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Only normalize once in mir validator typechecker

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Before, it called `normalize_erasing_regions` twice since
`equal_up_to_regions` called it as well for both types.
This commit is contained in:
Nilstrieb 2022-08-06 14:22:57 +02:00 committed by nils
parent 81a583c21e
commit 96d4137dee
1 changed files with 10 additions and 15 deletions
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25
compiler/rustc_const_eval/src/transform/validate.rs
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@ -182,27 +182,22 @@ fn mir_assign_valid_types(&self, src: Ty<'tcx>, dest: Ty<'tcx>) -> bool {
return true;
}
let try_equal_with_param_env = |param_env| {
let src = self.tcx.normalize_erasing_regions(param_env, src);
let dest = self.tcx.normalize_erasing_regions(param_env, dest);
// Type-changing assignments can happen when subtyping is used. While
// all normal lifetimes are erased, higher-ranked types with their
// late-bound lifetimes are still around and can lead to type
// differences. So we compare ignoring lifetimes.
equal_up_to_regions(self.tcx, param_env, src, dest)
};
// Normalize projections and things like that.
// Type-changing assignments can happen when subtyping is used. While
// all normal lifetimes are erased, higher-ranked types with their
// late-bound lifetimes are still around and can lead to type
// differences. So we compare ignoring lifetimes.
// First, try with reveal_all. This might not work in some cases, as the predicates
// can be cleared in reveal_all mode. We try the reveal first anyways as it is used
// by some other passes like inlining as well.
let param_env = self.param_env.with_reveal_all_normalized(self.tcx);
if try_equal_with_param_env(param_env) {
true
} else {
// If this fails, we can try it without the reveal.
try_equal_with_param_env(self.param_env)
if equal_up_to_regions(self.tcx, param_env, src, dest) {
return true;
}
// If this fails, we can try it without the reveal.
equal_up_to_regions(self.tcx, self.param_env, src, dest)
}
}