Properly handling CMake before 3.28

Author: gershnik

.github/workflows/test.yml

@@ -25,7 +25,6 @@ jobs:
         - { os: ubuntu-latest, compiler: gcc, version: 12 }
         - { os: ubuntu-latest, compiler: gcc, version: 13 }
         - { os: ubuntu-24.04, compiler: gcc, version: 14, module: true }
-        #- { os: ubuntu-24.04, compiler: gcc, version: 15, module: true }
 
         - { os: ubuntu-22.04, compiler: clang, version: 13 }
         - { os: ubuntu-22.04, compiler: clang ,version: 14 }
@@ -88,3 +87,47 @@ jobs:
       run: |
         cmake --build build --config Release --target run-test
 
+  container:
+    runs-on: ubuntu-latest
+    container: ${{ matrix.container }}
+    strategy:
+      fail-fast: false
+      matrix: 
+        include:
+        - {container: gcc:15.1, module: true}
+    
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+
+    - name: System Setup
+      shell: bash
+      run: |
+        apt-get update
+        apt-get install -y python3-dev
+
+        export CMAKE_VERSION=3.28.6
+        wget https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/cmake-${CMAKE_VERSION}-Linux-x86_64.sh \
+          -q -O /tmp/cmake-install.sh \
+        && chmod u+x /tmp/cmake-install.sh \
+        && /tmp/cmake-install.sh --skip-license --prefix=/usr \
+        rm -f /tmp/cmake-install.sh
+
+        wget -qO- https://github.com/ninja-build/ninja/releases/download/v1.12.1/ninja-linux.zip | \
+              gunzip > /usr/bin/ninja
+        chmod a+x /usr/bin/ninja
+        echo "CMAKE_GENERATOR=-GNinja" >> $GITHUB_ENV
+
+        if [[ '${{ matrix.module}}' == 'true' ]]; then
+            echo "CMAKE_ARGS=-DISPTR_ENABLE_MODULE=ON" >> $GITHUB_ENV
+        fi
+
+    - name: Configure
+      shell: bash
+      run: |
+        cmake $CMAKE_GENERATOR -S . -B build $CMAKE_ARGS -DISPTR_ENABLE_PYTHON=ON -DCMAKE_BUILD_TYPE=Release 
+  
+    - name: Build and Test
+      shell: bash
+      run: |
+        cmake --build build --config Release --target run-test

CMakeLists.txt

@@ -51,12 +51,15 @@ add_library(${LIBNAME}::${LIBNAME} ALIAS ${LIBNAME})
 set(ISPTR_MODULES_BASE_DIRS ${SRCDIR}/modules)
 set(ISPTR_MODULES_FILES ${SRCDIR}/modules/isptr.cppm)
 
+if (CMAKE_VERSION VERSION_GREATER_EQUAL "3.28")
+
 function(isptr_add_module target_name visibility)
     target_sources(${target_name} ${visibility}
         FILE_SET isptr_module TYPE CXX_MODULES BASE_DIRS ${ISPTR_MODULES_BASE_DIRS} FILES ${ISPTR_MODULES_FILES}
     )
 endfunction()
 
+endif()
 
 if (PROJECT_IS_TOP_LEVEL)
 

test/CMakeLists.txt

@@ -31,12 +31,16 @@ set(CXX_STANDARD_20 20)
 set(CXX_STANDARD_23 23)
 
 set(TEST_VARIANTS_17 "headers")
+set(TEST_VARIANTS_20 "headers")
+set(TEST_VARIANTS_23 "headers")
+
 if (${ISPTR_ENABLE_MODULE})
-    set(TEST_VARIANTS_20 "headers;module")
-    set(TEST_VARIANTS_23 "headers;module")
-else()
-    set(TEST_VARIANTS_20 "headers")
-    set(TEST_VARIANTS_23 "headers")
+    if (CMAKE_VERSION VERSION_GREATER_EQUAL "3.28")
+        list(APPEND TEST_VARIANTS_20 "module")
+        list(APPEND TEST_VARIANTS_23 "module")
+    else()
+        message(WARNING "CMake version ${CMAKE_VERSION} doesn't support modules, ignoring ISPTR_ENABLE_MODULE")
+    endif()
 endif()
 
 set(TEST_COMMAND "")