5a58b50698
Make bad "rust-call" arguments no longer ICE The simplest of bad rust-call definitions will no longer cause an ICE. There is a FIXME added for future work, as I wanted to get this easy fix in before trying to either add a hack or mess with the whole obligation system fixes #22565
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.