Function rustc_abi::layout::univariant

fn univariant<'a, FieldIdx: Idx, VariantIdx: Idx, F: Deref<Target = &'a LayoutS<FieldIdx, VariantIdx>> + Debug>(
    this: &(impl LayoutCalculator + ?Sized),
    dl: &TargetDataLayout,
    fields: &IndexSlice<FieldIdx, F>,
    repr: &ReprOptions,
    kind: StructKind,
    niche_bias: NicheBias
) -> Option<LayoutS<FieldIdx, VariantIdx>>