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Auto merge of #47873 - Aaron1011:final-ref-coerce, r=nikomatsakis

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Fix ref-to-ptr coercions not working with NLL in certain cases

Implicit coercions from references to pointers were lowered to slightly
different Mir than explicit casts (e.g. 'foo as *mut T'). This resulted
in certain uses of self-referential structs compiling correctly when an
explicit cast was used, but not when the implicit coercion was used.

To fix this, this commit adds an outer 'Use' expr when applying a
raw-ptr-borrow adjustment. This makes the lowered Mir for coercions
identical to that of explicit coercions, allowing the original code to
compile regardless of how the raw ptr cast occurs.

Fixes #47722
This commit is contained in:
bors 2018-02-05 04:32:06 +00:00
commit 07ea260407
3 changed files with 65 additions and 4 deletions
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9
src/test/mir-opt/validate_5.rs
View file

@ -52,12 +52,15 @@ fn main() {
// Validate(Acquire, [_1: &ReFree(DefId(0/1:9 ~ validate_5[317d]::main[0]::{{closure}}[0]), BrEnv) [closure@NodeId(46)], _2: &ReFree(DefId(0/1:9 ~ validate_5[317d]::main[0]::{{closure}}[0]), BrAnon(0)) mut i32]);
// StorageLive(_3);
// StorageLive(_4);
// StorageLive(_5);
// Validate(Suspend(ReScope(Node(ItemLocalId(9)))), [(*_2): i32]);
// _4 = &ReErased mut (*_2);
// Validate(Acquire, [(*_4): i32/ReScope(Node(ItemLocalId(9)))]);
// _3 = move _4 as *mut i32 (Misc);
// _5 = &ReErased mut (*_2);
// Validate(Acquire, [(*_5): i32/ReScope(Node(ItemLocalId(9)))]);
// _4 = move _5 as *mut i32 (Misc);
// _3 = move _4;
// EndRegion(ReScope(Node(ItemLocalId(9))));
// StorageDead(_4);
// StorageDead(_5);
// Validate(Release, [_0: bool, _3: *mut i32]);
// _0 = const write_42(move _3) -> bb1;
// }

26
src/test/run-pass/issue-47722.rs Normal file
View file

@ -0,0 +1,26 @@
// Copyright 2018 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 automatic coercions from &mut T to *mut T
// allow borrows of T to expire immediately - essentially, that
// they work identically to 'foo as *mut T'
#![feature(nll)]
struct SelfReference {
self_reference: *mut SelfReference,
}
impl SelfReference {
fn set_self_ref(&mut self) {
self.self_reference = self;
}
}
fn main() {}