Statically-sized stack strings

Sometimes, some specialists strive to store strings stackwise. Sadly, one's stock in stack strings is shot down on stable. See, in spite of 'static strings storing size statically, they're symbolised solely as a slice. So what service should stack-stored strings serve? Scrutinise surely:

const fn splice<
    const SOURCE_A: &str,
    const SOURCE_B: &str,
>() -> StaticStr<SOURCE_A.len() + SOURCE_B.len()> {
    let mut scratch = [0u8; SOURCE_A.len() + SOURCE_B.len()];
    
    // ...

    StaticStr::new(scratch).unwrap() // Surity of success
}

const SALUTATION: &str = "Hello";
const SPOT: &str = "world";

const SPLICED_STRING: &str = &splice::<SALUTATION, SPOT>();

"Simply store a slice", you shout. A slice from splice's scope survives not the 'static span! Sure, &'static str supplying splice solves this specific strait, but stack strings support spawning several services for &'static strs.

The issue proposes statically sized stack strings and gives a Rust example using splice and StaticStr, but names no files, tests, or implementation entry point. Start by clarifying the intended feature and its scope; completion criteria are not specified in the issue.