Rollup merge of rust-lang#126320 - oli-obk:pat_ice, r=lcnr

Avoid ICES after reporting errors on erroneous patterns

fixes rust-lang#109812
fixes rust-lang#125914
fixes rust-lang#124004

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -2888,7 +2888,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             ..
         } = explanation
         {
-            if let Some(diag) = self.try_report_cannot_return_reference_to_local(
+            if let Err(diag) = self.try_report_cannot_return_reference_to_local(
                 borrow,
                 borrow_span,
                 span,
@@ -3075,7 +3075,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         if let BorrowExplanation::MustBeValidFor { category, span, from_closure: false, .. } =
             explanation
         {
-            if let Some(diag) = self.try_report_cannot_return_reference_to_local(
+            if let Err(diag) = self.try_report_cannot_return_reference_to_local(
                 borrow,
                 proper_span,
                 span,
@@ -3237,11 +3237,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         return_span: Span,
         category: ConstraintCategory<'tcx>,
         opt_place_desc: Option<&String>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Result<(), Diag<'tcx>> {
         let return_kind = match category {
             ConstraintCategory::Return(_) => "return",
             ConstraintCategory::Yield => "yield",
-            _ => return None,
+            _ => return Ok(()),
         };
 
         // FIXME use a better heuristic than Spans
@@ -3317,7 +3317,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             }
         }
 
-        Some(err)
+        Err(err)
     }
 
     #[instrument(level = "debug", skip(self))]

compiler/rustc_hir_typeck/src/demand.rs

@@ -4,7 +4,7 @@ use rustc_errors::{Applicability, Diag};
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::intravisit::Visitor;
-use rustc_infer::infer::{DefineOpaqueTypes, InferOk};
+use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_middle::bug;
 use rustc_middle::ty::adjustment::AllowTwoPhase;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
@@ -166,7 +166,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// Requires that the two types unify, and prints an error message if
     /// they don't.
     pub fn demand_suptype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
-        if let Some(e) = self.demand_suptype_diag(sp, expected, actual) {
+        if let Err(e) = self.demand_suptype_diag(sp, expected, actual) {
             e.emit();
         }
     }
@@ -176,7 +176,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         sp: Span,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Result<(), Diag<'tcx>> {
         self.demand_suptype_with_origin(&self.misc(sp), expected, actual)
     }
 
@@ -186,18 +186,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         cause: &ObligationCause<'tcx>,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Option<Diag<'tcx>> {
-        match self.at(cause, self.param_env).sup(DefineOpaqueTypes::Yes, expected, actual) {
-            Ok(InferOk { obligations, value: () }) => {
-                self.register_predicates(obligations);
-                None
-            }
-            Err(e) => Some(self.err_ctxt().report_mismatched_types(cause, expected, actual, e)),
-        }
+    ) -> Result<(), Diag<'tcx>> {
+        self.at(cause, self.param_env)
+            .sup(DefineOpaqueTypes::Yes, expected, actual)
+            .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
+            .map_err(|e| self.err_ctxt().report_mismatched_types(cause, expected, actual, e))
     }
 
     pub fn demand_eqtype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
-        if let Some(err) = self.demand_eqtype_diag(sp, expected, actual) {
+        if let Err(err) = self.demand_eqtype_diag(sp, expected, actual) {
             err.emit();
         }
     }
@@ -207,7 +204,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         sp: Span,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Result<(), Diag<'tcx>> {
         self.demand_eqtype_with_origin(&self.misc(sp), expected, actual)
     }
 
@@ -216,14 +213,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         cause: &ObligationCause<'tcx>,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Option<Diag<'tcx>> {
-        match self.at(cause, self.param_env).eq(DefineOpaqueTypes::Yes, expected, actual) {
-            Ok(InferOk { obligations, value: () }) => {
-                self.register_predicates(obligations);
-                None
-            }
-            Err(e) => Some(self.err_ctxt().report_mismatched_types(cause, expected, actual, e)),
-        }
+    ) -> Result<(), Diag<'tcx>> {
+        self.at(cause, self.param_env)
+            .eq(DefineOpaqueTypes::Yes, expected, actual)
+            .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
+            .map_err(|e| self.err_ctxt().report_mismatched_types(cause, expected, actual, e))
     }
 
     pub fn demand_coerce(
@@ -234,12 +228,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
         allow_two_phase: AllowTwoPhase,
     ) -> Ty<'tcx> {
-        let (ty, err) =
-            self.demand_coerce_diag(expr, checked_ty, expected, expected_ty_expr, allow_two_phase);
-        if let Some(err) = err {
-            err.emit();
+        match self.demand_coerce_diag(expr, checked_ty, expected, expected_ty_expr, allow_two_phase)
+        {
+            Ok(ty) => ty,
+            Err(err) => {
+                err.emit();
+                // Return the original type instead of an error type here, otherwise the type of `x` in
+                // `let x: u32 = ();` will be a type error, causing all subsequent usages of `x` to not
+                // report errors, even though `x` is definitely `u32`.
+                expected
+            }
         }
-        ty
     }
 
     /// Checks that the type of `expr` can be coerced to `expected`.
@@ -254,11 +253,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         mut expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
         allow_two_phase: AllowTwoPhase,
-    ) -> (Ty<'tcx>, Option<Diag<'tcx>>) {
+    ) -> Result<Ty<'tcx>, Diag<'tcx>> {
         let expected = self.resolve_vars_with_obligations(expected);
 
         let e = match self.coerce(expr, checked_ty, expected, allow_two_phase, None) {
-            Ok(ty) => return (ty, None),
+            Ok(ty) => return Ok(ty),
             Err(e) => e,
         };
 
@@ -275,7 +274,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         self.emit_coerce_suggestions(&mut err, expr, expr_ty, expected, expected_ty_expr, Some(e));
 
-        (expected, Some(err))
+        Err(err)
     }
 
     /// Notes the point at which a variable is constrained to some type incompatible

compiler/rustc_hir_typeck/src/expr.rs

@@ -87,7 +87,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ty = adj_ty;
         }
 
-        if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
+        if let Err(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
             let _ = self.emit_type_mismatch_suggestions(
                 &mut err,
                 expr.peel_drop_temps(),
@@ -1132,7 +1132,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // say that the user intended to write `lhs == rhs` instead of `lhs = rhs`.
             // The likely cause of this is `if foo = bar { .. }`.
             let actual_ty = self.tcx.types.unit;
-            let mut err = self.demand_suptype_diag(expr.span, expected_ty, actual_ty).unwrap();
+            let mut err = self.demand_suptype_diag(expr.span, expected_ty, actual_ty).unwrap_err();
             let lhs_ty = self.check_expr(lhs);
             let rhs_ty = self.check_expr(rhs);
             let refs_can_coerce = |lhs: Ty<'tcx>, rhs: Ty<'tcx>| {
@@ -1236,7 +1236,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // This is (basically) inlined `check_expr_coercible_to_type`, but we want
         // to suggest an additional fixup here in `suggest_deref_binop`.
         let rhs_ty = self.check_expr_with_hint(rhs, lhs_ty);
-        if let (_, Some(mut diag)) =
+        if let Err(mut diag) =
             self.demand_coerce_diag(rhs, rhs_ty, lhs_ty, Some(lhs), AllowTwoPhase::No)
         {
             suggest_deref_binop(&mut diag, rhs_ty);
@@ -1738,10 +1738,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Make sure to give a type to the field even if there's
             // an error, so we can continue type-checking.
             let ty = self.check_expr_with_hint(field.expr, field_type);
-            let (_, diag) =
-                self.demand_coerce_diag(field.expr, ty, field_type, None, AllowTwoPhase::No);
+            let diag = self.demand_coerce_diag(field.expr, ty, field_type, None, AllowTwoPhase::No);
 
-            if let Some(diag) = diag {
+            if let Err(diag) = diag {
                 if idx == hir_fields.len() - 1 {
                     if remaining_fields.is_empty() {
                         self.suggest_fru_from_range_and_emit(field, variant, args, diag);

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -1578,7 +1578,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // type of the place it is referencing, and not some
             // supertype thereof.
             let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m));
-            if let Some(mut diag) = self.demand_eqtype_diag(init.span, local_ty, init_ty) {
+            if let Err(mut diag) = self.demand_eqtype_diag(init.span, local_ty, init_ty) {
                 self.emit_type_mismatch_suggestions(
                     &mut diag,
                     init.peel_drop_temps(),
@@ -1624,7 +1624,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let previous_diverges = self.diverges.get();
             let else_ty = self.check_block_with_expected(blk, NoExpectation);
             let cause = self.cause(blk.span, ObligationCauseCode::LetElse);
-            if let Some(err) = self.demand_eqtype_with_origin(&cause, self.tcx.types.never, else_ty)
+            if let Err(err) = self.demand_eqtype_with_origin(&cause, self.tcx.types.never, else_ty)
             {
                 err.emit();
             }