tools: compiler-gcc.h: Guard error attribute use with __has_attribute

Linux Kernel / Linux Kernel - Nathan Chancellor [kernel.org] - 13 September 2021 22:51 UTC

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")

d0ee23f9d78b tools: compiler-gcc.h: Guard error attribute use with __has_attribute
tools/include/linux/compiler-gcc.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

Upstream: git.kernel.org


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