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Rollup merge of #110465 - WaffleLapkin:assure_everyone_that_has_type_flags_is_fast, r=oli-obk

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Assure everyone that `has_type_flags` is fast

`number_of_people_who_tripped_on_this += 1`

r? ``@oli-obk``
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Matthias Krüger 2023-04-18 06:44:48 +02:00 committed by GitHub
commit 5606653f01
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8
compiler/rustc_middle/src/ty/visit.rs
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@ -33,6 +33,14 @@ pub trait TypeVisitableExt<'tcx>: TypeVisitable<TyCtxt<'tcx>> {
} }
fn has_type_flags(&self, flags: TypeFlags) -> bool { fn has_type_flags(&self, flags: TypeFlags) -> bool {
// N.B. Even though this uses a visitor, the visitor does not actually
// recurse through the whole `TypeVisitable` implementor type.
//
// Instead it stops on the first "level", visiting types, regions,
// consts and predicates just fetches their type flags.
//
// Thus this is a lot faster than it might seem and should be
// optimized to a simple field access.
let res = let res =
self.visit_with(&mut HasTypeFlagsVisitor { flags }).break_value() == Some(FoundFlags); self.visit_with(&mut HasTypeFlagsVisitor { flags }).break_value() == Some(FoundFlags);
trace!(?self, ?flags, ?res, "has_type_flags"); trace!(?self, ?flags, ?res, "has_type_flags");