# CMAKE_PROJECT_COMPAT_VERSION

Added in version 4.1.

Note

Experimental. Gated by `CMAKE_EXPERIMENTAL_EXPORT_PACKAGE_INFO`.

The compatibility version of the top level project.

This variable holds the compatibility version of the project as specified in the top level CMakeLists.txt file by a `project()` command. In the event that the top level CMakeLists.txt contains multiple `project()` calls, the most recently called one from that top level CMakeLists.txt will determine the value that `CMAKE_PROJECT_COMPAT_VERSION` contains. For example, consider the following top level CMakeLists.txt:

    cmake_minimum_required(VERSION 4.1)
    project(First VERSION 9.0 COMPAT_VERSION 1.2.3)
    project(Second VERSION 9.0 COMPAT_VERSION 3.4.5)
    add_subdirectory(sub)
    project(Third VERSION 9.0 COMPAT_VERSION 6.7.8)

And `sub/CMakeLists.txt` with the following contents:

    project(SubProj VERSION 2.0 COMPAT_VERSION 1.0)
    message("CMAKE_PROJECT_COMPAT_VERSION = ${CMAKE_PROJECT_COMPAT_VERSION}")

The most recently seen `project()` command from the top level CMakeLists.txt would be `project(Second ...)`, so this will print:

    CMAKE_PROJECT_COMPAT_VERSION = 3.4.5

To obtain the version from the most recent call to `project()` in the current directory scope or above, see the `PROJECT_COMPAT_VERSION` variable.