Rollup merge of #107779 - compiler-errors:issue-107775, r=jackh726

Remove astconv usage in diagnostic

Fixes #107775

Location of the test sucks, I know, but I needed to put it somewhere :sweat:
The issue here is that the root cause of the issue has nothing to do with what's being tested, so I couldn't really give it a better name. Oh well.

diff --cc compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
Simple merge