2 files changed, 62 insertions, 0 deletions
diff --git a/src/test/ui/regions/closure-in-projection-issue-97405.rs b/src/test/ui/regions/closure-in-projection-issue-97405.rs
new file mode 100644
index 00000000000..e567d5c2723
--- /dev/null
+++ b/src/test/ui/regions/closure-in-projection-issue-97405.rs
@@ -0,0 +1,32 @@
+// Regression test for #97405.
+// In `good_generic_fn` the param `T` ends up in the substs of closures/generators,
+// but we should be able to prove `<Gen<T> as Iterator>::Item: 'static` without
+// requiring `T: 'static`
+
+// edition:2018
+// check-fail
+
+fn opaque<F>(_: F) -> impl Iterator { b"".iter() }
+
+fn assert_static<T: 'static>(_: T) {}
+
+fn good_generic_fn<T>() {
+    // Previously, proving `<OpaqueTy<type_of(async {})> as Iterator>::Item: 'static`
+    // used to require `T: 'static`.
+    assert_static(opaque(async {}).next());
+    assert_static(opaque(|| {}).next());
+    assert_static(opaque(opaque(async {}).next()).next());
+}
+
+
+// This should fail because `T` ends up in the upvars of the closure.
+fn bad_generic_fn<T: Copy>(t: T) {
+    assert_static(opaque(async move { t; }).next());
+    //~^ ERROR the associated type `<impl Iterator as Iterator>::Item` may not live long enough
+    assert_static(opaque(move || { t; }).next());
+    //~^ ERROR the associated type `<impl Iterator as Iterator>::Item` may not live long enough
+    assert_static(opaque(opaque(async move { t; }).next()).next());
+    //~^ ERROR the associated type `<impl Iterator as Iterator>::Item` may not live long enough
+}
+
+fn main() {}
diff --git a/src/test/ui/regions/closure-in-projection-issue-97405.stderr b/src/test/ui/regions/closure-in-projection-issue-97405.stderr
new file mode 100644
index 00000000000..c08f1059ebf
--- /dev/null
+++ b/src/test/ui/regions/closure-in-projection-issue-97405.stderr
@@ -0,0 +1,30 @@
+error[E0310]: the associated type `<impl Iterator as Iterator>::Item` may not live long enough
+  --> $DIR/closure-in-projection-issue-97405.rs:24:5
+   |
+LL |     assert_static(opaque(async move { t; }).next());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding an explicit lifetime bound `<impl Iterator as Iterator>::Item: 'static`...
+   = note: ...so that the type `<impl Iterator as Iterator>::Item` will meet its required lifetime bounds
+
+error[E0310]: the associated type `<impl Iterator as Iterator>::Item` may not live long enough
+  --> $DIR/closure-in-projection-issue-97405.rs:26:5
+   |
+LL |     assert_static(opaque(move || { t; }).next());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding an explicit lifetime bound `<impl Iterator as Iterator>::Item: 'static`...
+   = note: ...so that the type `<impl Iterator as Iterator>::Item` will meet its required lifetime bounds
+
+error[E0310]: the associated type `<impl Iterator as Iterator>::Item` may not live long enough
+  --> $DIR/closure-in-projection-issue-97405.rs:28:5
+   |
+LL |     assert_static(opaque(opaque(async move { t; }).next()).next());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding an explicit lifetime bound `<impl Iterator as Iterator>::Item: 'static`...
+   = note: ...so that the type `<impl Iterator as Iterator>::Item` will meet its required lifetime bounds
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0310`.