Fix #910: Use python venv for macOS build

With this commit macOS build starts using Python virtual environment so
that our build steps can comply with PEP 668 [1].

This is only about the build procedure. There must be no behavior change
in the build artifacts.

#codehealth

 [1]: https://peps.python.org/pep-0668/

PiperOrigin-RevId: 621123606

.github/workflows/macos.yaml

@@ -11,6 +11,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
   cancel-in-progress: true
 
+env:
+  PYTHON_VENV_ROOT: ${{ github.workspace }}/src/python-venv
+
 jobs:
   build_arm64:
     # https://github.com/actions/virtual-environments/blob/main/images/macos/macos-14-Readme.md
@@ -23,9 +26,10 @@ jobs:
         with:
           submodules: 'recursive'
 
-      - name: Install pip dependencies
-        working-directory: ./src
+      - name: Setup Python
         run: |
+          python3 -m venv ${PYTHON_VENV_ROOT}
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 -m pip install requests
 
       - name: Try to restore update_deps cache
@@ -38,11 +42,13 @@ jobs:
         working-directory: ./src
         # This command uses src/third_party_cache as the download cache.
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/update_deps.py
 
       - name: Build Qt
         working-directory: ./src
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/build_qt.py --release --confirm_license --macos_cpus=arm64
           echo "MOZC_QT_PATH=${PWD}/third_party/qt" >> $GITHUB_ENV
 
@@ -69,9 +75,10 @@ jobs:
         with:
           submodules: 'recursive'
 
-      - name: Install pip dependencies
-        working-directory: ./src
+      - name: Setup Python
         run: |
+          python3 -m venv ${PYTHON_VENV_ROOT}
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 -m pip install requests
 
       - name: Try to restore update_deps cache
@@ -84,11 +91,13 @@ jobs:
         working-directory: ./src
         # This command uses src/third_party_cache as the download cache.
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/update_deps.py
 
       - name: Build Qt
         working-directory: ./src
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/build_qt.py --release --confirm_license --macos_cpus=x86_64
           echo "MOZC_QT_PATH=${PWD}/third_party/qt" >> $GITHUB_ENV
 
@@ -115,9 +124,10 @@ jobs:
         with:
           submodules: 'recursive'
 
-      - name: Install pip dependencies
-        working-directory: ./src
+      - name: Setup Python
         run: |
+          python3 -m venv ${PYTHON_VENV_ROOT}
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 -m pip install requests
 
       - name: Try to restore update_deps cache
@@ -130,11 +140,13 @@ jobs:
         working-directory: ./src
         # This command uses src/third_party_cache as the download cache.
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/update_deps.py
 
       - name: Build Qt
         working-directory: ./src
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/build_qt.py --release --confirm_license --macos_cpus=x86_64,arm64
           echo "MOZC_QT_PATH=${PWD}/third_party/qt" >> $GITHUB_ENV
 
@@ -161,9 +173,10 @@ jobs:
         with:
           submodules: 'recursive'
 
-      - name: Install pip dependencies
-        working-directory: ./src
+      - name: Setup Python
         run: |
+          python3 -m venv ${PYTHON_VENV_ROOT}
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 -m pip install requests
 
       - name: Try to restore update_deps cache
@@ -176,11 +189,13 @@ jobs:
         working-directory: ./src
         # This command uses src/third_party_cache as the download cache.
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/update_deps.py
 
       - name: Build Qt
         working-directory: ./src
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/build_qt.py --release --confirm_license
           echo "MOZC_QT_PATH=${PWD}/third_party/qt" >> $GITHUB_ENV
 
@@ -201,9 +216,10 @@ jobs:
       - name: checkout
         uses: actions/checkout@v4
 
-      - name: Install pip dependencies
-        working-directory: ./src
+      - name: Setup Python
         run: |
+          python3 -m venv ${PYTHON_VENV_ROOT}
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 -m pip install requests
 
       - name: Try to restore update_deps cache
@@ -216,4 +232,5 @@ jobs:
         working-directory: ./src
         # This command uses src/third_party_cache as the download cache.
         run: |
+          source ${PYTHON_VENV_ROOT}/bin/activate
           python3 build_tools/update_deps.py --cache_only

.gitignore

@@ -34,6 +34,10 @@
 /src-*
 /src_*
 
+# Python venv dir used to conform PEP 668
+# https://peps.python.org/pep-0668/
+/src/python-venv
+
 # Mozc build artifacts by Bazel (symbolic links)
 /src/bazel-bin
 /src/bazel-out

docs/build_mozc_in_osx.md

@@ -9,11 +9,14 @@ If you are not sure what the following commands do, please check the description
 and make sure the operations before running them.
 
 ```
-python3 -m pip install requests
-
 git clone https://github.com/google/mozc.git
 cd mozc/src
 
+export PYTHON_VENV_ROOT=${PWD}/python-venv
+python3 -m venv ${PYTHON_VENV_ROOT}
+source ${PYTHON_VENV_ROOT}/bin/activate
+python3 -m pip install requests
+
 python3 build_tools/update_deps.py
 
 # CMake is also required to build Qt.
@@ -62,6 +65,19 @@ cd mozc/src
 
 Hereafter you can do all the operations without changing directory.
 
+### Set up and enable Python virtual environment
+
+The following commands set up Python virtual environment under `mozc/src/python-venv`.
+
+```
+export PYTHON_VENV_ROOT=${PWD}/python-venv
+python3 -m venv ${PYTHON_VENV_ROOT}
+source ${PYTHON_VENV_ROOT}/bin/activate
+python3 -m pip install requests
+```
+
+Using `mozc/src/python-venv` as the virtual environment location is not mandatory. Any other location should also work.
+
 ### Check out additional build dependencies
 
 ```