00fcf79448
type-outlives works for closure types so that it ensures that all upvars outlive the region in question. This gives the same guarantees but without introducing artificial regions (and gives better error messages to boot).
100 lines
3.7 KiB
Rust
100 lines
3.7 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use middle::ty::{self, Ty};
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use syntax::ast;
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use self::SimplifiedType::*;
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/// See `simplify_type
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#[derive(Clone, Copy, PartialEq, Eq, Hash)]
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pub enum SimplifiedType {
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BoolSimplifiedType,
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CharSimplifiedType,
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IntSimplifiedType(ast::IntTy),
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UintSimplifiedType(ast::UintTy),
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FloatSimplifiedType(ast::FloatTy),
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EnumSimplifiedType(ast::DefId),
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StrSimplifiedType,
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VecSimplifiedType,
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PtrSimplifiedType,
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TupleSimplifiedType(uint),
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TraitSimplifiedType(ast::DefId),
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StructSimplifiedType(ast::DefId),
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ClosureSimplifiedType(ast::DefId),
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FunctionSimplifiedType(uint),
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ParameterSimplifiedType,
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}
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/// Tries to simplify a type by dropping type parameters, deref'ing away any reference types, etc.
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/// The idea is to get something simple that we can use to quickly decide if two types could unify
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/// during method lookup.
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///
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/// If `can_simplify_params` is false, then we will fail to simplify type parameters entirely. This
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/// is useful when those type parameters would be instantiated with fresh type variables, since
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/// then we can't say much about whether two types would unify. Put another way,
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/// `can_simplify_params` should be true if type parameters appear free in `ty` and `false` if they
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/// are to be considered bound.
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pub fn simplify_type(tcx: &ty::ctxt,
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ty: Ty,
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can_simplify_params: bool)
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-> Option<SimplifiedType>
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{
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match ty.sty {
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ty::ty_bool => Some(BoolSimplifiedType),
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ty::ty_char => Some(CharSimplifiedType),
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ty::ty_int(int_type) => Some(IntSimplifiedType(int_type)),
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ty::ty_uint(uint_type) => Some(UintSimplifiedType(uint_type)),
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ty::ty_float(float_type) => Some(FloatSimplifiedType(float_type)),
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ty::ty_enum(def_id, _) => Some(EnumSimplifiedType(def_id)),
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ty::ty_str => Some(StrSimplifiedType),
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ty::ty_vec(..) => Some(VecSimplifiedType),
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ty::ty_ptr(_) => Some(PtrSimplifiedType),
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ty::ty_trait(ref trait_info) => {
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Some(TraitSimplifiedType(trait_info.principal_def_id()))
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}
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ty::ty_struct(def_id, _) => {
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Some(StructSimplifiedType(def_id))
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}
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ty::ty_rptr(_, mt) => {
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// since we introduce auto-refs during method lookup, we
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// just treat &T and T as equivalent from the point of
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// view of possibly unifying
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simplify_type(tcx, mt.ty, can_simplify_params)
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}
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ty::ty_uniq(_) => {
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// treat like we would treat `Box`
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let def_id = tcx.lang_items.owned_box().unwrap();
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Some(StructSimplifiedType(def_id))
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}
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ty::ty_closure(def_id, _) => {
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Some(ClosureSimplifiedType(def_id))
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}
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ty::ty_tup(ref tys) => {
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Some(TupleSimplifiedType(tys.len()))
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}
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ty::ty_bare_fn(_, ref f) => {
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Some(FunctionSimplifiedType(f.sig.0.inputs.len()))
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}
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ty::ty_projection(_) => {
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None
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}
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ty::ty_param(_) => {
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if can_simplify_params {
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Some(ParameterSimplifiedType)
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} else {
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None
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}
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}
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ty::ty_infer(_) | ty::ty_err => None,
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}
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}
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