ci: Add CPython trunk build

Author: sizmailov

.github/workflows/upstream.yml

@@ -110,3 +110,144 @@ jobs:
     # setuptools
     - name: Setuptools helpers test
       run: pytest tests/extra_setuptools
+
+  trunk-cpython:
+
+    strategy:
+      matrix:
+        # branch, tag or SHA
+        cpython-ref:
+          - 'main'
+          - 'a0ad63e70e3682cdf7e87e28091bb54fe12a2d4e'
+        
+    name: '🐍 trunk (${{ matrix.cpython-ref }}) • ubuntu-latest • x64'
+    runs-on: ubuntu-latest
+    if: "contains(github.event.pull_request.labels.*.name, 'python dev')"
+
+    steps:
+      #
+      # Install trunk cpython
+      #
+      - name: Setup directory env for cpython build
+        run: echo "CPYTHON_DIR=$(realpath -m ${GITHUB_WORKSPACE}/cpython-trunk-build)" >> $GITHUB_ENV
+      - uses: actions/checkout@v3
+        with:
+          repository: 'python/cpython'
+          ref: ${{ matrix.cpython-ref }}
+          path: ${{ env.CPYTHON_DIR }}
+
+      - name: Install Dependencies
+        working-directory: ${{ env.CPYTHON_DIR }}
+        run: sudo ./.github/workflows/posix-deps-apt.sh
+
+      - name: Configure CPython
+        working-directory: ${{ env.CPYTHON_DIR }}
+        run: ./configure --with-pydebug
+
+      - name: Build CPython
+        working-directory: ${{ env.CPYTHON_DIR }}
+        run: make -j4
+
+      - name: Display build info
+        working-directory: ${{ env.CPYTHON_DIR }}
+        run: make pythoninfo
+
+      - name: Install CPython
+        working-directory: ${{ env.CPYTHON_DIR }}
+        run: sudo make install
+
+      - name: Clean-up after CPython build
+        run: sudo rm -rf ${{ env.CPYTHON_DIR }}
+
+      - name: Test default CPython version
+        run: python3 --version
+
+      #
+      # Pybind
+      #
+      - uses: actions/checkout@v3
+
+      - name: Setup Boost (Linux)
+        if: runner.os == 'Linux'
+        run: sudo apt-get install libboost-dev
+
+      - name: Update CMake
+        uses: jwlawson/[email protected]
+
+      - name: Prepare env
+        run: |
+          python -m pip install -r tests/requirements.txt
+
+      - name: Setup annotations on Linux
+        if: runner.os == 'Linux'
+        run: python -m pip install pytest-github-actions-annotate-failures
+
+      # First build - C++11 mode and inplace
+      - name: Configure C++11
+        run: >
+          cmake -S . -B .
+          -DPYBIND11_WERROR=ON
+          -DDOWNLOAD_CATCH=ON
+          -DDOWNLOAD_EIGEN=ON
+          -DCMAKE_CXX_STANDARD=11
+
+      - name: Build C++11
+        run: cmake --build . -j 2
+
+      - name: Python tests C++11
+        run: cmake --build . --target pytest -j 2
+
+      - name: C++11 tests
+        run: cmake --build .  --target cpptest -j 2
+
+      - name: Interface test C++11
+        run: cmake --build . --target test_cmake_build
+
+      - name: Clean directory
+        run: git clean -fdx
+
+      # Second build - C++17 mode and in a build directory
+      - name: Configure C++17
+        run: >
+          cmake -S . -B build2
+          -DPYBIND11_WERROR=ON
+          -DDOWNLOAD_CATCH=ON
+          -DDOWNLOAD_EIGEN=ON
+          -DCMAKE_CXX_STANDARD=17
+          ${{ matrix.args }}
+          ${{ matrix.args2 }}
+
+      - name: Build
+        run: cmake --build build2 -j 2
+
+      - name: Python tests
+        run: cmake --build build2 --target pytest
+
+      - name: C++ tests
+        run: cmake --build build2 --target cpptest
+
+      # Third build - C++17 mode with unstable ABI
+      - name: Configure (unstable ABI)
+        run: >
+          cmake -S . -B build3
+          -DPYBIND11_WERROR=ON
+          -DDOWNLOAD_CATCH=ON
+          -DDOWNLOAD_EIGEN=ON
+          -DCMAKE_CXX_STANDARD=17
+          -DPYBIND11_INTERNALS_VERSION=10000000
+          "-DPYBIND11_TEST_OVERRIDE=test_call_policies.cpp;test_gil_scoped.cpp;test_thread.cpp"
+          ${{ matrix.args }}
+
+      - name: Build (unstable ABI)
+        run: cmake --build build3 -j 2
+
+      - name: Python tests (unstable ABI)
+        run: cmake --build build3 --target pytest
+
+      - name: Interface test
+        run: cmake --build build3 --target test_cmake_build
+
+      # This makes sure the setup_helpers module can build packages using
+      # setuptools
+      - name: Setuptools helpers test
+        run: pytest tests/extra_setuptools