Nathan Chancellor d0ee23f9d7 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 4e59869aa6 ("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 815f0ddb34 ("include/linux/compiler*.h: make compiler-*.h
mutually exclusive") and commit a3f8a30f3f ("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: 4e59869aa6 ("compiler-gcc.h: drop checks for older GCC versions")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-13 15:51:41 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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