# CMP0184

Added in version 4.0.

MSVC runtime checks flags are selected by an abstraction.

Compilers targeting the MSVC ABI have flags to select the runtime checks. Runtime checks selection typically varies with build configuration.

In CMake 3.31 and below, runtime checks flags are added to the default `CMAKE_<LANG>_FLAGS_<CONFIG>` cache entries by CMake automatically. This allows users to edit their cache entries to adjust the flags. However, the presence of such default flags is problematic for projects that want to choose different runtime checks programmatically. In particular, it requires string editing of the `CMAKE_<LANG>_FLAGS_<CONFIG>` variables with knowledge of the CMake builtin defaults so they can be replaced.

CMake 4.0 and above prefer to leave the runtime checks flags out of the default `CMAKE_<LANG>_FLAGS_<CONFIG>` values and instead offer a first-class abstraction. The `CMAKE_MSVC_RUNTIME_CHECKS` variable and `MSVC_RUNTIME_CHECKS` target property may be set to select the MSVC runtime checks. If they are not set, CMake enables runtime checks for the `Debug` configuration only using the default value `$<$<CONFIG:Debug>:StackFrameErrorCheck;UninitializedVariable>`, if supported by the compiler, or an empty value otherwise.

This policy provides compatibility with projects that have not been updated to be aware of the abstraction. The policy setting takes effect as of the first `project()` or `enable_language()` command that enables a language whose compiler targets the MSVC ABI.

Note

Once the policy has taken effect at the top of a project, that choice will be used throughout the tree. In projects that have nested projects in subdirectories, be sure to confirm if everything is working with the selected policy behavior.

The `OLD` behavior for this policy is to place MSVC runtimes checks flags in the default `CMAKE_<LANG>_FLAGS_<CONFIG>` cache entries and ignore the `CMAKE_MSVC_RUNTIME_CHECKS` abstraction. The `NEW` behavior for this policy is to not place MSVC runtime checks flags in the default cache entries and use the abstraction instead.

This policy was introduced in CMake version 4.0. It may be set by `cmake_policy()` or `cmake_minimum_required()`. If it is not set, CMake does not warn, and uses `OLD` behavior.

Note

The `OLD` behavior of a policy is deprecated by definition and may be removed in a future version of CMake.