Enum rustc_const_eval::interpret::ConstValue

source · [−]
pub enum ConstValue<'tcx> {
    Scalar(Scalar<AllocId>),
    ZeroSized,
    Slice {
        data: ConstAllocation<'tcx, AllocId, ()>,
        start: usize,
        end: usize,
    },
    ByRef {
        alloc: ConstAllocation<'tcx, AllocId, ()>,
        offset: Size,
    },
}
Expand description

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.

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

ZeroSized

Only used for ZSTs.

Slice

Fields

data: ConstAllocation<'tcx, AllocId, ()>
start: usize
end: usize

Used only for &[u8] and &str

ByRef

Fields

alloc: ConstAllocation<'tcx, AllocId, ()>

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

offset: Size

Offset into alloc

A value not represented/representable by Scalar or Slice

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.

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
  • ZeroSized: 0 bytes
  • Slice: 24 bytes
  • ByRef: 16 bytes