Re: [PATCH v7 13/22] osdep: Avoid using Clang-specific __builtin_available()

[Akihiko Odaki]

Reviewed-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Tested-by: Akihiko Odaki <akihiko.odaki@gmail.com>

On Mon, Mar 7, 2022 at 8:19 AM Philippe Mathieu-Daudé
<philippe.mathieu.daude@gmail.com> wrote:
>
> From: Philippe Mathieu-Daudé <f4bug@amsat.org>
>
> Remove the Clang specific __builtin_available() to allow building
> with GCC, otherwise we get:
>
>   include/qemu/osdep.h: In function 'qemu_thread_jit_write':
>   include/qemu/osdep.h:787:9: warning: implicit declaration of function 
> '__builtin_available'; did you mean '__builtin_scalbl'? 
> [-Wimplicit-function-declaration]
>     787 |     if (__builtin_available(macOS 11.0, *)) {
>         |         ^~~~~~~~~~~~~~~~~~~
>         |         __builtin_scalbl
>   include/qemu/osdep.h:787:9: warning: nested extern declaration of 
> '__builtin_available' [-Wnested-externs]
>   include/qemu/osdep.h:787:29: error: 'macOS' undeclared (first use in this 
> function)
>     787 |     if (__builtin_available(macOS 11.0, *)) {
>         |                             ^~~~~
>   include/qemu/osdep.h:787:29: note: each undeclared identifier is reported 
> only once for each function it appears in
>   include/qemu/osdep.h:787:34: error: expected ')' before numeric constant
>     787 |     if (__builtin_available(macOS 11.0, *)) {
>         |                            ~     ^~~~~
>         |                                  )
>
> Beside, on macOS Catalina we get 2254 times:
>
>   include/qemu/osdep.h:780:5: warning: 'pthread_jit_write_protect_np' is only 
> available on macOS 11.0 or newer [-Wunguarded-availability-new]
>       pthread_jit_write_protect_np(true);
>       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Fix by using a stricker toolchain version low range, replacing
> MAC_OS_X_VERSION_MAX_ALLOWED by MAC_OS_X_VERSION_MIN_REQUIRED.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  include/qemu/osdep.h | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index 7bcce3bceb..488a286300 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -642,19 +642,15 @@ size_t qemu_get_host_physmem(void);
>   * for the current thread.
>   */
>  #if defined(MAC_OS_VERSION_11_0) && \
> -    MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_VERSION_11_0
> +    MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
>  static inline void qemu_thread_jit_execute(void)
>  {
> -    if (__builtin_available(macOS 11.0, *)) {
> -        pthread_jit_write_protect_np(true);
> -    }
> +    pthread_jit_write_protect_np(true);
>  }
>
>  static inline void qemu_thread_jit_write(void)
>  {
> -    if (__builtin_available(macOS 11.0, *)) {
> -        pthread_jit_write_protect_np(false);
> -    }
> +    pthread_jit_write_protect_np(false);
>  }
>  #else
>  static inline void qemu_thread_jit_write(void) {}
> --
> 2.34.1
>