[cmake-developers] [CMake 0011672]: FindQt4.cmake sometimes fails due to exec_program misbehavior

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://www.cmake.org/Bug/view.php?id=11672 
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Reported By:                Alexander
Assigned To:                
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Project:                    CMake
Issue ID:                   11672
Category:                   CMake
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
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Date Submitted:             2011-01-10 06:54 EST
Last Modified:              2011-01-10 06:54 EST
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Summary:                    FindQt4.cmake sometimes fails due to exec_program
misbehavior
Description: 
FindQt4.cmake uses exec_program() call to retrieve configuration values from
qmake, such as QT_VERSION, QT_INSTALL_LIBS or whatever.

However, in my tests exec_program() call sometimes delivers empty output, so
FindQt4 module reports errors like these ones (FindQt4.cmake was modified to
output intermediate variables):

[Debugging output starts here]

Running C:/Hudson/Common/ThirdParty/qt/win32/bin/qmake.exe with arg QT_VERSION
Got return code 0 and output 4.7.1
Converted output path to 4.7.1 and recorded to QTVERSION
Running C:/Hudson/Common/ThirdParty/qt/win32/bin/qmake.exe with arg
QMAKE_MKSPECS
Got return code 0 and output C:/Hudson/Common/ThirdParty/qt\mkspecs
Converted output path to C:/Hudson/Common/ThirdParty/qt/mkspecs and recorded to
qt_mkspecs_dirs
Running C:/Hudson/Common/ThirdParty/qt/win32/bin/qmake.exe with arg
QT_INSTALL_LIBS
Got return code 0 and output 
Converted output path to  and recorded to QT_LIBRARY_DIR_TMP

[Debugging output ends here]

Warning: QT_QMAKE_EXECUTABLE reported QT_INSTALL_LIBS as 
Warning: But QtCore couldn't be found.  Qt must NOT be installed correctly, or
it wasn't found for cross compiling.
CMake Error at C:/Program Files (x86)/CMake
2.8/share/cmake-2.8/Modules/FindQt4.cmake:642 (MESSAGE):
 Could NOT find QtCore.

The script qmakeTest.cmake, when run as cmake -P qmakeTest.cmake reproduces this
problem approximately ones per several hundreds iterations.

It should be noted that if first part of the script (which uses exec_program) is
commented and second part (which uses execute_process) is used instead, things
work fine (up to 10,000 iterations - the max I had the time to wait for ;-) ),
so, considering exec_program is deprecated, the way to fix this seems to be just
to replace exec_program with execute_process.

The primary testing environment was Windows 7 64 bit installed in VirtualBox
3.2.12, though I've got similar error, I believe, on native Windows 7 64 bit
installation too.
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Issue History 
Date Modified    Username       Field                    Change               
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2011-01-10 06:54 Alexander      New Issue                                    
2011-01-10 06:54 Alexander      File Added: qmakeTest.cmake                    
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