[cmake-developers] Improved support for using cmake-based libraries in non-cmake projects

[Alexander Neundorf]

On Monday, June 06, 2011 03:44:20 PM Brad King wrote:
> On 06/05/2011 07:14 PM, Eric Noulard wrote:
> >>> 2011/6/4 Alexander Neundorf <neundorf at kde.org>:
> >>>> * if so, it will check that for FOO_INCLUDES and FOO_LIBRARIES
> >>>> * create the command line arguments for the compiler from that
> >>>> * print "-I/opt/foo/include" to stdout
> 
> [snip]
> 
> > cmake-config would be a [portable] script (or even minimalistic
> > binary), which basically call
> > a cmake script (for portability).
> 
> This may be technically challenging, especially for the link options.
> CMake's link line generation happens at generation time and is not
> accessible to the CMake language.  Furthermore, it depends on a lot
> of information about the final library or executable because it is
> an expert system [1] (e.g. implicit language runtime libraries for
> mixed executables, transitive dependencies, etc.).

I have it basically working here now, including a cmake.m4 macro so you can do 
CMAKE_CHECK_MODULE() in configure.in.

Checking whether a package has been found is straightforward.

For creating the compile flags I'm using 
localGen->GetIncludeFlags(language.c_str(), false);

For the linking I currently get the FOO_LIBRARIES variables, create an empty 
executable target, set the LINKER_LANGUAGE to what the user wants, add all the 
libraries to the executable and then call 
localGen->GetTargetFlags()

This is what I get currently, the stuff for libxml2 is from cmake via 
FindLibXml2.cmake (with an additional libbar.so):

~/src/tests/pkgconfig/pkgconfig> ./configure 
checking for pkg-config... /usr/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
checking for QtSQL... yes
Result: CFLAGS: -DQT_SHARED -I/usr/include/QtSql -I/usr/include/QtCore   LIBS: 
-lQtSql -lQtCore  
checking for QtXML... yes
Result: CFLAGS: -DQT_SHARED -I/usr/include/QtXml -I/usr/include/QtCore   LIBS: 
-lQtXml -lQtCore  
checking for XFT... yes
Result: CFLAGS: -I/usr/include/freetype2   LIBS: -lXft  
checking for LIBXML2... LibXml2 found.
LibXml2 found.
yes
Result: CFLAGS: -I/usr/include/libxml2   LIBS: -rdynamic -lxml2 
/opt/bar/lib/libbar.so -Wl,-rpath,/opt/bar/lib   -fPIC     
configure: creating ./config.status
config.status: creating Makefile


Alex