1 files changed, 31 insertions, 0 deletions
diff --git a/tests/ui/dst/dst-bad-coerce2.rs b/tests/ui/dst/dst-bad-coerce2.rs
new file mode 100644
index 000000000..e7ce20b89
--- /dev/null
+++ b/tests/ui/dst/dst-bad-coerce2.rs
@@ -0,0 +1,31 @@
+// Attempt to change the mutability as well as unsizing.
+
+struct Fat<T: ?Sized> {
+    ptr: T
+}
+
+struct Foo;
+trait Bar {}
+impl Bar for Foo {}
+
+pub fn main() {
+    // With a vec of ints.
+    let f1 = Fat { ptr: [1, 2, 3] };
+    let f2: &Fat<[isize; 3]> = &f1;
+    let f3: &mut Fat<[isize]> = f2; //~ ERROR mismatched types
+
+    // With a trait.
+    let f1 = Fat { ptr: Foo };
+    let f2: &Fat<Foo> = &f1;
+    let f3: &mut Fat<dyn Bar> = f2; //~ ERROR mismatched types
+
+    // Tuple with a vec of ints.
+    let f1 = ([1, 2, 3],);
+    let f2: &([isize; 3],) = &f1;
+    let f3: &mut ([isize],) = f2; //~ ERROR mismatched types
+
+    // Tuple with a trait.
+    let f1 = (Foo,);
+    let f2: &(Foo,) = &f1;
+    let f3: &mut (dyn Bar,) = f2; //~ ERROR mismatched types
+}