1 files changed, 37 insertions, 0 deletions
diff --git a/tests/ui/rust-2021/future-prelude-collision-generic.rs b/tests/ui/rust-2021/future-prelude-collision-generic.rs
new file mode 100644
index 000000000..d7f8affc6
--- /dev/null
+++ b/tests/ui/rust-2021/future-prelude-collision-generic.rs
@@ -0,0 +1,37 @@
+// test for https://github.com/rust-lang/rust/issues/86940
+// run-rustfix
+// edition:2018
+// check-pass
+#![warn(rust_2021_prelude_collisions)]
+#![allow(dead_code)]
+#![allow(unused_imports)]
+
+struct Generic<'a, U>(&'a U);
+
+trait MyFromIter {
+    fn from_iter(_: i32) -> Self;
+}
+
+impl MyFromIter for Generic<'static, i32> {
+    fn from_iter(_: i32) -> Self {
+        todo!()
+    }
+}
+
+impl std::iter::FromIterator<i32> for Generic<'static, i32> {
+    fn from_iter<T: IntoIterator<Item = i32>>(_: T) -> Self {
+        todo!()
+    }
+}
+
+fn main() {
+    Generic::from_iter(1);
+    //~^ WARNING trait-associated function `from_iter` will become ambiguous in Rust 2021
+    //~| this is accepted in the current edition (Rust 2018)
+    Generic::<'static, i32>::from_iter(1);
+    //~^ WARNING trait-associated function `from_iter` will become ambiguous in Rust 2021
+    //~| this is accepted in the current edition (Rust 2018)
+    Generic::<'_, _>::from_iter(1);
+    //~^ WARNING trait-associated function `from_iter` will become ambiguous in Rust 2021
+    //~| this is accepted in the current edition (Rust 2018)
+}