Understanding Debug vs Release in CMake

In a GCC compiled project, CMake offers flexibility in configuring build settings for different target types (debug/release). Here's how you can address some common scenarios:

Running CMake for Target Types

To create separate build directories for debug and release builds, follow these steps:

mkdir Release
cd Release
cmake -DCMAKE_BUILD_TYPE=Release ..
make

For debug builds:

mkdir Debug
cd Debug
cmake -DCMAKE_BUILD_TYPE=Debug ..
make

CMake automatically adds appropriate compiler flags based on the CMAKE_BUILD_TYPE setting. Other predefined build configurations include RelWithDebInfo and MinSizeRel.

Customizing Debug and Release Flags

If you need to modify or add specific compiler flags, you can define custom toolchain files. Within these files, you can set variables such as:

set(CMAKE_CXX_FLAGS_DEBUG_INIT "-Wall")
set(CMAKE_CXX_FLAGS_RELEASE_INIT "-Wall")

These settings will be applied to the respective debug and release builds.

Specifying Compilers for Different Targets

The CMakeLists.txt typically sets the CMAKE_CXX_COMPILER and CMAKE_C_COMPILER variables to specify the default C and C compilers. However, if you need to use different compilers for different targets, you can define custom targets in CMakeLists.txt:

add_executable(my_debug_executable gcc)
target_link_libraries(my_debug_executable my_debug_library)

add_executable(my_release_executable g  )
target_link_libraries(my_release_executable my_release_library)

In this example, my_debug_executable uses GCC and my_release_executable uses G .