bjoernager/rust
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Reveal opaque types in exhaustiveness checking

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This commit is contained in:
Nadrieril 2023-11-16 04:28:22 +01:00
parent 7e4924b55d
commit 2a87bae48d
7 changed files with 76 additions and 42 deletions
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21
compiler/rustc_pattern_analysis/src/rustc.rs
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@ -44,6 +44,7 @@ pub type WitnessPat<'p, 'tcx> = crate::pat::WitnessPat<RustcMatchCheckCtxt<'p, '
#[derive(Clone)]
pub struct RustcMatchCheckCtxt<'p, 'tcx> {
pub tcx: TyCtxt<'tcx>,
pub typeck_results: &'tcx ty::TypeckResults<'tcx>,
/// The module in which the match occurs. This is necessary for
/// checking inhabited-ness of types because whether a type is (visibly)
/// inhabited can depend on whether it was defined in the current module or
@ -101,6 +102,21 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
}
}
/// Type inference occasionally gives us opaque types in places where corresponding patterns
/// have more specific types. To avoid inconsistencies as well as detect opaque uninhabited
/// types, we use the corresponding concrete type if possible.
fn reveal_opaque_ty(&self, ty: Ty<'tcx>) -> Ty<'tcx> {
if let ty::Alias(ty::Opaque, alias_ty) = ty.kind() {
if let Some(local_def_id) = alias_ty.def_id.as_local() {
let key = ty::OpaqueTypeKey { def_id: local_def_id, args: alias_ty.args };
if let Some(real_ty) = self.typeck_results.concrete_opaque_types.get(&key) {
return real_ty.ty;
}
}
}
ty
}
// In the cases of either a `#[non_exhaustive]` field list or a non-public field, we hide
// uninhabited fields in order not to reveal the uninhabitedness of the whole variant.
// This lists the fields we keep along with their types.
@ -873,8 +889,9 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
fn is_exhaustive_patterns_feature_on(&self) -> bool {
self.tcx.features().exhaustive_patterns
}
fn is_opaque_ty(ty: Self::Ty) -> bool {
matches!(ty.kind(), ty::Alias(ty::Opaque, ..))
fn reveal_opaque_ty(&self, ty: Ty<'tcx>) -> Ty<'tcx> {
self.reveal_opaque_ty(ty)
}
fn ctor_arity(&self, ctor: &crate::constructor::Constructor<Self>, ty: Self::Ty) -> usize {