rb = rscope::BindingRscope::new();
1726 // `implied_output_region` is the region that will be assumed for any
1727 // region parameters in the return type. In accordance with the rules for
1728 // lifetime elision, we can determine it in two ways. First (determined
1729 // here), if self is by-reference, then the implied output region is the
1730 // region of the self parameter.
1731 let mut explicit_self_category_result = None;
1732 let (self_ty, implied_output_region) = match opt_self_info {
1733 None => (None, None),
1734 Some(self_info) => {
1735 // This type comes from an impl or trait; no late-bound
1736 // regions should be present.
1737 assert!(!self_info.untransformed_self_ty.has_escaping_regions());
1739 // Figure out and record the explicit self category.
1740 let explicit_self_category =
1741 determine_explicit_self_category(this, &rb, &self_info);
1742 explicit_self_category_result = Some(explicit_self_category);
1743 match explicit_self_category {
1744 ty::StaticExplicitSelfCategory => {
1747 ty::ByValueExplicitSelfCategory => {
1748 (Some(self_info.untransformed_self_ty), None)
1750 ty::ByReferenceExplicitSelfCategory(region, mutability) => {
1751 (Some(this.tcx().mk_ref(
1752 this.tcx().mk_region(region),
1754 ty: self_info.untransformed_self_ty,
1759 ty::ByBoxExplicitSelfCategory => {
1760 (Some(this.tcx().mk_box(self_info.untransformed_self_ty)), None)
1766 // HACK(eddyb) replace the fake self type in the AST with the actual type.
1767 let input_params = if self_ty.is_some() {
1772 let input_tys = input_params.iter().map(|a| ty_of_arg(this, &rb, a, None));
1773 let input_pats: Vec<String> = input_params.iter()
1774 .map(|a| pprust::pat_to_string(&*a.pat))
1776 let self_and_input_tys: Vec<Ty> =
1777 self_ty.into_iter().chain(input_tys).collect();
1780 // Second, if there was exactly one lifetime (either a substitution or a
1781 // reference) in the arguments, then any anonymous regions in the output
1782 // have that lifetime.
1783 let implied_output_region = match implied_output_region {
1786 let input_tys = if self_ty.is_some() {
1787 // Skip the first argument if `self` is present.
1788 &self_and_input_tys[1..]
1790 &self_and_input_tys[..]
1793 find_implied_output_region(this.tcx(), input_tys, input_pats)
1797 let output_ty = match decl.output {
1798 ast::Return(ref output) if output.node == ast::TyInfer =>
1799 ty::FnConverging(this.ty_infer(None, output.span)),
1800 ast::Return(ref output) =>
1801 ty::FnConverging(convert_ty_with_lifetime_elision(this,
1802 implied_output_region,
1804 ast::DefaultReturn(..) => ty::FnConverging(this.tcx().mk_nil()),
1805 ast::NoReturn(..) => ty::FnDiverging
1811 sig: ty::Binder(ty::FnSig {
1812 inputs: self_and_input_tys,
1814 variadic: decl.variadic
1816 }, explicit_self_category_result)
1819 fn determine_explicit_self_category<'a, 'tcx>(this: &AstConv<'tcx>,
1820 rscope: &RegionScope,
1821 self_info: &SelfInfo<'a, 'tcx>)
1822 -> ty::ExplicitSelfCategory
1824 return match self_info.explicit_self.node {
1825 ast::SelfStatic => ty::StaticExplicitSelfCategory,
1826 ast::SelfValue(_) => ty::ByValueExplicitSelfCategory,
1827 ast::SelfRegion(ref lifetime, mutability, _) => {
1829 opt_ast_region_to_region(this,
1831 self_info.explicit_self.span,
1833 ty::ByReferenceExplicitSelfCategory(region, mutability)
1835 ast::SelfExplicit(ref ast_type, _) => {
1836 let explicit_type = ast_ty_to_ty(this, rscope, &**ast_type);
1838 // We wish to (for now) categorize an explicit self
1839 // declaration like `self: SomeType` into either `self`,
1840 // `&self`, `&mut self`, or `Box<self>`. We do this here
1841 // by some simple pattern matching. A more precise check
1842 // is done later in `check_method_self_type()`.
1847 // impl Foo for &T {
1848 // // Legal declarations:
1849 // fn method1(self: &&T); // ByReferenceExplicitSelfCategory
1850 // fn method2(self: &T); // ByValueExplicitSelfCategory
1851 // fn method3(self: Box<&T>); // ByBoxExplicitSelfCategory
1853 // // Invalid cases will be caught later by `check_method_self_type`:
1854 // fn method_err1(self: &mut T); // ByReferenceExplicitSelfCategory
1858 // To do the check we just count the number of "modifiers"
1859 // on each type and compare them. If they are the same or
1860 // the impl has more, we call it "by value". Otherwise, we
1861 // look at the outermost modifier on the method decl and
1862 // call it by-ref, by-box as appropriate. For method1, for
1863 // example, the impl type has one modifier, but the method
1864 // type has two, so we end up with
1865 // ByReferenceExplicitSelfCategory.
1867 let impl_modifiers = count_modifiers(self_info.untransformed_self_ty);
1868 let method_modifiers = count_modifiers(explicit_type);
1870 debug!("determine_explicit_self_category(self_info.untransformed_self_ty={:?} \
1871 explicit_type={:?} \
1873 self_info.untransformed_self_ty,
1878 if impl_modifiers >= method_modifiers {
1879 ty::ByValueExplicitSelfCategory
1881 match explicit_type.sty {
1882 ty::TyRef(r, mt) => ty::ByReferenceExplicitSelfCategory(*r, mt.mutbl),
1883 ty::TyBox(_) => ty::ByBoxExplicitSelfCategory,
1884 _ => ty::ByValueExplicitSelfCategory,
1890 fn count_modifiers(ty: Ty) -> usize {
1892 ty::TyRef(_, mt) => count_modifiers(mt.ty) + 1,
1893 ty::TyBox(t) => count_modifiers(t) + 1,
1899 pub fn ty_of_closure<'tcx>(
1900 this: &AstConv<'tcx>,
1901 unsafety: ast::Unsafety,
1904 expected_sig: Option<ty::FnSig<'tcx>>)
1905 -> ty::ClosureTy<'tcx>
1907 debug!("ty_of_closure(expected_sig={:?})",
1910 // new region names that appear inside of the fn decl are bound to
1911 // that function type
1912 let rb = rscope::BindingRscope::new();
1914 let input_tys: Vec<_> = decl.inputs.iter().enumerate().map(|(i, a)| {
1915 let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
1916 // no guarantee that the correct number of expected args
1918 if i < e.inputs.len() {
1924 ty_of_arg(this, &rb, a, expected_arg_ty)
1927 let expected_ret_ty = expected_sig.map(|e| e.output);
1929 let is_infer = match decl.output {
1930 ast::Return(ref output) if output.node == ast::TyInfer => true,
1931 ast::DefaultReturn(..) => true,
1935 let output_ty = match decl.output {
1936 _ if is_infer && expected_ret_ty.is_some() =>
1937 expected_ret_ty.unwrap(),
1939 ty::FnConverging(this.ty_infer(None, decl.output.span())),
1940 ast::Return(ref output) =>
1941 ty::FnConverging(ast_ty_to_ty(this, &rb, &**output)),
1942 ast::DefaultReturn(..) => unreachable!(),
1943 ast::NoReturn(..) => ty::FnDiverging
1946 debug!("ty_of_closure: input_tys={:?}", input_tys);
1947 debug!("ty_of_closure: output_ty={:?}", output_ty);
1952 sig: ty::Binder(ty::FnSig {inputs: input_tys,
1954 variadic: decl.variadic}),
1958 /// Given an existential type like `Foo+'a+Bar`, this routine converts the `'a` and `Bar` intos an
1959 /// `ExistentialBounds` struct. The `main_trait_refs` argument specifies the `Foo` -- it is absent
1960 /// for closures. Eventually this should all be normalized, I think, so that there is no "main
1961 /// trait ref" and instead we just have a flat list of bounds as the existential type.
1962 fn conv_existential_bounds<'tcx>(
1963 this: &AstConv<'tcx>,
1964 rscope: &RegionScope,
1966 principal_trait_ref: ty::PolyTraitRef<'tcx>,
1967 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
1968 ast_bounds: &[ast::TyParamBound])
1969 -> ty::ExistentialBounds<'tcx>
1971 let partitioned_bounds =
1972 partition_bounds(this.tcx(), span, ast_bounds);
1974 conv_existential_bounds_from_partitioned_bounds(
1975 this, rscope, span, principal_trait_ref, projection_bounds, partitioned_bounds)
1978 fn conv_ty_poly_trait_ref<'tcx>(
1979 this: &AstConv<'tcx>,
1980 rscope: &RegionScope,
1982 ast_bounds: &[ast::TyParamBound])
1985 let mut partitioned_bounds = partition_bounds(this.tcx(), span, &ast_bounds[..]);
1987 let mut projection_bounds = Vec::new();
1988 let main_trait_bound = if !partitioned_bounds.trait_bounds.is_empty() {
1989 let trait_bound = partitioned_bounds.trait_bounds.remove(0);
1990 instantiate_poly_trait_ref(this,
1994 &mut projection_bounds)
1996 span_err!(this.tcx().sess, span, E0224,
1997 "at least one non-builtin trait is required for an object type");
1998 return this.tcx().types.err;
2002 conv_existential_bounds_from_partitioned_bounds(this,
2005 main_trait_bound.clone(),
2007 partitioned_bounds);
2009 make_object_type(this, span, main_trait_bound, bounds)
2012 pub fn conv_existential_bounds_from_partitioned_bounds<'tcx>(
2013 this: &AstConv<'tcx>,
2014 rscope: &RegionScope,
2016 principal_trait_ref: ty::PolyTraitRef<'tcx>,
2017 mut projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>, // Empty for boxed closures
2018 partitioned_bounds: PartitionedBounds)
2019 -> ty::ExistentialBounds<'tcx>
2021 let PartitionedBounds { builtin_bounds,
2026 if !trait_bounds.is_empty() {
2027 let b = &trait_bounds[0];
2028 span_err!(this.tcx().sess, b.trait_ref.path.span, E0225,
2029 "only the builtin traits can be used as closure or object bounds");
2033 compute_object_lifetime_bound(this,
2036 principal_trait_ref,
2039 let region_bound = match region_bound {
2042 match rscope.object_lifetime_default(span) {
2045 span_err!(this.tcx().sess, span, E0228,
2046 "the lifetime bound for this object type cannot be deduced \
2047 from context; please supply an explicit bound");
2054 debug!("region_bound: {:?}", region_bound);
2056 ty::sort_bounds_list(&mut projection_bounds);
2058 ty::ExistentialBounds {
2059 region_bound: region_bound,
2060 builtin_bounds: builtin_bounds,
2061 projection_bounds: projection_bounds,
2065 /// Given the bounds on an object, determines what single region bound
2066 /// (if any) we can use to summarize this type. The basic idea is that we will use the bound the
2067 /// user provided, if they provided one, and otherwise search the supertypes of trait bounds for
2068 /// region bounds. It may be that we can derive no bound at all, in which case we return `None`.
2069 fn compute_object_lifetime_bound<'tcx>(
2070 this: &AstConv<'tcx>,
2072 explicit_region_bounds: &[&ast::Lifetime],
2073 principal_trait_ref: ty::PolyTraitRef<'tcx>,
2074 builtin_bounds: ty::BuiltinBounds)
2075 -> Option<ty::Region> // if None, use the default
2077 let tcx = this.tcx();
2079 debug!("compute_opt_region_bound(explicit_region_bounds={:?}, \
2080 principal_trait_ref={:?}, builtin_bounds={:?})",
2081 explicit_region_bounds,
2082 principal_trait_ref,
2085 if explicit_region_bounds.len() > 1 {
2086 span_err!(tcx.sess, explicit_region_bounds[1].span, E0226,
2087 "only a single explicit lifetime bound is permitted");
2090 if !explicit_region_bounds.is_empty() {
2091 // Explicitly specified region bound. Use that.
2092 let r = explicit_region_bounds[0];
2093 return Some(ast_region_to_region(tcx, r));
2096 if let Err(ErrorReported) = this.ensure_super_predicates(span,principal_trait_ref.def_id()) {
2097 return Some(ty::ReStatic);
2100 // No explicit region bound specified. Therefore, examine trait
2101 // bounds and see if we can derive region bounds from those.
2102 let derived_region_bounds =
2103 object_region_bounds(tcx, &principal_trait_ref, builtin_bounds);
2105 // If there are no derived region bounds, then report back that we
2106 // can find no region bound. The caller will use the default.
2107 if derived_region_bounds.is_empty() {
2111 // If any of the derived region bounds are 'static, that is always
2113 if derived_region_bounds.iter().any(|r| ty::ReStatic == *r) {
2114 return Some(ty::ReStatic);
2117 // Determine whether there is exactly one unique region in the set
2118 // of derived region bounds. If so, use that. Otherwise, report an
2120 let r = derived_region_bounds[0];
2121 if derived_region_bounds[1..].iter().any(|r1| r != *r1) {
2122 span_err!(tcx.sess, span, E0227,
2123 "ambiguous lifetime bound, explicit lifetime bound required");
2128 pub struct PartitionedBounds<'a> {
2129 pub builtin_bounds: ty::BuiltinBounds,
2130 pub trait_bounds: Vec<&'a ast::PolyTraitRef>,
2131 pub region_bounds: Vec<&'a ast::Lifetime>,
2134 /// Divides a list of bounds from the AST into three groups: builtin bounds (Copy, Sized etc),
2135 /// general trait bounds, and region bounds.
2136 pub fn partition_bounds<'a>(tcx: &ty::ctxt,
2138 ast_bounds: &'a [ast::TyParamBound])
2139 -> PartitionedBounds<'a>
2141 let mut builtin_bounds = ty::BuiltinBounds::empty();
2142 let mut region_bounds = Vec::new();
2143 let mut trait_bounds = Vec::new();
2144 for ast_bound in ast_bounds {
2146 ast::TraitTyParamBound(ref b, ast::TraitBoundModifier::None) => {
2147 match ::lookup_full_def(tcx, b.trait_ref.path.span, b.trait_ref.ref_id) {
2148 def::DefTrait(trait_did) => {
2149 if tcx.try_add_builtin_trait(trait_did,
2150 &mut builtin_bounds) {
2151 let segments = &b.trait_ref.path.segments;
2152 let parameters = &segments[segments.len() - 1].parameters;
2153 if !parameters.types().is_empty() {
2154 check_type_argument_count(tcx, b.trait_ref.path.span,
2155 parameters.types().len(), 0, 0);
2157 if !parameters.lifetimes().is_empty() {
2158 report_lifetime_number_error(tcx, b.trait_ref.path.span,
2159 parameters.lifetimes().len(), 0);
2161 continue; // success
2165 // Not a trait? that's an error, but it'll get
2169 trait_bounds.push(b);
2171 ast::TraitTyParamBound(_, ast::TraitBoundModifier::Maybe) => {}
2172 ast::RegionTyParamBound(ref l) => {
2173 region_bounds.push(l);
2179 builtin_bounds: builtin_bounds,
2180 trait_bounds: trait_bounds,
2181 region_bounds: region_bounds,
2185 fn prohibit_projections<'tcx>(tcx: &ty::ctxt<'tcx>,
2186 bindings: &[ConvertedBinding<'tcx>])
2188 for binding in bindings.iter().take(1) {
2189 span_err!(tcx.sess, binding.span, E0229,
2190 "associated type bindings are not allowed here");
2194 fn check_type_argument_count(tcx: &ty::ctxt, span: Span, supplied: usize,
2195 required: usize, accepted: usize) {
2196 if supplied < required {
2197 let expected = if required < accepted {
2202 span_err!(tcx.sess, span, E0243,
2203 "wrong number of type arguments: {} {}, found {}",
2204 expected, required, supplied);
2205 } else if supplied > accepted {
2206 let expected = if required < accepted {
2211 span_err!(tcx.sess, span, E0244,
2212 "wrong number of type arguments: {} {}, found {}",
2219 fn report_lifetime_number_error(tcx: &ty::ctxt, span: Span, number: usize, expected: usize) {
2220 span_err!(tcx.sess, span, E0107,
2221 "wrong number of lifetime parameters: expected {}, found {}",
2225 // A helper struct for conveniently grouping a set of bounds which we pass to
2226 // and return from functions in multiple places.
2227 #[derive(PartialEq, Eq, Clone, Debug)]
2228 pub struct Bounds<'tcx> {
2229 pub region_bounds: Vec<ty::Region>,
2230 pub builtin_bounds: ty::BuiltinBounds,
2231 pub trait_bounds: Vec<ty::PolyTraitRef<'tcx>>,
2232 pub projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
2235 impl<'tcx> Bounds<'tcx> {
2236 pub fn predicates(&self,
2237 tcx: &ty::ctxt<'tcx>,
2239 -> Vec<ty::Predicate<'tcx>>
2241 let mut vec = Vec::new();
2243 for builtin_bound in &self.builtin_bounds {
2244 match traits::trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty) {
2245 Ok(trait_ref) => { vec.push(trait_ref.to_predicate()); }
2246 Err(ErrorReported) => { }
2250 for ®ion_bound in &self.region_bounds {
2251 // account for the binder being introduced below; no need to shift `param_ty`
2252 // because, at present at least, it can only refer to early-bound regions
2253 let region_bound = ty_fold::shift_region(region_bound, 1);
2254 vec.push(ty::Binder(ty::OutlivesPredicate(param_ty, region_bound)).to_predicate());
2257 for bound_trait_ref in &self.trait_bounds {
2258 vec.push(bound_trait_ref.to_predicate());
2261 for projection in &self.projection_bounds {
2262 vec.push(projection.to_predicate());