[cmake-developers] Regression when using multiple Qt installations (FindQt4.make)

[Clinton Stimpson]

On Sunday, May 06, 2012 04:27:17 am Benoit Walter wrote:
> Hi CMake developers,
> 
> as I need to maintain different projects using different Qt versions, I
> needed to have a look at FindQt4.cmake.
> 
> Based on the path of qmake, I can successfully decide which Qt version is
> used (for example using Debian's update-alternatives).
> 
> Ex:
> /opt/qt4.7 (custom version)
> /usr/include/qt4 (default version)
> 
> However, even if I set qmake to the directory of the custom version, I see
> that cmake uses the headers of the default version.
> 
> It seems to me like a regression in commit
> 0ae8a3405bb32afadda13f43100484e85f7ef74f ("Add qt4/QtCore to help find Qt
> headers when cross-compiling.")
> 
> qt4/QtCore is found in /usr/include instead of /opt/qt4.7/include, in
> contradiction with the qmake information (qmake -query QT_INSTALL_HEADERS).
> 
> Corresponding lines in FindQt4.make:
>       FIND_PATH(QT_QTCORE_INCLUDE_DIR QtCore
>                 HINTS ${qt_headers} ${QT_LIBRARY_DIR}
>                 PATH_SUFFIXES QtCore qt4/QtCore
>         )
> 
> Removing qt4/QtCore fixes the problem, but I guess that the commit was
> useful for other reasons :)
> So my suggestion is to either revert the commit because it invalidates a
> common scenario when using cmake with several Qt installations, or to fix
> the FIND_PATH call, making sure that the custom location is found before
> the default one.
> 
> Any idea?
> 
> Best regards,
> Benoit.

What version of cmake are you using?

I also have
/usr/include/qt4
and a custom Qt, but do not see this problem with the latest cmake.

The FIND_PATH(QT_QTCORE_INCLUDE_DIR QtCore
                HINTS ${qt_headers} ${QT_LIBRARY_DIR}
                PATH_SUFFIXES QtCore qt4/QtCore

It should first look for ${qt_headers}/QtCore, which should be 
/opt/qt4.7/include/QtCore.

I tried these 3 ways, but was not able to reproduce.
1. PATH=/path/to/custom/qt/bin:$PATH cmake ..
2. CMAKE_PREFIX_PATH=/path/to/custom/qt cmake ..
3. cmake ..  -> modify CMakeCache.txt to use custom qmake then re-run cmake.

I have no "/usr/include" in my CMakeCache.txt file.

Can you expand the ${qt_headers} and tell me what you have?

-- 
Clinton Stimpson
Elemental Technologies, Inc
Computational Simulation Software, LLC
www.csimsoft.com