1 files changed, 32 insertions, 0 deletions
diff --git a/src/test/ui/impl-trait/unsafety-checking-cycle.rs b/src/test/ui/impl-trait/unsafety-checking-cycle.rs
new file mode 100644
index 000000000..4a5831c5b
--- /dev/null
+++ b/src/test/ui/impl-trait/unsafety-checking-cycle.rs
@@ -0,0 +1,32 @@
+// Ensure that we don't get a cycle error from trying to determine whether an
+// opaque type implements `Freeze` in safety checking, when it doesn't matter.
+
+// check-pass
+
+#![feature(rustc_attrs)]
+
+struct AnyValue<T>(T);
+
+// No need to check for `Freeze` here, there's no
+// `rustc_layout_scalar_valid_range_start` involved.
+fn not_restricted(c: bool) -> impl Sized {
+    if c {
+        let x = AnyValue(not_restricted(false));
+        &x.0;
+    }
+    2u32
+}
+
+#[rustc_layout_scalar_valid_range_start(1)]
+struct NonZero<T>(T);
+
+// No need to check for `Freeze` here, we're not borrowing the field.
+fn not_field(c: bool) -> impl Sized {
+    if c {
+        let x = unsafe { NonZero(not_field(false)) };
+        &x;
+    }
+    5u32
+}
+
+fn main() {}