Re: 5.2 rc2 tarball now available

[Daniel J S. <dan...@ie...>]

On 07/05/2017 05:08 PM, Petr Mikulik wrote:
>>>>>> I have troubles compiling rc2 on Linux (OpenSUSE 42.2, and some
>>>>>> Ubuntu) linking fails.
>>>>>>
>>>>>> It is this problem:
>>>>>>      https://sourceforge.net/p/gnuplot/support-requests/196/
>>>>>>
>>>>>> The workaround
>>>>>>      configure --with-X11
>>>>>> described above does not help, while
>>>>>>      TERMLIBS="-lX11" ./configure
>>>>>> let me gnuplot compile.
>>>>>>
>>>>>> Can this be fixed?
>>>>>
>>>>>   No.  It is a bug in the configuration files distributed for
>>>>> libwxgtk.
>>>>
>>>> Unfortunately it seems to be a wide-spread bug. It is quite
>>>> embarassing that a
>>>> compile needs googling to fix it locally.
>>>>
>>>> Cannot "./configure" take care of this? I.e. add the "-lX11" flag if
>>>> "something"?
>>>
>>> That "something" is exactly the problem.   Only some versions of
>>> wxWidgets need this, and only for some configurations.   The
>>> wx-config tool is supposed to tell us what libraries are needed so
>>> we can link them.  But it doesn't mention X11.    So how are we to know?
>>
>> Actually, I think this is gnuplot's responsibility.  If I do
>
>> Anyway, I think gnuplot configure is obligated to add -lX11, given the
>> situation.
>
> I think that ./configure is the place for tests of compile conditions.
> There can be some simple case testing whether "-lX11" is needed or not.
> Is such a workaround possible?

The necessary tests are already present.  The hunks of code that matter 
have pre-processor conditionals:

#if defined(WX_NEEDS_XINITTHREADS) && defined(X11)
#include <X11/Xlib.h>	/* Magic fix for linking against wxgtk3.0 */
#endif

and WX_NEEDS_XINITTHREADS and X11 are defined from tests within the 
configure process.

We only want to include library -lX11 for the building of wx_gui.cpp, 
and there is a convenient definition for that:

Makefile:LIBRARIES_FOR_X =  -lX11

The included libraries for wx_gui.cpp are gotten from the wx-config 
command as discussed earlier, and it shows up as

Makefile:WX_LIBS = -L/usr/lib/x86_64-linux-gnu -pthread 
-lwx_gtk2u_xrc-3.0 -lwx_gtk2u_html-3.0 -lwx_gtk2u_qa-3.0 
-lwx_gtk2u_adv-3.0 -lwx_gtk2u_core-3.0 -lwx_baseu_xml-3.0 
-lwx_baseu_net-3.0 -lwx_baseu-3.0  -lpangocairo-1.0 -lpango-1.0 -lcairo 
-lgobject-2.0 -lglib-2.0

So, all we really need do is append LIBRARIES_FOR_X to WX_LIBS if 
XInitThreads() is used in the wx_gui code.  If X11 is not present, 
LIBRARIES_FOR_X should be empty.

I've attached a six-line patch to the original bug report associated 
with the inclusion of XInitThreads() here:

https://sourceforge.net/p/gnuplot/bugs/_discuss/thread/94192961/d1c5/attachment/gnuplot-wxlibs_xinitthreads_configure-djs2017jul06.patch

Dan