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Don't normalize higher-ranked assumptions if they're not used

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This commit is contained in:
Michael Goulet
2025-10-03 10:32:11 -04:00
parent dd091003ac
commit e3f104608c
3 changed files with 107 additions and 13 deletions
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31
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@@ -423,19 +423,24 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
constituents.types,
);
// FIXME(coroutine_clone): We could uplift this into `collect_predicates_for_types`
// and do this for `Copy`/`Clone` too, but that's feature-gated so it doesn't really
// matter yet.
for assumption in constituents.assumptions {
let assumption = normalize_with_depth_to(
self,
obligation.param_env,
cause.clone(),
obligation.recursion_depth + 1,
assumption,
&mut obligations,
);
self.infcx.register_region_assumption(assumption);
// Only normalize these goals if `-Zhigher-ranked-assumptions` is enabled, since
// we don't want to cause ourselves to do extra work if we're not even able to
// take advantage of these assumption clauses.
if self.tcx().sess.opts.unstable_opts.higher_ranked_assumptions {
// FIXME(coroutine_clone): We could uplift this into `collect_predicates_for_types`
// and do this for `Copy`/`Clone` too, but that's feature-gated so it doesn't really
// matter yet.
for assumption in constituents.assumptions {
let assumption = normalize_with_depth_to(
self,
obligation.param_env,
cause.clone(),
obligation.recursion_depth + 1,
assumption,
&mut obligations,
);
self.infcx.register_region_assumption(assumption);
}
}
Ok(obligations)