1 files changed, 29 insertions, 0 deletions
diff --git a/src/test/ui/traits/alias/maybe-bound.rs b/src/test/ui/traits/alias/maybe-bound.rs
new file mode 100644
index 000000000..284baa481
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+++ b/src/test/ui/traits/alias/maybe-bound.rs
@@ -0,0 +1,29 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+// Test that `dyn ... + ?Sized + ...` resulting from the expansion of trait aliases is okay.
+
+#![feature(trait_alias)]
+
+trait Foo {}
+
+trait S = ?Sized;
+
+// Nest a couple of levels deep:
+trait _0 = S;
+trait _1 = _0;
+
+// Straight list expansion:
+type _T0 = dyn _1 + Foo;
+
+// In second position:
+type _T1 = dyn Foo + _1;
+
+// ... and with an auto trait:
+type _T2 = dyn Foo + Send + _1;
+
+// Twice:
+trait _2 = _1 + _1;
+
+type _T3 = dyn _2 + Foo;
+
+fn main() {}