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;
74 pub trait AstConv<'tcx> {
75 fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx>;
76 fn get_item_ty(&self, id: ast::DefId) -> ty::Polytype;
77 fn get_trait_def(&self, id: ast::DefId) -> Rc<ty::TraitDef>;
79 // what type should we use when a type is omitted?
80 fn ty_infer(&self, span: Span) -> ty::t;
83 pub fn ast_region_to_region(tcx: &ty::ctxt, lifetime: &ast::Lifetime)
85 let r = match tcx.named_region_map.find(&lifetime.id) {
87 // should have been recorded by the `resolve_lifetime` pass
88 tcx.sess.span_bug(lifetime.span, "unresolved lifetime");
91 Some(&rl::DefStaticRegion) => {
95 Some(&rl::DefLateBoundRegion(binder_id, _, id)) => {
96 ty::ReLateBound(binder_id, ty::BrNamed(ast_util::local_def(id),
100 Some(&rl::DefEarlyBoundRegion(space, index, id)) => {
101 ty::ReEarlyBound(id, space, index, lifetime.name)
104 Some(&rl::DefFreeRegion(scope_id, id)) => {
105 ty::ReFree(ty::FreeRegion {
107 bound_region: ty::BrNamed(ast_util::local_def(id),
113 debug!("ast_region_to_region(lifetime={} id={}) yields {}",
121 pub fn opt_ast_region_to_region<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
125 opt_lifetime: &Option<ast::Lifetime>) -> ty::Region
127 let r = match *opt_lifetime {
128 Some(ref lifetime) => {
129 ast_region_to_region(this.tcx(), lifetime)
133 match rscope.anon_regions(default_span, 1) {
135 debug!("optional region in illegal location");
136 span_err!(this.tcx().sess, default_span, E0106,
137 "missing lifetime specifier");
148 debug!("opt_ast_region_to_region(opt_lifetime={}) yields {}",
149 opt_lifetime.repr(this.tcx()),
155 fn ast_path_substs<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
158 decl_generics: &ty::Generics,
159 self_ty: Option<ty::t>,
160 path: &ast::Path) -> Substs
163 * Given a path `path` that refers to an item `I` with the
164 * declared generics `decl_generics`, returns an appropriate
165 * set of substitutions for this particular reference to `I`.
168 let tcx = this.tcx();
170 // ast_path_substs() is only called to convert paths that are
171 // known to refer to traits, types, or structs. In these cases,
172 // all type parameters defined for the item being referenced will
173 // be in the TypeSpace or SelfSpace.
175 // Note: in the case of traits, the self parameter is also
176 // defined, but we don't currently create a `type_param_def` for
177 // `Self` because it is implicit.
178 assert!(decl_generics.regions.all(|d| d.space == TypeSpace));
179 assert!(decl_generics.types.all(|d| d.space != FnSpace));
181 // If the type is parameterized by the this region, then replace this
182 // region with the current anon region binding (in other words,
183 // whatever & would get replaced with).
184 let expected_num_region_params = decl_generics.regions.len(TypeSpace);
185 let supplied_num_region_params = path.segments.last().unwrap().lifetimes.len();
186 let regions = if expected_num_region_params == supplied_num_region_params {
187 path.segments.last().unwrap().lifetimes.iter().map(
188 |l| ast_region_to_region(this.tcx(), l)).collect::<Vec<_>>()
191 rscope.anon_regions(path.span, expected_num_region_params);
193 if supplied_num_region_params != 0 || anon_regions.is_err() {
194 span_err!(tcx.sess, path.span, E0107,
195 "wrong number of lifetime parameters: expected {}, found {}",
196 expected_num_region_params, supplied_num_region_params);
200 Ok(v) => v.into_iter().collect(),
201 Err(()) => Vec::from_fn(expected_num_region_params,
202 |_| ty::ReStatic) // hokey
206 // Convert the type parameters supplied by the user.
207 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
208 let supplied_ty_param_count = path.segments.iter().flat_map(|s| s.types.iter()).count();
209 let formal_ty_param_count = ty_param_defs.len();
210 let required_ty_param_count = ty_param_defs.iter()
211 .take_while(|x| x.default.is_none())
213 if supplied_ty_param_count < required_ty_param_count {
214 let expected = if required_ty_param_count < formal_ty_param_count {
219 this.tcx().sess.span_fatal(path.span,
220 format!("wrong number of type arguments: {} {}, found {}",
222 required_ty_param_count,
223 supplied_ty_param_count).as_slice());
224 } else if supplied_ty_param_count > formal_ty_param_count {
225 let expected = if required_ty_param_count < formal_ty_param_count {
230 this.tcx().sess.span_fatal(path.span,
231 format!("wrong number of type arguments: {} {}, found {}",
233 formal_ty_param_count,
234 supplied_ty_param_count).as_slice());
237 if supplied_ty_param_count > required_ty_param_count
238 && !this.tcx().sess.features.default_type_params.get() {
239 span_err!(this.tcx().sess, path.span, E0108,
240 "default type parameters are experimental and possibly buggy");
241 span_note!(this.tcx().sess, path.span,
242 "add #![feature(default_type_params)] to the crate attributes to enable");
245 let tps = path.segments.iter().flat_map(|s| s.types.iter())
246 .map(|a_t| ast_ty_to_ty(this, rscope, &**a_t))
249 let mut substs = Substs::new_type(tps, regions);
253 // If no self-type is provided, it's still possible that
254 // one was declared, because this could be an object type.
257 // If a self-type is provided, one should have been
258 // "declared" (in other words, this should be a
260 assert!(decl_generics.types.get_self().is_some());
261 substs.types.push(SelfSpace, ty);
265 for param in ty_param_defs.slice_from(supplied_ty_param_count).iter() {
266 let default = param.default.unwrap();
267 let default = default.subst_spanned(tcx, &substs, Some(path.span));
268 substs.types.push(TypeSpace, default);
274 pub fn ast_path_to_trait_ref<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
277 trait_def_id: ast::DefId,
278 self_ty: Option<ty::t>,
279 path: &ast::Path) -> Rc<ty::TraitRef> {
280 let trait_def = this.get_trait_def(trait_def_id);
281 Rc::new(ty::TraitRef {
282 def_id: trait_def_id,
283 substs: ast_path_substs(this, rscope, &trait_def.generics, self_ty, path)
287 pub fn ast_path_to_ty<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
294 let tcx = this.tcx();
298 } = this.get_item_ty(did);
300 let substs = ast_path_substs(this, rscope, &generics, None, path);
301 let ty = decl_ty.subst(tcx, &substs);
302 TypeAndSubsts { substs: substs, ty: ty }
305 /// Returns the type that this AST path refers to. If the path has no type
306 /// parameters and the corresponding type has type parameters, fresh type
307 /// and/or region variables are substituted.
309 /// This is used when checking the constructor in struct literals.
310 pub fn ast_path_to_ty_relaxed<'tcx, AC: AstConv<'tcx>,
317 let tcx = this.tcx();
321 } = this.get_item_ty(did);
323 let substs = if (generics.has_type_params(TypeSpace) ||
324 generics.has_region_params(TypeSpace)) &&
325 path.segments.iter().all(|s| {
326 s.lifetimes.len() == 0 && s.types.len() == 0
328 let type_params = Vec::from_fn(generics.types.len(TypeSpace),
329 |_| this.ty_infer(path.span));
331 rscope.anon_regions(path.span, generics.regions.len(TypeSpace))
333 Substs::new(VecPerParamSpace::params_from_type(type_params),
334 VecPerParamSpace::params_from_type(region_params))
336 ast_path_substs(this, rscope, &generics, None, path)
339 let ty = decl_ty.subst(tcx, &substs);
346 pub static NO_REGIONS: uint = 1;
347 pub static NO_TPS: uint = 2;
349 fn check_path_args(tcx: &ty::ctxt,
352 if (flags & NO_TPS) != 0u {
353 if !path.segments.iter().all(|s| s.types.is_empty()) {
354 span_err!(tcx.sess, path.span, E0109,
355 "type parameters are not allowed on this type");
359 if (flags & NO_REGIONS) != 0u {
360 if !path.segments.last().unwrap().lifetimes.is_empty() {
361 span_err!(tcx.sess, path.span, E0110,
362 "region parameters are not allowed on this type");
367 pub fn ast_ty_to_prim_ty(tcx: &ty::ctxt, ast_ty: &ast::Ty) -> Option<ty::t> {
369 ast::TyPath(ref path, _, id) => {
370 let a_def = match tcx.def_map.borrow().find(&id) {
372 tcx.sess.span_bug(ast_ty.span,
373 format!("unbound path {}",
374 path.repr(tcx)).as_slice())
379 def::DefPrimTy(nty) => {
382 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
386 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
390 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
391 Some(ty::mk_mach_int(it))
393 ast::TyUint(uit) => {
394 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
395 Some(ty::mk_mach_uint(uit))
397 ast::TyFloat(ft) => {
398 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
399 Some(ty::mk_mach_float(ft))
402 Some(ty::mk_str(tcx))
413 /// Converts the given AST type to a built-in type. A "built-in type" is, at
414 /// present, either a core numeric type, a string, or `Box`.
415 pub fn ast_ty_to_builtin_ty<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
420 match ast_ty_to_prim_ty(this.tcx(), ast_ty) {
421 Some(typ) => return Some(typ),
426 ast::TyPath(ref path, _, id) => {
427 let a_def = match this.tcx().def_map.borrow().find(&id) {
431 .span_bug(ast_ty.span,
432 format!("unbound path {}",
433 path.repr(this.tcx())).as_slice())
438 // FIXME(#12938): This is a hack until we have full support for
441 def::DefTy(did) | def::DefStruct(did)
442 if Some(did) == this.tcx().lang_items.owned_box() => {
445 .flat_map(|s| s.types.iter())
447 span_err!(this.tcx().sess, path.span, E0047,
448 "`Box` has only one type parameter");
451 for inner_ast_type in path.segments
453 .flat_map(|s| s.types.iter()) {
454 return Some(mk_pointer(this,
459 |typ| ty::mk_uniq(this.tcx(), typ)));
461 span_err!(this.tcx().sess, path.span, E0113,
462 "not enough type parameters supplied to `Box<T>`");
465 def::DefTy(did) | def::DefStruct(did)
466 if Some(did) == this.tcx().lang_items.gc() => {
469 .flat_map(|s| s.types.iter())
471 span_err!(this.tcx().sess, path.span, E0048,
472 "`Gc` has only one type parameter");
475 for inner_ast_type in path.segments
477 .flat_map(|s| s.types.iter()) {
478 return Some(mk_pointer(this,
484 match ty::get(typ).sty {
486 span_err!(this.tcx().sess, path.span, E0114,
487 "`Gc<str>` is not a type");
490 ty::ty_vec(_, None) => {
491 span_err!(this.tcx().sess, path.span, E0115,
492 "`Gc<[T]>` is not a type");
495 _ => ty::mk_box(this.tcx(), typ),
499 this.tcx().sess.span_bug(path.span,
500 "not enough type parameters \
501 supplied to `Gc<T>`")
518 fn default_region(&self) -> ty::Region {
521 Uniq => ty::ReStatic,
527 pub fn trait_ref_for_unboxed_function<'tcx, AC: AstConv<'tcx>,
531 unboxed_function: &ast::UnboxedFnTy,
532 self_ty: Option<ty::t>)
534 let lang_item = match unboxed_function.kind {
535 ast::FnUnboxedClosureKind => FnTraitLangItem,
536 ast::FnMutUnboxedClosureKind => FnMutTraitLangItem,
537 ast::FnOnceUnboxedClosureKind => FnOnceTraitLangItem,
539 let trait_did = this.tcx().lang_items.require(lang_item).unwrap();
541 unboxed_function.decl
545 ast_ty_to_ty(this, rscope, &*input.ty)
546 }).collect::<Vec<_>>();
547 let input_tuple = if input_types.len() == 0 {
550 ty::mk_tup(this.tcx(), input_types)
552 let output_type = ast_ty_to_ty(this,
554 &*unboxed_function.decl.output);
555 let mut substs = Substs::new_type(vec!(input_tuple, output_type),
559 Some(s) => substs.types.push(SelfSpace, s),
569 // Handle `~`, `Box`, and `&` being able to mean strs and vecs.
570 // If a_seq_ty is a str or a vec, make it a str/vec.
571 // Also handle first-class trait types.
572 fn mk_pointer<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
575 a_seq_mutbl: ast::Mutability,
578 constr: |ty::t| -> ty::t)
580 let tcx = this.tcx();
581 debug!("mk_pointer(ptr_ty={})", ptr_ty);
583 match a_seq_ty.node {
584 ast::TyVec(ref ty) => {
585 let ty = ast_ty_to_ty(this, rscope, &**ty);
586 return constr(ty::mk_vec(tcx, ty, None));
588 ast::TyUnboxedFn(ref unboxed_function) => {
592 } = trait_ref_for_unboxed_function(this,
596 let r = ptr_ty.default_region();
597 let tr = ty::mk_trait(this.tcx(),
600 ty::region_existential_bound(r));
603 return ty::mk_uniq(this.tcx(), tr);
606 return ty::mk_rptr(this.tcx(),
608 ty::mt {mutbl: a_seq_mutbl, ty: tr});
613 "~trait or &trait are the only supported \
614 forms of casting-to-trait");
620 ast::TyPath(ref path, ref opt_bounds, id) => {
621 // Note that the "bounds must be empty if path is not a trait"
622 // restriction is enforced in the below case for ty_path, which
623 // will run after this as long as the path isn't a trait.
624 match tcx.def_map.borrow().find(&id) {
625 Some(&def::DefPrimTy(ast::TyStr)) => {
626 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
629 return constr(ty::mk_str(tcx));
632 return ty::mk_str_slice(tcx, r, ast::MutImmutable);
637 "managed strings are not supported")
641 Some(&def::DefTrait(trait_def_id)) => {
642 let result = ast_path_to_trait_ref(
643 this, rscope, trait_def_id, None, path);
644 let bounds = match *opt_bounds {
646 conv_existential_bounds(this,
649 [result.clone()].as_slice(),
652 Some(ref bounds) => {
653 conv_existential_bounds(this,
656 [result.clone()].as_slice(),
660 let tr = ty::mk_trait(tcx,
662 result.substs.clone(),
664 return match ptr_ty {
666 return ty::mk_uniq(tcx, tr);
669 return ty::mk_rptr(tcx, r, ty::mt{mutbl: a_seq_mutbl, ty: tr});
674 "~trait or &trait are the only supported \
675 forms of casting-to-trait");
686 constr(ast_ty_to_ty(this, rscope, a_seq_ty))
689 // Parses the programmer's textual representation of a type into our
690 // internal notion of a type.
691 pub fn ast_ty_to_ty<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(
692 this: &AC, rscope: &RS, ast_ty: &ast::Ty) -> ty::t {
694 let tcx = this.tcx();
696 let mut ast_ty_to_ty_cache = tcx.ast_ty_to_ty_cache.borrow_mut();
697 match ast_ty_to_ty_cache.find(&ast_ty.id) {
698 Some(&ty::atttce_resolved(ty)) => return ty,
699 Some(&ty::atttce_unresolved) => {
700 tcx.sess.span_fatal(ast_ty.span,
701 "illegal recursive type; insert an enum \
702 or struct in the cycle, if this is \
705 None => { /* go on */ }
707 ast_ty_to_ty_cache.insert(ast_ty.id, ty::atttce_unresolved);
708 drop(ast_ty_to_ty_cache);
710 let typ = ast_ty_to_builtin_ty(this, rscope, ast_ty).unwrap_or_else(|| {
712 ast::TyNil => ty::mk_nil(),
713 ast::TyBot => ty::mk_bot(),
714 ast::TyBox(ref ty) => {
715 mk_pointer(this, rscope, ast::MutImmutable, &**ty, Box,
716 |ty| ty::mk_box(tcx, ty))
718 ast::TyUniq(ref ty) => {
719 mk_pointer(this, rscope, ast::MutImmutable, &**ty, Uniq,
720 |ty| ty::mk_uniq(tcx, ty))
722 ast::TyVec(ref ty) => {
723 ty::mk_vec(tcx, ast_ty_to_ty(this, rscope, &**ty), None)
725 ast::TyPtr(ref mt) => {
726 ty::mk_ptr(tcx, ty::mt {
727 ty: ast_ty_to_ty(this, rscope, &*mt.ty),
731 ast::TyRptr(ref region, ref mt) => {
732 let r = opt_ast_region_to_region(this, rscope, ast_ty.span, region);
733 debug!("ty_rptr r={}", r.repr(this.tcx()));
734 mk_pointer(this, rscope, mt.mutbl, &*mt.ty, RPtr(r),
735 |ty| ty::mk_rptr(tcx, r, ty::mt {ty: ty, mutbl: mt.mutbl}))
737 ast::TyTup(ref fields) => {
738 let flds = fields.iter()
739 .map(|t| ast_ty_to_ty(this, rscope, &**t))
741 ty::mk_tup(tcx, flds)
743 ast::TyParen(ref typ) => ast_ty_to_ty(this, rscope, &**typ),
744 ast::TyBareFn(ref bf) => {
745 if bf.decl.variadic && bf.abi != abi::C {
746 tcx.sess.span_err(ast_ty.span,
747 "variadic function must have C calling convention");
749 ty::mk_bare_fn(tcx, ty_of_bare_fn(this, ast_ty.id, bf.fn_style,
752 ast::TyClosure(ref f) => {
753 // Use corresponding trait store to figure out default bounds
754 // if none were specified.
755 let bounds = conv_existential_bounds(this,
759 f.bounds.as_slice());
760 let fn_decl = ty_of_closure(this,
765 ty::RegionTraitStore(
771 ty::mk_closure(tcx, fn_decl)
773 ast::TyProc(ref f) => {
774 // Use corresponding trait store to figure out default bounds
775 // if none were specified.
776 let bounds = conv_existential_bounds(this, rscope,
779 f.bounds.as_slice());
781 let fn_decl = ty_of_closure(this,
791 ty::mk_closure(tcx, fn_decl)
793 ast::TyUnboxedFn(..) => {
794 tcx.sess.span_err(ast_ty.span,
795 "cannot use unboxed functions here");
798 ast::TyPath(ref path, ref bounds, id) => {
799 let a_def = match tcx.def_map.borrow().find(&id) {
802 .span_bug(ast_ty.span,
803 format!("unbound path {}",
804 path.repr(tcx)).as_slice())
808 // Kind bounds on path types are only supported for traits.
810 // But don't emit the error if the user meant to do a trait anyway.
811 def::DefTrait(..) => { },
812 _ if bounds.is_some() =>
813 tcx.sess.span_err(ast_ty.span,
814 "kind bounds can only be used on trait types"),
818 def::DefTrait(trait_def_id) => {
819 let result = ast_path_to_trait_ref(
820 this, rscope, trait_def_id, None, path);
821 let empty_bounds: &[ast::TyParamBound] = &[];
822 let ast_bounds = match *bounds {
823 Some(ref b) => b.as_slice(),
826 let bounds = conv_existential_bounds(this,
833 result.substs.clone(),
836 def::DefTy(did) | def::DefStruct(did) => {
837 ast_path_to_ty(this, rscope, did, path).ty
839 def::DefTyParam(space, id, n) => {
840 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
841 ty::mk_param(tcx, space, n, id)
843 def::DefSelfTy(id) => {
844 // n.b.: resolve guarantees that the this type only appears in a
845 // trait, which we rely upon in various places when creating
847 check_path_args(tcx, path, NO_TPS | NO_REGIONS);
848 let did = ast_util::local_def(id);
849 ty::mk_self_type(tcx, did)
852 tcx.sess.span_fatal(ast_ty.span,
853 format!("found module name used as a type: {}",
854 tcx.map.node_to_string(id.node)).as_slice());
856 def::DefPrimTy(_) => {
857 fail!("DefPrimTy arm missed in previous ast_ty_to_prim_ty call");
860 tcx.sess.span_fatal(ast_ty.span,
861 format!("found value name used \
867 ast::TyFixedLengthVec(ref ty, ref e) => {
868 match const_eval::eval_const_expr_partial(tcx, &**e) {
871 const_eval::const_int(i) =>
872 ty::mk_vec(tcx, ast_ty_to_ty(this, rscope, &**ty),
874 const_eval::const_uint(i) =>
875 ty::mk_vec(tcx, ast_ty_to_ty(this, rscope, &**ty),
879 ast_ty.span, "expected constant expr for vector length");
886 format!("expected constant expr for vector \
892 ast::TyTypeof(ref _e) => {
893 tcx.sess.span_bug(ast_ty.span, "typeof is reserved but unimplemented");
896 // TyInfer also appears as the type of arguments or return
897 // values in a ExprFnBlock, ExprProc, or ExprUnboxedFn, or as
898 // the type of local variables. Both of these cases are
899 // handled specially and will not descend into this routine.
900 this.ty_infer(ast_ty.span)
905 tcx.ast_ty_to_ty_cache.borrow_mut().insert(ast_ty.id, ty::atttce_resolved(typ));
909 pub fn ty_of_arg<'tcx, AC: AstConv<'tcx>, RS: RegionScope>(this: &AC, rscope: &RS,
911 expected_ty: Option<ty::t>)
914 ast::TyInfer if expected_ty.is_some() => expected_ty.unwrap(),
915 ast::TyInfer => this.ty_infer(a.ty.span),
916 _ => ast_ty_to_ty(this, rscope, &*a.ty),
920 struct SelfInfo<'a> {
921 untransformed_self_ty: ty::t,
922 explicit_self: &'a ast::ExplicitSelf,
925 pub fn ty_of_method<'tcx, AC: AstConv<'tcx>>(
928 fn_style: ast::FnStyle,
929 untransformed_self_ty: ty::t,
930 explicit_self: &ast::ExplicitSelf,
933 -> (ty::BareFnTy, ty::ExplicitSelfCategory) {
934 let self_info = Some(SelfInfo {
935 untransformed_self_ty: untransformed_self_ty,
936 explicit_self: explicit_self,
938 let (bare_fn_ty, optional_explicit_self_category) =
939 ty_of_method_or_bare_fn(this,
945 (bare_fn_ty, optional_explicit_self_category.unwrap())
948 pub fn ty_of_bare_fn<'tcx, AC: AstConv<'tcx>>(this: &AC, id: ast::NodeId,
949 fn_style: ast::FnStyle, abi: abi::Abi,
950 decl: &ast::FnDecl) -> ty::BareFnTy {
951 let (bare_fn_ty, _) =
952 ty_of_method_or_bare_fn(this, id, fn_style, abi, None, decl);
956 fn ty_of_method_or_bare_fn<'tcx, AC: AstConv<'tcx>>(
959 fn_style: ast::FnStyle,
961 opt_self_info: Option<SelfInfo>,
964 Option<ty::ExplicitSelfCategory>) {
965 debug!("ty_of_method_or_bare_fn");
967 // New region names that appear inside of the arguments of the function
968 // declaration are bound to that function type.
969 let rb = rscope::BindingRscope::new(id);
971 // `implied_output_region` is the region that will be assumed for any
972 // region parameters in the return type. In accordance with the rules for
973 // lifetime elision, we can determine it in two ways. First (determined
974 // here), if self is by-reference, then the implied output region is the
975 // region of the self parameter.
976 let mut explicit_self_category_result = None;
977 let (self_ty, mut implied_output_region) = match opt_self_info {
978 None => (None, None),
980 // Figure out and record the explicit self category.
981 let explicit_self_category =
982 determine_explicit_self_category(this, &rb, &self_info);
983 explicit_self_category_result = Some(explicit_self_category);
984 match explicit_self_category {
985 ty::StaticExplicitSelfCategory => (None, None),
986 ty::ByValueExplicitSelfCategory => {
987 (Some(self_info.untransformed_self_ty), None)
989 ty::ByReferenceExplicitSelfCategory(region, mutability) => {
990 (Some(ty::mk_rptr(this.tcx(),
993 ty: self_info.untransformed_self_ty,
998 ty::ByBoxExplicitSelfCategory => {
999 (Some(ty::mk_uniq(this.tcx(),
1000 self_info.untransformed_self_ty)),
1007 // HACK(eddyb) replace the fake self type in the AST with the actual type.
1008 let input_tys = if self_ty.is_some() {
1009 decl.inputs.slice_from(1)
1011 decl.inputs.as_slice()
1013 let input_tys = input_tys.iter().map(|a| ty_of_arg(this, &rb, a, None));
1014 let self_and_input_tys: Vec<_> =
1015 self_ty.into_iter().chain(input_tys).collect();
1017 // Second, if there was exactly one lifetime (either a substitution or a
1018 // reference) in the arguments, then any anonymous regions in the output
1019 // have that lifetime.
1020 if implied_output_region.is_none() {
1021 let mut self_and_input_tys_iter = self_and_input_tys.iter();
1022 if self_ty.is_some() {
1023 // Skip the first argument if `self` is present.
1024 drop(self_and_input_tys_iter.next())
1027 let mut accumulator = Vec::new();
1028 for input_type in self_and_input_tys_iter {
1029 ty::accumulate_lifetimes_in_type(&mut accumulator, *input_type)
1031 if accumulator.len() == 1 {
1032 implied_output_region = Some(*accumulator.get(0));
1036 let output_ty = match decl.output.node {
1037 ast::TyInfer => this.ty_infer(decl.output.span),
1039 match implied_output_region {
1040 Some(implied_output_region) => {
1041 let rb = SpecificRscope::new(implied_output_region);
1042 ast_ty_to_ty(this, &rb, &*decl.output)
1045 // All regions must be explicitly specified in the output
1046 // if the lifetime elision rules do not apply. This saves
1047 // the user from potentially-confusing errors.
1048 let rb = ExplicitRscope;
1049 ast_ty_to_ty(this, &rb, &*decl.output)
1060 inputs: self_and_input_tys,
1062 variadic: decl.variadic
1064 }, explicit_self_category_result)
1067 fn determine_explicit_self_category<'tcx, AC: AstConv<'tcx>,
1071 self_info: &SelfInfo)
1072 -> ty::ExplicitSelfCategory {
1073 match self_info.explicit_self.node {
1074 ast::SelfStatic => ty::StaticExplicitSelfCategory,
1075 ast::SelfValue(_) => ty::ByValueExplicitSelfCategory,
1076 ast::SelfRegion(ref lifetime, mutability, _) => {
1078 opt_ast_region_to_region(this,
1080 self_info.explicit_self.span,
1082 ty::ByReferenceExplicitSelfCategory(region, mutability)
1084 ast::SelfExplicit(ref ast_type, _) => {
1085 let explicit_type = ast_ty_to_ty(this, rscope, &**ast_type);
1088 let inference_context = infer::new_infer_ctxt(this.tcx());
1089 let expected_self = self_info.untransformed_self_ty;
1090 let actual_self = explicit_type;
1091 let result = infer::mk_eqty(
1094 infer::Misc(self_info.explicit_self.span),
1099 inference_context.resolve_regions_and_report_errors();
1100 return ty::ByValueExplicitSelfCategory
1106 match ty::get(explicit_type).sty {
1107 ty::ty_rptr(region, tm) => {
1108 typeck::require_same_types(
1112 self_info.explicit_self.span,
1113 self_info.untransformed_self_ty,
1115 || "not a valid type for `self`".to_owned());
1116 return ty::ByReferenceExplicitSelfCategory(region,
1119 ty::ty_uniq(typ) => {
1120 typeck::require_same_types(
1124 self_info.explicit_self.span,
1125 self_info.untransformed_self_ty,
1127 || "not a valid type for `self`".to_owned());
1128 return ty::ByBoxExplicitSelfCategory
1133 .span_err(self_info.explicit_self.span,
1134 "not a valid type for `self`");
1135 return ty::ByValueExplicitSelfCategory
1142 pub fn ty_of_closure<'tcx, AC: AstConv<'tcx>>(
1145 fn_style: ast::FnStyle,
1146 onceness: ast::Onceness,
1147 bounds: ty::ExistentialBounds,
1148 store: ty::TraitStore,
1151 expected_sig: Option<ty::FnSig>)
1154 debug!("ty_of_fn_decl");
1156 // new region names that appear inside of the fn decl are bound to
1157 // that function type
1158 let rb = rscope::BindingRscope::new(id);
1160 let input_tys = decl.inputs.iter().enumerate().map(|(i, a)| {
1161 let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
1162 // no guarantee that the correct number of expected args
1164 if i < e.inputs.len() {
1165 Some(*e.inputs.get(i))
1170 ty_of_arg(this, &rb, a, expected_arg_ty)
1173 let expected_ret_ty = expected_sig.map(|e| e.output);
1174 let output_ty = match decl.output.node {
1175 ast::TyInfer if expected_ret_ty.is_some() => expected_ret_ty.unwrap(),
1176 ast::TyInfer => this.ty_infer(decl.output.span),
1177 _ => ast_ty_to_ty(this, &rb, &*decl.output)
1186 sig: ty::FnSig {binder_id: id,
1189 variadic: decl.variadic}
1193 pub fn conv_existential_bounds<'tcx, AC: AstConv<'tcx>, RS:RegionScope>(
1197 main_trait_refs: &[Rc<ty::TraitRef>],
1198 ast_bounds: &[ast::TyParamBound])
1199 -> ty::ExistentialBounds
1202 * Given an existential type like `Foo+'a+Bar`, this routine
1203 * converts the `'a` and `Bar` intos an `ExistentialBounds`
1204 * struct. The `main_trait_refs` argument specifies the `Foo` --
1205 * it is absent for closures. Eventually this should all be
1206 * normalized, I think, so that there is no "main trait ref" and
1207 * instead we just have a flat list of bounds as the existential
1211 let ast_bound_refs: Vec<&ast::TyParamBound> =
1212 ast_bounds.iter().collect();
1214 let PartitionedBounds { builtin_bounds,
1217 unboxed_fn_ty_bounds } =
1218 partition_bounds(this.tcx(), span, ast_bound_refs.as_slice());
1220 if !trait_bounds.is_empty() {
1221 let b = trait_bounds.get(0);
1222 this.tcx().sess.span_err(
1224 format!("only the builtin traits can be used \
1225 as closure or object bounds").as_slice());
1228 if !unboxed_fn_ty_bounds.is_empty() {
1229 this.tcx().sess.span_err(
1231 format!("only the builtin traits can be used \
1232 as closure or object bounds").as_slice());
1235 // The "main trait refs", rather annoyingly, have no type
1236 // specified for the `Self` parameter of the trait. The reason for
1237 // this is that they are, after all, *existential* types, and
1238 // hence that type is unknown. However, leaving this type missing
1239 // causes the substitution code to go all awry when walking the
1240 // bounds, so here we clone those trait refs and insert ty::err as
1241 // the self type. Perhaps we should do this more generally, it'd
1242 // be convenient (or perhaps something else, i.e., ty::erased).
1243 let main_trait_refs: Vec<Rc<ty::TraitRef>> =
1244 main_trait_refs.iter()
1246 Rc::new(ty::TraitRef {
1248 substs: t.substs.with_self_ty(ty::mk_err()) }))
1251 let region_bound = compute_region_bound(this,
1255 region_bounds.as_slice(),
1256 main_trait_refs.as_slice());
1258 ty::ExistentialBounds {
1259 region_bound: region_bound,
1260 builtin_bounds: builtin_bounds,
1264 pub fn compute_opt_region_bound(tcx: &ty::ctxt,
1266 builtin_bounds: ty::BuiltinBounds,
1267 region_bounds: &[&ast::Lifetime],
1268 trait_bounds: &[Rc<ty::TraitRef>])
1269 -> Option<ty::Region>
1272 * Given the bounds on a type parameter / existential type,
1273 * determines what single region bound (if any) we can use to
1274 * summarize this type. The basic idea is that we will use the
1275 * bound the user provided, if they provided one, and otherwise
1276 * search the supertypes of trait bounds for region bounds. It may
1277 * be that we can derive no bound at all, in which case we return
1281 if region_bounds.len() > 1 {
1283 region_bounds[1].span,
1284 format!("only a single explicit lifetime bound is permitted").as_slice());
1287 if region_bounds.len() != 0 {
1288 // Explicitly specified region bound. Use that.
1289 let r = region_bounds[0];
1290 return Some(ast_region_to_region(tcx, r));
1293 // No explicit region bound specified. Therefore, examine trait
1294 // bounds and see if we can derive region bounds from those.
1295 let derived_region_bounds =
1296 ty::required_region_bounds(
1302 // If there are no derived region bounds, then report back that we
1303 // can find no region bound.
1304 if derived_region_bounds.len() == 0 {
1308 // If any of the derived region bounds are 'static, that is always
1310 if derived_region_bounds.iter().any(|r| ty::ReStatic == *r) {
1311 return Some(ty::ReStatic);
1314 // Determine whether there is exactly one unique region in the set
1315 // of derived region bounds. If so, use that. Otherwise, report an
1317 let r = *derived_region_bounds.get(0);
1318 if derived_region_bounds.slice_from(1).iter().any(|r1| r != *r1) {
1321 format!("ambiguous lifetime bound, \
1322 explicit lifetime bound required").as_slice());
1327 fn compute_region_bound<'tcx, AC: AstConv<'tcx>, RS:RegionScope>(
1331 builtin_bounds: ty::BuiltinBounds,
1332 region_bounds: &[&ast::Lifetime],
1333 trait_bounds: &[Rc<ty::TraitRef>])
1337 * A version of `compute_opt_region_bound` for use where some
1338 * region bound is required (existential types,
1339 * basically). Reports an error if no region bound can be derived
1340 * and we are in an `rscope` that does not provide a default.
1343 match compute_opt_region_bound(this.tcx(), span, builtin_bounds,
1344 region_bounds, trait_bounds) {
1347 match rscope.default_region_bound(span) {
1350 this.tcx().sess.span_err(
1352 format!("explicit lifetime bound required").as_slice());
1360 pub struct PartitionedBounds<'a> {
1361 pub builtin_bounds: ty::BuiltinBounds,
1362 pub trait_bounds: Vec<&'a ast::TraitRef>,
1363 pub unboxed_fn_ty_bounds: Vec<&'a ast::UnboxedFnTy>,
1364 pub region_bounds: Vec<&'a ast::Lifetime>,
1367 pub fn partition_bounds<'a>(tcx: &ty::ctxt,
1369 ast_bounds: &'a [&ast::TyParamBound])
1370 -> PartitionedBounds<'a>
1373 * Divides a list of bounds from the AST into three groups:
1374 * builtin bounds (Copy, Sized etc), general trait bounds,
1375 * and region bounds.
1378 let mut builtin_bounds = ty::empty_builtin_bounds();
1379 let mut region_bounds = Vec::new();
1380 let mut trait_bounds = Vec::new();
1381 let mut unboxed_fn_ty_bounds = Vec::new();
1382 let mut trait_def_ids = HashMap::new();
1383 for &ast_bound in ast_bounds.iter() {
1385 ast::TraitTyParamBound(ref b) => {
1386 match lookup_def_tcx(tcx, b.path.span, b.ref_id) {
1387 def::DefTrait(trait_did) => {
1388 match trait_def_ids.find(&trait_did) {
1389 // Already seen this trait. We forbid
1390 // duplicates in the list (for some
1394 tcx.sess, b.path.span, E0127,
1395 "trait `{}` already appears in the \
1397 b.path.user_string(tcx));
1400 "previous appearance is here");
1408 trait_def_ids.insert(trait_did, b.path.span);
1410 if ty::try_add_builtin_trait(tcx,
1412 &mut builtin_bounds) {
1413 continue; // success
1417 // Not a trait? that's an error, but it'll get
1421 trait_bounds.push(b);
1423 ast::RegionTyParamBound(ref l) => {
1424 region_bounds.push(l);
1426 ast::UnboxedFnTyParamBound(ref unboxed_function) => {
1427 unboxed_fn_ty_bounds.push(unboxed_function);
1433 builtin_bounds: builtin_bounds,
1434 trait_bounds: trait_bounds,
1435 region_bounds: region_bounds,
1436 unboxed_fn_ty_bounds: unboxed_fn_ty_bounds