diff options
| -rw-r--r-- | compiler/rustc_abi/src/layout.rs | 13 | ||||
| -rw-r--r-- | tests/ui/structs-enums/type-sizes.rs | 20 |
2 files changed, 24 insertions, 9 deletions
diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs index f4de4e06d1b..01593d34c97 100644 --- a/compiler/rustc_abi/src/layout.rs +++ b/compiler/rustc_abi/src/layout.rs @@ -527,15 +527,10 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> { let count = (niche_variants.end().index() as u128 - niche_variants.start().index() as u128) + 1; - // Find the field with the largest niche - let (field_index, niche, (niche_start, niche_scalar)) = variants[largest_variant_index] - .iter() - .enumerate() - .filter_map(|(j, field)| Some((j, field.largest_niche?))) - .max_by_key(|(_, niche)| niche.available(dl)) - .and_then(|(j, niche)| Some((j, niche, niche.reserve(dl, count)?)))?; - let niche_offset = - niche.offset + variant_layouts[largest_variant_index].fields.offset(field_index); + // Use the largest niche in the largest variant. + let niche = variant_layouts[largest_variant_index].largest_niche?; + let (niche_start, niche_scalar) = niche.reserve(dl, count)?; + let niche_offset = niche.offset; let niche_size = niche.value.size(dl); let size = variant_layouts[largest_variant_index].size.align_to(align.abi); diff --git a/tests/ui/structs-enums/type-sizes.rs b/tests/ui/structs-enums/type-sizes.rs index 5ca9c8678b7..f49ce33841a 100644 --- a/tests/ui/structs-enums/type-sizes.rs +++ b/tests/ui/structs-enums/type-sizes.rs @@ -209,6 +209,23 @@ struct ReorderEndNiche { b: MiddleNiche4, } +// We want that the niche selection doesn't depend on order of the fields. See issue #125630. +pub enum NicheFieldOrder1 { + A { + x: NonZero<u64>, + y: [NonZero<u64>; 2], + }, + B([u64; 2]), +} + +pub enum NicheFieldOrder2 { + A { + y: [NonZero<u64>; 2], + x: NonZero<u64>, + }, + B([u64; 2]), +} + // standins for std types which we want to be laid out in a reasonable way struct RawVecDummy { @@ -260,6 +277,9 @@ pub fn main() { size_of::<EnumWithMaybeUninhabitedVariant<()>>()); assert_eq!(size_of::<NicheFilledEnumWithAbsentVariant>(), size_of::<&'static ()>()); + assert_eq!(size_of::<NicheFieldOrder1>(), 24); + assert_eq!(size_of::<NicheFieldOrder2>(), 24); + assert_eq!(size_of::<Option<Option<(bool, &())>>>(), size_of::<(bool, &())>()); assert_eq!(size_of::<Option<Option<(&(), bool)>>>(), size_of::<(bool, &())>()); assert_eq!(size_of::<Option<Option2<bool, &()>>>(), size_of::<(bool, &())>()); |