cjson fails to build with CMake 4.0.3

[C-Holo-Krzysztof]

Baseline is 4f8fe05871555c1798dbcb1957d0d595e94f7b57, vcpkg version is 2025-04-01-9c604254140797833b6f76908435c9fcbf09920e.

I have CMake 4.0.3 installed on my system and I've made a sample setup with following commands:

mkdir testapp
cd testapp
vcpkg new --application
vcpkg add port cjson

Then when trying to run vcpkg install I get the following error:

Installing 1/1 cjson:x64-windows@1.7.18...
Building cjson:x64-windows@1.7.18...
C:\Users\KrzysztofLesiak\AppData\Local\vcpkg\registries\git-trees\dc5bbd0b7faf78acb68a65b06c0bc8bfdb0a7c2a: info: installing from git registry git+https://github.com/microsoft/vcpkg@dc5bbd0b7faf78acb68a65b06c0bc8bfdb0a7c2a
Downloading https://github.com/DaveGamble/cJSON/archive/v1.7.18.tar.gz -> DaveGamble-cJSON-v1.7.18.tar.gz
Successfully downloaded DaveGamble-cJSON-v1.7.18.tar.gz
-- Cleaning sources at D:/testapp/vcpkg_installed/vcpkg/blds/cjson/src/v1.7.18-66cc8df541.clean. Use --editable to skip cleaning for the packages you specify.
-- Extracting source C:/Users/KrzysztofLesiak/AppData/Local/vcpkg/downloads/DaveGamble-cJSON-v1.7.18.tar.gz
-- Using source at D:/testapp/vcpkg_installed/vcpkg/blds/cjson/src/v1.7.18-66cc8df541.clean
-- Found external ninja('1.12.1').
-- Configuring x64-windows
CMake Error at scripts/cmake/vcpkg_execute_required_process.cmake:127 (message):
    Command failed: "D:/Microsoft Visual Studio/2022/Community/Common7/IDE/CommonExtensions/Microsoft/CMake/Ninja/ninja.exe" -v
    Working Directory: D:/testapp/vcpkg_installed/vcpkg/blds/cjson/x64-windows-rel/vcpkg-parallel-configure
    Error code: 1
    See logs for more information:
      D:\testapp\vcpkg_installed\vcpkg\blds\cjson\config-x64-windows-dbg-CMakeCache.txt.log
      D:\testapp\vcpkg_installed\vcpkg\blds\cjson\config-x64-windows-rel-CMakeCache.txt.log
      D:\testapp\vcpkg_installed\vcpkg\blds\cjson\config-x64-windows-out.log

Call Stack (most recent call first):
  D:/testapp/vcpkg_installed/x64-windows/share/vcpkg-cmake/vcpkg_cmake_configure.cmake:269 (vcpkg_execute_required_process)
  C:/Users/KrzysztofLesiak/AppData/Local/vcpkg/registries/git-trees/dc5bbd0b7faf78acb68a65b06c0bc8bfdb0a7c2a/portfile.cmake:23 (vcpkg_cmake_configure)
  scripts/ports.cmake:203 (include)


error: building cjson:x64-windows failed with: BUILD_FAILED

Looking inside the config-x64-windows-out.log file I see the following:

CMake Error at CMakeLists.txt:2 (cmake_minimum_required):
  Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.


-- Configuring incomplete, errors occurred!

Setting CMAKE_POLICY_VERSION_MINIMUM to 3.5 as an environment variable doesn't seem to do anything.

Edit: looks like this is a known upstream issue that has an open PR, but looks like it's not getting merged anytime soon: DaveGamble/cJSON#935
Is it possible/desirable to patch this on the vcpkg side?

[C-Holo-Krzysztof]

I modified the cached portfile.cmake for cjson to add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 into the config options list and configure worked. Would that be an acceptable workaround to enable builds with CMake 4.0?

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