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::def_id::{DefId, LOCAL_CRATE};
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};
61 use middle::ty::wf::object_region_bounds;
62 use require_c_abi_if_variadic;
63 use rscope::{self, UnelidableRscope, RegionScope, ElidableRscope,
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};
71 use syntax::codemap::{Span, Pos};
72 use syntax::feature_gate::{GateIssue, emit_feature_err};
73 use syntax::parse::token;
75 use rustc_front::print::pprust;
79 pub trait AstConv<'tcx> {
80 fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx>;
82 /// Identify the type scheme for an item with a type, like a type
83 /// alias, fn, or struct. This allows you to figure out the set of
84 /// type parameters defined on the item.
85 fn get_item_type_scheme(&self, span: Span, id: DefId)
86 -> Result<ty::TypeScheme<'tcx>, ErrorReported>;
88 /// Returns the `TraitDef` for a given trait. This allows you to
89 /// figure out the set of type parameters defined on the trait.
90 fn get_trait_def(&self, span: Span, id: DefId)
91 -> Result<&'tcx ty::TraitDef<'tcx>, ErrorReported>;
93 /// Ensure that the super-predicates for the trait with the given
94 /// id are available and also for the transitive set of
96 fn ensure_super_predicates(&self, span: Span, id: DefId)
97 -> Result<(), ErrorReported>;
99 /// Returns the set of bounds in scope for the type parameter with
101 fn get_type_parameter_bounds(&self, span: Span, def_id: ast::NodeId)
102 -> Result<Vec<ty::PolyTraitRef<'tcx>>, ErrorReported>;
104 /// Returns true if the trait with id `trait_def_id` defines an
105 /// associated type with the name `name`.
106 fn trait_defines_associated_type_named(&self, trait_def_id: DefId, name: ast::Name)
109 /// Return an (optional) substitution to convert bound type parameters that
110 /// are in scope into free ones. This function should only return Some
111 /// within a fn body.
112 /// See ParameterEnvironment::free_substs for more information.
113 fn get_free_substs(&self) -> Option<&Substs<'tcx>> {
117 /// What type should we use when a type is omitted?
119 param_and_substs: Option<ty::TypeParameterDef<'tcx>>,
120 substs: Option<&mut Substs<'tcx>>,
121 space: Option<ParamSpace>,
122 span: Span) -> Ty<'tcx>;
124 /// Projecting an associated type from a (potentially)
125 /// higher-ranked trait reference is more complicated, because of
126 /// the possibility of late-bound regions appearing in the
127 /// associated type binding. This is not legal in function
128 /// signatures for that reason. In a function body, we can always
129 /// handle it because we can use inference variables to remove the
130 /// late-bound regions.
131 fn projected_ty_from_poly_trait_ref(&self,
133 poly_trait_ref: ty::PolyTraitRef<'tcx>,
134 item_name: ast::Name)
137 if let Some(trait_ref) = self.tcx().no_late_bound_regions(&poly_trait_ref) {
138 self.projected_ty(span, trait_ref, item_name)
140 // no late-bound regions, we can just ignore the binder
141 span_err!(self.tcx().sess, span, E0212,
142 "cannot extract an associated type from a higher-ranked trait bound \
148 /// Project an associated type from a non-higher-ranked trait reference.
149 /// This is fairly straightforward and can be accommodated in any context.
150 fn projected_ty(&self,
152 _trait_ref: ty::TraitRef<'tcx>,
153 _item_name: ast::Name)
157 pub fn ast_region_to_region(tcx: &ty::ctxt, lifetime: &hir::Lifetime)
159 let r = match tcx.named_region_map.get(&lifetime.id) {
161 // should have been recorded by the `resolve_lifetime` pass
162 tcx.sess.span_bug(lifetime.span, "unresolved lifetime");
165 Some(&rl::DefStaticRegion) => {
169 Some(&rl::DefLateBoundRegion(debruijn, id)) => {
170 ty::ReLateBound(debruijn, ty::BrNamed(DefId::local(id), lifetime.name))
173 Some(&rl::DefEarlyBoundRegion(space, index, id)) => {
174 ty::ReEarlyBound(ty::EarlyBoundRegion {
182 Some(&rl::DefFreeRegion(scope, id)) => {
183 ty::ReFree(ty::FreeRegion {
184 scope: tcx.region_maps.item_extent(scope.node_id),
185 bound_region: ty::BrNamed(DefId::local(id),
191 debug!("ast_region_to_region(lifetime={:?} id={}) yields {:?}",
199 fn report_elision_failure(
202 params: Vec<ElisionFailureInfo>)
204 let mut m = String::new();
205 let len = params.len();
206 for (i, info) in params.into_iter().enumerate() {
207 let ElisionFailureInfo {
208 name, lifetime_count: n, have_bound_regions
211 let help_name = if name.is_empty() {
212 format!("argument {}", i + 1)
214 format!("`{}`", name)
217 m.push_str(&(if n == 1 {
220 format!("one of {}'s {} elided {}lifetimes", help_name, n,
221 if have_bound_regions { "free " } else { "" } )
224 if len == 2 && i == 0 {
226 } else if i + 2 == len {
228 } else if i + 1 != len {
233 fileline_help!(tcx.sess, default_span,
234 "this function's return type contains a borrowed value, but \
235 the signature does not say which {} it is borrowed from",
238 fileline_help!(tcx.sess, default_span,
239 "this function's return type contains a borrowed value, but \
240 there is no value for it to be borrowed from");
241 fileline_help!(tcx.sess, default_span,
242 "consider giving it a 'static lifetime");
244 fileline_help!(tcx.sess, default_span,
245 "this function's return type contains a borrowed value, but \
246 the signature does not say whether it is borrowed from {}",
251 pub fn opt_ast_region_to_region<'tcx>(
252 this: &AstConv<'tcx>,
253 rscope: &RegionScope,
255 opt_lifetime: &Option<hir::Lifetime>) -> ty::Region
257 let r = match *opt_lifetime {
258 Some(ref lifetime) => {
259 ast_region_to_region(this.tcx(), lifetime)
262 None => match rscope.anon_regions(default_span, 1) {
265 span_err!(this.tcx().sess, default_span, E0106,
266 "missing lifetime specifier");
267 if let Some(params) = params {
268 report_elision_failure(this.tcx(), default_span, params);
275 debug!("opt_ast_region_to_region(opt_lifetime={:?}) yields {:?}",
282 /// Given a path `path` that refers to an item `I` with the declared generics `decl_generics`,
283 /// returns an appropriate set of substitutions for this particular reference to `I`.
284 pub fn ast_path_substs_for_ty<'tcx>(
285 this: &AstConv<'tcx>,
286 rscope: &RegionScope,
288 param_mode: PathParamMode,
289 decl_generics: &ty::Generics<'tcx>,
290 item_segment: &hir::PathSegment)
293 let tcx = this.tcx();
295 // ast_path_substs() is only called to convert paths that are
296 // known to refer to traits, types, or structs. In these cases,
297 // all type parameters defined for the item being referenced will
298 // be in the TypeSpace or SelfSpace.
300 // Note: in the case of traits, the self parameter is also
301 // defined, but we don't currently create a `type_param_def` for
302 // `Self` because it is implicit.
303 assert!(decl_generics.regions.all(|d| d.space == TypeSpace));
304 assert!(decl_generics.types.all(|d| d.space != FnSpace));
306 let (regions, types, assoc_bindings) = match item_segment.parameters {
307 hir::AngleBracketedParameters(ref data) => {
308 convert_angle_bracketed_parameters(this, rscope, span, decl_generics, data)
310 hir::ParenthesizedParameters(..) => {
311 span_err!(tcx.sess, span, E0214,
312 "parenthesized parameters may only be used with a trait");
313 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
315 ty_param_defs.iter().map(|_| tcx.types.err).collect(),
320 prohibit_projections(this.tcx(), &assoc_bindings);
322 create_substs_for_ast_path(this,
331 #[derive(PartialEq, Eq)]
332 pub enum PathParamMode {
333 // Any path in a type context.
335 // The `module::Type` in `module::Type::method` in an expression.
339 fn create_region_substs<'tcx>(
340 this: &AstConv<'tcx>,
341 rscope: &RegionScope,
343 decl_generics: &ty::Generics<'tcx>,
344 regions_provided: Vec<ty::Region>)
347 let tcx = this.tcx();
349 // If the type is parameterized by the this region, then replace this
350 // region with the current anon region binding (in other words,
351 // whatever & would get replaced with).
352 let expected_num_region_params = decl_generics.regions.len(TypeSpace);
353 let supplied_num_region_params = regions_provided.len();
354 let regions = if expected_num_region_params == supplied_num_region_params {
358 rscope.anon_regions(span, expected_num_region_params);
360 if supplied_num_region_params != 0 || anon_regions.is_err() {
361 report_lifetime_number_error(tcx, span,
362 supplied_num_region_params,
363 expected_num_region_params);
367 Ok(anon_regions) => anon_regions,
368 Err(_) => (0..expected_num_region_params).map(|_| ty::ReStatic).collect()
371 Substs::new_type(vec![], regions)
374 /// Given the type/region arguments provided to some path (along with
375 /// an implicit Self, if this is a trait reference) returns the complete
376 /// set of substitutions. This may involve applying defaulted type parameters.
378 /// Note that the type listing given here is *exactly* what the user provided.
380 /// The `region_substs` should be the result of `create_region_substs`
381 /// -- that is, a substitution with no types but the correct number of
383 fn create_substs_for_ast_path<'tcx>(
384 this: &AstConv<'tcx>,
386 param_mode: PathParamMode,
387 decl_generics: &ty::Generics<'tcx>,
388 self_ty: Option<Ty<'tcx>>,
389 types_provided: Vec<Ty<'tcx>>,
390 region_substs: Substs<'tcx>)
393 let tcx = this.tcx();
395 debug!("create_substs_for_ast_path(decl_generics={:?}, self_ty={:?}, \
396 types_provided={:?}, region_substs={:?}",
397 decl_generics, self_ty, types_provided,
400 assert_eq!(region_substs.regions().len(TypeSpace), decl_generics.regions.len(TypeSpace));
401 assert!(region_substs.types.is_empty());
403 // Convert the type parameters supplied by the user.
404 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
405 let formal_ty_param_count = ty_param_defs.len();
406 let required_ty_param_count = ty_param_defs.iter()
407 .take_while(|x| x.default.is_none())
410 // Fill with `ty_infer` if no params were specified, as long as
411 // they were optional (e.g. paths inside expressions).
412 let mut type_substs = if param_mode == PathParamMode::Optional &&
413 types_provided.is_empty() {
414 let mut substs = region_substs.clone();
417 .map(|p| this.ty_infer(Some(p.clone()), Some(&mut substs), Some(TypeSpace), span))
423 let supplied_ty_param_count = type_substs.len();
424 check_type_argument_count(this.tcx(), span, supplied_ty_param_count,
425 required_ty_param_count, formal_ty_param_count);
427 if supplied_ty_param_count < required_ty_param_count {
428 while type_substs.len() < required_ty_param_count {
429 type_substs.push(tcx.types.err);
431 } else if supplied_ty_param_count > formal_ty_param_count {
432 type_substs.truncate(formal_ty_param_count);
434 assert!(type_substs.len() >= required_ty_param_count &&
435 type_substs.len() <= formal_ty_param_count);
437 let mut substs = region_substs;
438 substs.types.extend(TypeSpace, type_substs.into_iter());
442 // If no self-type is provided, it's still possible that
443 // one was declared, because this could be an object type.
446 // If a self-type is provided, one should have been
447 // "declared" (in other words, this should be a
449 assert!(decl_generics.types.get_self().is_some());
450 substs.types.push(SelfSpace, ty);
454 let actual_supplied_ty_param_count = substs.types.len(TypeSpace);
455 for param in &ty_param_defs[actual_supplied_ty_param_count..] {
456 if let Some(default) = param.default {
457 // If we are converting an object type, then the
458 // `Self` parameter is unknown. However, some of the
459 // other type parameters may reference `Self` in their
460 // defaults. This will lead to an ICE if we are not
462 if self_ty.is_none() && default.has_self_ty() {
463 span_err!(tcx.sess, span, E0393,
464 "the type parameter `{}` must be explicitly specified \
465 in an object type because its default value `{}` references \
469 substs.types.push(TypeSpace, tcx.types.err);
471 // This is a default type parameter.
472 let default = default.subst_spanned(tcx,
475 substs.types.push(TypeSpace, default);
478 tcx.sess.span_bug(span, "extra parameter without default");
485 struct ConvertedBinding<'tcx> {
486 item_name: ast::Name,
491 fn convert_angle_bracketed_parameters<'tcx>(this: &AstConv<'tcx>,
492 rscope: &RegionScope,
494 decl_generics: &ty::Generics<'tcx>,
495 data: &hir::AngleBracketedParameterData)
498 Vec<ConvertedBinding<'tcx>>)
500 let regions: Vec<_> =
501 data.lifetimes.iter()
502 .map(|l| ast_region_to_region(this.tcx(), l))
506 create_region_substs(this, rscope, span, decl_generics, regions);
511 .map(|(i,t)| ast_ty_arg_to_ty(this, rscope, decl_generics,
512 i, ®ion_substs, t))
515 let assoc_bindings: Vec<_> =
517 .map(|b| ConvertedBinding { item_name: b.ident.name,
518 ty: ast_ty_to_ty(this, rscope, &*b.ty),
522 (region_substs, types, assoc_bindings)
525 /// Returns the appropriate lifetime to use for any output lifetimes
526 /// (if one exists) and a vector of the (pattern, number of lifetimes)
527 /// corresponding to each input type/pattern.
528 fn find_implied_output_region<'tcx>(tcx: &ty::ctxt<'tcx>,
529 input_tys: &[Ty<'tcx>],
530 input_pats: Vec<String>) -> ElidedLifetime
532 let mut lifetimes_for_params = Vec::new();
533 let mut possible_implied_output_region = None;
535 for (input_type, input_pat) in input_tys.iter().zip(input_pats) {
536 let mut regions = FnvHashSet();
537 let have_bound_regions = tcx.collect_regions(input_type, &mut regions);
539 debug!("find_implied_output_regions: collected {:?} from {:?} \
540 have_bound_regions={:?}", ®ions, input_type, have_bound_regions);
542 if regions.len() == 1 {
543 // there's a chance that the unique lifetime of this
544 // iteration will be the appropriate lifetime for output
545 // parameters, so lets store it.
546 possible_implied_output_region = regions.iter().cloned().next();
549 lifetimes_for_params.push(ElisionFailureInfo {
551 lifetime_count: regions.len(),
552 have_bound_regions: have_bound_regions
556 if lifetimes_for_params.iter().map(|e| e.lifetime_count).sum::<usize>() == 1 {
557 Ok(possible_implied_output_region.unwrap())
559 Err(Some(lifetimes_for_params))
563 fn convert_ty_with_lifetime_elision<'tcx>(this: &AstConv<'tcx>,
564 elided_lifetime: ElidedLifetime,
568 match elided_lifetime {
569 Ok(implied_output_region) => {
570 let rb = ElidableRscope::new(implied_output_region);
571 ast_ty_to_ty(this, &rb, ty)
573 Err(param_lifetimes) => {
574 // All regions must be explicitly specified in the output
575 // if the lifetime elision rules do not apply. This saves
576 // the user from potentially-confusing errors.
577 let rb = UnelidableRscope::new(param_lifetimes);
578 ast_ty_to_ty(this, &rb, ty)
583 fn convert_parenthesized_parameters<'tcx>(this: &AstConv<'tcx>,
584 rscope: &RegionScope,
586 decl_generics: &ty::Generics<'tcx>,
587 data: &hir::ParenthesizedParameterData)
590 Vec<ConvertedBinding<'tcx>>)
593 create_region_substs(this, rscope, span, decl_generics, Vec::new());
595 let binding_rscope = BindingRscope::new();
598 .map(|a_t| ast_ty_arg_to_ty(this, &binding_rscope, decl_generics,
599 0, ®ion_substs, a_t))
600 .collect::<Vec<Ty<'tcx>>>();
602 let input_params = vec![String::new(); inputs.len()];
603 let implied_output_region = find_implied_output_region(this.tcx(), &inputs, input_params);
605 let input_ty = this.tcx().mk_tup(inputs);
607 let (output, output_span) = match data.output {
608 Some(ref output_ty) => {
609 (convert_ty_with_lifetime_elision(this,
610 implied_output_region,
615 (this.tcx().mk_nil(), data.span)
619 let output_binding = ConvertedBinding {
620 item_name: token::intern(FN_OUTPUT_NAME),
625 (region_substs, vec![input_ty], vec![output_binding])
628 pub fn instantiate_poly_trait_ref<'tcx>(
629 this: &AstConv<'tcx>,
630 rscope: &RegionScope,
631 ast_trait_ref: &hir::PolyTraitRef,
632 self_ty: Option<Ty<'tcx>>,
633 poly_projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
634 -> ty::PolyTraitRef<'tcx>
636 let trait_ref = &ast_trait_ref.trait_ref;
637 let trait_def_id = trait_def_id(this, trait_ref);
638 ast_path_to_poly_trait_ref(this,
641 PathParamMode::Explicit,
644 trait_ref.path.segments.last().unwrap(),
648 /// Instantiates the path for the given trait reference, assuming that it's
649 /// bound to a valid trait type. Returns the def_id for the defining trait.
650 /// Fails if the type is a type other than a trait type.
652 /// If the `projections` argument is `None`, then assoc type bindings like `Foo<T=X>`
653 /// are disallowed. Otherwise, they are pushed onto the vector given.
654 pub fn instantiate_mono_trait_ref<'tcx>(
655 this: &AstConv<'tcx>,
656 rscope: &RegionScope,
657 trait_ref: &hir::TraitRef,
658 self_ty: Option<Ty<'tcx>>)
659 -> ty::TraitRef<'tcx>
661 let trait_def_id = trait_def_id(this, trait_ref);
662 ast_path_to_mono_trait_ref(this,
665 PathParamMode::Explicit,
668 trait_ref.path.segments.last().unwrap())
671 fn trait_def_id<'tcx>(this: &AstConv<'tcx>, trait_ref: &hir::TraitRef) -> DefId {
672 let path = &trait_ref.path;
673 match ::lookup_full_def(this.tcx(), path.span, trait_ref.ref_id) {
674 def::DefTrait(trait_def_id) => trait_def_id,
676 span_fatal!(this.tcx().sess, path.span, E0245, "`{}` is not a trait",
682 fn object_path_to_poly_trait_ref<'a,'tcx>(
683 this: &AstConv<'tcx>,
684 rscope: &RegionScope,
686 param_mode: PathParamMode,
688 trait_segment: &hir::PathSegment,
689 mut projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
690 -> ty::PolyTraitRef<'tcx>
692 ast_path_to_poly_trait_ref(this,
702 fn ast_path_to_poly_trait_ref<'a,'tcx>(
703 this: &AstConv<'tcx>,
704 rscope: &RegionScope,
706 param_mode: PathParamMode,
708 self_ty: Option<Ty<'tcx>>,
709 trait_segment: &hir::PathSegment,
710 poly_projections: &mut Vec<ty::PolyProjectionPredicate<'tcx>>)
711 -> ty::PolyTraitRef<'tcx>
713 // The trait reference introduces a binding level here, so
714 // we need to shift the `rscope`. It'd be nice if we could
715 // do away with this rscope stuff and work this knowledge
716 // into resolve_lifetimes, as we do with non-omitted
717 // lifetimes. Oh well, not there yet.
718 let shifted_rscope = &ShiftedRscope::new(rscope);
720 let (substs, assoc_bindings) =
721 create_substs_for_ast_trait_ref(this,
728 let poly_trait_ref = ty::Binder(ty::TraitRef::new(trait_def_id, substs));
731 let converted_bindings =
734 .filter_map(|binding| {
735 // specify type to assert that error was already reported in Err case:
736 let predicate: Result<_, ErrorReported> =
737 ast_type_binding_to_poly_projection_predicate(this,
738 poly_trait_ref.clone(),
741 predicate.ok() // ok to ignore Err() because ErrorReported (see above)
743 poly_projections.extend(converted_bindings);
749 fn ast_path_to_mono_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
750 rscope: &RegionScope,
752 param_mode: PathParamMode,
754 self_ty: Option<Ty<'tcx>>,
755 trait_segment: &hir::PathSegment)
756 -> ty::TraitRef<'tcx>
758 let (substs, assoc_bindings) =
759 create_substs_for_ast_trait_ref(this,
766 prohibit_projections(this.tcx(), &assoc_bindings);
767 ty::TraitRef::new(trait_def_id, substs)
770 fn create_substs_for_ast_trait_ref<'a,'tcx>(this: &AstConv<'tcx>,
771 rscope: &RegionScope,
773 param_mode: PathParamMode,
775 self_ty: Option<Ty<'tcx>>,
776 trait_segment: &hir::PathSegment)
777 -> (&'tcx Substs<'tcx>, Vec<ConvertedBinding<'tcx>>)
779 debug!("create_substs_for_ast_trait_ref(trait_segment={:?})",
782 let trait_def = match this.get_trait_def(span, trait_def_id) {
783 Ok(trait_def) => trait_def,
784 Err(ErrorReported) => {
785 // No convenient way to recover from a cycle here. Just bail. Sorry!
786 this.tcx().sess.abort_if_errors();
787 this.tcx().sess.bug("ErrorReported returned, but no errors reports?")
791 let (regions, types, assoc_bindings) = match trait_segment.parameters {
792 hir::AngleBracketedParameters(ref data) => {
793 // For now, require that parenthetical notation be used
794 // only with `Fn()` etc.
795 if !this.tcx().sess.features.borrow().unboxed_closures && trait_def.paren_sugar {
796 emit_feature_err(&this.tcx().sess.parse_sess.span_diagnostic,
797 "unboxed_closures", span, GateIssue::Language,
799 the precise format of `Fn`-family traits' type parameters is \
800 subject to change. Use parenthetical notation (Fn(Foo, Bar) -> Baz) instead");
803 convert_angle_bracketed_parameters(this, rscope, span, &trait_def.generics, data)
805 hir::ParenthesizedParameters(ref data) => {
806 // For now, require that parenthetical notation be used
807 // only with `Fn()` etc.
808 if !this.tcx().sess.features.borrow().unboxed_closures && !trait_def.paren_sugar {
809 emit_feature_err(&this.tcx().sess.parse_sess.span_diagnostic,
810 "unboxed_closures", span, GateIssue::Language,
812 parenthetical notation is only stable when used with `Fn`-family traits");
815 convert_parenthesized_parameters(this, rscope, span, &trait_def.generics, data)
819 let substs = create_substs_for_ast_path(this,
827 (this.tcx().mk_substs(substs), assoc_bindings)
830 fn ast_type_binding_to_poly_projection_predicate<'tcx>(
831 this: &AstConv<'tcx>,
832 mut trait_ref: ty::PolyTraitRef<'tcx>,
833 self_ty: Option<Ty<'tcx>>,
834 binding: &ConvertedBinding<'tcx>)
835 -> Result<ty::PolyProjectionPredicate<'tcx>, ErrorReported>
837 let tcx = this.tcx();
839 // Given something like `U : SomeTrait<T=X>`, we want to produce a
840 // predicate like `<U as SomeTrait>::T = X`. This is somewhat
841 // subtle in the event that `T` is defined in a supertrait of
842 // `SomeTrait`, because in that case we need to upcast.
844 // That is, consider this case:
847 // trait SubTrait : SuperTrait<int> { }
848 // trait SuperTrait<A> { type T; }
850 // ... B : SubTrait<T=foo> ...
853 // We want to produce `<B as SuperTrait<int>>::T == foo`.
855 // Simple case: X is defined in the current trait.
856 if this.trait_defines_associated_type_named(trait_ref.def_id(), binding.item_name) {
857 return Ok(ty::Binder(ty::ProjectionPredicate { // <-------------------+
858 projection_ty: ty::ProjectionTy { // |
859 trait_ref: trait_ref.skip_binder().clone(), // Binder moved here --+
860 item_name: binding.item_name,
866 // Otherwise, we have to walk through the supertraits to find
867 // those that do. This is complicated by the fact that, for an
868 // object type, the `Self` type is not present in the
869 // substitutions (after all, it's being constructed right now),
870 // but the `supertraits` iterator really wants one. To handle
871 // this, we currently insert a dummy type and then remove it
874 let dummy_self_ty = tcx.mk_infer(ty::FreshTy(0));
875 if self_ty.is_none() { // if converting for an object type
876 let mut dummy_substs = trait_ref.skip_binder().substs.clone(); // binder moved here -+
877 assert!(dummy_substs.self_ty().is_none()); // |
878 dummy_substs.types.push(SelfSpace, dummy_self_ty); // |
879 trait_ref = ty::Binder(ty::TraitRef::new(trait_ref.def_id(), // <------------+
880 tcx.mk_substs(dummy_substs)));
883 try!(this.ensure_super_predicates(binding.span, trait_ref.def_id()));
885 let mut candidates: Vec<ty::PolyTraitRef> =
886 traits::supertraits(tcx, trait_ref.clone())
887 .filter(|r| this.trait_defines_associated_type_named(r.def_id(), binding.item_name))
890 // If converting for an object type, then remove the dummy-ty from `Self` now.
892 if self_ty.is_none() {
893 for candidate in &mut candidates {
894 let mut dummy_substs = candidate.0.substs.clone();
895 assert!(dummy_substs.self_ty() == Some(dummy_self_ty));
896 dummy_substs.types.pop(SelfSpace);
897 *candidate = ty::Binder(ty::TraitRef::new(candidate.def_id(),
898 tcx.mk_substs(dummy_substs)));
902 let candidate = try!(one_bound_for_assoc_type(tcx,
904 &trait_ref.to_string(),
905 &binding.item_name.as_str(),
908 Ok(ty::Binder(ty::ProjectionPredicate { // <-------------------------+
909 projection_ty: ty::ProjectionTy { // |
910 trait_ref: candidate.skip_binder().clone(), // binder is moved up here --+
911 item_name: binding.item_name,
917 fn ast_path_to_ty<'tcx>(
918 this: &AstConv<'tcx>,
919 rscope: &RegionScope,
921 param_mode: PathParamMode,
923 item_segment: &hir::PathSegment)
926 let tcx = this.tcx();
927 let (generics, decl_ty) = match this.get_item_type_scheme(span, did) {
928 Ok(ty::TypeScheme { generics, ty: decl_ty }) => {
931 Err(ErrorReported) => {
932 return tcx.types.err;
936 let substs = ast_path_substs_for_ty(this,
943 // FIXME(#12938): This is a hack until we have full support for DST.
944 if Some(did) == this.tcx().lang_items.owned_box() {
945 assert_eq!(substs.types.len(TypeSpace), 1);
946 return this.tcx().mk_box(*substs.types.get(TypeSpace, 0));
949 decl_ty.subst(this.tcx(), &substs)
952 type TraitAndProjections<'tcx> = (ty::PolyTraitRef<'tcx>, Vec<ty::PolyProjectionPredicate<'tcx>>);
954 fn ast_ty_to_trait_ref<'tcx>(this: &AstConv<'tcx>,
955 rscope: &RegionScope,
957 bounds: &[hir::TyParamBound])
958 -> Result<TraitAndProjections<'tcx>, ErrorReported>
961 * In a type like `Foo + Send`, we want to wait to collect the
962 * full set of bounds before we make the object type, because we
963 * need them to infer a region bound. (For example, if we tried
964 * made a type from just `Foo`, then it wouldn't be enough to
965 * infer a 'static bound, and hence the user would get an error.)
966 * So this function is used when we're dealing with a sum type to
967 * convert the LHS. It only accepts a type that refers to a trait
968 * name, and reports an error otherwise.
972 hir::TyPath(None, ref path) => {
973 let def = match this.tcx().def_map.borrow().get(&ty.id) {
974 Some(&def::PathResolution { base_def, depth: 0, .. }) => Some(base_def),
978 Some(def::DefTrait(trait_def_id)) => {
979 let mut projection_bounds = Vec::new();
980 let trait_ref = object_path_to_poly_trait_ref(this,
983 PathParamMode::Explicit,
985 path.segments.last().unwrap(),
986 &mut projection_bounds);
987 Ok((trait_ref, projection_bounds))
990 span_err!(this.tcx().sess, ty.span, E0172, "expected a reference to a trait");
996 span_err!(this.tcx().sess, ty.span, E0178,
997 "expected a path on the left-hand side of `+`, not `{}`",
998 pprust::ty_to_string(ty));
999 let hi = bounds.iter().map(|x| match *x {
1000 hir::TraitTyParamBound(ref tr, _) => tr.span.hi,
1001 hir::RegionTyParamBound(ref r) => r.span.hi,
1002 }).max_by(|x| x.to_usize());
1003 let full_span = hi.map(|hi| Span {
1006 expn_id: ty.span.expn_id,
1008 match (&ty.node, full_span) {
1009 (&hir::TyRptr(None, ref mut_ty), Some(full_span)) => {
1010 let mutbl_str = if mut_ty.mutbl == hir::MutMutable { "mut " } else { "" };
1012 .span_suggestion(full_span, "try adding parentheses (per RFC 438):",
1013 format!("&{}({} +{})",
1015 pprust::ty_to_string(&*mut_ty.ty),
1016 pprust::bounds_to_string(bounds)));
1018 (&hir::TyRptr(Some(ref lt), ref mut_ty), Some(full_span)) => {
1019 let mutbl_str = if mut_ty.mutbl == hir::MutMutable { "mut " } else { "" };
1021 .span_suggestion(full_span, "try adding parentheses (per RFC 438):",
1022 format!("&{} {}({} +{})",
1023 pprust::lifetime_to_string(lt),
1025 pprust::ty_to_string(&*mut_ty.ty),
1026 pprust::bounds_to_string(bounds)));
1030 fileline_help!(this.tcx().sess, ty.span,
1031 "perhaps you forgot parentheses? (per RFC 438)");
1039 fn trait_ref_to_object_type<'tcx>(this: &AstConv<'tcx>,
1040 rscope: &RegionScope,
1042 trait_ref: ty::PolyTraitRef<'tcx>,
1043 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
1044 bounds: &[hir::TyParamBound])
1047 let existential_bounds = conv_existential_bounds(this,
1054 let result = make_object_type(this, span, trait_ref, existential_bounds);
1055 debug!("trait_ref_to_object_type: result={:?}",
1061 fn make_object_type<'tcx>(this: &AstConv<'tcx>,
1063 principal: ty::PolyTraitRef<'tcx>,
1064 bounds: ty::ExistentialBounds<'tcx>)
1066 let tcx = this.tcx();
1067 let object = ty::TraitTy {
1068 principal: principal,
1071 let object_trait_ref =
1072 object.principal_trait_ref_with_self_ty(tcx, tcx.types.err);
1074 // ensure the super predicates and stop if we encountered an error
1075 if this.ensure_super_predicates(span, object.principal_def_id()).is_err() {
1076 return tcx.types.err;
1079 let mut associated_types: FnvHashSet<(DefId, ast::Name)> =
1080 traits::supertraits(tcx, object_trait_ref)
1082 let trait_def = tcx.lookup_trait_def(tr.def_id());
1083 trait_def.associated_type_names
1086 .map(move |associated_type_name| (tr.def_id(), associated_type_name))
1090 for projection_bound in &object.bounds.projection_bounds {
1091 let pair = (projection_bound.0.projection_ty.trait_ref.def_id,
1092 projection_bound.0.projection_ty.item_name);
1093 associated_types.remove(&pair);
1096 for (trait_def_id, name) in associated_types {
1097 span_err!(tcx.sess, span, E0191,
1098 "the value of the associated type `{}` (from the trait `{}`) must be specified",
1100 tcx.item_path_str(trait_def_id));
1103 tcx.mk_trait(object.principal, object.bounds)
1106 fn report_ambiguous_associated_type(tcx: &ty::ctxt,
1111 span_err!(tcx.sess, span, E0223,
1112 "ambiguous associated type; specify the type using the syntax \
1114 type_str, trait_str, name);
1117 // Search for a bound on a type parameter which includes the associated item
1118 // given by assoc_name. ty_param_node_id is the node id for the type parameter
1119 // (which might be `Self`, but only if it is the `Self` of a trait, not an
1120 // impl). This function will fail if there are no suitable bounds or there is
1122 fn find_bound_for_assoc_item<'tcx>(this: &AstConv<'tcx>,
1123 ty_param_node_id: ast::NodeId,
1124 ty_param_name: ast::Name,
1125 assoc_name: ast::Name,
1127 -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
1129 let tcx = this.tcx();
1131 let bounds = match this.get_type_parameter_bounds(span, ty_param_node_id) {
1133 Err(ErrorReported) => {
1134 return Err(ErrorReported);
1138 // Ensure the super predicates and stop if we encountered an error.
1139 if bounds.iter().any(|b| this.ensure_super_predicates(span, b.def_id()).is_err()) {
1140 return Err(ErrorReported);
1143 // Check that there is exactly one way to find an associated type with the
1145 let suitable_bounds: Vec<_> =
1146 traits::transitive_bounds(tcx, &bounds)
1147 .filter(|b| this.trait_defines_associated_type_named(b.def_id(), assoc_name))
1150 one_bound_for_assoc_type(tcx,
1152 &ty_param_name.as_str(),
1153 &assoc_name.as_str(),
1158 // Checks that bounds contains exactly one element and reports appropriate
1159 // errors otherwise.
1160 fn one_bound_for_assoc_type<'tcx>(tcx: &ty::ctxt<'tcx>,
1161 bounds: Vec<ty::PolyTraitRef<'tcx>>,
1162 ty_param_name: &str,
1165 -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
1167 if bounds.is_empty() {
1168 span_err!(tcx.sess, span, E0220,
1169 "associated type `{}` not found for `{}`",
1172 return Err(ErrorReported);
1175 if bounds.len() > 1 {
1176 span_err!(tcx.sess, span, E0221,
1177 "ambiguous associated type `{}` in bounds of `{}`",
1181 for bound in &bounds {
1182 span_note!(tcx.sess, span,
1183 "associated type `{}` could derive from `{}`",
1189 Ok(bounds[0].clone())
1192 // Create a type from a a path to an associated type.
1193 // For a path A::B::C::D, ty and ty_path_def are the type and def for A::B::C
1194 // and item_segment is the path segment for D. We return a type and a def for
1196 // Will fail except for T::A and Self::A; i.e., if ty/ty_path_def are not a type
1197 // parameter or Self.
1198 fn associated_path_def_to_ty<'tcx>(this: &AstConv<'tcx>,
1201 ty_path_def: def::Def,
1202 item_segment: &hir::PathSegment)
1203 -> (Ty<'tcx>, def::Def)
1205 let tcx = this.tcx();
1206 let assoc_name = item_segment.identifier.name;
1208 debug!("associated_path_def_to_ty: {:?}::{}", ty, assoc_name);
1210 check_path_args(tcx, slice::ref_slice(item_segment), NO_TPS | NO_REGIONS);
1212 // Find the type of the associated item, and the trait where the associated
1213 // item is declared.
1214 let bound = match (&ty.sty, ty_path_def) {
1215 (_, def::DefSelfTy(Some(trait_did), Some((impl_id, _)))) => {
1216 // `Self` in an impl of a trait - we have a concrete self type and a
1218 let trait_ref = tcx.impl_trait_ref(DefId::local(impl_id)).unwrap();
1219 let trait_ref = if let Some(free_substs) = this.get_free_substs() {
1220 trait_ref.subst(tcx, free_substs)
1225 if this.ensure_super_predicates(span, trait_did).is_err() {
1226 return (tcx.types.err, ty_path_def);
1229 let candidates: Vec<ty::PolyTraitRef> =
1230 traits::supertraits(tcx, ty::Binder(trait_ref))
1231 .filter(|r| this.trait_defines_associated_type_named(r.def_id(),
1235 match one_bound_for_assoc_type(tcx,
1238 &assoc_name.as_str(),
1241 Err(ErrorReported) => return (tcx.types.err, ty_path_def),
1244 (&ty::TyParam(_), def::DefSelfTy(Some(trait_did), None)) => {
1245 assert_eq!(trait_did.krate, 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, 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 &assoc_name.as_str());
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.is_local() {
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 hir::ItemTrait(_, _, _, ref trait_items) => {
1284 let item = trait_items.iter()
1285 .find(|i| i.ident.name == assoc_name)
1286 .expect("missing associated type");
1287 DefId::local(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: DefId,
1306 trait_segment: &hir::PathSegment,
1307 item_segment: &hir::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 &item_segment.identifier.name.as_str());
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: &[hir::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: &[hir::PathSegment],
1493 assoc_segments: &[hir::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(id={:?}, ast_ty={:?})",
1530 let tcx = this.tcx();
1532 if let Some(&ty) = tcx.ast_ty_to_ty_cache.borrow().get(&ast_ty.id) {
1533 debug!("ast_ty_to_ty: id={:?} ty={:?} (cached)", ast_ty.id, ty);
1537 let typ = match ast_ty.node {
1538 hir::TyVec(ref ty) => {
1539 tcx.mk_slice(ast_ty_to_ty(this, rscope, &**ty))
1541 hir::TyObjectSum(ref ty, ref bounds) => {
1542 match ast_ty_to_trait_ref(this, rscope, &**ty, bounds) {
1543 Ok((trait_ref, projection_bounds)) => {
1544 trait_ref_to_object_type(this,
1551 Err(ErrorReported) => {
1552 this.tcx().types.err
1556 hir::TyPtr(ref mt) => {
1557 tcx.mk_ptr(ty::TypeAndMut {
1558 ty: ast_ty_to_ty(this, rscope, &*mt.ty),
1562 hir::TyRptr(ref region, ref mt) => {
1563 let r = opt_ast_region_to_region(this, rscope, ast_ty.span, region);
1564 debug!("TyRef r={:?}", r);
1566 &ObjectLifetimeDefaultRscope::new(
1568 ty::ObjectLifetimeDefault::Specific(r));
1569 let t = ast_ty_to_ty(this, rscope1, &*mt.ty);
1570 tcx.mk_ref(tcx.mk_region(r), ty::TypeAndMut {ty: t, mutbl: mt.mutbl})
1572 hir::TyTup(ref fields) => {
1573 let flds = fields.iter()
1574 .map(|t| ast_ty_to_ty(this, rscope, &**t))
1578 hir::TyParen(ref typ) => ast_ty_to_ty(this, rscope, &**typ),
1579 hir::TyBareFn(ref bf) => {
1580 require_c_abi_if_variadic(tcx, &bf.decl, bf.abi, ast_ty.span);
1581 let bare_fn = ty_of_bare_fn(this, bf.unsafety, bf.abi, &*bf.decl);
1582 tcx.mk_fn(None, tcx.mk_bare_fn(bare_fn))
1584 hir::TyPolyTraitRef(ref bounds) => {
1585 conv_ty_poly_trait_ref(this, rscope, ast_ty.span, bounds)
1587 hir::TyPath(ref maybe_qself, ref path) => {
1588 let path_res = if let Some(&d) = tcx.def_map.borrow().get(&ast_ty.id) {
1590 } else if let Some(hir::QSelf { position: 0, .. }) = *maybe_qself {
1591 // Create some fake resolution that can't possibly be a type.
1592 def::PathResolution {
1593 base_def: def::DefMod(DefId::local(ast::CRATE_NODE_ID)),
1594 last_private: LastMod(AllPublic),
1595 depth: path.segments.len()
1598 tcx.sess.span_bug(ast_ty.span, &format!("unbound path {:?}", ast_ty))
1600 let def = path_res.base_def;
1601 let base_ty_end = path.segments.len() - path_res.depth;
1602 let opt_self_ty = maybe_qself.as_ref().map(|qself| {
1603 ast_ty_to_ty(this, rscope, &qself.ty)
1605 let ty = finish_resolving_def_to_ty(this,
1608 PathParamMode::Explicit,
1611 &path.segments[..base_ty_end],
1612 &path.segments[base_ty_end..]);
1614 if path_res.depth != 0 && ty.sty != ty::TyError {
1615 // Write back the new resolution.
1616 tcx.def_map.borrow_mut().insert(ast_ty.id, def::PathResolution {
1618 last_private: path_res.last_private,
1625 hir::TyFixedLengthVec(ref ty, ref e) => {
1626 let hint = UncheckedExprHint(tcx.types.usize);
1627 match const_eval::eval_const_expr_partial(tcx, &e, hint) {
1631 tcx.mk_array(ast_ty_to_ty(this, rscope, &**ty),
1633 ConstVal::Uint(i) =>
1634 tcx.mk_array(ast_ty_to_ty(this, rscope, &**ty),
1637 span_err!(tcx.sess, ast_ty.span, E0249,
1638 "expected constant integer expression \
1640 this.tcx().types.err
1646 ast_ty.span.lo <= r.span.lo && r.span.hi <= ast_ty.span.hi;
1647 span_err!(tcx.sess, r.span, E0250,
1648 "array length constant evaluation error: {}",
1651 span_note!(tcx.sess, ast_ty.span, "for array length here")
1653 this.tcx().types.err
1657 hir::TyTypeof(ref _e) => {
1658 tcx.sess.span_bug(ast_ty.span, "typeof is reserved but unimplemented");
1661 // TyInfer also appears as the type of arguments or return
1662 // values in a ExprClosure, or as
1663 // the type of local variables. Both of these cases are
1664 // handled specially and will not descend into this routine.
1665 this.ty_infer(None, None, None, ast_ty.span)
1669 debug!("ast_ty_to_ty: id={:?} ty={:?}", ast_ty.id, typ);
1670 tcx.ast_ty_to_ty_cache.borrow_mut().insert(ast_ty.id, typ);
1674 pub fn ty_of_arg<'tcx>(this: &AstConv<'tcx>,
1675 rscope: &RegionScope,
1677 expected_ty: Option<Ty<'tcx>>)
1681 hir::TyInfer if expected_ty.is_some() => expected_ty.unwrap(),
1682 hir::TyInfer => this.ty_infer(None, None, None, a.ty.span),
1683 _ => ast_ty_to_ty(this, rscope, &*a.ty),
1687 struct SelfInfo<'a, 'tcx> {
1688 untransformed_self_ty: Ty<'tcx>,
1689 explicit_self: &'a hir::ExplicitSelf,
1692 pub fn ty_of_method<'tcx>(this: &AstConv<'tcx>,
1693 sig: &hir::MethodSig,
1694 untransformed_self_ty: Ty<'tcx>)
1695 -> (ty::BareFnTy<'tcx>, ty::ExplicitSelfCategory) {
1696 let self_info = Some(SelfInfo {
1697 untransformed_self_ty: untransformed_self_ty,
1698 explicit_self: &sig.explicit_self,
1700 let (bare_fn_ty, optional_explicit_self_category) =
1701 ty_of_method_or_bare_fn(this,
1706 (bare_fn_ty, optional_explicit_self_category.unwrap())
1709 pub fn ty_of_bare_fn<'tcx>(this: &AstConv<'tcx>, unsafety: hir::Unsafety, abi: abi::Abi,
1710 decl: &hir::FnDecl) -> ty::BareFnTy<'tcx> {
1711 let (bare_fn_ty, _) = ty_of_method_or_bare_fn(this, unsafety, abi, None, decl);
1715 fn ty_of_method_or_bare_fn<'a, 'tcx>(this: &AstConv<'tcx>,
1716 unsafety: hir::Unsafety,
1718 opt_self_info: Option<SelfInfo<'a, 'tcx>>,
1720 -> (ty::BareFnTy<'tcx>, Option<ty::ExplicitSelfCategory>)
1722 debug!("ty_of_method_or_bare_fn");
1724 // New region names that appear inside of the arguments of the function
1725 // declaration are bound to that function type.
1726 let rb = rscope::BindingRscope::new();
1728 // `implied_output_region` is the region that will be assumed for any
1729 // region parameters in the return type. In accordance with the rules for
1730 // lifetime elision, we can determine it in two ways. First (determined
1731 // here), if self is by-reference, then the implied output region is the
1732 // region of the self parameter.
1733 let mut explicit_self_category_result = None;
1734 let (self_ty, implied_output_region) = match opt_self_info {
1735 None => (None, None),
1736 Some(self_info) => {
1737 // This type comes from an impl or trait; no late-bound
1738 // regions should be present.
1739 assert!(!self_info.untransformed_self_ty.has_escaping_regions());
1741 // Figure out and record the explicit self category.
1742 let explicit_self_category =
1743 determine_explicit_self_category(this, &rb, &self_info);
1744 explicit_self_category_result = Some(explicit_self_category);
1745 match explicit_self_category {
1746 ty::StaticExplicitSelfCategory => {
1749 ty::ByValueExplicitSelfCategory => {
1750 (Some(self_info.untransformed_self_ty), None)
1752 ty::ByReferenceExplicitSelfCategory(region, mutability) => {
1753 (Some(this.tcx().mk_ref(
1754 this.tcx().mk_region(region),
1756 ty: self_info.untransformed_self_ty,
1761 ty::ByBoxExplicitSelfCategory => {
1762 (Some(this.tcx().mk_box(self_info.untransformed_self_ty)), None)
1768 // HACK(eddyb) replace the fake self type in the AST with the actual type.
1769 let input_params = if self_ty.is_some() {
1774 let input_tys = input_params.iter().map(|a| ty_of_arg(this, &rb, a, None));
1775 let input_pats: Vec<String> = input_params.iter()
1776 .map(|a| pprust::pat_to_string(&*a.pat))
1778 let self_and_input_tys: Vec<Ty> =
1779 self_ty.into_iter().chain(input_tys).collect();
1782 // Second, if there was exactly one lifetime (either a substitution or a
1783 // reference) in the arguments, then any anonymous regions in the output
1784 // have that lifetime.
1785 let implied_output_region = match implied_output_region {
1788 let input_tys = if self_ty.is_some() {
1789 // Skip the first argument if `self` is present.
1790 &self_and_input_tys[1..]
1792 &self_and_input_tys[..]
1795 find_implied_output_region(this.tcx(), input_tys, input_pats)
1799 let output_ty = match decl.output {
1800 hir::Return(ref output) if output.node == hir::TyInfer =>
1801 ty::FnConverging(this.ty_infer(None, None, None, output.span)),
1802 hir::Return(ref output) =>
1803 ty::FnConverging(convert_ty_with_lifetime_elision(this,
1804 implied_output_region,
1806 hir::DefaultReturn(..) => ty::FnConverging(this.tcx().mk_nil()),
1807 hir::NoReturn(..) => ty::FnDiverging
1813 sig: ty::Binder(ty::FnSig {
1814 inputs: self_and_input_tys,
1816 variadic: decl.variadic
1818 }, explicit_self_category_result)
1821 fn determine_explicit_self_category<'a, 'tcx>(this: &AstConv<'tcx>,
1822 rscope: &RegionScope,
1823 self_info: &SelfInfo<'a, 'tcx>)
1824 -> ty::ExplicitSelfCategory
1826 return match self_info.explicit_self.node {
1827 hir::SelfStatic => ty::StaticExplicitSelfCategory,
1828 hir::SelfValue(_) => ty::ByValueExplicitSelfCategory,
1829 hir::SelfRegion(ref lifetime, mutability, _) => {
1831 opt_ast_region_to_region(this,
1833 self_info.explicit_self.span,
1835 ty::ByReferenceExplicitSelfCategory(region, mutability)
1837 hir::SelfExplicit(ref ast_type, _) => {
1838 let explicit_type = ast_ty_to_ty(this, rscope, &**ast_type);
1840 // We wish to (for now) categorize an explicit self
1841 // declaration like `self: SomeType` into either `self`,
1842 // `&self`, `&mut self`, or `Box<self>`. We do this here
1843 // by some simple pattern matching. A more precise check
1844 // is done later in `check_method_self_type()`.
1849 // impl Foo for &T {
1850 // // Legal declarations:
1851 // fn method1(self: &&T); // ByReferenceExplicitSelfCategory
1852 // fn method2(self: &T); // ByValueExplicitSelfCategory
1853 // fn method3(self: Box<&T>); // ByBoxExplicitSelfCategory
1855 // // Invalid cases will be caught later by `check_method_self_type`:
1856 // fn method_err1(self: &mut T); // ByReferenceExplicitSelfCategory
1860 // To do the check we just count the number of "modifiers"
1861 // on each type and compare them. If they are the same or
1862 // the impl has more, we call it "by value". Otherwise, we
1863 // look at the outermost modifier on the method decl and
1864 // call it by-ref, by-box as appropriate. For method1, for
1865 // example, the impl type has one modifier, but the method
1866 // type has two, so we end up with
1867 // ByReferenceExplicitSelfCategory.
1869 let impl_modifiers = count_modifiers(self_info.untransformed_self_ty);
1870 let method_modifiers = count_modifiers(explicit_type);
1872 debug!("determine_explicit_self_category(self_info.untransformed_self_ty={:?} \
1873 explicit_type={:?} \
1875 self_info.untransformed_self_ty,
1880 if impl_modifiers >= method_modifiers {
1881 ty::ByValueExplicitSelfCategory
1883 match explicit_type.sty {
1884 ty::TyRef(r, mt) => ty::ByReferenceExplicitSelfCategory(*r, mt.mutbl),
1885 ty::TyBox(_) => ty::ByBoxExplicitSelfCategory,
1886 _ => ty::ByValueExplicitSelfCategory,
1892 fn count_modifiers(ty: Ty) -> usize {
1894 ty::TyRef(_, mt) => count_modifiers(mt.ty) + 1,
1895 ty::TyBox(t) => count_modifiers(t) + 1,
1901 pub fn ty_of_closure<'tcx>(
1902 this: &AstConv<'tcx>,
1903 unsafety: hir::Unsafety,
1906 expected_sig: Option<ty::FnSig<'tcx>>)
1907 -> ty::ClosureTy<'tcx>
1909 debug!("ty_of_closure(expected_sig={:?})",
1912 // new region names that appear inside of the fn decl are bound to
1913 // that function type
1914 let rb = rscope::BindingRscope::new();
1916 let input_tys: Vec<_> = decl.inputs.iter().enumerate().map(|(i, a)| {
1917 let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
1918 // no guarantee that the correct number of expected args
1920 if i < e.inputs.len() {
1926 ty_of_arg(this, &rb, a, expected_arg_ty)
1929 let expected_ret_ty = expected_sig.map(|e| e.output);
1931 let is_infer = match decl.output {
1932 hir::Return(ref output) if output.node == hir::TyInfer => true,
1933 hir::DefaultReturn(..) => true,
1937 let output_ty = match decl.output {
1938 _ if is_infer && expected_ret_ty.is_some() =>
1939 expected_ret_ty.unwrap(),
1941 ty::FnConverging(this.ty_infer(None, None, None, decl.output.span())),
1942 hir::Return(ref output) =>
1943 ty::FnConverging(ast_ty_to_ty(this, &rb, &**output)),
1944 hir::DefaultReturn(..) => unreachable!(),
1945 hir::NoReturn(..) => ty::FnDiverging
1948 debug!("ty_of_closure: input_tys={:?}", input_tys);
1949 debug!("ty_of_closure: output_ty={:?}", output_ty);
1954 sig: ty::Binder(ty::FnSig {inputs: input_tys,
1956 variadic: decl.variadic}),
1960 /// Given an existential type like `Foo+'a+Bar`, this routine converts the `'a` and `Bar` intos an
1961 /// `ExistentialBounds` struct. The `main_trait_refs` argument specifies the `Foo` -- it is absent
1962 /// for closures. Eventually this should all be normalized, I think, so that there is no "main
1963 /// trait ref" and instead we just have a flat list of bounds as the existential type.
1964 fn conv_existential_bounds<'tcx>(
1965 this: &AstConv<'tcx>,
1966 rscope: &RegionScope,
1968 principal_trait_ref: ty::PolyTraitRef<'tcx>,
1969 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
1970 ast_bounds: &[hir::TyParamBound])
1971 -> ty::ExistentialBounds<'tcx>
1973 let partitioned_bounds =
1974 partition_bounds(this.tcx(), span, ast_bounds);
1976 conv_existential_bounds_from_partitioned_bounds(
1977 this, rscope, span, principal_trait_ref, projection_bounds, partitioned_bounds)
1980 fn conv_ty_poly_trait_ref<'tcx>(
1981 this: &AstConv<'tcx>,
1982 rscope: &RegionScope,
1984 ast_bounds: &[hir::TyParamBound])
1987 let mut partitioned_bounds = partition_bounds(this.tcx(), span, &ast_bounds[..]);
1989 let mut projection_bounds = Vec::new();
1990 let main_trait_bound = if !partitioned_bounds.trait_bounds.is_empty() {
1991 let trait_bound = partitioned_bounds.trait_bounds.remove(0);
1992 instantiate_poly_trait_ref(this,
1996 &mut projection_bounds)
1998 span_err!(this.tcx().sess, span, E0224,
1999 "at least one non-builtin trait is required for an object type");
2000 return this.tcx().types.err;
2004 conv_existential_bounds_from_partitioned_bounds(this,
2007 main_trait_bound.clone(),
2009 partitioned_bounds);
2011 make_object_type(this, span, main_trait_bound, bounds)
2014 pub fn conv_existential_bounds_from_partitioned_bounds<'tcx>(
2015 this: &AstConv<'tcx>,
2016 rscope: &RegionScope,
2018 principal_trait_ref: ty::PolyTraitRef<'tcx>,
2019 projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>, // Empty for boxed closures
2020 partitioned_bounds: PartitionedBounds)
2021 -> ty::ExistentialBounds<'tcx>
2023 let PartitionedBounds { builtin_bounds,
2028 if !trait_bounds.is_empty() {
2029 let b = &trait_bounds[0];
2030 span_err!(this.tcx().sess, b.trait_ref.path.span, E0225,
2031 "only the builtin traits can be used as closure or object bounds");
2035 compute_object_lifetime_bound(this,
2038 principal_trait_ref,
2041 let region_bound = match region_bound {
2044 match rscope.object_lifetime_default(span) {
2047 span_err!(this.tcx().sess, span, E0228,
2048 "the lifetime bound for this object type cannot be deduced \
2049 from context; please supply an explicit bound");
2056 debug!("region_bound: {:?}", region_bound);
2058 ty::ExistentialBounds::new(region_bound, builtin_bounds, projection_bounds)
2061 /// Given the bounds on an object, determines what single region bound
2062 /// (if any) we can use to summarize this type. The basic idea is that we will use the bound the
2063 /// user provided, if they provided one, and otherwise search the supertypes of trait bounds for
2064 /// region bounds. It may be that we can derive no bound at all, in which case we return `None`.
2065 fn compute_object_lifetime_bound<'tcx>(
2066 this: &AstConv<'tcx>,
2068 explicit_region_bounds: &[&hir::Lifetime],
2069 principal_trait_ref: ty::PolyTraitRef<'tcx>,
2070 builtin_bounds: ty::BuiltinBounds)
2071 -> Option<ty::Region> // if None, use the default
2073 let tcx = this.tcx();
2075 debug!("compute_opt_region_bound(explicit_region_bounds={:?}, \
2076 principal_trait_ref={:?}, builtin_bounds={:?})",
2077 explicit_region_bounds,
2078 principal_trait_ref,
2081 if explicit_region_bounds.len() > 1 {
2082 span_err!(tcx.sess, explicit_region_bounds[1].span, E0226,
2083 "only a single explicit lifetime bound is permitted");
2086 if !explicit_region_bounds.is_empty() {
2087 // Explicitly specified region bound. Use that.
2088 let r = explicit_region_bounds[0];
2089 return Some(ast_region_to_region(tcx, r));
2092 if let Err(ErrorReported) = this.ensure_super_predicates(span,principal_trait_ref.def_id()) {
2093 return Some(ty::ReStatic);
2096 // No explicit region bound specified. Therefore, examine trait
2097 // bounds and see if we can derive region bounds from those.
2098 let derived_region_bounds =
2099 object_region_bounds(tcx, &principal_trait_ref, builtin_bounds);
2101 // If there are no derived region bounds, then report back that we
2102 // can find no region bound. The caller will use the default.
2103 if derived_region_bounds.is_empty() {
2107 // If any of the derived region bounds are 'static, that is always
2109 if derived_region_bounds.iter().any(|r| ty::ReStatic == *r) {
2110 return Some(ty::ReStatic);
2113 // Determine whether there is exactly one unique region in the set
2114 // of derived region bounds. If so, use that. Otherwise, report an
2116 let r = derived_region_bounds[0];
2117 if derived_region_bounds[1..].iter().any(|r1| r != *r1) {
2118 span_err!(tcx.sess, span, E0227,
2119 "ambiguous lifetime bound, explicit lifetime bound required");
2124 pub struct PartitionedBounds<'a> {
2125 pub builtin_bounds: ty::BuiltinBounds,
2126 pub trait_bounds: Vec<&'a hir::PolyTraitRef>,
2127 pub region_bounds: Vec<&'a hir::Lifetime>,
2130 /// Divides a list of bounds from the AST into three groups: builtin bounds (Copy, Sized etc),
2131 /// general trait bounds, and region bounds.
2132 pub fn partition_bounds<'a>(tcx: &ty::ctxt,
2134 ast_bounds: &'a [hir::TyParamBound])
2135 -> PartitionedBounds<'a>
2137 let mut builtin_bounds = ty::BuiltinBounds::empty();
2138 let mut region_bounds = Vec::new();
2139 let mut trait_bounds = Vec::new();
2140 for ast_bound in ast_bounds {
2142 hir::TraitTyParamBound(ref b, hir::TraitBoundModifier::None) => {
2143 match ::lookup_full_def(tcx, b.trait_ref.path.span, b.trait_ref.ref_id) {
2144 def::DefTrait(trait_did) => {
2145 if tcx.try_add_builtin_trait(trait_did,
2146 &mut builtin_bounds) {
2147 let segments = &b.trait_ref.path.segments;
2148 let parameters = &segments[segments.len() - 1].parameters;
2149 if !parameters.types().is_empty() {
2150 check_type_argument_count(tcx, b.trait_ref.path.span,
2151 parameters.types().len(), 0, 0);
2153 if !parameters.lifetimes().is_empty() {
2154 report_lifetime_number_error(tcx, b.trait_ref.path.span,
2155 parameters.lifetimes().len(), 0);
2157 continue; // success
2161 // Not a trait? that's an error, but it'll get
2165 trait_bounds.push(b);
2167 hir::TraitTyParamBound(_, hir::TraitBoundModifier::Maybe) => {}
2168 hir::RegionTyParamBound(ref l) => {
2169 region_bounds.push(l);
2175 builtin_bounds: builtin_bounds,
2176 trait_bounds: trait_bounds,
2177 region_bounds: region_bounds,
2181 fn prohibit_projections<'tcx>(tcx: &ty::ctxt<'tcx>,
2182 bindings: &[ConvertedBinding<'tcx>])
2184 for binding in bindings.iter().take(1) {
2185 span_err!(tcx.sess, binding.span, E0229,
2186 "associated type bindings are not allowed here");
2190 fn check_type_argument_count(tcx: &ty::ctxt, span: Span, supplied: usize,
2191 required: usize, accepted: usize) {
2192 if supplied < required {
2193 let expected = if required < accepted {
2198 span_err!(tcx.sess, span, E0243,
2199 "wrong number of type arguments: {} {}, found {}",
2200 expected, required, supplied);
2201 } else if supplied > accepted {
2202 let expected = if required < accepted {
2207 span_err!(tcx.sess, span, E0244,
2208 "wrong number of type arguments: {} {}, found {}",
2215 fn report_lifetime_number_error(tcx: &ty::ctxt, span: Span, number: usize, expected: usize) {
2216 span_err!(tcx.sess, span, E0107,
2217 "wrong number of lifetime parameters: expected {}, found {}",
2221 // A helper struct for conveniently grouping a set of bounds which we pass to
2222 // and return from functions in multiple places.
2223 #[derive(PartialEq, Eq, Clone, Debug)]
2224 pub struct Bounds<'tcx> {
2225 pub region_bounds: Vec<ty::Region>,
2226 pub builtin_bounds: ty::BuiltinBounds,
2227 pub trait_bounds: Vec<ty::PolyTraitRef<'tcx>>,
2228 pub projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>,
2231 impl<'tcx> Bounds<'tcx> {
2232 pub fn predicates(&self,
2233 tcx: &ty::ctxt<'tcx>,
2235 -> Vec<ty::Predicate<'tcx>>
2237 let mut vec = Vec::new();
2239 for builtin_bound in &self.builtin_bounds {
2240 match traits::trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty) {
2241 Ok(trait_ref) => { vec.push(trait_ref.to_predicate()); }
2242 Err(ErrorReported) => { }
2246 for ®ion_bound in &self.region_bounds {
2247 // account for the binder being introduced below; no need to shift `param_ty`
2248 // because, at present at least, it can only refer to early-bound regions
2249 let region_bound = ty::fold::shift_region(region_bound, 1);
2250 vec.push(ty::Binder(ty::OutlivesPredicate(param_ty, region_bound)).to_predicate());
2253 for bound_trait_ref in &self.trait_bounds {
2254 vec.push(bound_trait_ref.to_predicate());
2257 for projection in &self.projection_bounds {
2258 vec.push(projection.to_predicate());