Merge tag 'kbuild-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux

Pull Kbuild/Kconfig updates from Nicolas Schier:
"Kbuild:
- reject unexpected values for LLVM=
- uapi: r

Merge tag 'kbuild-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux

Pull Kbuild/Kconfig updates from Nicolas Schier:
"Kbuild:
- reject unexpected values for LLVM=
- uapi: remove usage of toolchain headers
- switch from '-fms-extensions' to '-fms-anonymous-structs' when
available (currently: clang >= 23.0.0)
- reduce the number of compiler-generated suffixes for clang thin-lto
build
- reduce output spam ("GEN Makefile") when building out of tree
- improve portability for testing headers
- also test UAPI headers against C++ compilers
- drop build ID architecture allow-list in vdso_install
- only run checksyscalls when necessary
- update the debug information notes in reproducible-builds.rst
- expand inlining hints with -fdiagnostics-show-inlining-chain

Kconfig:
- forbid multiple entries with the same symbol in a choice
- error out on duplicated kconfig inclusion"

* tag 'kbuild-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (35 commits)
kbuild: expand inlining hints with -fdiagnostics-show-inlining-chain
kconfig: forbid multiple entries with the same symbol in a choice
Documentation: kbuild: Update the debug information notes in reproducible-builds.rst
checksyscalls: move instance functionality into generic code
checksyscalls: only run when necessary
checksyscalls: fail on all intermediate errors
checksyscalls: move path to reference table to a variable
kbuild: vdso_install: drop build ID architecture allow-list
kbuild: vdso_install: gracefully handle images without build ID
kbuild: vdso_install: hide readelf warnings
kbuild: vdso_install: split out the readelf invocation
kbuild: uapi: also test UAPI headers against C++ compilers
kbuild: uapi: provide a C++ compatible dummy definition of NULL
kbuild: uapi: handle UML in architecture-specific exclusion lists
kbuild: uapi: move all include path flags together
kbuild: uapi: move some compiler arguments out of the command definition
check-uapi: use dummy libc includes
check-uapi: honor ${CROSS_COMPILE} setting
check-uapi: link into shared objects
kbuild: reduce output spam when building out of tree
...

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kbuild: uapi: provide a C++ compatible dummy definition of NULL

NULL works differently in C++ compared to C.

To allow testing the UAPI headers against C++ compilers, provide
a variant of NULL which

kbuild: uapi: provide a C++ compatible dummy definition of NULL

NULL works differently in C++ compared to C.

To allow testing the UAPI headers against C++ compilers, provide
a variant of NULL which works with those.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260316-kbuild-uapi-c-v2-4-35d6d0ed863f@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>

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kbuild: uapi: provide stub includes for some libc headers

Some UAPI headers incorrectly use libc headers. To compile-test these
UAPI headers, their respective libc dependencies need to be present.
N

kbuild: uapi: provide stub includes for some libc headers

Some UAPI headers incorrectly use libc headers. To compile-test these
UAPI headers, their respective libc dependencies need to be present.
Not all kernel toolchains provide these headers, reducing test coverage.

Introduce some stub headers which provide just enough symbols to test
all UAPI headers. Most headers are empty anyways, as their symbols are
only used in macros which are not actually evaluated.

As these headers are only ever used with newer kernel toolchains, they
can defer to compiler builtins in many cases.

As more UAPI headers are cleaned up to not require these stubs anymore,
they can be removed again.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-6-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>

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