CMake Configuration fails with CMake 4

[MarcSchaetz]

Checklist

• [ x] I did not find a duplicate of this in the
  Issues section.

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Description

The file cmake/AddSelfContainmentTest.cmake of this project enforces a minimum CMake version of 3.1.
Additionally CMakeLists.txt requires a minimum version of 3.5.

# cmake/AddSelfContainmentTest.cmake
cmake_minimum_required(VERSION 3.1)

# CMakeLists.txt
cmake_minimum_required(VERSION 3.5)

With the release of CMake 4 the compatibility with a minimum version < 3.5 has been removed. Future versions will also remove compatibility with versions < 3.10.

Steps to reproduce

Simply create a minimum Cpp project with a CMakeLists.txt

1. Make sure you have CMake version 4 installed
2. Create project and clone result

mkdir resulttest
cd resulttest
git clone https://github.com/bitwizeshift/result.git

3. Create CMakeLists.txt

touch CMakeLists.txt

cmake_minimum_required(VERSION 3.19)
project(result_test)
add_executable(result_test main.cpp)
add_subdirectory(./result)

4. Run Cmake

cmake -B build

Expected Behavior

The CMake configuration should run through without problems

-- Configuring done (0.0s)
-- Generating done (0.0s)
-- Build files have been written to: /home/marc/sandbox/resulttests/build

Actual Behavior

The CMake configuration stops with a warning an an error

CMake Deprecation Warning at result/CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.10 will be removed from a future version of
  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.


CMake Error at result/cmake/AddSelfContainmentTest.cmake:1 (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.
Call Stack (most recent call first):
  result/CMakeLists.txt:110 (include)


-- Configuring incomplete, errors occurred!

Extra information

• Library version: 1.0.0
• Operating System: Linux workhorse 6.14.3-arch1-1 Checklist #1 SMP PREEMPT_DYNAMIC Sun, 20 Apr 2025 12:38:52 +0000 x86_64 GNU/Linux
• Compiler: gcc (GCC) 14.2.1 20250207