New in version 3.17.

Specifies a semicolon-separated list of configurations to build for a target in if no :<Config> suffix is specified in the Ninja Multi-Config generator. If it is set to all, all configurations from CMAKE_CROSS_CONFIGS are used. If it is not specified, it defaults to CMAKE_DEFAULT_BUILD_TYPE.

For example, if you set CMAKE_DEFAULT_BUILD_TYPE to Release, but set CMAKE_DEFAULT_CONFIGS to Debug or all, all <target> aliases in will resolve to <target>:Debug or <target>:all, but custom commands will still use the Release configuration.

The value of this variable must be a subset of CMAKE_CROSS_CONFIGS or be the same as CMAKE_DEFAULT_BUILD_TYPE. It must not be specified if CMAKE_DEFAULT_BUILD_TYPE or CMAKE_CROSS_CONFIGS is not used.