From e7a6ac81a27aaa96e0e7622aef8b8a9801dcb8b3 Mon Sep 17 00:00:00 2001
From: Lukas Atkinson <opensource@LukasAtkinson.de>
Date: Fri, 7 Jan 2022 13:55:06 +0100
Subject: [PATCH] drop support for Python 3.6

---
 .github/workflows/test.yml  | 42 ++++++++++++++++++++++++++++++-------
 CHANGELOG.rst               |  2 ++
 admin/Dockerfile.qa         | 25 +++++++++++++++++++---
 doc/requirements.txt        |  3 +--
 doc/source/installation.rst |  5 +++--
 setup.py                    |  2 +-
 6 files changed, 64 insertions(+), 15 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 256668e70f..cb8ad75729 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -69,29 +69,57 @@ jobs:
 
     needs: [milestone-check, changelog-check]
 
+    # Testing strategy
+    # ----------------
+    #
+    # We have different axes of the testing matrix:
+    #
+    # OS: Linux, Windows
+    # Compiler: GCC-5, GCC-6, GCC-8, Clang-10
+    # Python: 3.7 -- 3.10, pypy3
+    #
+    # Instead of testing all combinations, we try to achieve full coverage
+    # across each axis. The main test matrix just represents the Python axis on
+    # Linux. The OS=Windows and Compiler axis are added manually.
+    #
+    # Some cases (Linux with Python 3.7, Clang-10) are handled via the Docker-tests.
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-20.04, windows-2019]
+        os: [ubuntu-20.04]
         gcc: [gcc-8]
-        python-version: [3.7, 3.8] # 3.6 is used in Docker
+        python-version: ['3.8', '3.9', '3.10', 'pypy-3.7'] # 3.7 is used in Docker
 
         include:
+
+          # Test additional compilers with Linux.
+          # Note that Clang-10 is handled via Docker.
           - os: ubuntu-18.04
             gcc: gcc-5
-            python-version: 3.7
+            python-version: '3.8'
           - os: ubuntu-18.04
             gcc: gcc-6
-            python-version: 3.8
-          - os: ubuntu-20.04
+            python-version: '3.8'
+
+          # Test minimum and maximum Python version on Windows.
+          - os: windows-2019
+            gcc: gcc-8
+            python-version: '3.7'
+          - os: windows-2019
             gcc: gcc-8
-            python-version: pypy3
+            python-version: '3.10'
 
     steps:
     - uses: actions/checkout@v2
     - name: Setup environment
       run: |
-        echo "USE_COVERAGE=${{ ( ( matrix.os == 'windows-2019' ) && ( matrix.python-version == '3.7' ) ) || ( ( matrix.os == 'ubuntu-18.04' ) && ( matrix.gcc == 'gcc-6' ) && ( matrix.python-version == '3.8' ) ) }}" >> $GITHUB_ENV
+        # Enable coverage for specific target configurations
+        case "${{ matrix.os }}/${{ matrix.gcc }}/${{ matrix.python-version }}" in
+          windows-2019/gcc-8/3.7) USE_COVERAGE=true ;;
+          ubuntu-18.04/gcc-6/3.8) USE_COVERAGE=true ;;
+          *)                      USE_COVERAGE=false ;;
+        esac
+        echo USE_COVERAGE=$USE_COVERAGE >> $GITHUB_ENV
       shell: bash
     - name: Install msys with GCC (Windows)
       if: ${{ startsWith(matrix.os,'windows-') }}
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index f9519b5037..865fccc4ad 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -8,6 +8,8 @@ Next Release
 
 Breaking changes:
 
+- Dropped support for Python 3.6 (:issue:`550`)
+
 Improvements and new features:
 
 - Add function coverage metric (:issue:`362`)
diff --git a/admin/Dockerfile.qa b/admin/Dockerfile.qa
index 59d25b8450..2af9aba1a8 100644
--- a/admin/Dockerfile.qa
+++ b/admin/Dockerfile.qa
@@ -4,10 +4,29 @@ ARG USERID
 ARG CC
 ARG CXX
 
+# Install dependencies.
+#
+# Installing pip is a bit more complicated though:
+# * `apt install python3.7-pip` -> does not exist
+# * `python3.7 -m ensurepip` -> standard library module removed by Debian
+# * `apt install python3-pip` -> pulls in >100MB of unneeded stuff
+# * `get-pip.py` script -> depends on distutils standard library module, removed by Debian
+#
+# Solution: install python3-setuptools (includes Python 3.6),
+# then use the get-pip script from Python 3.7.
 RUN \
-  apt update && \
-  apt-get install -y sudo make $CC $CXX python3 python3-pip ninja-build && \
-  apt-get clean
+    apt-get update && \
+    apt-get install -y sudo make $CC $CXX python3-setuptools python3.7 ninja-build curl && \
+    apt-get clean
+
+# Install pip manually
+RUN \
+    curl -sSL https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
+    python3.7 get-pip.py && \
+    rm get-pip.py
+
+# Install Python 3.7 as the default "python3" executable
+RUN update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.7 10
 
 WORKDIR /gcovr
 
diff --git a/doc/requirements.txt b/doc/requirements.txt
index 6da1ceef80..52b4114e45 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,4 +1,3 @@
 sphinx
 sphinx_rtd_theme
-sphinxcontrib-autoprogram == 0.1.5 ; python_version == "3.6"
-sphinxcontrib-autoprogram >= 0.1.5 ; python_version >= "3.7"
+sphinxcontrib-autoprogram >= 0.1.5
diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index 95f0322212..4e2fd5ed31 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -8,9 +8,9 @@ Installation
 Which environments does ``gcovr`` support?
 
 Python:
-    3.6+.
+    3.7+.
 
-    The automated tests run on CPython (versions 3.6, 3.7, 3.8)
+    The automated tests run on CPython (versions 3.7, 3.8, 3.9, 3.10)
     and a compatible PyPy3.
     Gcovr will only run on Python versions with upstream support.
 
@@ -23,6 +23,7 @@ Python:
     2.7    4.2
     3.4    4.1
     3.5    4.2
+    3.6    5.0
     ====== =====
 
 Operating System:
diff --git a/setup.py b/setup.py
index b1cf7c9e3e..87323126a1 100644
--- a/setup.py
+++ b/setup.py
@@ -51,7 +51,7 @@
     long_description=long_description,
     long_description_content_type="text/x-rst",
     platforms=["any"],
-    python_requires=">=3.6",
+    python_requires=">=3.7",
     packages=find_packages(include=["gcovr*"], exclude=["gcovr.tests"]),
     install_requires=["jinja2", "lxml", "pygments"],
     package_data={