Regression of "mismatched types" error on trait method call with multiple candidates

[divergentdave]

Code

I tried this code:

pub trait FieldElement {
    type Integer: TryFrom<usize, Error = std::num::TryFromIntError>;

    fn valid_integer_try_from<N>(i: N) -> Result<Self::Integer, ()>
    where
        Self::Integer: TryFrom<N>,
    {
        Self::Integer::try_from(i).map_err(|_| ())
    }
}

I expected to see this happen: Successful compilation.

Instead, this happened: I now get the following compiler error.

error[E0308]: mismatched types
   --> src/lib.rs:8:33
    |
4   |     fn valid_integer_try_from<N>(i: N) -> Result<Self::Integer, ()>
    |                               - this type parameter
...
8   |         Self::Integer::try_from(i).map_err(|_| ())
    |         ----------------------- ^ expected `usize`, found type parameter `N`
    |         |
    |         arguments to this function are incorrect
    |
    = note:        expected type `usize`
            found type parameter `N`
note: associated function defined here
   --> /home/david/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/convert/mod.rs:478:8
    |
478 |     fn try_from(value: T) -> Result<Self, Self::Error>;
    |        ^^^^^^^^

For more information about this error, try `rustc --explain E0308`.
error: could not compile `nightly-prio-regression` due to previous error

Version it worked on

It most recently worked on: stable channel Rust 1.63.0, and nightly-2022-08-17.

Version with regression

searched nightlies: from nightly-2022-08-11 to nightly-2022-08-26
regressed nightly: nightly-2022-08-18
searched commit range: 86c6ebe...9c20b2a
regressed commit: 9c20b2a

bisected with cargo-bisect-rustc v0.6.4

Host triple: x86_64-unknown-linux-gnu
Reproduce with:

cargo bisect-rustc 

@rustbot modify labels: +regression-from-stable-to-nightly -regression-untriaged

While reducing this example, I noticed that the following changes to the code will make the error go away:

• Replacing the function call with N::try_into(i)
• Deleting the specification of Error in the associated type's trait bound
• Adding the same Error specification in the where clause's trait bound

[compiler-errors]

This is caused by #100652, and therefore fixed by #100966.

[apiraino]

WG-prioritization assigning priority (Zulip discussion) to add visibility to the relevant pr fixing it

@rustbot label -I-prioritize +P-critical t-compiler