tests: Add regression test for derive token invalidation (#81099)

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/ui/proc-macro/derive-cfg-nested-tokens.rs b/tests/ui/proc-macro/derive-cfg-nested-tokens.rs
new file mode 100644
index 00000000000..7d4e8d8373d
--- /dev/null
+++ b/tests/ui/proc-macro/derive-cfg-nested-tokens.rs
@@ -0,0 +1,23 @@
+// A regression test for issue #81099.
+
+//@ check-pass
+//@ proc-macro:test-macros.rs
+
+#![feature(stmt_expr_attributes)]
+#![feature(proc_macro_hygiene)]
+
+#[macro_use]
+extern crate test_macros;
+
+#[derive(Clone, Copy)]
+struct S {
+    // `print_args` runs twice
+    // - on eagerly configured `S` (from `impl Copy`), only 11 should be printed
+    // - on non-configured `S` (from `struct S`), both 10 and 11 should be printed
+    field: [u8; #[print_attr] {
+        #[cfg(FALSE)] { 10 }
+        #[cfg(not(FALSE))]  { 11 }
+    }],
+}
+
+fn main() {}