fix: Make build system compatible with CMake-4.0

Set CMAKE_POLICY_VERSION_MINIMUM=3.5 for our ZLIB and pybind11 build scripts and modules.
Update the cmake_minimum_required syntax in the top-level CMakeLists.txt

Signed-off-by: Zach Lewis <zachcanbereached@gmail.com>

Author: zachlewis

.github/workflows/wheel_workflow.yml

@@ -147,6 +147,7 @@ jobs:
           CIBW_BUILD: ${{ matrix.python }}
           CIBW_ARCHS: ${{ matrix.arch }}
           CIBW_MANYLINUX_X86_64_IMAGE: ${{ matrix.manylinux }}
+          CMAKE_POLICY_VERSION_MINIMUM: 3.5
 
       - uses: actions/upload-artifact@v4
         with:
@@ -209,6 +210,7 @@ jobs:
           CIBW_BUILD: ${{ matrix.python }}
           CIBW_ARCHS: ${{ matrix.arch }}
           CIBW_MANYLINUX_AARCH64_IMAGE: ${{ matrix.manylinux }}
+          CMAKE_POLICY_VERSION_MINIMUM: 3.5
 
       - uses: actions/upload-artifact@v4
         with:
@@ -264,6 +266,7 @@ jobs:
         env:
           CIBW_BUILD: ${{ matrix.python }}
           CIBW_ARCHS: ${{ matrix.arch }}
+          CMAKE_POLICY_VERSION_MINIMUM: 3.5
 
       - uses: actions/upload-artifact@v4
         with:
@@ -319,6 +322,7 @@ jobs:
         env:
           CIBW_BUILD: ${{ matrix.python }}
           CIBW_ARCHS: ${{ matrix.arch }}
+          CMAKE_POLICY_VERSION_MINIMUM: 3.5
 
       - uses: actions/upload-artifact@v4
         with:
@@ -374,6 +378,7 @@ jobs:
         env:
           CIBW_BUILD: ${{ matrix.python }}
           CIBW_ARCHS: ${{ matrix.arch }}
+          CMAKE_POLICY_VERSION_MINIMUM: 3.5
 
       - uses: actions/upload-artifact@v4
         with:

CMakeLists.txt

@@ -5,7 +5,7 @@
 ###############################################################################
 # CMake definition.
 
-cmake_minimum_required(VERSION 3.14)
+cmake_minimum_required(VERSION 3.14...4.0)
 
 set(CMAKE_MODULE_PATH
     ${CMAKE_MODULE_PATH}

share/ci/scripts/multi/install_pybind11.sh

@@ -7,6 +7,9 @@ set -ex
 PYBIND11_VERSION="$1"
 INSTALL_TARGET="$2"
 
+# Required for CMake-4.0+ compatibility
+export CMAKE_POLICY_VERSION_MINIMUM=3.5
+
 git clone https://github.com/pybind/pybind11.git
 cd pybind11
 

share/ci/scripts/multi/install_zlib.sh

@@ -13,6 +13,9 @@ ZLIB_MINOR=$(echo "${ZLIB_MAJOR_MINOR}" | cut   -d. -f2-)
 ZLIB_PATCH=$(echo "${ZLIB_VERSION}" | cut   -d. -f3-)
 ZLIB_VERSION_U="${ZLIB_MAJOR}.${ZLIB_MINOR}.${ZLIB_PATCH}"
 
+# Required for CMake-4.0+ compatibility
+export CMAKE_POLICY_VERSION_MINIMUM=3.5
+
 git clone https://github.com/madler/zlib
 cd zlib
 

share/cmake/modules/install/InstallZLIB.cmake

@@ -72,6 +72,8 @@ if(NOT ZLIB_FOUND AND OCIO_INSTALL_EXT_PACKAGES AND NOT OCIO_INSTALL_EXT_PACKAGE
             # version as the cmake_minimum_required and that version has no knowledge of the policy.
             # Since that policy gets unset, it causes a warning with CMake 3.25+.
             -DCMAKE_POLICY_DEFAULT_CMP0042=NEW
+            # Required for CMake 4.0+ compatibility
+            -DCMAKE_POLICY_VERSION_MINIMUM=3.5
             -DCMAKE_CXX_VISIBILITY_PRESET=${CMAKE_CXX_VISIBILITY_PRESET}
             -DCMAKE_VISIBILITY_INLINES_HIDDEN=${CMAKE_VISIBILITY_INLINES_HIDDEN}
             -DCMAKE_POSITION_INDEPENDENT_CODE=ON

share/cmake/modules/install/Installpybind11.cmake

@@ -46,6 +46,8 @@ if(NOT pybind11_FOUND AND OCIO_INSTALL_EXT_PACKAGES AND NOT OCIO_INSTALL_EXT_PAC
 
         set(pybind11_CMAKE_ARGS
             ${pybind11_CMAKE_ARGS}
+            # Required for CMake 4.0+ compatibility.
+            -DCMAKE_POLICY_VERSION_MINIMUM=3.5
             -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
             -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
             -DCMAKE_INSTALL_MESSAGE=${CMAKE_INSTALL_MESSAGE}