bjoernager/rust
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Properly consider binder vars in HasTypeFlagsVisitor

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This commit is contained in:
Michael Goulet 2023-09-14 03:49:41 +00:00
parent 5adddad28c
commit 7ae301ec47
3 changed files with 72 additions and 15 deletions
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36
compiler/rustc_middle/src/ty/flags.rs
View file

@ -34,6 +34,26 @@ impl FlagComputation {
result.flags
}
pub fn bound_var_flags(vars: &ty::List<ty::BoundVariableKind>) -> FlagComputation {
let mut computation = FlagComputation::new();
for bv in vars {
match bv {
ty::BoundVariableKind::Ty(_) => {
computation.flags |= TypeFlags::HAS_TY_LATE_BOUND;
}
ty::BoundVariableKind::Region(_) => {
computation.flags |= TypeFlags::HAS_RE_LATE_BOUND;
}
ty::BoundVariableKind::Const => {
computation.flags |= TypeFlags::HAS_CT_LATE_BOUND;
}
}
}
computation
}
fn add_flags(&mut self, flags: TypeFlags) {
self.flags = self.flags | flags;
}
@ -57,21 +77,7 @@ impl FlagComputation {
where
F: FnOnce(&mut Self, T),
{
let mut computation = FlagComputation::new();
for bv in value.bound_vars() {
match bv {
ty::BoundVariableKind::Ty(_) => {
computation.flags |= TypeFlags::HAS_TY_LATE_BOUND;
}
ty::BoundVariableKind::Region(_) => {
computation.flags |= TypeFlags::HAS_RE_LATE_BOUND;
}
ty::BoundVariableKind::Const => {
computation.flags |= TypeFlags::HAS_CT_LATE_BOUND;
}
}
}
let mut computation = FlagComputation::bound_var_flags(value.bound_vars());
f(&mut computation, value.skip_binder());

24
compiler/rustc_middle/src/ty/visit.rs
View file

@ -481,9 +481,33 @@ impl std::fmt::Debug for HasTypeFlagsVisitor {
// `Ty`/`Const`/`Predicate`, but not within those types. This is because the
// type flags at the outer layer are enough. So it's faster than it first
// looks, particular for `Ty`/`Predicate` where it's just a field access.
//
// N.B. The only case where this isn't totally true is binders, which also
// add `HAS_{RE,TY,CT}_LATE_BOUND` flag depending on the *bound variables* that
// are present, regardless of whether those bound variables are used. This
// is important for anonymization of binders in `TyCtxt::erase_regions`. We
// specifically detect this case in `visit_binder`.
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for HasTypeFlagsVisitor {
type BreakTy = FoundFlags;
fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
&mut self,
t: &Binder<'tcx, T>,
) -> ControlFlow<Self::BreakTy> {
// If we're looking for any of the HAS_*_LATE_BOUND flags, we need to
// additionally consider the bound vars on the binder itself, even if
// the contents of a the binder (e.g. a `TraitRef`) doesn't reference
// the bound vars.
if self.flags.intersects(TypeFlags::HAS_LATE_BOUND) {
let bound_var_flags = FlagComputation::bound_var_flags(t.bound_vars());
if bound_var_flags.flags.intersects(self.flags) {
return ControlFlow::Break(FoundFlags);
}
}
t.super_visit_with(self)
}
#[inline]
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
// Note: no `super_visit_with` call.