CMAKE_PROJECT_SPDX_LICENSE

The license(s) of the top level project.

This variable holds the license expression 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_SPDX_LICENSE contains. For example, consider the following top level CMakeLists.txt:

cmake_minimum_required(VERSION 4.3)
project(First SPDX_LICENSE "BSD-3-Clause")
project(Second SPDX_LICENSE "BSD-3-Clause AND CC-BY-SA-4.0")
add_subdirectory(sub)
project(Third SPDX_LICENSE "BSD-3-Clause AND CC0-1.0")

And sub/CMakeLists.txt with the following contents:

project(SubProj SPDX_LICENSE Apache-2.0)
message("CMAKE_PROJECT_SPDX_LICENSE = ${CMAKE_PROJECT_SPDX_LICENSE}")

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

CMAKE_PROJECT_SPDX_LICENSE = BSD-3-Clause AND CC-BY-SA-4.0

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