From d0ee23f9d78be5531c4b055ea424ed0b489dfe9b Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Mon, 13 Sep 2021 15:09:00 -0700 Subject: [PATCH] tools: compiler-gcc.h: Guard error attribute use with __has_attribute When building objtool with HOSTCC=clang, there are several errors along the lines of orc_dump.c:201:28: error: unknown attribute 'error' ignored [-Werror,-Wunknown-attributes] This occurs after commit 4e59869aa655 ("compiler-gcc.h: drop checks for older GCC versions"), which removed the GCC_VERSION gating. The removed version check just so happened to prevent __compiletime_error() from being defined with clang because it pretends to be GCC 4.2.1 for compatibility but the error attribute was not added to clang until 14.0.0. Commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") and commit a3f8a30f3f00 ("Compiler Attributes: use feature checks instead of version checks") refactored the handling of attributes in the main kernel to avoid situations like this but that refactoring has never been done for the tools directory. Refactoring is a rather large undertaking and this has never been an issue before so instead, just guard the definition of __compiletime_error() with __has_attribute() so that there are no more errors. Fixes: 4e59869aa655 ("compiler-gcc.h: drop checks for older GCC versions") Signed-off-by: Nathan Chancellor Signed-off-by: Linus Torvalds --- tools/include/linux/compiler-gcc.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/include/linux/compiler-gcc.h b/tools/include/linux/compiler-gcc.h index 43d9a46d36f0..8816f06fc6c7 100644 --- a/tools/include/linux/compiler-gcc.h +++ b/tools/include/linux/compiler-gcc.h @@ -16,7 +16,9 @@ # define __fallthrough __attribute__ ((fallthrough)) #endif -#define __compiletime_error(message) __attribute__((error(message))) +#if __has_attribute(__error__) +# define __compiletime_error(message) __attribute__((error(message))) +#endif /* &a[0] degrades to a pointer: a different type from an array */ #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))