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Rollup merge of #136985 - zachs18:backend-repr-remove-uninhabited, r=workingjubilee
Do not ignore uninhabited types for function-call ABI purposes. (Remove BackendRepr::Uninhabited)
Accepted MCP: https://github.com/rust-lang/compiler-team/issues/832
Fixes #135802
Do not consider the inhabitedness of a type for function call ABI purposes.
* Remove the [`rustc_abi::BackendRepr::Uninhabited`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_abi/enum.BackendRepr.html) variant
* Instead calculate the `BackendRepr` of uninhabited types "normally" (as though they were not uninhabited "at the top level", but still considering inhabitedness of variants to determine enum layout, etc)
* Add an `uninhabited: bool` field to [`rustc_abi::LayoutData`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_abi/struct.LayoutData.html) so inhabitedness of a `LayoutData` can still be queried when necessary (e.g. when determining if an enum variant needs a tag value allocated to it).
This should not affect type layouts (size/align/field offset); this should only affect function call ABI, and only of uninhabited types.
cc ``@RalfJung``
| -rw-r--r-- | crates/hir-ty/src/layout.rs | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/crates/hir-ty/src/layout.rs b/crates/hir-ty/src/layout.rs index b6f7c44c2a..f5a7b65812 100644 --- a/crates/hir-ty/src/layout.rs +++ b/crates/hir-ty/src/layout.rs @@ -194,6 +194,7 @@ fn layout_of_simd_ty( fields, backend_repr: BackendRepr::Vector { element: e_abi, count: e_len }, largest_niche: e_ly.largest_niche, + uninhabited: false, size, align, max_repr_align: None, @@ -297,20 +298,17 @@ pub fn layout_of_ty_query( .checked_mul(count, dl) .ok_or(LayoutError::BadCalc(LayoutCalculatorError::SizeOverflow))?; - let backend_repr = - if count != 0 && matches!(element.backend_repr, BackendRepr::Uninhabited) { - BackendRepr::Uninhabited - } else { - BackendRepr::Memory { sized: true } - }; + let backend_repr = BackendRepr::Memory { sized: true }; let largest_niche = if count != 0 { element.largest_niche } else { None }; + let uninhabited = if count != 0 { element.uninhabited } else { false }; Layout { variants: Variants::Single { index: struct_variant_idx() }, fields: FieldsShape::Array { stride: element.size, count }, backend_repr, largest_niche, + uninhabited, align: element.align, size, max_repr_align: None, @@ -325,6 +323,7 @@ pub fn layout_of_ty_query( fields: FieldsShape::Array { stride: element.size, count: 0 }, backend_repr: BackendRepr::Memory { sized: false }, largest_niche: None, + uninhabited: false, align: element.align, size: Size::ZERO, max_repr_align: None, @@ -337,6 +336,7 @@ pub fn layout_of_ty_query( fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 }, backend_repr: BackendRepr::Memory { sized: false }, largest_niche: None, + uninhabited: false, align: dl.i8_align, size: Size::ZERO, max_repr_align: None, |