Unnecessary "{}" suggestion for panic with const string

[ldm0]

#78088 implements suggestion for panic with first argument not literal, but forget to handle such code:

const ICE: &str = "Internal compiler error";
fn main() {
    panic!(ICE);
}

This code is actually legit., but non_fmt_panic suggestion is emitted.
Check: https://gist.github.com/6002a4f7fedfda0e615d0b1158015eee

[SNCPlay42]

This isn't #78088's warning, it's #81645's.

And I don't think it's incorrect; only literals, not expressions can be used as format strings, even if the expression is evaluable at compile time. e.g. this doesn't work:

const FORMAT: &str = "{}";
fn main() {
    panic!(FORMAT, "Hello");
}

And indeed the code given does not compile in the 2021 edition.

[ldm0]

@SNCPlay42 Thanks!