1 files changed, 40 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/defaults-cyclic-fail-1.rs b/src/test/ui/associated-types/defaults-cyclic-fail-1.rs
new file mode 100644
index 000000000..61ef01323
--- /dev/null
+++ b/src/test/ui/associated-types/defaults-cyclic-fail-1.rs
@@ -0,0 +1,40 @@
+#![feature(associated_type_defaults)]
+
+// Having a cycle in assoc. type defaults is okay...
+trait Tr {
+    type A = Self::B;
+    type B = Self::A;
+}
+
+impl Tr for () {}
+
+impl Tr for u8 {
+    type A = u8;
+}
+
+impl Tr for u16 {
+    type B = ();
+}
+
+impl Tr for u32 {
+    type A = ();
+    type B = u8;
+}
+
+// ...but not in an impl that redefines one of the types.
+impl Tr for bool {
+    type A = Box<Self::B>;
+    //~^ ERROR overflow evaluating the requirement `<bool as Tr>::B == _`
+}
+// (the error is shown twice for some reason)
+
+impl Tr for usize {
+    type B = &'static Self::A;
+    //~^ ERROR overflow evaluating the requirement `<usize as Tr>::A == _`
+}
+
+fn main() {
+    // We don't check that the types project correctly because the cycle errors stop compilation
+    // before `main` is type-checked.
+    // `defaults-cyclic-pass-1.rs` does this.
+}