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supress niches in coroutines

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This commit is contained in:
Ralf Jung
2024-08-20 16:54:36 +02:00
parent a971212545
commit a281f93d3d
2 changed files with 73 additions and 1 deletions
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8
compiler/rustc_ty_utils/src/layout.rs
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@@ -1001,7 +1001,13 @@ fn coroutine_layout<'tcx>(
},
fields: outer_fields,
abi,
largest_niche: prefix.largest_niche,
// Suppress niches inside coroutines. If the niche is inside a field that is aliased (due to
// self-referentiality), getting the discriminant can cause aliasing violations.
// `UnsafeCell` blocks niches for the same reason, but we don't yet have `UnsafePinned` that
// would do the same for us here.
// See <https://github.com/rust-lang/rust/issues/63818>, <https://github.com/rust-lang/miri/issues/3780>.
// FIXME: Remove when <https://github.com/rust-lang/rust/issues/125735> is implemented and aliased coroutine fields are wrapped in `UnsafePinned`.
largest_niche: None,
size,
align,
max_repr_align: None,