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Handle ty::Opaque correctly
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Nadrieril committed Oct 27, 2023
1 parent d5070e3 commit 3fa2e71
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Showing 2 changed files with 33 additions and 11 deletions.
17 changes: 16 additions & 1 deletion compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
Original file line number Diff line number Diff line change
Expand Up @@ -883,7 +883,22 @@ impl<'p, 'tcx> PatternColumn<'p, 'tcx> {
self.patterns.is_empty()
}
fn head_ty(&self) -> Option<Ty<'tcx>> {
self.patterns.get(0).map(|p| p.ty())
if self.patterns.len() == 0 {
return None;
}
// If the type is opaque and it is revealed anywhere in the column, we take the revealed
// version. Otherwise we could encounter constructors for the revealed type and crash.
let is_opaque = |ty: Ty<'tcx>| matches!(ty.kind(), ty::Alias(ty::Opaque, ..));
let first_ty = self.patterns[0].ty();
if is_opaque(first_ty) {
for pat in &self.patterns {
let ty = pat.ty();
if !is_opaque(ty) {
return Some(ty);
}
}
}
Some(first_ty)
}

fn analyze_ctors(&self, pcx: &PatCtxt<'_, 'p, 'tcx>) -> SplitConstructorSet<'tcx> {
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27 changes: 17 additions & 10 deletions tests/ui/type-alias-impl-trait/issue-96572-unconstrained.rs
Original file line number Diff line number Diff line change
Expand Up @@ -26,11 +26,9 @@ fn upvar() {
fn enum_upvar() {
type T = impl Copy;
let foo: T = Some((1u32, 2u32));
let x = move || {
match foo {
None => (),
Some((a, b)) => (),
}
let x = move || match foo {
None => (),
Some((a, b)) => (),
};
}

Expand Down Expand Up @@ -63,6 +61,19 @@ mod only_pattern {
None => {}
}
}

type V = impl Copy;

fn baz(baz: Option<V>) {
match baz {
_ => {}
Some((mut x, mut y)) => {
x = 42;
y = "foo";
}
None => {}
}
}
}

mod only_pattern_rpit {
Expand All @@ -71,11 +82,7 @@ mod only_pattern_rpit {
let (mut x, mut y) = foo(false);
x = 42;
y = "foo";
if b {
panic!()
} else {
foo(true)
}
if b { panic!() } else { foo(true) }
}

fn bar(b: bool) -> Option<impl Copy> {
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