CMAKECFLAGSRELEASE

CMAKE_C_FLAGS_RELEASE is a CMake cache variable that specifies the command-line options passed to the C compiler when building in the Release configuration. It is part of a family of per-configuration flags such as CMAKE_C_FLAGS_DEBUG and CMAKE_C_FLAGS_RELWITHDEBINFO, used by CMake to tailor compiler behavior for different build types. The value is a single string containing space-separated flags and is appended to the compiler invocation by the build system. Note that the conventional, documented name is CMAKE_C_FLAGS_RELEASE; there is no standard variable named CMAKECFLAGSRELEASE.

Usage depends on the generator. For single-configuration generators (such as Unix Makefiles or Ninja), the Release config is selected via CMAKE_BUILD_TYPE, and CMAKE_C_FLAGS_RELEASE is applied when building Release. For multi-config generators (such as Visual Studio or Xcode), Release is a separate configuration at build time; CMAKE_C_FLAGS_RELEASE provides the default Release options, and a user can override via cache or per-project settings.

Setting options can be done by passing flags on the command line with cmake -DCMAKE_C_FLAGS_RELEASE="-O3 -DNDEBUG" .., or by setting in a toolchain file or in the CMakeLists.txt using set(CMAKE_C_FLAGS_RELEASE "-O3 -DNDEBUG" CACHE STRING "Flags for Release builds of the C compiler").

Modern CMake practice encourages using target_compile_options for per-target and per-configuration options, or generator expressions to apply options only to the Release configuration, rather than relying on global CMAKE_C_FLAGS_RELEASE. This improves portability and clarity across generators.

Note: The variable name is language-specific; there are analogous variables for C++: CMAKE_CXX_FLAGS_RELEASE, and the non-config-specific CMAKE_C_FLAGS.