1 files changed, 15 insertions, 2 deletions
diff --git a/tests/ui/check-cfg/allow-same-level.rs b/tests/ui/check-cfg/allow-same-level.rs
index ff724174cea..2fd296c05a8 100644
--- a/tests/ui/check-cfg/allow-same-level.rs
+++ b/tests/ui/check-cfg/allow-same-level.rs
@@ -1,12 +1,25 @@
-// This test check that #[allow(unexpected_cfgs)] doesn't work if put on the same level
+// This test check that #[allow(unexpected_cfgs)] **doesn't work**
+// when put on the same level as the #[cfg] attribute.
+//
+// It should work, but due to interactions between how #[cfg]s are
+// expanded, the lint machinery and the check-cfg impl, we
+// miss the #[allow], althrough we probably shoudln't.
+//
+// cf. https://github.com/rust-lang/rust/issues/124735
 //
 //@ check-pass
 //@ no-auto-check-cfg
-//@ compile-flags: --check-cfg=cfg()
+//@ compile-flags: --check-cfg=cfg() --cfg=unknown_but_active_cfg
+//@ normalize-stderr: "expected names are: .*" -> "..."
 
 #[allow(unexpected_cfgs)]
 #[cfg(FALSE)]
 //~^ WARNING unexpected `cfg` condition name
 fn bar() {}
 
+#[allow(unexpected_cfgs)]
+#[cfg(unknown_but_active_cfg)]
+//~^ WARNING unexpected `cfg` condition name
+fn bar() {}
+
 fn main() {}