Auto merge of #3238 - rust-lang:rustup-2023-12-24, r=saethlin

Automatic Rustup

1 files changed, 36 insertions, 9 deletions

diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs
index 65c90aa9f1d..a5a47724f3f 100644
--- a/compiler/rustc_pattern_analysis/src/rustc.rs
+++ b/compiler/rustc_pattern_analysis/src/rustc.rs
@@ -12,7 +12,7 @@ use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::mir::{self, Const};
 use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange, PatRangeBoundary};
 use rustc_middle::ty::layout::IntegerExt;
-use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
+use rustc_middle::ty::{self, OpaqueTypeKey, Ty, TyCtxt, VariantDef};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, Integer, VariantIdx, FIRST_VARIANT};
 use smallvec::SmallVec;
@@ -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
@@ -73,8 +74,16 @@ impl<'p, 'tcx> fmt::Debug for RustcMatchCheckCtxt<'p, 'tcx> {
 }
 
 impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
-    pub(crate) fn is_uninhabited(&self, ty: Ty<'tcx>) -> bool {
-        !ty.is_inhabited_from(self.tcx, self.module, self.param_env)
+    fn reveal_opaque(&self, key: OpaqueTypeKey<'tcx>) -> Option<Ty<'tcx>> {
+        self.typeck_results.concrete_opaque_types.get(&key).map(|x| x.ty)
+    }
+    pub fn is_uninhabited(&self, ty: Ty<'tcx>) -> bool {
+        !ty.inhabited_predicate(self.tcx).apply_revealing_opaque(
+            self.tcx,
+            self.param_env,
+            self.module,
+            &|key| self.reveal_opaque(key),
+        )
     }
 
     /// Returns whether the given type is an enum from another crate declared `#[non_exhaustive]`.
@@ -101,6 +110,21 @@ 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.
@@ -303,7 +327,9 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                         let is_inhabited = v
                             .inhabited_predicate(cx.tcx, *def)
                             .instantiate(cx.tcx, args)
-                            .apply(cx.tcx, cx.param_env, cx.module);
+                            .apply_revealing_opaque(cx.tcx, cx.param_env, cx.module, &|key| {
+                                cx.reveal_opaque(key)
+                            });
                         // Variants that depend on a disabled unstable feature.
                         let is_unstable = matches!(
                             cx.tcx.eval_stability(variant_def_id, None, DUMMY_SP, None),
@@ -400,7 +426,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                     ty::Tuple(fs) => {
                         ctor = Struct;
                         let mut wilds: SmallVec<[_; 2]> =
-                            fs.iter().map(|ty| DeconstructedPat::wildcard(ty, pat.span)).collect();
+                            fs.iter().map(|ty| DeconstructedPat::wildcard(ty)).collect();
                         for pat in subpatterns {
                             wilds[pat.field.index()] = self.lower_pat(&pat.pattern);
                         }
@@ -423,7 +449,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                         let pat = if let Some(pat) = pattern {
                             self.lower_pat(&pat.pattern)
                         } else {
-                            DeconstructedPat::wildcard(args.type_at(0), pat.span)
+                            DeconstructedPat::wildcard(args.type_at(0))
                         };
                         ctor = Struct;
                         fields = singleton(pat);
@@ -448,7 +474,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                                 ty
                             });
                         let mut wilds: SmallVec<[_; 2]> =
-                            tys.map(|ty| DeconstructedPat::wildcard(ty, pat.span)).collect();
+                            tys.map(|ty| DeconstructedPat::wildcard(ty)).collect();
                         for pat in subpatterns {
                             if let Some(i) = field_id_to_id[pat.field.index()] {
                                 wilds[i] = self.lower_pat(&pat.pattern);
@@ -873,8 +899,9 @@ 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 {