Enum rustc_target::abi::Variants

pub enum Variants {
    Single {
        index: VariantIdx,
    },
    Tagged {
        tag: Scalar,
        variants: IndexVec<VariantIdx, LayoutDetails>,
    },
    NicheFilling {
        dataful_variant: VariantIdx,
        niche_variants: RangeInclusive<VariantIdx>,
        niche: Scalar,
        niche_start: u128,
        variants: IndexVec<VariantIdx, LayoutDetails>,
    },
}

Variants

Single

Single enum variants, structs/tuples, unions, and all non-ADTs.

Fields of Single

index: VariantIdx

Tagged

General-case enums: for each case there is a struct, and they all have all space reserved for the tag, and their first field starts at a non-0 offset, after where the tag would go.

Fields of Tagged

tag: Scalarvariants: IndexVec<VariantIdx, LayoutDetails>

NicheFilling

Multiple cases distinguished by a niche (values invalid for a type): the variant dataful_variant contains a niche at an arbitrary offset (field 0 of the enum), which for a variant with discriminant d is set to (d - niche_variants.start).wrapping_add(niche_start).

For example, Option<(usize, &T)> is represented such that None has a null pointer for the second tuple field, and Some is the identity function (with a non-null reference).

Fields of NicheFilling

dataful_variant: VariantIdxniche_variants: RangeInclusive<VariantIdx>niche: Scalarniche_start: u128variants: IndexVec<VariantIdx, LayoutDetails>

Trait Implementations

impl Eq for Variants

impl PartialEq<Variants> for Variants

fn eq(&self, other: &Variants) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Variants) -> bool

This method tests for !=.

impl Debug for Variants

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Hash for Variants

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].