1 files changed, 27 insertions, 0 deletions
diff --git a/tests/incremental/issue-39569.rs b/tests/incremental/issue-39569.rs
new file mode 100644
index 000000000..881ecfca7
--- /dev/null
+++ b/tests/incremental/issue-39569.rs
@@ -0,0 +1,27 @@
+// Regression test for a weird corner case in our dep-graph reduction
+// code. When we solve `CoerceUnsized<Foo>`, we find no impls, so we
+// don't end up with an edge to any HIR nodes, but it still gets
+// preserved in the dep graph.
+
+// revisions:rpass1 rpass2
+// compile-flags: -Z query-dep-graph
+
+use std::sync::Arc;
+
+#[cfg(rpass1)]
+struct Foo { x: usize }
+
+#[cfg(rpass1)]
+fn main() {
+    let x: Arc<Foo> = Arc::new(Foo { x: 22 });
+    let y: Arc<Foo> = x;
+}
+
+#[cfg(rpass2)]
+struct FooX { x: usize }
+
+#[cfg(rpass2)]
+fn main() {
+    let x: Arc<FooX> = Arc::new(FooX { x: 22 });
+    let y: Arc<FooX> = x;
+}