Some bright sparks have decided that a cast on a constant cannot be a constant, so offsetof() produces this warning on clang-10:

include/intel_gnvs.h:113:1: error: static_assert expression is not an integral constant expression check_member(acpi_global_nvs, unused2, GNVS_CHROMEOS_ACPI_OFFSET); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/kernel.h:284:2: note: expanded from macro 'check_member' offsetof(struct structure, member) == (offset), \ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/stddef.h:20:32: note: expanded from macro 'offsetof' ^ include/intel_gnvs.h:113:1: note: cast that performs the conversions of a reinterpret_cast is ot allowed in a constant expression include/linux/stddef.h:20:33: note: expanded from macro 'offsetof'

Fix it by using the compiler built-in version, if available. This syncs the function to the same implementation as Linux v5.16 in this header file.

Signed-off-by: Simon Glass sjg@chromium.org ---

Changes in v3: - Update commit message to mention this syncs with Linux

include/linux/stddef.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/stddef.h b/include/linux/stddef.h index c540f6100d4..a7f546fdfe5 100644 --- a/include/linux/stddef.h +++ b/include/linux/stddef.h @@ -1,6 +1,8 @@ #ifndef _LINUX_STDDEF_H #define _LINUX_STDDEF_H

+#include <linux/compiler_types.h> + #undef NULL #if defined(__cplusplus) #define NULL 0 @@ -14,7 +16,11 @@

#ifndef __CHECKER__ #undef offsetof -#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) +#ifdef __compiler_offsetof +#define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER) +#else +#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) +#endif #endif

#endif