"multiple applicable items" since raw pointers to unsized implement Debug

[TimNN]

Breaking change from #36880

use std::fmt::{Formatter, Debug, Pointer};

fn foo(f: &mut Formatter) {
    let a: *const [i32] = &[0] as *const _;
    let _ = a.fmt(f);
}

fn main() {}

Affects mbox v0.1.3.

[nagisa]

One of those things we consider not-actually-breaking changes as being more explicit in user code would have prevented the breakage.

Still need to re-evaluate if such a breakage is acceptable for what it brings to the table. Certainly not T-compiler, most likely T-libs.

[TimNN]

Certainly not T-compiler, most likely T-libs.

Yes, of course, not sure what I was thinking there...

[eddyb]

We shouldn't have ever done that bloody "all formatting traits have a fmt method" thing, but my solutions weren't exactly that great either (e.g. unsafe conversion between &T and &fmt::Debug<T>).

Either way there's a reason they're not in the prelude: you should never import those traits.
Just use std::fmt; and use paths from that.

[alexcrichton]

The libs team discussed this during triage and the conclusion was that this falls under the "acceptable breakage" umbrella and we'll send a patch upstream for this, so closing.