[PATCH RFC next 15/18] kbuild: enable -Werror for hostprogs

[Quentin Schulz]

Hi Simon,

On 5/4/26 10:38 PM, Simon Glass wrote:
> Hi Quentin,
> 
> On 2026-05-04T13:20:27, Quentin Schulz <foss+uboot at 0leil.net> wrote:
>> kbuild: enable -Werror for hostprogs
>>
>> [ Upstream commit 27758d8c2583d10472b745a43ff86fef96c11ef7 ]
>>
>> Original commit log:
>>
>>    The hostprog compilers and linkers do not share the regular compiler flags,
>>    so they are not affected by CONFIG_WERROR or W=e. As hostprogs are used
>>    during the bootstrap of the build, they can't depend on kconfig options.
>>
>>    Enable -Werror unconditionally.
>>
>> Signed-off-by: Quentin Schulz <quentin.schulz at cherry.de>
>>
>> scripts/Makefile.extrawarn | 5 +++++
>>   1 file changed, 5 insertions(+)
> 
>> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
>> @@ -109,3 +109,8 @@ KBUILD_LDFLAGS            += --fatal-warnings
>>   KBUILD_RUSTFLAGS     += -Dwarnings
>>
>>   endif
>> +
>> +# Hostprog flags are used during build bootstrapping and can not rely on CONFIG_ symbols.
>> +KBUILD_HOSTCFLAGS    += -Werror
>> +KBUILD_HOSTLDFLAGS   += -Wl,--fatal-warnings
>> +KBUILD_HOSTRUSTFLAGS += -Dwarnings
> 
> Just to check, is there a reason to keep this and patch 16 separate?

Backports from Linux kernel where they already are separate.

> The next patch immediately undoes the 'unconditionally' claim made
> here. Anyone bisecting through this point gets host tools failing on
> any new compiler warning, with no way to opt out short of
> HOSTCFLAGS=-Wno-error - squashing would also let you drop the comment
> that patch 16 then has to rewrite.
> 

Fair enough.

> If you'd rather keep them split to preserve upstream history, you
> could mention in the commit message that the next patch makes it
> conditional.
> 

I would prefer to, it should make it easier to then see which patches 
were backported or not (git log --oneline). But I understand this 
unnecessarily breaks bisectability, so no strong opinion.

Cheers,
Quentin