[PATCH] meson: Check for stdarg.h

[Ján Tomko]

On a Wednesday in 2020, Daniel P. Berrangé wrote:
>On Wed, Sep 02, 2020 at 02:07:54PM +0200, Michal Privoznik wrote:
>> As it turns out, one of my previous commits in which I removed
>> checking for stdarg.h was too aggressive. Long story short, the
>> readline public headers rely on stdarg.h and what is worse, they
>> expect us to declare the autotools style of macro (HAVE_STDARG_H)
>> if the header file exists. If we don't do it then compiling virsh
>> on macos fails.
>>
>> See 9ea3424a178 for more info.
>
>Ewww....
>
>Deprecated in 2000,  removed in 2013, then immediately readded to
>"fix" apps which still relied on K&R C with no function prototypes.
>
>The readline maintainer is more forgiving of ancient application code
>than I would be :-) 30 years since arrival of ANSI C is enough time
>to update code to use function prototypes, especially if you want to
>build against a readline library released in 2020, as opposed to the
>old version released years ago.
>
>>
>> Fixes: 85808b73846f93d656b4c81b6ebddd2dc3881bf6
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>  meson.build | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/meson.build b/meson.build
>> index 1aad385ad1..98f7545495 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -1333,8 +1333,12 @@ if readline_dep.found()
>>      endif
>>    endif
>>
>> -  # We need this to avoid compilation issues with modern compilers.
>> -  # See 9ea3424a178 for a more detailed explanation
>> +  # We need both of these hacks to avoid compilation issues with modern
>> +  # compilers. See 9ea3424a178 for a more detailed explanation.
>> +  if cc.has_header('stdarg.h')
>> +    conf.set('HAVE_STDARG_H', 1)
>> +  endif
>
>Do we have any platforms which lack stdarg.h ? eg can be just add
>"#define HAVE_STDARG_H 1" unconditionally in the virsh code before
>it includes the readline headers ?
>

It's part of the C99 standard:
https://pubs.opengroup.org/onlinepubs/009695399/basedefs/stdarg.h.html

(but I'm still confused why this builds on other platforms even though
  HAVE_STDARG_H is not defined anywhere)

Jano

>Regards,
>Daniel
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>