Build types in CMake

A build type indicates a set of compile-time decisions used while compiling your code. For example, whether or not to optimize or to include debug information. A build type or build mode or configuration is popular in Visual Studio, where C++ projects typically have at least two types: Release and Debug.

CMake has build types and follows similar rules. For compiling C++, there are at least 4 build types in CMake: Release, Debug, MinSizeRel and RelWithDebInfo.

• The compile options or rules associated with a build type for a source file of a particular language can be found in /usr/share/cmake-2.8/Modules/Find*.cmake. For compiled languages like C++, look for the matching compiler in /usr/share/cmake-2.8/Modules/Compiler directory.

• For C++ code compiled using GNU C++ compiler, see the files /usr/share/cmake-2.8/Modules/Compiler/GNU.cmake for the options used during compilation.

• When no build type is provided, I found the compilation string to be: g++ /your/code.cpp

• For Release build type, I found the compilation string to be: g++ -O3 -DNDEBUG /your/code.cpp. Note that assert will be disabled with this build type.

• For Debug build type, I found the compilation string to be: g++ -g /your/code.cpp

• You can specify a build type in the CMakeLists.txt file. For example:

set(CMAKE_BUILD_TYPE Release)

• You can also specify a build type at the shell. For example:

$ cmake -D CMAKE_BUILD_TYPE=Debug ..

• You can make one of the build types as default, when no build type is provided. For example, to make Release build type as default, add this to CMakeLists.txt:

if(NOT CMAKE_BUILD_TYPE) 
    set(CMAKE_BUILD_TYPE Release)
endif(NOT CMAKE_BUILD_TYPE)

Note: Build types for Visual Studio cannot be set in CMakeLists.txt using CMAKE_BUILD_TYPE or any other method. It can only be set when CMake is invoked or later in the Visual Studio solution.

Tried with: CMake 2.8.12.2 and Ubuntu 14.04