kbuild: use -S instead of -E for precise cc-option test in Kconfig

[ Upstream commit 3bed1b7b9d79ca40e41e3af130931a3225e951a3 ]

Currently, -E (stop after the preprocessing stage) is used to check
whether the given compiler flag is supported.

While it is faster than -S (or -c), it can be false-positive. You need
to run the compilation proper to check the flag more precisely.

For example, -E and -S disagree about the support of
"--param asan-instrument-allocas=1".

$ gcc -Werror --param asan-instrument-allocas=1 -E -x c /dev/null -o /dev/null
$ echo $?
0

$ gcc -Werror --param asan-instrument-allocas=1 -S -x c /dev/null -o /dev/null
cc1: error: invalid --param name ‘asan-instrument-allocas’; did you mean ‘asan-instrument-writes’?
$ echo $?
1

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

0 files changed, 0 insertions, 0 deletions