more descriptive warning for irrefutable while-let pattern

[ash2x3zb9cy]

Writing a while-let loop for e. g. an event loop triggers a compiler warning:

warning: irrefutable while-let pattern
  --> src/main.rs:34:5
   |
34 | /     while let e = crossterm::event::read()? {
35 | |         // code
36 | |     }
   | |_____^
   |
   = note: `#[warn(irrefutable_let_patterns)]` on by default

There's no error code, and no further information, so it isn't the easiest to investigate as a user.

In my case, I believe it's warning about potentially running an unintentionally infinite/indefinite loop, which in my case is intentional. So my guess would be that I am OK to #[allow] it - at a guess.

I would suggest that additional notes be added to this warning detailing why it's a potential problem

[ehuss]

@ash2x3zb9cy FYI, there is an explanation of the warning at https://doc.rust-lang.org/nightly/rustc/lints/listing/warn-by-default.html#irrefutable-let-patterns. A loop is recommended instead of while let to make it clearer that it is an indefinite loop.

I think it would be nice to link to the lint documentation in the compiler output, but there is some uncertainty of how to best go about that.