Since we build TCI with FFI (commit 22f15579fa1 "tcg: Build ffi data
structures for helpers") we get on Darwin:

  In file included from ../../tcg/tci.c:22:
  In file included from include/tcg/helper-info.h:13:
  /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/ffi/ffi.h:483:5: warning: 'FFI_GO_CLOSURES' is not defined, evaluates to 0 [-Wundef]
    483 | #if FFI_GO_CLOSURES
        |     ^
  1 warning generated.

This was fixed in upstream libffi in 2023, but not backported to MacOSX.
Simply disable the warning locally.

Reported-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/tcg/helper-info.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/tcg/helper-info.h b/include/tcg/helper-info.h
index 909fe73afa..49a27e4eae 100644
--- a/include/tcg/helper-info.h
+++ b/include/tcg/helper-info.h
@@ -10,7 +10,19 @@
 #define TCG_HELPER_INFO_H
 
 #ifdef CONFIG_TCG_INTERPRETER
+/*
+ * MacOSX 15 uses an old version of libffi which contains
+ *   #if FFI_GO_CLOSURES
+ * but does not define that in <ffitarget.h>, included from <ffi.h>.
+ * This was fixed upstream with
+ *   https://github.com/libffi/libffi/commit/c23e9a1c
+ * We don't care about go closures one way or the other;
+ * just suppress the warning.
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wundef"
 #include <ffi.h>
+#pragma GCC diagnostic pop
 #endif
 #include "tcg-target-reg-bits.h"
 
-- 
2.43.0

On 3/12/25 17:14, Richard Henderson wrote:
> Since we build TCI with FFI (commit 22f15579fa1 "tcg: Build ffi data
> structures for helpers") we get on Darwin:
> 
>    In file included from ../../tcg/tci.c:22:
>    In file included from include/tcg/helper-info.h:13:
>    /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk/usr/include/ffi/ffi.h:483:5: warning: 'FFI_GO_CLOSURES' is not defined, evaluates to 0 [-Wundef]
>      483 | #if FFI_GO_CLOSURES
>          |     ^
>    1 warning generated.
> 
> This was fixed in upstream libffi in 2023, but not backported to MacOSX.
> Simply disable the warning locally.
> 
> Reported-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   include/tcg/helper-info.h | 12 ++++++++++++
>   1 file changed, 12 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>