1 files changed, 68 insertions, 0 deletions
diff --git a/tests/ui/suggestions/impl-trait-missing-lifetime-gated.rs b/tests/ui/suggestions/impl-trait-missing-lifetime-gated.rs
new file mode 100644
index 000000000..a1a51c481
--- /dev/null
+++ b/tests/ui/suggestions/impl-trait-missing-lifetime-gated.rs
@@ -0,0 +1,68 @@
+// edition:2021
+// gate-test-anonymous_lifetime_in_impl_trait
+// Verify the behaviour of `feature(anonymous_lifetime_in_impl_trait)`.
+
+mod elided {
+    fn f(_: impl Iterator<Item = &()>) {}
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+
+    fn g(mut x: impl Iterator<Item = &()>) -> Option<&()> { x.next() }
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+    //~| ERROR missing lifetime specifier
+
+    // Anonymous lifetimes in async fn are already allowed.
+    // This is understood as `fn foo<'_1>(_: impl Iterator<Item = &'_1 ()>) {}`.
+    async fn h(_: impl Iterator<Item = &()>) {}
+
+    // Anonymous lifetimes in async fn are already allowed.
+    // But that lifetime does not participate in resolution.
+    async fn i(mut x: impl Iterator<Item = &()>) -> Option<&()> { x.next() }
+    //~^ ERROR missing lifetime specifier
+}
+
+mod underscore {
+    fn f(_: impl Iterator<Item = &'_ ()>) {}
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+
+    fn g(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()> { x.next() }
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+    //~| ERROR missing lifetime specifier
+
+    // Anonymous lifetimes in async fn are already allowed.
+    // This is understood as `fn foo<'_1>(_: impl Iterator<Item = &'_1 ()>) {}`.
+    async fn h(_: impl Iterator<Item = &'_ ()>) {}
+
+    // Anonymous lifetimes in async fn are already allowed.
+    // But that lifetime does not participate in resolution.
+    async fn i(mut x: impl Iterator<Item = &'_ ()>) -> Option<&'_ ()> { x.next() }
+    //~^ ERROR missing lifetime specifier
+}
+
+mod alone_in_path {
+    trait Foo<'a> { fn next(&mut self) -> Option<&'a ()>; }
+
+    fn f(_: impl Foo) {}
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+
+    fn g(mut x: impl Foo) -> Option<&()> { x.next() }
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+    //~| ERROR missing lifetime specifier
+}
+
+mod in_path {
+    trait Foo<'a, T> { fn next(&mut self) -> Option<&'a T>; }
+
+    fn f(_: impl Foo<()>) {}
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+
+    fn g(mut x: impl Foo<()>) -> Option<&()> { x.next() }
+    //~^ ERROR anonymous lifetimes in `impl Trait` are unstable
+    //~| ERROR missing lifetime specifier
+}
+
+// This must not err, as the `&` actually resolves to `'a`.
+fn resolved_anonymous<'a, T>(f: impl Fn(&'a str) -> &T) {
+    f("f")
+}
+
+fn main() {}