Nathan Chancellor natechancellor@gmail.com writes:
Commit aea447141c7e ("powerpc: Disable -Wbuiltin-requires-header when setjmp is used") disabled -Wbuiltin-requires-header because of a warning about the setjmp and longjmp declarations.
r367387 in clang added another diagnostic around this, complaining that there is no jmp_buf declaration.
In file included from ../arch/powerpc/xmon/xmon.c:47: ../arch/powerpc/include/asm/setjmp.h:10:13: error: declaration of built-in function 'setjmp' requires the declaration of the 'jmp_buf' type, commonly provided in the header <setjmp.h>. [-Werror,-Wincomplete-setjmp-declaration] extern long setjmp(long *); ^ ../arch/powerpc/include/asm/setjmp.h:11:13: error: declaration of built-in function 'longjmp' requires the declaration of the 'jmp_buf' type, commonly provided in the header <setjmp.h>. [-Werror,-Wincomplete-setjmp-declaration] extern void longjmp(long *, long); ^ 2 errors generated.
Take the same approach as the above commit by disabling the warning for the same reason, we provide our own longjmp/setjmp function.
Cc: stable@vger.kernel.org # 4.19+ Link: https://github.com/ClangBuiltLinux/linux/issues/625 Link: https://github.com/llvm/llvm-project/commit/3be25e79477db2d31ac46493d97eca8c... Signed-off-by: Nathan Chancellor natechancellor@gmail.com
It may be worth using -fno-builtin-setjmp and -fno-builtin-longjmp instead as it makes it clear to clang that we are not using the builtin longjmp and setjmp functions, which I think is why these warnings are appearing (at least according to the commit that introduced this waring).
Sample patch: https://github.com/ClangBuiltLinux/linux/issues/625#issuecomment-519251372
Couldn't we just add those flags to CFLAGS for the whole kernel? Rather than making them per-file.
I mean there's no kernel code that wants to use clang's builtin setjmp/longjmp implementation at all right?
cheers