Add test batch 4

tests/ui/panic-handler/catch-unwind-during-unwind-68696.rs

@@ -0,0 +1,28 @@
+// https://github.com/rust-lang/rust/issues/68696
+// Checks that catch_unwind can be used if unwinding is already in progress.
+// Used to fail when standard library had been compiled with debug assertions,
+// due to incorrect assumption that a current thread is not panicking when
+// entering the catch_unwind.
+//
+//@ run-pass
+//@ ignore-backends: gcc
+
+use std::panic::catch_unwind;
+
+#[allow(dead_code)]
+#[derive(Default)]
+struct Guard;
+
+impl Drop for Guard {
+    fn drop(&mut self) {
+        let _ = catch_unwind(|| {});
+    }
+}
+
+fn main() {
+    #[cfg(panic = "unwind")]
+    let _ = catch_unwind(|| {
+        let _guard = Guard::default();
+        panic!();
+    });
+}