The following issue has been SUBMITTED. ====================================================================== https://cmake.org/Bug/view.php?id=15970 ====================================================================== Reported By: jbohren Assigned To: ====================================================================== Project: CMake Issue ID: 15970 Category: CMake Reproducibility: always Severity: major Priority: normal Status: new ====================================================================== Date Submitted: 2016-02-11 13:44 EST Last Modified: 2016-02-11 13:44 EST ====================================================================== Summary: CMake changes order of include directories when a directory is specified both as a SYSTEM and non-SYSTEM include Description: I ran into a problem recently where a package I was building set a SYSTEM include directory which was already a non-SYSTEM include directory imported from a dependency. When this happened, CMake dropped the non-SYSTEM directory in favor of the SYSTEM one, causing my build to fail.
According to GCC [1], it gives precedence to non-SYSTEM include directories, and specifying both for the same path produces a warning. [1] https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html > All directories named by -isystem are searched after all directories named by -I, no matter what their order was on the command line. If the same directory is named by both -I and -isystem, the -I option is ignored. GCC provides an informative message when this occurs if -v is used. With CMake, if both are specified, it drops the non-SYSTEM include and fails silently. For example, when building this project with any recent version of CMake on Linux, the build command is: ```bash /usr/bin/c++ -isystem /path/to/overlay/devel/include -I/opt/ros/indigo/include -o CMakeFiles/foo.dir/foo.cpp.o -c /home/jbohren/scratch/isystem/foo.cpp ``` But with the three `incude_directory` options given in `CMakeLists.txt`, I would expect it to read: ```bash /usr/bin/c++ -I/path/to/overlay/devel/include -I/opt/ros/indigo/include -isystem /path/to/overlay/devel/include -o CMakeFiles/foo.dir/foo.cpp.o -c /home/jbohren/scratch/isystem/foo.cpp ``` Even the following would maintain the order of the search paths, since the non-SYSTEM directories are all scanned before the SYSTEM ones: ```bash /usr/bin/c++ -I/path/to/overlay/devel/include -I/opt/ros/indigo/include -o CMakeFiles/foo.dir/foo.cpp.o -c /home/jbohren/scratch/isystem/foo.cpp ``` Steps to Reproduce: Build this trivial CMake project to observe the effect: https://github.com/jbohren/isystem ====================================================================== Issue History Date Modified Username Field Change ====================================================================== 2016-02-11 13:44 jbohren New Issue ====================================================================== -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake-developers
