1 files changed, 29 insertions, 0 deletions
diff --git a/tests/ui/traits/next-solver/projection/param-env-trait-candidate-2.rs b/tests/ui/traits/next-solver/projection/param-env-trait-candidate-2.rs
new file mode 100644
index 000000000..db8dc1eb9
--- /dev/null
+++ b/tests/ui/traits/next-solver/projection/param-env-trait-candidate-2.rs
@@ -0,0 +1,29 @@
+// check-pass
+// compile-flags: -Znext-solver
+
+// See https://github.com/rust-lang/trait-system-refactor-initiative/issues/1,
+// a minimization of a pattern in core.
+
+trait Iterator {
+    type Item;
+}
+
+struct Flatten<I>(I);
+
+impl<I, U> Iterator for Flatten<I>
+where
+    I: Iterator<Item = U>,
+{
+    type Item = U;
+}
+
+fn needs_iterator<I: Iterator>() {}
+
+fn environment<J>()
+where
+    J: Iterator,
+{
+    needs_iterator::<Flatten<J>>();
+}
+
+fn main() {}