Enum rustc_const_eval::interpret::ConstValue

pub enum ConstValue<'tcx> {
    Scalar(Scalar<AllocId>),
    Slice {
        data: &Allocation<AllocId, ()>,
        start: usize,
        end: usize,
    },
    ByRef {
        alloc: &Allocation<AllocId, ()>,
        offset: Size,
    },
}

Represents a constant value in Rust. Scalar and Slice are optimizations for array length computations, enum discriminants and the pattern matching logic.

Variants

Scalar(Scalar<AllocId>)

Used only for types with layout::abi::Scalar ABI and ZSTs.

Not using the enum Value to encode that this must not be Uninit.

Slice

Fields

data: &Allocation<AllocId, ()>

start: usize

end: usize

Used only for &[u8] and &str

ByRef

Fields

alloc: &Allocation<AllocId, ()>

The backing memory of the value, may contain more memory than needed for just the value in order to share Allocations between values

offset: Size

Offset into alloc

A value not represented/representable by Scalar or Slice

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: 32 bytes

Size for each variant:

• Scalar: 24 bytes
• Slice: 24 bytes
• ByRef: 16 bytes