1 files changed, 32 insertions, 0 deletions
diff --git a/tests/ui/impl-trait/nested_impl_trait.rs b/tests/ui/impl-trait/nested_impl_trait.rs
new file mode 100644
index 000000000..e95fab3b6
--- /dev/null
+++ b/tests/ui/impl-trait/nested_impl_trait.rs
@@ -0,0 +1,32 @@
+#![feature(impl_trait_in_fn_trait_return)]
+use std::fmt::Debug;
+
+fn fine(x: impl Into<u32>) -> impl Into<u32> { x }
+
+fn bad_in_ret_position(x: impl Into<u32>) -> impl Into<impl Debug> { x }
+//~^ ERROR nested `impl Trait` is not allowed
+//~| ERROR the trait bound `impl Debug: From<impl Into<u32>>` is not satisfied
+
+fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
+//~^ ERROR nested `impl Trait` is not allowed
+//~| `impl Trait` only allowed in function and inherent method return types
+
+fn bad_in_arg_position(_: impl Into<impl Debug>) { }
+//~^ ERROR nested `impl Trait` is not allowed
+
+struct X;
+impl X {
+    fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
+    //~^ ERROR nested `impl Trait` is not allowed
+    //~| ERROR the trait bound `impl Debug: From<impl Into<u32>>` is not satisfied
+}
+
+fn allowed_in_assoc_type() -> impl Iterator<Item=impl Fn()> {
+    vec![|| println!("woot")].into_iter()
+}
+
+fn allowed_in_ret_type() -> impl Fn() -> impl Into<u32> {
+    || 5u8
+}
+
+fn main() {}