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Make the next variable mutable to allow for ref mut in for patterns.

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This commit is contained in:
John Kåre Alsaker 2017-06-17 01:51:55 +02:00
parent 09bc09201c
commit bd7cc779b6
2 changed files with 22 additions and 7 deletions
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14
src/librustc/hir/lowering.rs
View File

@ -2170,12 +2170,12 @@ impl<'a> LoweringContext<'a> {
// let result = match ::std::iter::IntoIterator::into_iter(<head>) {
// mut iter => {
// [opt_ident]: loop {
// let next;
// let mut _next;
// match ::std::iter::Iterator::next(&mut iter) {
// ::std::option::Option::Some(val) => next = val,
// ::std::option::Option::Some(val) => _next = val,
// ::std::option::Option::None => break
// };
// let <pat> = next;
// let <pat> = _next;
// StmtExpr(<body>);
// }
// }
@ -2188,8 +2188,8 @@ impl<'a> LoweringContext<'a> {
let iter = self.str_to_ident("iter");
let next_ident = self.str_to_ident("next");
let next_pat = self.pat_ident(e.span, next_ident);
let next_ident = self.str_to_ident("_next");
let next_pat = self.pat_ident_binding_mode(e.span, next_ident, hir::BindByValue(hir::MutMutable));
// `::std::option::Option::Some(val) => next = val`
let pat_arm = {
@ -2235,13 +2235,13 @@ impl<'a> LoweringContext<'a> {
let next_expr = P(self.expr_ident(e.span, next_ident, next_pat.id));
// `let next`
// `let mut _next`
let next_let = self.stmt_let_pat(e.span,
None,
next_pat,
hir::LocalSource::ForLoopDesugar);
// `let <pat> = next`
// `let <pat> = _next`
let pat = self.lower_pat(pat);
let pat_let = self.stmt_let_pat(e.span,
Some(next_expr),

15
src/test/run-pass/for-loop-mut-ref-element.rs Normal file
View File

@ -0,0 +1,15 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Tests that for loops can bind elements as mutable references
fn main() {
for ref mut _a in std::iter::once(true) {}
}