Rollup merge of #104701 - compiler-errors:rpitit-remove-reempty-hack, r=TaKO8Ki

Remove a lifetime resolution hack from `compare_predicate_entailment`

This is not needed anymore, probably due to #102334 equating the function signatures fully in `collect_trait_impl_trait_tys`. Also, the assertion in in #102903 makes sure that this is actually fixed, so I'm pretty confident this isn't needed.
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Dylan DPC 2022-11-22 16:36:38 +05:30 committed by GitHub
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@ -288,17 +288,7 @@ fn compare_predicate_entailment<'tcx>(
// type would be more appropriate. In other places we have a `Vec<Span>`
// corresponding to their `Vec<Predicate>`, but we don't have that here.
// Fixing this would improve the output of test `issue-83765.rs`.
let mut result = ocx.sup(&cause, param_env, trait_fty, impl_fty);
// HACK(RPITIT): #101614. When we are trying to infer the hidden types for
// RPITITs, we need to equate the output tys instead of just subtyping. If
// we just use `sup` above, we'll end up `&'static str <: _#1t`, which causes
// us to infer `_#1t = #'_#2r str`, where `'_#2r` is unconstrained, which gets
// fixed up to `ReEmpty`, and which is certainly not what we want.
if trait_fty.has_infer_types() {
result =
result.and_then(|()| ocx.eq(&cause, param_env, trait_sig.output(), impl_sig.output()));
}
let result = ocx.sup(&cause, param_env, trait_fty, impl_fty);
if let Err(terr) = result {
debug!(?terr, "sub_types failed: impl ty {:?}, trait ty {:?}", impl_fty, trait_fty);