e40d5e83dc
rewrite error handling for unresolved inference vars Pretty much completely rewrites `fn emit_inference_failure_err`. This new setup should hopefully be easier to extend and is already a lot better when looking for generic arguments. Because this is a rewrite there are still some parts which are lacking, these are tracked in #94483 and will be fixed in later PRs. r? `@estebank` `@petrochenkov`