[cmake-developers] module merge mania

[Brad King]

Alexander Neundorf wrote:
> I'd like to add the following cmake modules we have in KDE svn to CMake cvs:
> 
> http://websvn.kde.org/trunk/KDE/kdelibs/cmake/modules/CheckCXXCompilerFlag.cmake?view=auto
> CHECK_CXX_COMPILER_FLAG(FLAG VARIABLE) 
> - Check whether the compiler supports a given flag.
> 
> (if you want to I add a C compiler version too)

Yes, please.

> http://websvn.kde.org/trunk/KDE/kdelibs/cmake/modules/CheckPointerMember.cmake?view=auto
> CHECK_POINTER_MEMBER (POINTER MEMBER HEADER VARIABLE)
> - Check if the given struct or class has the specified member variable
> 
> http://websvn.kde.org/trunk/KDE/kdelibs/cmake/modules/CheckStructMember.cmake?view=auto
> CHECK_STRUCT_MEMBER (STRUCT MEMBER HEADER VARIABLE)
> - Check if the given struct or class has the specified member variable
> 
> http://websvn.kde.org/trunk/KDE/kdelibs/cmake/modules/CheckPrototypeExists.cmake?view=auto
> CHECK_PROTOTYPE_EXISTS (FUNCTION HEADER VARIABLE)
> - Check if the prototype for a function exists.

Sure, but the prototype check may need a separate C and CXX version too.

> And the following Find*.cmake modules:
> 
> FindBZip2.cmake
> FindGIF.cmake
> FindJasper.cmake
> FindLibXml2.cmake
> FindLibXslt.cmake
> FindOpenSSL.cmake
> FindASPELL.cmake
> FindHSPELL.cmake
> 
> They all follow this scheme:
> 
> IF (GIF_INCLUDE_DIR AND GIF_LIBRARIES)
>    # Already in cache, be silent
>    SET(GIF_FIND_QUIETLY TRUE)
> ENDIF (GIF_INCLUDE_DIR AND GIF_LIBRARIES)

Good idea.

> FIND_PATH(GIF_INCLUDE_DIR gif_lib.h
>   /usr/include
>   /usr/local/include
> )
> 
> set(POTENTIAL_GIF_LIBS gif libgif ungif libungif giflib)
> FIND_LIBRARY(GIF_LIBRARIES NAMES ${POTENTIAL_GIF_LIBS}
>   PATHS
>   /usr/lib
>   /usr/local/lib
> )

You can leave out the /usr/* paths because these are already searched by
the CMake 2.4 FIND_PATH and FIND_LIBRARY commands.

However, you should not use GIF_LIBRARIES as the name of the variable.
It should be

FIND_LIBRARY(GIF_LIBRARY ...)
SET(GIF_LIBRARIES ${GIF_LIBRARY})

If more than one library is needed by a package it needs a separate
FIND_* result variable for each one so the user can adjust the cache,
but the project should have to reference only the XXX_LIBRARIES variable
to get the results.

> if (GIF_INCLUDE_DIR AND GIF_LIBRARIES)
>    set(CMAKE_REQUIRED_INCLUDES "${GIF_INCLUDE_DIR}" 
> "${CMAKE_REQUIRED_INCLUDES}")
>    CHECK_STRUCT_MEMBER(GifFileType UserData gif_lib.h GIF_FOUND)

This should probably restore the original value of CMAKE_REQUIRED_INCLUDES.

> Ok to commit ?
> Especially note the part at the beginning where QUIETLY is set explicitely if 
> it has already been found before.

Sure.

Thanks,
-Brad