Macro unavailable_backend 

macro_rules! unavailable_backend {
    ($runtime:ident, $backend:expr, $name:expr) => { ... };
}

Generate a stub runtime for an unavailable backend.

Creates a struct that implements RingKernelRuntime with all methods returning BackendUnavailable errors.

Example

ringkernel_core::unavailable_backend!(CudaRuntime, Backend::Cuda, "CUDA");