Fix an ICE caused by type mismatch errors being ignored

Author: theo-lw

compiler/rustc_typeck/src/check/demand.rs

@@ -145,12 +145,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let expr_ty = self.resolve_vars_with_obligations(checked_ty);
         let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e);
 
-        if self.is_assign_to_bool(expr, expected) {
-            // Error reported in `check_assign` so avoid emitting error again.
-            err.delay_as_bug();
-            return (expected, None);
-        }
-
         self.emit_coerce_suggestions(&mut err, expr, expr_ty, expected, expected_ty_expr);
 
         (expected, Some(err))

src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let mut a;
+    a = a = true; //~ ERROR mismatched types
+}

src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr

@@ -0,0 +1,9 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-87771-ice-assign-assign-to-bool.rs:3:9
+   |
+LL |     a = a = true;
+   |         ^^^^^^^^ expected `bool`, found `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.