1 files changed, 15 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/runaway-impl-candidate-selection.rs b/tests/ui/traits/new-solver/runaway-impl-candidate-selection.rs
new file mode 100644
index 000000000..1dca86d36
--- /dev/null
+++ b/tests/ui/traits/new-solver/runaway-impl-candidate-selection.rs
@@ -0,0 +1,15 @@
+// compile-flags: -Ztrait-solver=next
+
+// In the new solver, we are trying to select `<?0 as Iterator>::Item: Debug`,
+// which, naively can be unified with every impl of `Debug` if we're not careful.
+// This test makes sure that we treat projections with inference var substs as
+// placeholders during fast reject.
+
+fn iter<T: Iterator>() -> <T as Iterator>::Item {
+    todo!()
+}
+
+fn main() {
+    println!("{:?}", iter::<_>());
+    //~^ ERROR type annotations needed
+}