On Thu, Sep 17, 2026 at 06:21:19PM -0700, Nathan Chancellor wrote:
> While we could certainly try to cook something like this up, we could
> also avoid the split across two files by just defining the flags in
> Kconfig directly and using them in the Makefile through their symbol,
> like we already do for -Wimplicit-fallthrough. For example, instead of
>
> config CC_HAS_STRICT_FLEX_ARRAYS
> def_bool $(cc-option,-fstrict-flex-arrays=3)
>
> KBUILD_CFLAGS += $(if
> $(CONFIG_CC_HAS_STRICT_FLEX_ARRAYS),-fstrict-flex-arrays=3)
>
> We would just do
>
> config CC_STRICT_FLEX_ARRAYS
> string
> default "-fstrict-flex-arrays=3" if $(cc-option,-fstrict-flex-arrays=3)
>
> KBUILD_CFLAGS += $(CONFIG_CC_STRICT_FLEX_ARRAYS)
>
> While we still get the duplication (and we could look at getting rid of
> it with your cc-option-str idea or whatever), it is at least contained
> to the same location, so out of sync issues should be much rarer. I do
> diff Kconfigs so this might make certain issues with checks a little bit
> more obvious if something changes on the compiler side.
Yeah, and note that cc-option-bit already exists. It's just a weird name
is all and there isn't an ld-option-bit.
As for naming conventions, I think "CC_OPT_" would be a good prefix. And
this works today with no change:
config CC_OPT_STRICT_FLEX_ARRAYS
string
default "$(cc-option-bit,-fstrict-flex-arrays=3)"
(do we need "def_string" now?)
--
Kees Cook
