bjoernager/rust
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Auto merge of #112070 - lcnr:disjoint-closure-capture-ub, r=oli-obk

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change `BorrowKind::Unique` to be a mutating `PlaceContext`

fixes #112056

I believe that `BorrowKind::Unique` is a footgun in general, so I added a FIXME and opened https://github.com/rust-lang/rust/issues/112072. This is a bit too involved for this PR though.
This commit is contained in:
bors 2023-05-31 00:24:39 +00:00
commit e6e4f7ed15
14 changed files with 90 additions and 19 deletions
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5
compiler/rustc_middle/src/mir/syntax.rs
View file

@ -220,6 +220,11 @@ pub enum BorrowKind {
/// immutable, but not aliasable. This solves the problem. For
/// simplicity, we don't give users the way to express this
/// borrow, it's just used when translating closures.
///
// FIXME(#112072): This is wrong. Unique borrows are mutable borrows except
// that they do not require their pointee to be marked as a mutable.
// They should still be treated as mutable borrows in every other way,
// e.g. for variance or overlap checking.
Unique,
/// Data is mutable and not aliasable.

10
compiler/rustc_middle/src/mir/visit.rs
View file

@ -650,8 +650,8 @@ macro_rules! make_mir_visitor {
BorrowKind::Shallow => PlaceContext::NonMutatingUse(
NonMutatingUseContext::ShallowBorrow
),
BorrowKind::Unique => PlaceContext::NonMutatingUse(
NonMutatingUseContext::UniqueBorrow
BorrowKind::Unique => PlaceContext::MutatingUse(
MutatingUseContext::Borrow
),
BorrowKind::Mut { .. } =>
PlaceContext::MutatingUse(MutatingUseContext::Borrow),
@ -1265,8 +1265,6 @@ pub enum NonMutatingUseContext {
SharedBorrow,
/// Shallow borrow.
ShallowBorrow,
/// Unique borrow.
UniqueBorrow,
/// AddressOf for *const pointer.
AddressOf,
/// PlaceMention statement.
@ -1345,9 +1343,7 @@ impl PlaceContext {
matches!(
self,
PlaceContext::NonMutatingUse(
NonMutatingUseContext::SharedBorrow
| NonMutatingUseContext::ShallowBorrow
| NonMutatingUseContext::UniqueBorrow
NonMutatingUseContext::SharedBorrow | NonMutatingUseContext::ShallowBorrow
) | PlaceContext::MutatingUse(MutatingUseContext::Borrow)
)
}