From dec7fc3ced5bc3c18d0e5d29921d087f93189cb8 Mon Sep 17 00:00:00 2001
From: Theodore Luo Wang <wangtheo662@gmail.com>
Date: Sat, 28 Aug 2021 21:18:20 -0400
Subject: [PATCH] Fix an ICE caused by type mismatch errors being ignored

---
 compiler/rustc_typeck/src/check/demand.rs                | 6 ------
 .../ui/typeck/issue-87771-ice-assign-assign-to-bool.rs   | 4 ++++
 .../typeck/issue-87771-ice-assign-assign-to-bool.stderr  | 9 +++++++++
 3 files changed, 13 insertions(+), 6 deletions(-)
 create mode 100644 src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs
 create mode 100644 src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr

diff --git a/compiler/rustc_typeck/src/check/demand.rs b/compiler/rustc_typeck/src/check/demand.rs
index 808685d7fa9c..f186d35bcbc8 100644
--- a/compiler/rustc_typeck/src/check/demand.rs
+++ b/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))
diff --git a/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs b/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.rs
new file mode 100644
index 000000000000..751dc8719cf3
--- /dev/null
+++ b/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
+}
diff --git a/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr b/src/test/ui/typeck/issue-87771-ice-assign-assign-to-bool.stderr
new file mode 100644
index 000000000000..fe10fa733d23
--- /dev/null
+++ b/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`.