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List:       kde-buildsystem
Subject:    config.h.cmake issue ?
From:       faure () kde ! org (David Faure)
Date:       2006-05-03 14:09:42
Message-ID: 200605031609.43220.faure () kde ! org
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On Wednesday 03 May 2006 15:32, Ralf Habacker wrote:
> 	#cmakedefine HAVE_PCREPOSIX 1
> 
> The problem is that if someone forgets to add this constants the resulting errors \
> are hards to detect. 

We could fix this by using #if HAVE_FOO and #if !HAVE_FOO instead of ifdef,
then we would have compiler warnings when HAVE_FOO isn't defined (due to forgetting
to add it to config-foo.h, or due to forgetting to include config-foo.h in the cpp \
file).

But for this we need a #cmakedefine equivalent that sets 0 or 1, instead of "undef or \
1". Could this be done?

> Another example I encountered was the preparation of the CMakeLists.txt for a dbus \
> test build. I took the config.h.cmake from kdecore and added it to the dbus \
> sources.  Now I had to disable all not required #cmakedefine by hand, which wasn't \
> very easy to detect.  And if I had forgotten one, this was only detected by an \
> compiler error, so this ends up in an iterative process until i had fixed this \
> area.    

I can't see why you started from the huge, monolithic, unsplit, config.h.cmake from \
kdecore... I would have collected the HAVE_ needed by the code, and put those into \
config.h.cmake.

> Now imagine there is an developer, who adds stuff to a package which uses cmake and \
> it new to cmake. He adds and Find....cmake from another package and is thinking, \
> thats all, but unfortunally he had to add the #cmakedefine by hand, which will be \
> probably forgotten after a time not working with the build system.   
I don't really agree, since this is also how it worked with autoconf, you had to add \
something to config.h.in.

> macro_optional_find_package(PCRE,HAVE_PCREPOSIX)
That's really too simplified, there could be multiple defines to make, and it doesn't \
say where the output should go.... I think what you want is more like 

  macro_optional_find_package(PCRE)
  add_define( ${CMAKE_CURRENT_BINARY_DIR}/global.h PCRE_FOUND HAVE_PCREPOSIX )

which would add #define HAVE_PCREPOSIX 1 in global.h (and create that file if \
necessary) if PCRE_FOUND is true  [and 0 otherwise, if we agree about switching to \
#if - but this should probably be an option to add_define]. 
It would also have to check if global.h already defines it to the right value, to \
avoid  making unnecessary changes to the global.h file.

-- 
David Faure, faure at kde.org, sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).


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