CMP0180

Added in version 3.31.

project() always sets <PROJECT-NAME>_* as normal variables.

In CMake 3.29 and below, the project() command set <PROJECT-NAME>_SOURCE_DIR, <PROJECT-NAME>_BINARY_DIR, and <PROJECT-NAME>_IS_TOP_LEVEL as cache entries, but not as normal variables. CMake 3.30 started setting them as normal variables, but only if they are already set as normal variables. This was needed to preserve support for some FetchContent use cases under policy CMP0169's NEW behavior, while also preserving behavior of nested directories that call project() with the same project name. See release notes for 3.30.3, 3.30.4, and 3.30.5 for details.

CMake 3.31 and later prefer to always set <PROJECT-NAME>_SOURCE_DIR, <PROJECT-NAME>_BINARY_DIR, and <PROJECT-NAME>_IS_TOP_LEVEL, as both cache entries and normal variables, regardless of what cache or normal variables already exist. This policy provides compatibility for projects that have not been updated to expect this behavior.

The OLD behavior for this policy will only set normal variables for <PROJECT-NAME>_SOURCE_DIR, <PROJECT-NAME>_BINARY_DIR, and <PROJECT-NAME>_IS_TOP_LEVEL if there is already a normal variable by that name when project() is called. The NEW behavior for this policy will always set normal variables for <PROJECT-NAME>_SOURCE_DIR, <PROJECT-NAME>_BINARY_DIR, and <PROJECT-NAME>_IS_TOP_LEVEL when project() is called.

This policy was introduced in CMake version 3.31. 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.