diff options
| -rw-r--r-- | compiler/rustc_middle/src/mir/visit.rs | 8 | ||||
| -rw-r--r-- | tests/ui/lint/unaligned_references_fake_borrow.rs | 27 |
2 files changed, 31 insertions, 4 deletions
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs index 98e8f269c57..af09a6d570b 100644 --- a/compiler/rustc_middle/src/mir/visit.rs +++ b/compiler/rustc_middle/src/mir/visit.rs @@ -1364,13 +1364,13 @@ impl PlaceContext { matches!(self, PlaceContext::MutatingUse(MutatingUseContext::Drop)) } - /// Returns `true` if this place context represents a borrow. + /// Returns `true` if this place context represents a borrow, excluding fake borrows + /// (which are an artifact of borrowck and not actually borrows in runtime MIR). pub fn is_borrow(self) -> bool { matches!( self, - PlaceContext::NonMutatingUse( - NonMutatingUseContext::SharedBorrow | NonMutatingUseContext::FakeBorrow - ) | PlaceContext::MutatingUse(MutatingUseContext::Borrow) + PlaceContext::NonMutatingUse(NonMutatingUseContext::SharedBorrow) + | PlaceContext::MutatingUse(MutatingUseContext::Borrow) ) } diff --git a/tests/ui/lint/unaligned_references_fake_borrow.rs b/tests/ui/lint/unaligned_references_fake_borrow.rs new file mode 100644 index 00000000000..b0ef8b471ca --- /dev/null +++ b/tests/ui/lint/unaligned_references_fake_borrow.rs @@ -0,0 +1,27 @@ +//@ check-pass + +// Regression test for <https://github.com/rust-lang/rust/issues/137250>. + +// Ensure that we don't emit unaligned packed field reference errors for the fake +// borrows that we generate during match lowering. These fake borrows are there to +// ensure in *borrow-checking* that we don't modify the value being matched, but +// they are removed after the MIR is processed by `CleanupPostBorrowck`. + +#[repr(packed)] +pub struct Packed(i32); + +fn f(x: Packed) { + match &x { + Packed(4) => {}, + _ if true => {}, + _ => {} + } + + match x { + Packed(4) => {}, + _ if true => {}, + _ => {} + } +} + +fn main() {} |