Enforce const evaluation in path! macro

[robin-nitrokey]

By using a temporary const value, we can enforce that the path! macro always causes a compiler error for illegal values even if it is not used in a const context. This makes it easier to write correct code.

[sosthene-nitrokey]

With 1.78 it will also be possible to use an inline const:

[macro_export]
macro_rules! path {
    ($path:literal) => {
        const { $crate::path::Path::from_str_with_nul(::core::concat!($path, "\0")) }
    };
}

[robin-nitrokey]

Right, but I would prefer to not break compatibility with older Rust versions for this. Or is there a benefit to the const block other than better readability?

[sosthene-nitrokey]

Certainly not worth using in this case where the current solution works well. The only benefit would be the ability to use it in match statements but I don't think is ever useful.