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Rollup merge of #36004 - petrochenkov:hashloan, r=arielb1

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rustc_borrowck: Don't hash types in loan paths

1) Types for equal loan paths are not always equal, they can sometimes differ in lifetimes, making equal loan paths hash differently.

Example:
71bdeea561/src/libcollections/linked_list.rs (L835-L856)

One of `self.list`s has type
```
&ReFree(CodeExtent(15013/CallSiteScope { fn_id: 18907, body_id: 18912 }), BrNamed(0:DefIndex(3066), 'a(397), WontChange)) mut linked_list::LinkedList<T>
```
and other has type
```
&ReScope(CodeExtent(15018/Remainder(BlockRemainder { block: 18912, first_statement_index: 0 }))) mut linked_list::LinkedList<T>
```
(... but I'm not sure it's not a bug actually.)

2) Not hashing types is faster than hashing types.

r? @arielb1
This commit is contained in:
Manish Goregaokar 2016-08-27 09:31:15 +05:30 committed by GitHub
commit 933d481bdd
1 changed files with 9 additions and 5 deletions
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14
src/librustc_borrowck/borrowck/mod.rs
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@ -41,6 +41,7 @@ use rustc::ty::{self, TyCtxt};
use std::fmt;
use std::mem;
use std::rc::Rc;
use std::hash::{Hash, Hasher};
use syntax::ast;
use syntax::attr::AttrMetaMethods;
use syntax_pos::{MultiSpan, Span};
@ -345,7 +346,7 @@ impl<'tcx> Loan<'tcx> {
}
}
#[derive(Eq, Hash)]
#[derive(Eq)]
pub struct LoanPath<'tcx> {
kind: LoanPathKind<'tcx>,
ty: ty::Ty<'tcx>,
@ -353,10 +354,13 @@ pub struct LoanPath<'tcx> {
impl<'tcx> PartialEq for LoanPath<'tcx> {
fn eq(&self, that: &LoanPath<'tcx>) -> bool {
let r = self.kind == that.kind;
debug_assert!(self.ty == that.ty || !r,
"Somehow loan paths are equal though their tys are not.");
r
self.kind == that.kind
}
}
impl<'tcx> Hash for LoanPath<'tcx> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.kind.hash(state);
}
}