cmakecmake-guilibharu

Proper way to compile project with debug symbols and cmake

Here is recommended to pass CMAKE_BUILD_TYPE as an argument to cmake when I want to obtain debug or release project builds. I'm trying to compile libharu with cmake and I would like to compile it with debug symbols. I've searched CMakeLists.txt included in libharu for following strings:

CMAKE_BUILD_TYPE
CMAKE_C_FLAGS_RELEASE
CMAKE_C_FLAGS_DEBUG

but I've found nothing. My question is that if it does make any sense to specify CMAKE_BUILD_TYPE when libharu's CMakeLists.txt doesn't mention it? If not, how can I compile libharu with debug symbols?

PS: I've noticed that project that was generated for Visual Studio 2013 with cmake had set Debug/Win32, is this sufficient? Where in CMakeLists.txt is specified this info?

PPS: I guess this question is highly depending on particular project but is there some way to do this in general? I mean, does CMAKE_BUILD_TYPE=Debug always create Debug build or is there something else that I should be aware of?

Thanks

Solution

  • Setting configuration type via CMAKE_BUILD_TYPE switches set of additional options for compiler to one, which normally reflects meaning of the configuration. That is, passing 

    -DCMAKE_BUILD_TYPE=Debug

    to cmake tells compiler to generate debugging information unless CMakeLists.txt modifies that behavior.

    Config-dependent compiler options are contained in variables CMAKE_<LANG>_FLAGS_<CONFIG>. For example, variable CMAKE_C_FLAGS_DEBUG contains additional options for C compiler in "Debug" configuration. These variables are filled by CMake automatically, and CMakeLists.txt itself rare modifies them.

    So, if you found that CMakeLists.txt doesn't play with variables CMAKE_BUILD_TYPE and CMAKE_<LANG>_FLAGS_<CONFIG>, then it follows common conventions about configuration type.

    This doesn't mean that CMakeLists.txt shouldn't play with that variables.

    Often CMakeLists.txt sets CMAKE_BUILD_TYPE to some default value, provided the variable is not set by the user and single-config generator is used. CMakeLists.txt also may set some of variables CMAKE_<LANG>_FLAGS_<CONFIG>, if default setting for compiler is not suited for the project.

    But even if CMakeLists.txt does not touch these variables, they work.