Incorrect suggestion of string_lit_as_bytes lint

[ordovicia]

Clippy version: clippy 0.0.212 (e3cb40e 2019-06-25)

Clippy suggests using a byte string literal b"string literal" instead of "string literal".as_bytes().
The suggestion does not compile in the following case because the type of byte string literal &[u8; N] does not implement std::io::Read.

fn f(_: impl std::io::Read) {
}

fn main() {
    f("string literal".as_bytes());
//    ^^^^^^^^^^^^^ help: consider using a byte string literal instead: `b"string literal"`

    // f(b"string literal");    // does not compile
    // ^ the trait `std::io::Read` is not implemented for `&[u8; 14]`
    
    f(&b"string literal"[..]);  // compiles
}

Playground

Clippy should allow the above case or suggest &b"string literal"[..].

[ghost]

We should always suggest &b"string literal"[..]. Changing the type of the expression is asking for trouble and &b"string literal"[..] -> b"string literal" could be a separate lint anyway.

[mahkoh]

The lint should instead be removed. The only justification for the lint given is that using byte strings is shorter. &b"string literal"[..] is perl-tier.