Enum rustc_target::abi::Variants

pub enum Variants {
    Single {
        index: VariantIdx,
    },
    Multiple {
        tag: Scalar,
        tag_encoding: TagEncoding,
        tag_field: usize,
        variants: IndexVec<VariantIdx, LayoutS>,
    },
}

Variants

Single

Fields

index: VariantIdx

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

Multiple

Fields

tag: Scalar

tag_encoding: TagEncoding

tag_field: usize

variants: IndexVec<VariantIdx, LayoutS>

Enum-likes with more than one inhabited variant: each variant comes with a discriminant (usually the same as the variant index but the user can assign explicit discriminant values). That discriminant is encoded as a tag on the machine. The layout of each variant is a struct, and they all have space reserved for the tag. For enums, the tag is the sole field of the layout.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 112 bytes

Size for each variant:

• Single: 8 bytes
• Multiple: 112 bytes