Add regression test for overwriting qualifs by assignment

2 files changed, 22 insertions, 0 deletions

diff --git a/src/test/ui/consts/qualif_overwrite.rs b/src/test/ui/consts/qualif_overwrite.rs
new file mode 100644
index 00000000000..65e182945bf
--- /dev/null
+++ b/src/test/ui/consts/qualif_overwrite.rs
@@ -0,0 +1,13 @@
+// compile-pass
+
+#![feature(const_let)]
+
+use std::cell::Cell;
+
+const FOO: &Option<Cell<usize>> = {
+    let mut a = Some(Cell::new(0));
+    a = None; // resets `qualif(a)` to `qualif(None)`
+    &{a}
+};
+
+fn main() {}
diff --git a/src/test/ui/consts/qualif_overwrite.stderr b/src/test/ui/consts/qualif_overwrite.stderr
new file mode 100644
index 00000000000..b24c0fa70f0
--- /dev/null
+++ b/src/test/ui/consts/qualif_overwrite.stderr
@@ -0,0 +1,9 @@
+error[E0492]: cannot borrow a constant which may contain interior mutability, create a static instead
+  --> $DIR/qualif_overwrite.rs:8:5
+   |
+LL |     &{a} //~ ERROR cannot borrow a constant which may contain interior mutability
+   |     ^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0492`.