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SubjectRe: Makefile: CC_IMPLICIT_FALLTHROUGH passed quoted as argument to gcc
On Sun, Dec 5, 2021 at 1:53 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Sat, Dec 4, 2021 at 5:13 AM Salvatore Bonaccorso <carnil@debian.org> wrote:
> >
> > Andreas suggested to replace the
> >
> > KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
> >
> > with
> >
> > KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(patsubst "%",%,$(CONFIG_CC_IMPLICIT_FALLTHROUGH))
>
> Ugh. I think the external build environment is a bit broken, but
> whatever. The above is ugly but I guess it works.
>
> Another alternative would be to make the Kconfig strings simply not
> have '"' as part of them.
>
> When you do
>
> a = "hello"
> print $a
>
> in any normal language, you generally wouldn't expect it to print the
> quotes, it should just print the bare word.
>
> But that's what the Kconfig string language basically does in this
> case. And I guess several users expect and take advantage of that ;(
>
> Masahiro? Comments?

Yes, you get to the point.

In fact, this is in my TODO list for a while
(and this is the reason I was doing prerequisite Kconfig refactoring
in the previous development cycle).
I will try to find some spare time to complete this work.



Kconfig generates two similar files,

- .config
- include/config/auto.conf

Changing the format of the .config is presumably problematic
since it is the saved user configuration as well.

It is possible (and more reasonable) to change include/config/auto.conf
so strings are not quoted.

In Makefiles, quotations are just normal characters; they have no
special functionality.

So, in Makefile context, it is more handy to do

CONFIG_X=foo bar

instead of

CONFIG_X="foo bar"



One problem is include/config/auto.conf is included not only by Makefiles
but also by shell scripts.


In shell context, the right hand side must be quoted
in case the value contains spaces.

CONFIG_X="foo bar"



My plan is to fix
scripts/link-vmlinux.sh
scripts/gen_autoksyms.sh
etc. to not directly include the auto.conf.
Later, change Kconfig to generate the auto.conf without "".



In the meantime,

KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(patsubst
"%",%,$(CONFIG_CC_IMPLICIT_FALLTHROUGH))

or if you prefer slightly shorter form,

KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH:"%"=%)

will be a workaround.





>
> Linus



--
Best Regards
Masahiro Yamada

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