This attribute is not recognized by clang.

An investigation has been performed to ensure this attribute has no
effect on layout of structures we use in QEMU [1], so it's safe to
remove now.

In the future, we'll forbid introducing new bitfields in packed struct,
as they are the one potentially impacted by this change.

[1] https://lore.kernel.org/qemu-devel/66c346de-7e20-4831-b3eb-1cda83240af9@linaro.org/

Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
---
 meson.build                               | 5 -----
 include/qemu/compiler.h                   | 7 +------
 scripts/cocci-macro-file.h                | 6 +-----
 subprojects/libvhost-user/libvhost-user.h | 6 +-----
 4 files changed, 3 insertions(+), 21 deletions(-)

diff --git a/meson.build b/meson.build
index a290dbfa331..97cefb7cdd7 100644
--- a/meson.build
+++ b/meson.build
@@ -354,11 +354,6 @@ elif host_os == 'sunos'
   qemu_common_flags += '-D__EXTENSIONS__'
 elif host_os == 'haiku'
   qemu_common_flags += ['-DB_USE_POSITIVE_POSIX_ERRORS', '-D_BSD_SOURCE', '-fPIC']
-elif host_os == 'windows'
-  if not compiler.compiles('struct x { int y; } __attribute__((gcc_struct));',
-                           args: '-Werror')
-    error('Your compiler does not support __attribute__((gcc_struct)) - please use GCC instead of Clang')
-  endif
 endif
 
 # Choose instruction set (currently x86-only)
diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index c06954ccb41..d904408e5ed 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -22,12 +22,7 @@
 #define QEMU_EXTERN_C extern
 #endif
 
-#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
-# define QEMU_PACKED __attribute__((gcc_struct, packed))
-#else
-# define QEMU_PACKED __attribute__((packed))
-#endif
-
+#define QEMU_PACKED __attribute__((packed))
 #define QEMU_ALIGNED(X) __attribute__((aligned(X)))
 
 #ifndef glue
diff --git a/scripts/cocci-macro-file.h b/scripts/cocci-macro-file.h
index d247a5086e9..c64831d5408 100644
--- a/scripts/cocci-macro-file.h
+++ b/scripts/cocci-macro-file.h
@@ -23,11 +23,7 @@
 #define G_GNUC_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 #define G_GNUC_NULL_TERMINATED __attribute__((sentinel))
 
-#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
-# define QEMU_PACKED __attribute__((gcc_struct, packed))
-#else
-# define QEMU_PACKED __attribute__((packed))
-#endif
+#define QEMU_PACKED __attribute__((packed))
 
 #define cat(x,y) x ## y
 #define cat2(x,y) cat(x,y)
diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
index deb40e77b3f..2ffc58c11b1 100644
--- a/subprojects/libvhost-user/libvhost-user.h
+++ b/subprojects/libvhost-user/libvhost-user.h
@@ -186,11 +186,7 @@ typedef struct VhostUserShared {
     unsigned char uuid[UUID_LEN];
 } VhostUserShared;
 
-#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
-# define VU_PACKED __attribute__((gcc_struct, packed))
-#else
-# define VU_PACKED __attribute__((packed))
-#endif
+#define VU_PACKED __attribute__((packed))
 
 typedef struct VhostUserMsg {
     int request;
-- 
2.39.5

On 11/28/24 14:15, Pierrick Bouvier wrote:
> This attribute is not recognized by clang.
> 
> An investigation has been performed to ensure this attribute has no
> effect on layout of structures we use in QEMU [1], so it's safe to
> remove now.
> 
> In the future, we'll forbid introducing new bitfields in packed struct,
> as they are the one potentially impacted by this change.
> 
> [1] https://lore.kernel.org/qemu-devel/66c346de-7e20-4831-b3eb-1cda83240af9@linaro.org/
> 
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Acked-by: Stefano Garzarella <sgarzare@redhat.com>
> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> ---
>   meson.build                               | 5 -----
>   include/qemu/compiler.h                   | 7 +------
>   scripts/cocci-macro-file.h                | 6 +-----
>   subprojects/libvhost-user/libvhost-user.h | 6 +-----
>   4 files changed, 3 insertions(+), 21 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~