[Pkg-swan-devel] Bug#1147712: Bug#1147712: strongswan: FTBFS with GCC 16: custom printf specifier %B rejected because -Wno-format is overridden

[Paul Menzel]

Dear Yves-Alexis,


Am 15.09.26 um 09:04 schrieb Yves-Alexis Perez:
> On Mon, 2026-09-14 at 23:32 +0200, Paul Menzel wrote:
>>> I'm not comfortable disabling this part of upstream checks. You might want to
>>> reach them to check if those could be overridden.
>>
>> What checks do you mean exactly, that would get disabled? Upstream’s
>> configure explicitly adds `-Wno-format` [1]:
>>
>>       # disable some warnings, whether explicitly enabled above or by default
>>       # these are not compatible with our custom printf specifiers
>>       WARN_CFLAGS="$WARN_CFLAGS -Wno-format"
>>       WARN_CFLAGS="$WARN_CFLAGS -Wno-format-security"
> 
> Then I'm not actually sure what's the problem anyway. Warnings are enabled by
> default if .git is present [1] but you can pass --disable-warnings [2] or just
> override CFLAGS [3].

Just to be clear: warnings are enabled (also in your build), but more 
importantly `-Werror` is passed failing the build.

> You (or Claude) actually said it in your first message:
> 
>> Alternatively, or in addition, d/rules can append the flags itself,
>> which does not depend on the patch surviving the next upstream merge:
>>
>>      export DEB_CFLAGS_MAINT_APPEND=-Wno-format -Wno-format-security
> 
> So I don't think there's a bug at all here. The package builds fine in Debian
> environment, and if you build in your own environment (for investigating/debug
> purposes) you can override things at will.

Well, it depends on the definition for bug. ;-) Debian appends 
`-Wformat`, upstream explicitly disables. So you get the warnings in 
your build log, that upstream does not see. Additionally, `debcheckout` 
is part of *devscripts*, and quite useful to me. Making it easy for 
people to actually build the software/package would be quite helpful and 
in the spirit of FLOSS.


Kind regards,

Paul


> [1]: https://github.com/strongswan/strongswan/blob/78937d2190656f175599411c14be5ecbeb2c2c02/configure.ac#L518
> [2]: https://github.com/strongswan/strongswan/blob/78937d2190656f175599411c14be5ecbeb2c2c02/configure.ac#L316
> [3]: https://github.com/strongswan/strongswan/blob/78937d2190656f175599411c14be5ecbeb2c2c02/configure.ac#L1425