Increase in type mismatches on `webrender` and `diesel`

[lnicola]

These went yesterday from 16 and 84 to 23 and 116, presumably because of a change in 1.59.

[lnicola]

Repro for the webrender errors:

fn foo() -> i32 {
    unreachable!();
 // ^ Expected i32, got ()
}

[lnicola]

This is because the definition of unreachable! changed in rust-lang/rust#93179 from:

#[macro_export]
#[stable(feature = "rust1", since = "1.0.0")]
macro_rules! unreachable {
    () => ({
        $crate::panic!("internal error: entered unreachable code")
    });
    ($msg:expr $(,)?) => ({
        $crate::unreachable!("{}", $msg)
    });
    ($fmt:expr, $($arg:tt)*) => ({
        $crate::panic!($crate::concat!("internal error: entered unreachable code: ", $fmt), $($arg)*)
    });
}

to:

#[cfg(not(bootstrap))]
#[macro_export]
#[rustc_builtin_macro(unreachable)]
#[allow_internal_unstable(edition_panic)]
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "unreachable_macro")]
macro_rules! unreachable {
    // Expands to either `$crate::panic::unreachable_2015` or `$crate::panic::unreachable_2021`
    // depending on the edition of the caller.
    ($($arg:tt)*) => {
        /* compiler built-in */
    };
}