pub unsafe trait UintCast {
type Uint;
}Expand description
Marker trait for types that can be represented as an unsigned integer.
A type that implements this trait is assumed to have the exact same memory layout and representation as an unsigned integer, with the current compile target’s endianness. This implies a couple of useful properties:
- Casting between
TandT::Uintis free and will (or should) be optimized away. [T]can be cast to and from[T::Uint].
This allows a number of common and useful optimizations, including casting buffers and reusing memory. It does however come with some strict requirements.
§Safety
- The type must be inhabited (eg: no Infallible).
- The type must allow any bit pattern (eg: either no requirements or some ability to recover from invalid values).
- The type must be either a wrapper around
Self::Uintor be safe to transmute to and fromSelf::Uint. - The type must not contain any internal padding.
- The type must be
repr(C)orrepr(transparent). - The type must have the same size and alignment as
Self::Uint.
Note also that the type is assumed to not implement Drop. This will
rarely, if ever, be an issue. The requirements above ensures that the
underlying field types stay the same and will be dropped.