From 560e5dcbcf776e06302ecb2fa81f77313d514306 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 21 Jul 2025 18:35:34 +0000
Subject: [PATCH] Add test for upvar breakage

---
 .../drop-live-upvar-2.may_not_dangle.stderr   | 18 +++++++++
 tests/ui/async-await/drop-live-upvar-2.rs     | 37 +++++++++++++++++++
 2 files changed, 55 insertions(+)
 create mode 100644 tests/ui/async-await/drop-live-upvar-2.may_not_dangle.stderr
 create mode 100644 tests/ui/async-await/drop-live-upvar-2.rs

diff --git a/tests/ui/async-await/drop-live-upvar-2.may_not_dangle.stderr b/tests/ui/async-await/drop-live-upvar-2.may_not_dangle.stderr
new file mode 100644
index 000000000000..34f6ba79246c
--- /dev/null
+++ b/tests/ui/async-await/drop-live-upvar-2.may_not_dangle.stderr
@@ -0,0 +1,18 @@
+error[E0597]: `y` does not live long enough
+  --> $DIR/drop-live-upvar-2.rs:31:26
+   |
+LL |         let y = ();
+   |             - binding `y` declared here
+LL |         drop_me = Droppy(&y);
+   |                          ^^ borrowed value does not live long enough
+...
+LL |     }
+   |     - `y` dropped here while still borrowed
+LL | }
+   | - borrow might be used here, when `fut` is dropped and runs the destructor for coroutine
+   |
+   = note: values in a scope are dropped in the opposite order they are defined
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0597`.
diff --git a/tests/ui/async-await/drop-live-upvar-2.rs b/tests/ui/async-await/drop-live-upvar-2.rs
new file mode 100644
index 000000000000..605db4c8f765
--- /dev/null
+++ b/tests/ui/async-await/drop-live-upvar-2.rs
@@ -0,0 +1,37 @@
+//@ revisions: may_dangle may_not_dangle
+//@[may_dangle] check-pass
+//@ edition: 2018
+
+// Ensure that if a coroutine's interior has no drop types then we don't require the upvars to
+// be *use-live*, but instead require them to be *drop-live*. In this case, `Droppy<&'?0 ()>`
+// does not require that `'?0` is live for drops since the parameter is `#[may_dangle]` in
+// the may_dangle revision, but not in the may_not_dangle revision.
+
+#![feature(dropck_eyepatch)]
+
+struct Droppy<T>(T);
+
+#[cfg(may_dangle)]
+unsafe impl<#[may_dangle] T> Drop for Droppy<T> {
+    fn drop(&mut self) {
+        // This does not use `T` of course.
+    }
+}
+
+#[cfg(may_not_dangle)]
+impl<T> Drop for Droppy<T> {
+    fn drop(&mut self) {}
+}
+
+fn main() {
+    let drop_me;
+    let fut;
+    {
+        let y = ();
+        drop_me = Droppy(&y);
+        //[may_not_dangle]~^ ERROR `y` does not live long enough
+        fut = async {
+            std::mem::drop(drop_me);
+        };
+    }
+}