Abort analysis on type error

compiler/rustc_pattern_analysis/src/lib.rs

@@ -77,7 +77,7 @@ pub trait TypeCx: Sized + fmt::Debug {
     /// The set of all the constructors for `ty`.
     ///
     /// This must follow the invariants of `ConstructorSet`
-    fn ctors_for_ty(&self, ty: Self::Ty) -> ConstructorSet<Self>;
+    fn ctors_for_ty(&self, ty: Self::Ty) -> Result<ConstructorSet<Self>, Self::Error>;
 
     /// Best-effort `Debug` implementation.
     fn debug_pat(f: &mut fmt::Formatter<'_>, pat: &DeconstructedPat<'_, Self>) -> fmt::Result;

compiler/rustc_pattern_analysis/src/lints.rs

@@ -52,9 +52,13 @@ impl<'p, 'tcx> PatternColumn<'p, 'tcx> {
     }
 
     /// Do constructor splitting on the constructors of the column.
-    fn analyze_ctors(&self, pcx: &PlaceCtxt<'_, 'p, 'tcx>) -> SplitConstructorSet<'p, 'tcx> {
+    fn analyze_ctors(
+        &self,
+        pcx: &PlaceCtxt<'_, 'p, 'tcx>,
+    ) -> Result<SplitConstructorSet<'p, 'tcx>, ErrorGuaranteed> {
         let column_ctors = self.patterns.iter().map(|p| p.ctor());
-        pcx.ctors_for_ty().split(pcx, column_ctors)
+        let ctors_for_ty = &pcx.ctors_for_ty()?;
+        Ok(ctors_for_ty.split(pcx, column_ctors))
     }
 
     fn iter(&self) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Captures<'_> {
@@ -116,7 +120,7 @@ fn collect_nonexhaustive_missing_variants<'a, 'p, 'tcx>(
     };
     let pcx = &PlaceCtxt::new_dummy(cx, ty);
 
-    let set = column.analyze_ctors(pcx);
+    let set = column.analyze_ctors(pcx)?;
     if set.present.is_empty() {
         // We can't consistently handle the case where no constructors are present (since this would
         // require digging deep through any type in case there's a non_exhaustive enum somewhere),
@@ -219,7 +223,7 @@ pub(crate) fn lint_overlapping_range_endpoints<'a, 'p, 'tcx>(
     let pcx = &PlaceCtxt::new_dummy(cx, ty);
     let rcx: &RustcMatchCheckCtxt<'_, '_> = cx.tycx;
 
-    let set = column.analyze_ctors(pcx);
+    let set = column.analyze_ctors(pcx)?;
 
     if matches!(ty.kind(), ty::Char | ty::Int(_) | ty::Uint(_)) {
         let emit_lint = |overlap: &IntRange, this_span: Span, overlapped_spans: &[Span]| {

compiler/rustc_pattern_analysis/src/rustc.rs

@@ -12,6 +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::TypeVisitableExt;
 use rustc_middle::ty::{self, OpaqueTypeKey, Ty, TyCtxt, VariantDef};
 use rustc_span::ErrorGuaranteed;
 use rustc_span::{Span, DUMMY_SP};
@@ -303,7 +304,10 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
     ///
     /// See [`crate::constructor`] for considerations of emptiness.
     #[instrument(level = "debug", skip(self), ret)]
-    pub fn ctors_for_ty(&self, ty: RevealedTy<'tcx>) -> ConstructorSet<'p, 'tcx> {
+    pub fn ctors_for_ty(
+        &self,
+        ty: RevealedTy<'tcx>,
+    ) -> Result<ConstructorSet<'p, 'tcx>, ErrorGuaranteed> {
         let cx = self;
         let make_uint_range = |start, end| {
             IntRange::from_range(
@@ -312,9 +316,11 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
                 RangeEnd::Included,
             )
         };
+        // Abort on type error.
+        ty.error_reported()?;
         // This determines the set of all possible constructors for the type `ty`. For numbers,
         // arrays and slices we use ranges and variable-length slices when appropriate.
-        match ty.kind() {
+        Ok(match ty.kind() {
             ty::Bool => ConstructorSet::Bool,
             ty::Char => {
                 // The valid Unicode Scalar Value ranges.
@@ -424,7 +430,7 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
             ty::CoroutineWitness(_, _) | ty::Bound(_, _) | ty::Placeholder(_) | ty::Infer(_) => {
                 bug!("Encountered unexpected type in `ConstructorSet::for_ty`: {ty:?}")
             }
-        }
+        })
     }
 
     pub(crate) fn lower_pat_range_bdy(
@@ -965,7 +971,10 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
     ) -> &[Self::Ty] {
         self.ctor_sub_tys(ctor, ty)
     }
-    fn ctors_for_ty(&self, ty: Self::Ty) -> crate::constructor::ConstructorSet<Self> {
+    fn ctors_for_ty(
+        &self,
+        ty: Self::Ty,
+    ) -> Result<crate::constructor::ConstructorSet<Self>, Self::Error> {
         self.ctors_for_ty(ty)
     }
 

compiler/rustc_pattern_analysis/src/usefulness.rs

@@ -753,7 +753,7 @@ impl<'a, 'p, Cx: TypeCx> PlaceCtxt<'a, 'p, Cx> {
     pub(crate) fn ctor_sub_tys(&self, ctor: &Constructor<Cx>) -> &[Cx::Ty] {
         self.mcx.tycx.ctor_sub_tys(ctor, self.ty)
     }
-    pub(crate) fn ctors_for_ty(&self) -> ConstructorSet<Cx> {
+    pub(crate) fn ctors_for_ty(&self) -> Result<ConstructorSet<Cx>, Cx::Error> {
         self.mcx.tycx.ctors_for_ty(self.ty)
     }
 }
@@ -1383,7 +1383,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
 
     // Analyze the constructors present in this column.
     let ctors = matrix.heads().map(|p| p.ctor());
-    let ctors_for_ty = pcx.ctors_for_ty();
+    let ctors_for_ty = pcx.ctors_for_ty()?;
     let is_integers = matches!(ctors_for_ty, ConstructorSet::Integers { .. }); // For diagnostics.
     let split_set = ctors_for_ty.split(pcx, ctors);
     let all_missing = split_set.present.is_empty();

tests/ui/pattern/usefulness/issue-119493-type-error-ice.rs

@@ -0,0 +1,13 @@
+fn main() {}
+
+fn foo() {
+    #[derive(Copy, Clone)]
+    struct Foo(NonExistent);
+    //~^ ERROR cannot find type
+    //~| ERROR cannot find type
+
+    type U = impl Copy;
+    //~^ ERROR `impl Trait` in type aliases is unstable
+    let foo: U = Foo(());
+    let Foo(()) = foo;
+}

tests/ui/pattern/usefulness/issue-119493-type-error-ice.stderr

@@ -0,0 +1,30 @@
+error[E0412]: cannot find type `NonExistent` in this scope
+  --> $DIR/issue-119493-type-error-ice.rs:5:16
+   |
+LL |     struct Foo(NonExistent);
+   |                ^^^^^^^^^^^ not found in this scope
+
+error[E0412]: cannot find type `NonExistent` in this scope
+  --> $DIR/issue-119493-type-error-ice.rs:5:16
+   |
+LL |     struct Foo(NonExistent);
+   |                ^^^^^^^^^^^ not found in this scope
+   |
+help: you might be missing a type parameter
+   |
+LL |     struct Foo<NonExistent>(NonExistent);
+   |               +++++++++++++
+
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/issue-119493-type-error-ice.rs:9:14
+   |
+LL |     type U = impl Copy;
+   |              ^^^^^^^^^
+   |
+   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0412, E0658.
+For more information about an error, try `rustc --explain E0412`.