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.
12 * Conversion from AST representation of types to the ty.rs
13 * representation. The main routine here is `ast_ty_to_ty()`: each use
14 * is parameterized by an instance of `AstConv` and a `RegionScope`.
16 * The parameterization of `ast_ty_to_ty()` is because it behaves
17 * somewhat differently during the collect and check phases,
18 * particularly with respect to looking up the types of top-level
19 * items. In the collect phase, the crate context is used as the
20 * `AstConv` instance; in this phase, the `get_item_ty()` function
21 * triggers a recursive call to `ty_of_item()` (note that
22 * `ast_ty_to_ty()` will detect recursive types and report an error).
23 * In the check phase, when the FnCtxt is used as the `AstConv`,
24 * `get_item_ty()` just looks up the item type in `tcx.tcache`.
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:
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.
52 use middle::const_eval;
54 use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem};
55 use middle::lang_items::{FnOnceTraitLangItem};
56 use middle::resolve_lifetime as rl;
57 use middle::subst::{FnSpace, TypeSpace, SelfSpace, Subst, Substs};
58 use middle::subst::{VecPerParamSpace};
60 use middle::typeck::lookup_def_tcx;
61 use middle::typeck::infer;
62 use middle::typeck::rscope::{ExplicitRscope, RegionScope, SpecificRscope};
63 use middle::typeck::rscope;
64 use middle::typeck::TypeAndSubsts;
66 use util::ppaux::{Repr, UserString};
68 use std::collections::HashMap;
71 use syntax::{ast, ast_util};
72 use syntax::codemap::Span;
73 use syntax::parse::token;
75 pub trait AstConv<'tcx> {
76 fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx>;
77 fn get_item_ty(&self, id: ast::DefId) -> ty::Polytype;
78 fn get_trait_def(&self, id: ast::DefId) -> Rc<ty::TraitDef>;
80 /// What type should we use when a type is omitted?
81 fn ty_infer(&self, span: Span) -> ty::t;
83 /// Returns true if associated types from the given trait and type are
84 /// allowed to be used here and false otherwise.
85 fn associated_types_of_trait_are_valid(&self,
90 /// Returns the binding of the given associated type for some type.
91 fn associated_type_binding(&self,
95 associated_type_id: ast::DefId)
99 pub fn ast_region_to_region(tcx: &ty::ctxt, lifetime: &ast::Lifetime)
101 let r = match tcx.named_region_map.find(&lifetime.id) {
103 // should have been recorded by the `resolve_lifetime` pass
104 tcx.sess.span_bug(lifetime.span, "unresolved lifetime");
107 Some(&rl::DefStaticRegion) => {
111 Some(&rl::DefLateBoundRegion(binder_id, _, id)) => {
112 ty::ReLateBound(binder_id, ty::BrNamed(ast_util::local_def(id),
116 Some(&rl::DefEarlyBoundRegion(space, index, id)) => {
117 ty::ReEarlyBound(id, space, index, lifetime.name)
120 Some(&rl::DefFreeRegion(scope_id, id)) => {
121 ty::ReFree(ty::FreeRegion {
123 bound_region: ty::BrNamed(ast_util::local_def(id),
129 debug!("ast_region_to_region(lifetime={} id={}) yields {}",
137 pub fn opt_ast_region_to_region<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
141 opt_lifetime: &Option<ast::Lifetime>) -> ty::Region
143 let r = match *opt_lifetime {
144 Some(ref lifetime) => {
145 ast_region_to_region(this.tcx(), lifetime)
149 match rscope.anon_regions(default_span, 1) {
151 debug!("optional region in illegal location");
152 span_err!(this.tcx().sess, default_span, E0106,
153 "missing lifetime specifier");
164 debug!("opt_ast_region_to_region(opt_lifetime={}) yields {}",
165 opt_lifetime.repr(this.tcx()),
171 fn ast_path_substs<'tcx,AC,RS>(
174 decl_def_id: ast::DefId,
175 decl_generics: &ty::Generics,
176 self_ty: Option<ty::t>,
177 associated_ty: Option<ty::t>,
180 where AC: AstConv<'tcx>, RS: RegionScope {
182 * Given a path `path` that refers to an item `I` with the
183 * declared generics `decl_generics`, returns an appropriate
184 * set of substitutions for this particular reference to `I`.
187 let tcx = this.tcx();
189 // ast_path_substs() is only called to convert paths that are
190 // known to refer to traits, types, or structs. In these cases,
191 // all type parameters defined for the item being referenced will
192 // be in the TypeSpace or SelfSpace.
194 // Note: in the case of traits, the self parameter is also
195 // defined, but we don't currently create a `type_param_def` for
196 // `Self` because it is implicit.
197 assert!(decl_generics.regions.all(|d| d.space == TypeSpace));
198 assert!(decl_generics.types.all(|d| d.space != FnSpace));
200 // If the type is parameterized by the this region, then replace this
201 // region with the current anon region binding (in other words,
202 // whatever & would get replaced with).
203 let expected_num_region_params = decl_generics.regions.len(TypeSpace);
204 let supplied_num_region_params = path.segments.last().unwrap().lifetimes.len();
205 let regions = if expected_num_region_params == supplied_num_region_params {
206 path.segments.last().unwrap().lifetimes.iter().map(
207 |l| ast_region_to_region(this.tcx(), l)).collect::<Vec<_>>()
210 rscope.anon_regions(path.span, expected_num_region_params);
212 if supplied_num_region_params != 0 || anon_regions.is_err() {
213 span_err!(tcx.sess, path.span, E0107,
214 "wrong number of lifetime parameters: expected {}, found {}",
215 expected_num_region_params, supplied_num_region_params);
219 Ok(v) => v.into_iter().collect(),
220 Err(()) => Vec::from_fn(expected_num_region_params,
221 |_| ty::ReStatic) // hokey
225 // Convert the type parameters supplied by the user.
226 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
227 let supplied_ty_param_count = path.segments.iter().flat_map(|s| s.types.iter()).count();
228 let formal_ty_param_count =
230 .take_while(|x| !ty::is_associated_type(tcx, x.def_id))
232 let required_ty_param_count =
235 x.default.is_none() &&
236 !ty::is_associated_type(tcx, x.def_id)
239 if supplied_ty_param_count < required_ty_param_count {
240 let expected = if required_ty_param_count < formal_ty_param_count {
245 this.tcx().sess.span_fatal(path.span,
246 format!("wrong number of type arguments: {} {}, found {}",
248 required_ty_param_count,
249 supplied_ty_param_count).as_slice());
250 } else if supplied_ty_param_count > formal_ty_param_count {
251 let expected = if required_ty_param_count < formal_ty_param_count {
256 this.tcx().sess.span_fatal(path.span,
257 format!("wrong number of type arguments: {} {}, found {}",
259 formal_ty_param_count,
260 supplied_ty_param_count).as_slice());
263 if supplied_ty_param_count > required_ty_param_count
264 && !this.tcx().sess.features.borrow().default_type_params {
265 span_err!(this.tcx().sess, path.span, E0108,
266 "default type parameters are experimental and possibly buggy");
267 span_note!(this.tcx().sess, path.span,
268 "add #![feature(default_type_params)] to the crate attributes to enable");
271 let tps = path.segments
273 .flat_map(|s| s.types.iter())
274 .map(|a_t| ast_ty_to_ty(this, rscope, &**a_t))
277 let mut substs = Substs::new_type(tps, regions);
281 // If no self-type is provided, it's still possible that
282 // one was declared, because this could be an object type.
285 // If a self-type is provided, one should have been
286 // "declared" (in other words, this should be a
288 assert!(decl_generics.types.get_self().is_some());
289 substs.types.push(SelfSpace, ty);
293 for param in ty_param_defs.slice_from(supplied_ty_param_count).iter() {
294 match param.default {
296 // This is a default type parameter.
297 let default = default.subst_spanned(tcx,
300 substs.types.push(TypeSpace, default);
303 // This is an associated type.
306 this.associated_type_binding(path.span,
317 pub fn ast_path_to_trait_ref<'tcx,AC,RS>(this: &AC,
319 trait_def_id: ast::DefId,
320 self_ty: Option<ty::t>,
321 associated_type: Option<ty::t>,
324 where AC: AstConv<'tcx>,
326 let trait_def = this.get_trait_def(trait_def_id);
327 Rc::new(ty::TraitRef {
328 def_id: trait_def_id,
329 substs: ast_path_substs(this,
339 pub fn ast_path_to_ty<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
345 let tcx = this.tcx();
349 } = this.get_item_ty(did);
351 let substs = ast_path_substs(this,
358 let ty = decl_ty.subst(tcx, &substs);
359 TypeAndSubsts { substs: substs, ty: ty }
362 /// Returns the type that this AST path refers to. If the path has no type
363 /// parameters and the corresponding type has type parameters, fresh type
364 /// and/or region variables are substituted.
366 /// This is used when checking the constructor in struct literals.
367 pub fn ast_path_to_ty_relaxed<'tcx, AC: AstConv<'tcx>,
374 let tcx = this.tcx();
378 } = this.get_item_ty(did);
380 let substs = if (generics.has_type_params(TypeSpace) ||
381 generics.has_region_params(TypeSpace)) &&
382 path.segments.iter().all(|s| {
383 s.lifetimes.len() == 0 && s.types.len() == 0
385 let type_params = Vec::from_fn(generics.types.len(TypeSpace),
386 |_| this.ty_infer(path.span));
388 rscope.anon_regions(path.span, generics.regions.len(TypeSpace))
390 Substs::new(VecPerParamSpace::params_from_type(type_params),
391 VecPerParamSpace::params_from_type(region_params))
393 ast_path_substs(this, rscope, did, &generics, None, None, path)
396 let ty = decl_ty.subst(tcx, &substs);
403 pub static NO_REGIONS: uint = 1;
404 pub static NO_TPS: uint = 2;
406 fn check_path_args(tcx: &ty::ctxt,
409 if (flags & NO_TPS) != 0u {
410 if !path.segments.iter().all(|s| s.types.is_empty()) {
411 span_err!(tcx.sess, path.span, E0109,
412 "type parameters are not allowed on this type");
416 if (flags & NO_REGIONS) != 0u {
417 if !path.segments.last().unwrap().lifetimes.is_empty() {
418 span_err!(tcx.sess, path.span, E0110,
419 "region parameters are not allowed on this type");
424 pub fn ast_ty_to_prim_ty(tcx: &ty::ctxt, ast_ty: &ast::Ty) -> Option<ty::t> {
426 ast::TyPath(ref path, _, id) => {
427 let a_def = match tcx.def_map.borrow().find(&id) {
429 tcx.sess.span_bug(ast_ty.span,
430 format!("unbound path {}",
431 path.repr(tcx)).as_slice())
436 def::DefPrimTy(nty) => {
439 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
443 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
447 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
448 Some(ty::mk_mach_int(it))
450 ast::TyUint(uit) => {
451 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
452 Some(ty::mk_mach_uint(uit))
454 ast::TyFloat(ft) => {
455 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
456 Some(ty::mk_mach_float(ft))
459 Some(ty::mk_str(tcx))
470 /// Converts the given AST type to a built-in type. A "built-in type" is, at
471 /// present, either a core numeric type, a string, or `Box`.
472 pub fn ast_ty_to_builtin_ty<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
477 match ast_ty_to_prim_ty(this.tcx(), ast_ty) {
478 Some(typ) => return Some(typ),
483 ast::TyPath(ref path, _, id) => {
484 let a_def = match this.tcx().def_map.borrow().find(&id) {
488 .span_bug(ast_ty.span,
489 format!("unbound path {}",
490 path.repr(this.tcx())).as_slice())
495 // FIXME(#12938): This is a hack until we have full support for
498 def::DefTy(did, _) | def::DefStruct(did)
499 if Some(did) == this.tcx().lang_items.owned_box() => {
502 .flat_map(|s| s.types.iter())
504 span_err!(this.tcx().sess, path.span, E0047,
505 "`Box` has only one type parameter");
508 for inner_ast_type in path.segments
510 .flat_map(|s| s.types.iter()) {
511 return Some(mk_pointer(this,
516 |typ| ty::mk_uniq(this.tcx(), typ)));
518 span_err!(this.tcx().sess, path.span, E0113,
519 "not enough type parameters supplied to `Box<T>`");
522 def::DefTy(did, _) | def::DefStruct(did)
523 if Some(did) == this.tcx().lang_items.gc() => {
526 .flat_map(|s| s.types.iter())
528 span_err!(this.tcx().sess, path.span, E0048,
529 "`Gc` has only one type parameter");
532 for inner_ast_type in path.segments
534 .flat_map(|s| s.types.iter()) {
535 return Some(mk_pointer(this,
541 match ty::get(typ).sty {
543 span_err!(this.tcx().sess, path.span, E0114,
544 "`Gc<str>` is not a type");
547 ty::ty_vec(_, None) => {
548 span_err!(this.tcx().sess, path.span, E0115,
549 "`Gc<[T]>` is not a type");
552 _ => ty::mk_box(this.tcx(), typ),
556 this.tcx().sess.span_bug(path.span,
557 "not enough type parameters \
558 supplied to `Gc<T>`")
575 fn default_region(&self) -> ty::Region {
578 Uniq => ty::ReStatic,
584 pub fn trait_ref_for_unboxed_function<'tcx, AC: AstConv<'tcx>,
588 unboxed_function: &ast::UnboxedFnTy,
589 self_ty: Option<ty::t>)
591 let lang_item = match unboxed_function.kind {
592 ast::FnUnboxedClosureKind => FnTraitLangItem,
593 ast::FnMutUnboxedClosureKind => FnMutTraitLangItem,
594 ast::FnOnceUnboxedClosureKind => FnOnceTraitLangItem,
596 let trait_did = this.tcx().lang_items.require(lang_item).unwrap();
598 unboxed_function.decl
602 ast_ty_to_ty(this, rscope, &*input.ty)
603 }).collect::<Vec<_>>();
604 let input_tuple = if input_types.len() == 0 {
607 ty::mk_tup(this.tcx(), input_types)
609 let output_type = ast_ty_to_ty(this,
611 &*unboxed_function.decl.output);
612 let mut substs = Substs::new_type(vec!(input_tuple, output_type),
616 Some(s) => substs.types.push(SelfSpace, s),
626 // Handle `~`, `Box`, and `&` being able to mean strs and vecs.
627 // If a_seq_ty is a str or a vec, make it a str/vec.
628 // Also handle first-class trait types.
629 fn mk_pointer<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
632 a_seq_mutbl: ast::Mutability,
635 constr: |ty::t| -> ty::t)
637 let tcx = this.tcx();
638 debug!("mk_pointer(ptr_ty={})", ptr_ty);
640 match a_seq_ty.node {
641 ast::TyVec(ref ty) => {
642 let ty = ast_ty_to_ty(this, rscope, &**ty);
643 return constr(ty::mk_vec(tcx, ty, None));
645 ast::TyUnboxedFn(ref unboxed_function) => {
649 } = trait_ref_for_unboxed_function(this,
653 let r = ptr_ty.default_region();
654 let tr = ty::mk_trait(this.tcx(),
657 ty::region_existential_bound(r));
660 return ty::mk_uniq(this.tcx(), tr);
663 return ty::mk_rptr(this.tcx(),
665 ty::mt {mutbl: a_seq_mutbl, ty: tr});
670 "~trait or &trait are the only supported \
671 forms of casting-to-trait");
677 ast::TyPath(ref path, ref opt_bounds, id) => {
678 // Note that the "bounds must be empty if path is not a trait"
679 // restriction is enforced in the below case for ty_path, which
680 // will run after this as long as the path isn't a trait.
681 match tcx.def_map.borrow().find(&id) {
682 Some(&def::DefPrimTy(ast::TyStr)) => {
683 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
686 return constr(ty::mk_str(tcx));
689 return ty::mk_str_slice(tcx, r, ast::MutImmutable);
694 "managed strings are not supported")
698 Some(&def::DefTrait(trait_def_id)) => {
699 let result = ast_path_to_trait_ref(this,
705 let bounds = match *opt_bounds {
707 conv_existential_bounds(this,
710 [result.clone()].as_slice(),
713 Some(ref bounds) => {
714 conv_existential_bounds(this,
717 [result.clone()].as_slice(),
721 let tr = ty::mk_trait(tcx,
723 result.substs.clone(),
725 return match ptr_ty {
727 return ty::mk_uniq(tcx, tr);
730 return ty::mk_rptr(tcx, r, ty::mt{mutbl: a_seq_mutbl, ty: tr});
735 "~trait or &trait are the only supported \
736 forms of casting-to-trait");
747 constr(ast_ty_to_ty(this, rscope, a_seq_ty))
750 fn associated_ty_to_ty<'tcx,AC,RS>(this: &AC,
752 trait_path: &ast::Path,
753 for_ast_type: &ast::Ty,
754 trait_type_id: ast::DefId,
757 where AC: AstConv<'tcx>, RS: RegionScope {
758 // Find the trait that this associated type belongs to.
759 let trait_did = match ty::impl_or_trait_item(this.tcx(),
760 trait_type_id).container() {
761 ty::ImplContainer(_) => {
762 this.tcx().sess.span_bug(span,
763 "associated_ty_to_ty(): impl associated \
764 types shouldn't go through this \
767 ty::TraitContainer(trait_id) => trait_id,
770 let for_type = ast_ty_to_ty(this, rscope, for_ast_type);
771 if !this.associated_types_of_trait_are_valid(for_type, trait_did) {
772 this.tcx().sess.span_err(span,
773 "this associated type is not \
774 allowed in this context");
778 let trait_ref = ast_path_to_trait_ref(this,
784 let trait_def = this.get_trait_def(trait_did);
785 for type_parameter in trait_def.generics.types.iter() {
786 if type_parameter.def_id == trait_type_id {
787 return *trait_ref.substs.types.get(type_parameter.space,
788 type_parameter.index)
791 this.tcx().sess.span_bug(span,
792 "this associated type didn't get added \
793 as a parameter for some reason")
796 // Parses the programmer's textual representation of a type into our
797 // internal notion of a type.
798 pub fn ast_ty_to_ty<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
799 this: &AC, rscope: &RS, ast_ty: &ast::Ty) -> ty::t {
801 let tcx = this.tcx();
803 let mut ast_ty_to_ty_cache = tcx.ast_ty_to_ty_cache.borrow_mut();
804 match ast_ty_to_ty_cache.find(&ast_ty.id) {
805 Some(&ty::atttce_resolved(ty)) => return ty,
806 Some(&ty::atttce_unresolved) => {
807 tcx.sess.span_fatal(ast_ty.span,
808 "illegal recursive type; insert an enum \
809 or struct in the cycle, if this is \
812 None => { /* go on */ }
814 ast_ty_to_ty_cache.insert(ast_ty.id, ty::atttce_unresolved);
815 drop(ast_ty_to_ty_cache);
817 let typ = ast_ty_to_builtin_ty(this, rscope, ast_ty).unwrap_or_else(|| {
819 ast::TyNil => ty::mk_nil(),
820 ast::TyBot => ty::mk_bot(),
821 ast::TyBox(ref ty) => {
822 mk_pointer(this, rscope, ast::MutImmutable, &**ty, Box,
823 |ty| ty::mk_box(tcx, ty))
825 ast::TyUniq(ref ty) => {
826 mk_pointer(this, rscope, ast::MutImmutable, &**ty, Uniq,
827 |ty| ty::mk_uniq(tcx, ty))
829 ast::TyVec(ref ty) => {
830 ty::mk_vec(tcx, ast_ty_to_ty(this, rscope, &**ty), None)
832 ast::TyPtr(ref mt) => {
833 ty::mk_ptr(tcx, ty::mt {
834 ty: ast_ty_to_ty(this, rscope, &*mt.ty),
838 ast::TyRptr(ref region, ref mt) => {
839 let r = opt_ast_region_to_region(this, rscope, ast_ty.span, region);
840 debug!("ty_rptr r={}", r.repr(this.tcx()));
841 mk_pointer(this, rscope, mt.mutbl, &*mt.ty, RPtr(r),
842 |ty| ty::mk_rptr(tcx, r, ty::mt {ty: ty, mutbl: mt.mutbl}))
844 ast::TyTup(ref fields) => {
845 let flds = fields.iter()
846 .map(|t| ast_ty_to_ty(this, rscope, &**t))
848 ty::mk_tup(tcx, flds)
850 ast::TyParen(ref typ) => ast_ty_to_ty(this, rscope, &**typ),
851 ast::TyBareFn(ref bf) => {
852 if bf.decl.variadic && bf.abi != abi::C {
853 tcx.sess.span_err(ast_ty.span,
854 "variadic function must have C calling convention");
856 ty::mk_bare_fn(tcx, ty_of_bare_fn(this, ast_ty.id, bf.fn_style,
859 ast::TyClosure(ref f) => {
860 // Use corresponding trait store to figure out default bounds
861 // if none were specified.
862 let bounds = conv_existential_bounds(this,
866 f.bounds.as_slice());
867 let fn_decl = ty_of_closure(this,
872 ty::RegionTraitStore(
878 ty::mk_closure(tcx, fn_decl)
880 ast::TyProc(ref f) => {
881 // Use corresponding trait store to figure out default bounds
882 // if none were specified.
883 let bounds = conv_existential_bounds(this, rscope,
886 f.bounds.as_slice());
888 let fn_decl = ty_of_closure(this,
898 ty::mk_closure(tcx, fn_decl)
900 ast::TyUnboxedFn(..) => {
901 tcx.sess.span_err(ast_ty.span,
902 "cannot use unboxed functions here");
905 ast::TyPath(ref path, ref bounds, id) => {
906 let a_def = match tcx.def_map.borrow().find(&id) {
909 .span_bug(ast_ty.span,
910 format!("unbound path {}",
911 path.repr(tcx)).as_slice())
915 // Kind bounds on path types are only supported for traits.
917 // But don't emit the error if the user meant to do a trait anyway.
918 def::DefTrait(..) => { },
919 _ if bounds.is_some() =>
920 tcx.sess.span_err(ast_ty.span,
921 "kind bounds can only be used on trait types"),
925 def::DefTrait(trait_def_id) => {
926 let result = ast_path_to_trait_ref(this,
932 let empty_bounds: &[ast::TyParamBound] = &[];
933 let ast_bounds = match *bounds {
934 Some(ref b) => b.as_slice(),
937 let bounds = conv_existential_bounds(this,
944 result.substs.clone(),
947 def::DefTy(did, _) | def::DefStruct(did) => {
948 ast_path_to_ty(this, rscope, did, path).ty
950 def::DefTyParam(space, id, n) => {
951 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
952 ty::mk_param(tcx, space, n, id)
954 def::DefSelfTy(id) => {
955 // n.b.: resolve guarantees that the this type only appears in a
956 // trait, which we rely upon in various places when creating
958 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
959 let did = ast_util::local_def(id);
960 ty::mk_self_type(tcx, did)
963 tcx.sess.span_fatal(ast_ty.span,
964 format!("found module name used as a type: {}",
965 tcx.map.node_to_string(id.node)).as_slice());
967 def::DefPrimTy(_) => {
968 fail!("DefPrimTy arm missed in previous ast_ty_to_prim_ty call");
970 def::DefAssociatedTy(trait_type_id) => {
971 let path_str = tcx.map.path_to_string(
972 tcx.map.get_parent(trait_type_id.node));
973 tcx.sess.span_err(ast_ty.span,
974 format!("ambiguous associated \
975 type; specify the type \
976 using the syntax `<Type \
988 tcx.sess.span_fatal(ast_ty.span,
989 format!("found value name used \
995 ast::TyQPath(ref qpath) => {
996 match tcx.def_map.borrow().find(&ast_ty.id) {
998 tcx.sess.span_bug(ast_ty.span,
999 "unbound qualified path")
1001 Some(&def::DefAssociatedTy(trait_type_id)) => {
1002 associated_ty_to_ty(this,
1010 tcx.sess.span_err(ast_ty.span,
1011 "this qualified path does not name \
1012 an associated type");
1017 ast::TyFixedLengthVec(ref ty, ref e) => {
1018 match const_eval::eval_const_expr_partial(tcx, &**e) {
1021 const_eval::const_int(i) =>
1022 ty::mk_vec(tcx, ast_ty_to_ty(this, rscope, &**ty),
1024 const_eval::const_uint(i) =>
1025 ty::mk_vec(tcx, ast_ty_to_ty(this, rscope, &**ty),
1028 tcx.sess.span_fatal(
1029 ast_ty.span, "expected constant expr for vector length");
1034 tcx.sess.span_fatal(
1036 format!("expected constant expr for vector \
1042 ast::TyTypeof(ref _e) => {
1043 tcx.sess.span_bug(ast_ty.span, "typeof is reserved but unimplemented");
1046 // TyInfer also appears as the type of arguments or return
1047 // values in a ExprFnBlock, ExprProc, or ExprUnboxedFn, or as
1048 // the type of local variables. Both of these cases are
1049 // handled specially and will not descend into this routine.
1050 this.ty_infer(ast_ty.span)
1055 tcx.ast_ty_to_ty_cache.borrow_mut().insert(ast_ty.id, ty::atttce_resolved(typ));
1059 pub fn ty_of_arg<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(this: &AC, rscope: &RS,
1061 expected_ty: Option<ty::t>)
1064 ast::TyInfer if expected_ty.is_some() => expected_ty.unwrap(),
1065 ast::TyInfer => this.ty_infer(a.ty.span),
1066 _ => ast_ty_to_ty(this, rscope, &*a.ty),
1070 struct SelfInfo<'a> {
1071 untransformed_self_ty: ty::t,
1072 explicit_self: &'a ast::ExplicitSelf,
1075 pub fn ty_of_method<'tcx, AC: AstConv<'tcx>>(
1078 fn_style: ast::FnStyle,
1079 untransformed_self_ty: ty::t,
1080 explicit_self: &ast::ExplicitSelf,
1083 -> (ty::BareFnTy, ty::ExplicitSelfCategory) {
1084 let self_info = Some(SelfInfo {
1085 untransformed_self_ty: untransformed_self_ty,
1086 explicit_self: explicit_self,
1088 let (bare_fn_ty, optional_explicit_self_category) =
1089 ty_of_method_or_bare_fn(this,
1095 (bare_fn_ty, optional_explicit_self_category.unwrap())
1098 pub fn ty_of_bare_fn<'tcx, AC: AstConv<'tcx>>(this: &AC, id: ast::NodeId,
1099 fn_style: ast::FnStyle, abi: abi::Abi,
1100 decl: &ast::FnDecl) -> ty::BareFnTy {
1101 let (bare_fn_ty, _) =
1102 ty_of_method_or_bare_fn(this, id, fn_style, abi, None, decl);
1106 fn ty_of_method_or_bare_fn<'tcx, AC: AstConv<'tcx>>(
1109 fn_style: ast::FnStyle,
1111 opt_self_info: Option<SelfInfo>,
1114 Option<ty::ExplicitSelfCategory>) {
1115 debug!("ty_of_method_or_bare_fn");
1117 // New region names that appear inside of the arguments of the function
1118 // declaration are bound to that function type.
1119 let rb = rscope::BindingRscope::new(id);
1121 // `implied_output_region` is the region that will be assumed for any
1122 // region parameters in the return type. In accordance with the rules for
1123 // lifetime elision, we can determine it in two ways. First (determined
1124 // here), if self is by-reference, then the implied output region is the
1125 // region of the self parameter.
1126 let mut explicit_self_category_result = None;
1127 let (self_ty, mut implied_output_region) = match opt_self_info {
1128 None => (None, None),
1129 Some(self_info) => {
1130 // Figure out and record the explicit self category.
1131 let explicit_self_category =
1132 determine_explicit_self_category(this, &rb, &self_info);
1133 explicit_self_category_result = Some(explicit_self_category);
1134 match explicit_self_category {
1135 ty::StaticExplicitSelfCategory => (None, None),
1136 ty::ByValueExplicitSelfCategory => {
1137 (Some(self_info.untransformed_self_ty), None)
1139 ty::ByReferenceExplicitSelfCategory(region, mutability) => {
1140 (Some(ty::mk_rptr(this.tcx(),
1143 ty: self_info.untransformed_self_ty,
1148 ty::ByBoxExplicitSelfCategory => {
1149 (Some(ty::mk_uniq(this.tcx(),
1150 self_info.untransformed_self_ty)),
1157 // HACK(eddyb) replace the fake self type in the AST with the actual type.
1158 let input_tys = if self_ty.is_some() {
1159 decl.inputs.slice_from(1)
1161 decl.inputs.as_slice()
1163 let input_tys = input_tys.iter().map(|a| ty_of_arg(this, &rb, a, None));
1164 let self_and_input_tys: Vec<_> =
1165 self_ty.into_iter().chain(input_tys).collect();
1167 // Second, if there was exactly one lifetime (either a substitution or a
1168 // reference) in the arguments, then any anonymous regions in the output
1169 // have that lifetime.
1170 if implied_output_region.is_none() {
1171 let mut self_and_input_tys_iter = self_and_input_tys.iter();
1172 if self_ty.is_some() {
1173 // Skip the first argument if `self` is present.
1174 drop(self_and_input_tys_iter.next())
1177 let mut accumulator = Vec::new();
1178 for input_type in self_and_input_tys_iter {
1179 ty::accumulate_lifetimes_in_type(&mut accumulator, *input_type)
1181 if accumulator.len() == 1 {
1182 implied_output_region = Some(*accumulator.get(0));
1186 let output_ty = match decl.output.node {
1187 ast::TyInfer => this.ty_infer(decl.output.span),
1189 match implied_output_region {
1190 Some(implied_output_region) => {
1191 let rb = SpecificRscope::new(implied_output_region);
1192 ast_ty_to_ty(this, &rb, &*decl.output)
1195 // All regions must be explicitly specified in the output
1196 // if the lifetime elision rules do not apply. This saves
1197 // the user from potentially-confusing errors.
1198 let rb = ExplicitRscope;
1199 ast_ty_to_ty(this, &rb, &*decl.output)
1210 inputs: self_and_input_tys,
1212 variadic: decl.variadic
1214 }, explicit_self_category_result)
1217 fn determine_explicit_self_category<'tcx, AC: AstConv<'tcx>,
1221 self_info: &SelfInfo)
1222 -> ty::ExplicitSelfCategory {
1223 match self_info.explicit_self.node {
1224 ast::SelfStatic => ty::StaticExplicitSelfCategory,
1225 ast::SelfValue(_) => ty::ByValueExplicitSelfCategory,
1226 ast::SelfRegion(ref lifetime, mutability, _) => {
1228 opt_ast_region_to_region(this,
1230 self_info.explicit_self.span,
1232 ty::ByReferenceExplicitSelfCategory(region, mutability)
1234 ast::SelfExplicit(ref ast_type, _) => {
1235 let explicit_type = ast_ty_to_ty(this, rscope, &**ast_type);
1238 let inference_context = infer::new_infer_ctxt(this.tcx());
1239 let expected_self = self_info.untransformed_self_ty;
1240 let actual_self = explicit_type;
1241 let result = infer::mk_eqty(
1244 infer::Misc(self_info.explicit_self.span),
1249 inference_context.resolve_regions_and_report_errors();
1250 return ty::ByValueExplicitSelfCategory
1256 match ty::get(explicit_type).sty {
1257 ty::ty_rptr(region, tm) => {
1258 typeck::require_same_types(
1262 self_info.explicit_self.span,
1263 self_info.untransformed_self_ty,
1265 || "not a valid type for `self`".to_owned());
1266 return ty::ByReferenceExplicitSelfCategory(region,
1269 ty::ty_uniq(typ) => {
1270 typeck::require_same_types(
1274 self_info.explicit_self.span,
1275 self_info.untransformed_self_ty,
1277 || "not a valid type for `self`".to_owned());
1278 return ty::ByBoxExplicitSelfCategory
1283 .span_err(self_info.explicit_self.span,
1284 "not a valid type for `self`");
1285 return ty::ByValueExplicitSelfCategory
1292 pub fn ty_of_closure<'tcx, AC: AstConv<'tcx>>(
1295 fn_style: ast::FnStyle,
1296 onceness: ast::Onceness,
1297 bounds: ty::ExistentialBounds,
1298 store: ty::TraitStore,
1301 expected_sig: Option<ty::FnSig>)
1304 debug!("ty_of_fn_decl");
1306 // new region names that appear inside of the fn decl are bound to
1307 // that function type
1308 let rb = rscope::BindingRscope::new(id);
1310 let input_tys = decl.inputs.iter().enumerate().map(|(i, a)| {
1311 let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
1312 // no guarantee that the correct number of expected args
1314 if i < e.inputs.len() {
1315 Some(*e.inputs.get(i))
1320 ty_of_arg(this, &rb, a, expected_arg_ty)
1323 let expected_ret_ty = expected_sig.map(|e| e.output);
1324 let output_ty = match decl.output.node {
1325 ast::TyInfer if expected_ret_ty.is_some() => expected_ret_ty.unwrap(),
1326 ast::TyInfer => this.ty_infer(decl.output.span),
1327 _ => ast_ty_to_ty(this, &rb, &*decl.output)
1336 sig: ty::FnSig {binder_id: id,
1339 variadic: decl.variadic}
1343 pub fn conv_existential_bounds<'tcx, AC: AstConv<'tcx>, RS:RegionScope>(
1347 main_trait_refs: &[Rc<ty::TraitRef>],
1348 ast_bounds: &[ast::TyParamBound])
1349 -> ty::ExistentialBounds
1352 * Given an existential type like `Foo+'a+Bar`, this routine
1353 * converts the `'a` and `Bar` intos an `ExistentialBounds`
1354 * struct. The `main_trait_refs` argument specifies the `Foo` --
1355 * it is absent for closures. Eventually this should all be
1356 * normalized, I think, so that there is no "main trait ref" and
1357 * instead we just have a flat list of bounds as the existential
1361 let ast_bound_refs: Vec<&ast::TyParamBound> =
1362 ast_bounds.iter().collect();
1364 let PartitionedBounds { builtin_bounds,
1367 unboxed_fn_ty_bounds } =
1368 partition_bounds(this.tcx(), span, ast_bound_refs.as_slice());
1370 if !trait_bounds.is_empty() {
1371 let b = trait_bounds.get(0);
1372 this.tcx().sess.span_err(
1374 format!("only the builtin traits can be used \
1375 as closure or object bounds").as_slice());
1378 if !unboxed_fn_ty_bounds.is_empty() {
1379 this.tcx().sess.span_err(
1381 format!("only the builtin traits can be used \
1382 as closure or object bounds").as_slice());
1385 // The "main trait refs", rather annoyingly, have no type
1386 // specified for the `Self` parameter of the trait. The reason for
1387 // this is that they are, after all, *existential* types, and
1388 // hence that type is unknown. However, leaving this type missing
1389 // causes the substitution code to go all awry when walking the
1390 // bounds, so here we clone those trait refs and insert ty::err as
1391 // the self type. Perhaps we should do this more generally, it'd
1392 // be convenient (or perhaps something else, i.e., ty::erased).
1393 let main_trait_refs: Vec<Rc<ty::TraitRef>> =
1394 main_trait_refs.iter()
1396 Rc::new(ty::TraitRef {
1398 substs: t.substs.with_self_ty(ty::mk_err()) }))
1401 let region_bound = compute_region_bound(this,
1405 region_bounds.as_slice(),
1406 main_trait_refs.as_slice());
1408 ty::ExistentialBounds {
1409 region_bound: region_bound,
1410 builtin_bounds: builtin_bounds,
1414 pub fn compute_opt_region_bound(tcx: &ty::ctxt,
1416 builtin_bounds: ty::BuiltinBounds,
1417 region_bounds: &[&ast::Lifetime],
1418 trait_bounds: &[Rc<ty::TraitRef>])
1419 -> Option<ty::Region>
1422 * Given the bounds on a type parameter / existential type,
1423 * determines what single region bound (if any) we can use to
1424 * summarize this type. The basic idea is that we will use the
1425 * bound the user provided, if they provided one, and otherwise
1426 * search the supertypes of trait bounds for region bounds. It may
1427 * be that we can derive no bound at all, in which case we return
1431 if region_bounds.len() > 1 {
1433 region_bounds[1].span,
1434 format!("only a single explicit lifetime bound is permitted").as_slice());
1437 if region_bounds.len() != 0 {
1438 // Explicitly specified region bound. Use that.
1439 let r = region_bounds[0];
1440 return Some(ast_region_to_region(tcx, r));
1443 // No explicit region bound specified. Therefore, examine trait
1444 // bounds and see if we can derive region bounds from those.
1445 let derived_region_bounds =
1446 ty::required_region_bounds(
1452 // If there are no derived region bounds, then report back that we
1453 // can find no region bound.
1454 if derived_region_bounds.len() == 0 {
1458 // If any of the derived region bounds are 'static, that is always
1460 if derived_region_bounds.iter().any(|r| ty::ReStatic == *r) {
1461 return Some(ty::ReStatic);
1464 // Determine whether there is exactly one unique region in the set
1465 // of derived region bounds. If so, use that. Otherwise, report an
1467 let r = *derived_region_bounds.get(0);
1468 if derived_region_bounds.slice_from(1).iter().any(|r1| r != *r1) {
1471 format!("ambiguous lifetime bound, \
1472 explicit lifetime bound required").as_slice());
1477 fn compute_region_bound<'tcx, AC: AstConv<'tcx>, RS:RegionScope>(
1481 builtin_bounds: ty::BuiltinBounds,
1482 region_bounds: &[&ast::Lifetime],
1483 trait_bounds: &[Rc<ty::TraitRef>])
1487 * A version of `compute_opt_region_bound` for use where some
1488 * region bound is required (existential types,
1489 * basically). Reports an error if no region bound can be derived
1490 * and we are in an `rscope` that does not provide a default.
1493 match compute_opt_region_bound(this.tcx(), span, builtin_bounds,
1494 region_bounds, trait_bounds) {
1497 match rscope.default_region_bound(span) {
1500 this.tcx().sess.span_err(
1502 format!("explicit lifetime bound required").as_slice());
1510 pub struct PartitionedBounds<'a> {
1511 pub builtin_bounds: ty::BuiltinBounds,
1512 pub trait_bounds: Vec<&'a ast::TraitRef>,
1513 pub unboxed_fn_ty_bounds: Vec<&'a ast::UnboxedFnTy>,
1514 pub region_bounds: Vec<&'a ast::Lifetime>,
1517 pub fn partition_bounds<'a>(tcx: &ty::ctxt,
1519 ast_bounds: &'a [&ast::TyParamBound])
1520 -> PartitionedBounds<'a>
1523 * Divides a list of bounds from the AST into three groups:
1524 * builtin bounds (Copy, Sized etc), general trait bounds,
1525 * and region bounds.
1528 let mut builtin_bounds = ty::empty_builtin_bounds();
1529 let mut region_bounds = Vec::new();
1530 let mut trait_bounds = Vec::new();
1531 let mut unboxed_fn_ty_bounds = Vec::new();
1532 let mut trait_def_ids = HashMap::new();
1533 for &ast_bound in ast_bounds.iter() {
1535 ast::TraitTyParamBound(ref b) => {
1536 match lookup_def_tcx(tcx, b.path.span, b.ref_id) {
1537 def::DefTrait(trait_did) => {
1538 match trait_def_ids.find(&trait_did) {
1539 // Already seen this trait. We forbid
1540 // duplicates in the list (for some
1544 tcx.sess, b.path.span, E0127,
1545 "trait `{}` already appears in the \
1547 b.path.user_string(tcx));
1550 "previous appearance is here");
1558 trait_def_ids.insert(trait_did, b.path.span);
1560 if ty::try_add_builtin_trait(tcx,
1562 &mut builtin_bounds) {
1563 continue; // success
1567 // Not a trait? that's an error, but it'll get
1571 trait_bounds.push(b);
1573 ast::RegionTyParamBound(ref l) => {
1574 region_bounds.push(l);
1576 ast::UnboxedFnTyParamBound(ref unboxed_function) => {
1577 unboxed_fn_ty_bounds.push(unboxed_function);
1583 builtin_bounds: builtin_bounds,
1584 trait_bounds: trait_bounds,
1585 region_bounds: region_bounds,
1586 unboxed_fn_ty_bounds: unboxed_fn_ty_bounds