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Make sure that predicates with unmentioned bound vars are still consi…
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…dered global in the old solver
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compiler-errors committed Nov 4, 2023
1 parent adda05f commit 32294fc
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Showing 5 changed files with 47 additions and 32 deletions.
4 changes: 2 additions & 2 deletions compiler/rustc_middle/src/ty/erase_regions.rs
Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,8 @@ impl<'tcx> TyCtxt<'tcx> {
where
T: TypeFoldable<TyCtxt<'tcx>>,
{
// If there's nothing to erase avoid performing the query at all
if !value.has_type_flags(TypeFlags::HAS_LATE_BOUND | TypeFlags::HAS_FREE_REGIONS) {
// If there's nothing to erase or anonymize, avoid performing the query at all
if !value.has_type_flags(TypeFlags::HAS_BINDER_VARS | TypeFlags::HAS_FREE_REGIONS) {
return value;
}
debug!("erase_regions({:?})", value);
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26 changes: 5 additions & 21 deletions compiler/rustc_middle/src/ty/flags.rs
Original file line number Diff line number Diff line change
Expand Up @@ -34,26 +34,6 @@ 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;
}
Expand All @@ -77,7 +57,11 @@ impl FlagComputation {
where
F: FnOnce(&mut Self, T),
{
let mut computation = FlagComputation::bound_var_flags(value.bound_vars());
let mut computation = FlagComputation::new();

if !value.bound_vars().is_empty() {
computation.add_flags(TypeFlags::HAS_BINDER_VARS);
}

f(&mut computation, value.skip_binder());

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14 changes: 5 additions & 9 deletions compiler/rustc_middle/src/ty/visit.rs
Original file line number Diff line number Diff line change
Expand Up @@ -494,15 +494,11 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for HasTypeFlagsVisitor {
&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);
}
// If we're looking for the HAS_BINDER_VARS flag, check if the
// binder has vars. This won't be present in the binder's bound
// value, so we need to check here too.
if self.flags.intersects(TypeFlags::HAS_BINDER_VARS) && !t.bound_vars().is_empty() {
return ControlFlow::Break(FoundFlags);
}

t.super_visit_with(self)
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3 changes: 3 additions & 0 deletions compiler/rustc_type_ir/src/flags.rs
Original file line number Diff line number Diff line change
Expand Up @@ -115,5 +115,8 @@ bitflags! {

/// Does this have `Coroutine` or `CoroutineWitness`?
const HAS_TY_COROUTINE = 1 << 23;

/// Does this have any binders with bound vars (e.g. that need to be anonymized)?
const HAS_BINDER_VARS = 1 << 24;
}
}
32 changes: 32 additions & 0 deletions tests/ui/late-bound-lifetimes/predicate-is-global.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
// check-pass

trait Foo {
type Assoc;

fn do_it(_: &Self::Assoc)
where
for<'a> Self: Baz<'a>;
}

trait Baz<'a>: Foo {}

impl Foo for () {
type Assoc = Inherent;

// Ensure that the `for<'a> Self: Baz<'a>` predicate, which has
// a supertrait `for<'a> Self: Foo`, does not cause us to fail
// to normalize `Self::Assoc`.
fn do_it(x: &Self::Assoc)
where
for<'a> Self: Baz<'a>,
{
x.inherent();
}
}

struct Inherent;
impl Inherent {
fn inherent(&self) {}
}

fn main() {}

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