From b3bdaceea2b495bac6d20140a597dd445173a837 Mon Sep 17 00:00:00 2001
From: Eric Cousineau <eric.cousineau@tri.global>
Date: Thu, 4 Mar 2021 15:56:40 -0500
Subject: [PATCH] drake: Pull in partial ci changes from upstream

---
 .github/workflows/ci.yml        | 745 +++++++++++++++++++++++++++-----
 .github/workflows/configure.yml |  94 ++--
 .github/workflows/format.yml    |  60 ++-
 3 files changed, 720 insertions(+), 179 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 762fafca2f..fc7ea9b7ee 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,65 +8,55 @@ on:
       - drake
 
 jobs:
+  # This is the "main" test suite, which tests a large number of different
+  # versions of default compilers and Python versions in GitHub Actions.
   standard:
     strategy:
       fail-fast: false
       matrix:
         # runs-on: [ubuntu-latest, windows-latest, macos-latest]
         runs-on: [ubuntu-latest, macos-latest]
-        arch: [x64]
-        max-cxx-std: [17]
         python:
         # - 2.7
         # - 3.5
+        - 3.6
         - 3.7
         - 3.8
-        - 3.9-dev
+        - 3.9
+        - 3.10-dev
         # - pypy2
         # - pypy3
 
+        # Items in here will either be added to the build matrix (if not
+        # present), or add new keys to an existing matrix element if all the
+        # existing keys match.
+        #
+        # We support three optional keys: args (both build), args1 (first
+        # build), and args2 (second build).
         include:
+          # Just add a key
           - runs-on: ubuntu-latest
             python: 3.6
-            arch: x64
-            max-cxx-std: 17
-          - runs-on: macos-latest
-            python: 3.7
-            arch: x64
-            max-cxx-std: 17
-          # - runs-on: windows-2016
-          #   python: 3.7
-          #   arch: x86
-          #   max-cxx-std: 14
-
-        exclude:
-          #   # Currently 32bit only, and we build 64bit
+            args: >
+              -DPYBIND11_FINDPYTHON=ON
           # - runs-on: windows-latest
-          #   python: pypy2
-          #   arch: x64
-          #   max-cxx-std: 17
-          # - runs-on: windows-latest
-          #   python: pypy3
-          #   arch: x64
-          #   max-cxx-std: 17
-
-            # Currently can't build due to warning, fixed in CPython > 3.9b5
-          - runs-on: macos-latest
-            python: 3.9-dev
-            arch: x64
-            max-cxx-std: 17
-
-          #   # Currently broken on embed_test
-          # - runs-on: windows-latest
-          #   python: 3.8
-          #   arch: x64
-          #   max-cxx-std: 17
-          # - runs-on: windows-latest
-          #   python: 3.9-dev
-          #   arch: x64
-          #   max-cxx-std: 17
-
-    name: "🐍 ${{ matrix.python }} • ${{ matrix.runs-on }} • ${{ matrix.arch }}"
+          #   python: 3.6
+          #   args: >
+          #     -DPYBIND11_FINDPYTHON=ON
+
+        # # These items will be removed from the build matrix, keys must match.
+        # exclude:
+        #     # Currently 32bit only, and we build 64bit
+        #   - runs-on: windows-latest
+        #     python: pypy2
+        #   - runs-on: windows-latest
+        #     python: pypy3
+
+        #   # TODO: PyPy2 7.3.3 segfaults, while 7.3.2 was fine.
+        #   - runs-on: ubuntu-latest
+        #     python: pypy2
+
+    name: "🐍 ${{ matrix.python }} • ${{ matrix.runs-on }} • x64 ${{ matrix.args }}"
     runs-on: ${{ matrix.runs-on }}
 
     steps:
@@ -76,10 +66,16 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python }}
-        architecture: ${{ matrix.arch }}
+
+    - name: Setup Boost (Windows / Linux latest)
+      shell: bash
+      run: echo "BOOST_ROOT=$BOOST_ROOT_1_72_0" >> $GITHUB_ENV
+
+    - name: Update CMake
+      uses: jwlawson/actions-setup-cmake@v1.8
 
     - name: Cache wheels
-      if: startsWith(runner.os, 'macOS')
+      if: runner.os == 'macOS'
       uses: actions/cache@v2
       with:
         # This path is specific to macOS - we really only need it for PyPy NumPy wheels
@@ -87,55 +83,168 @@ jobs:
         # for ways to do this more generally
         path: ~/Library/Caches/pip
         # Look to see if there is a cache hit for the corresponding requirements file
-        key: ${{ runner.os }}-pip-${{ matrix.python }}-${{ matrix.arch }}-${{ hashFiles('tests/requirements.txt') }}
+        key: ${{ runner.os }}-pip-${{ matrix.python }}-x64-${{ hashFiles('tests/requirements.txt') }}
 
     - name: Prepare env
-      run: python -m pip install -r tests/requirements.txt
+      run: python -m pip install -r tests/requirements.txt --prefer-binary
 
-    - name: Configure C++11
-      shell: bash
+    - 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 ${{ matrix.args }}
       run: >
-        cmake -S . -B build
+        cmake -S . -B .
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=11
-        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+        ${{ matrix.args }}
 
     - name: Build C++11
-      run: cmake --build build -j 2
+      run: cmake --build . -j 2
 
     - name: Python tests C++11
-      run: cmake --build build --target pytest -j 2
+      run: cmake --build . --target pytest -j 2
 
     - name: C++11 tests
-      run: cmake --build build --target cpptest -j 2
+      # TODO: Figure out how to load the DLL on Python 3.8+
+      if: "!(runner.os == 'Windows' && (matrix.python == 3.8 || matrix.python == 3.9 || matrix.python == '3.10-dev'))"
+      run: cmake --build .  --target cpptest -j 2
 
     - name: Interface test C++11
-      run: cmake --build build --target test_cmake_build
+      run: cmake --build . --target test_cmake_build
 
-    - name: Configure C++${{ matrix.max-cxx-std }}
-      shell: bash
+    - name: Clean directory
+      run: git clean -fdx
+
+    # Second build - C++17 mode and in a build directory
+    - name: Configure ${{ matrix.args2 }}
       run: >
         cmake -S . -B build2
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DDOWNLOAD_EIGEN=ON
-        -DCMAKE_CXX_STANDARD=${{ matrix.max-cxx-std }}
-        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+        -DCMAKE_CXX_STANDARD=17
+        ${{ matrix.args }}
+        ${{ matrix.args2 }}
 
-    - name: Build C++${{ matrix.max-cxx-std }}
+    - name: Build
       run: cmake --build build2 -j 2
 
-    - name: Python tests C++${{ matrix.max-cxx-std }}
+    - name: Python tests
       run: cmake --build build2 --target pytest
 
-    - name: C++${{ matrix.max-cxx-std }} tests
+    - name: C++ tests
+      # TODO: Figure out how to load the DLL on Python 3.8+
+      if: "!(runner.os == 'Windows' && (matrix.python == 3.8 || matrix.python == 3.9 || matrix.python == '3.10-dev'))"
       run: cmake --build build2 --target cpptest
 
-    - name: Interface test C++${{ matrix.max-cxx-std }}
+    - name: Interface test
       run: cmake --build build2 --target test_cmake_build
 
+    # Eventually Microsoft might have an action for setting up
+    # MSVC, but for now, this action works:
+    - name: Prepare compiler environment for Windows 🐍 2.7
+      if: matrix.python == 2.7 && runner.os == 'Windows'
+      uses: ilammy/msvc-dev-cmd@v1
+      with:
+        arch: x64
+
+    # This makes two environment variables available in the following step(s)
+    - name: Set Windows 🐍 2.7 environment variables
+      if: matrix.python == 2.7 && runner.os == 'Windows'
+      shell: bash
+      run: |
+        echo "DISTUTILS_USE_SDK=1" >> $GITHUB_ENV
+        echo "MSSdk=1" >> $GITHUB_ENV
+
+    # This makes sure the setup_helpers module can build packages using
+    # setuptools
+    - name: Setuptools helpers test
+      run: pytest tests/extra_setuptools
+
+
+  # deadsnakes:
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       include:
+  #       - python-version: 3.9
+  #         python-debug: true
+  #         valgrind: true
+  #       - python-version: 3.10-dev
+  #         python-debug: false
+
+  #   name: "🐍 ${{ matrix.python-version }}${{ matrix.python-debug && '-dbg' || '' }} (deadsnakes)${{ matrix.valgrind && ' • Valgrind' || '' }} • x64"
+  #   runs-on: ubuntu-latest
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   - name: Setup Python ${{ matrix.python-version }} (deadsnakes)
+  #     uses: deadsnakes/action@v2.1.1
+  #     with:
+  #       python-version: ${{ matrix.python-version }}
+  #       debug: ${{ matrix.python-debug }}
+
+  #   - name: Update CMake
+  #     uses: jwlawson/actions-setup-cmake@v1.7
+
+  #   - name: Valgrind cache
+  #     if: matrix.valgrind
+  #     uses: actions/cache@v2
+  #     id: cache-valgrind
+  #     with:
+  #       path: valgrind
+  #       key: 3.16.1 # Valgrind version
+
+  #   - name: Compile Valgrind
+  #     if: matrix.valgrind && steps.cache-valgrind.outputs.cache-hit != 'true'
+  #     run: |
+  #       VALGRIND_VERSION=3.16.1
+  #       curl https://sourceware.org/pub/valgrind/valgrind-$VALGRIND_VERSION.tar.bz2 -o - | tar xj
+  #       mv valgrind-$VALGRIND_VERSION valgrind
+  #       cd valgrind
+  #       ./configure
+  #       make -j 2 > /dev/null
+
+  #   - name: Install Valgrind
+  #     if: matrix.valgrind
+  #     working-directory: valgrind
+  #     run: |
+  #       sudo make install
+  #       sudo apt-get update
+  #       sudo apt-get install libc6-dbg  # Needed by Valgrind
+
+  #   - name: Prepare env
+  #     run: python -m pip install -r tests/requirements.txt --prefer-binary
+
+  #   - name: Configure
+  #     run: >
+  #       cmake -S . -B build
+  #       -DCMAKE_BUILD_TYPE=Debug
+  #       -DPYBIND11_WERROR=ON
+  #       -DDOWNLOAD_CATCH=ON
+  #       -DDOWNLOAD_EIGEN=ON
+  #       -DCMAKE_CXX_STANDARD=17
+
+  #   - name: Build
+  #     run: cmake --build build -j 2
+
+  #   - name: Python tests
+  #     run: cmake --build build --target pytest
+
+  #   - name: C++ tests
+  #     run: cmake --build build --target cpptest
+
+  #   - name: Run Valgrind on Python tests
+  #     if: matrix.valgrind
+  #     run: cmake --build build --target memcheck
+
+
+  # Testing on clang using the excellent silkeh clang docker images
   clang:
     runs-on: ubuntu-latest
     strategy:
@@ -145,12 +254,20 @@ jobs:
           # - 3.6
           # - 3.7
           # - 3.9
-          # - 5
-          # - 7
+          - 7
           - 9
           - dev
-
-    name: "🐍 3 • Clang ${{ matrix.clang }} • x64"
+        std:
+          - 11
+        include:
+          # - clang: 5
+          #   std: 14
+          - clang: 10
+            std: 20
+          - clang: 10
+            std: 17
+
+    name: "🐍 3 • Clang ${{ matrix.clang }} • C++${{ matrix.std }} • x64"
     container: "silkeh/clang:${{ matrix.clang }}"
 
     steps:
@@ -165,6 +282,7 @@ jobs:
         cmake -S . -B build
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
+        -DCMAKE_CXX_STANDARD=${{ matrix.std }}
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
     - name: Build
@@ -179,6 +297,124 @@ jobs:
     - name: Interface test
       run: cmake --build build --target test_cmake_build
 
+
+  # # Testing NVCC; forces sources to behave like .cu files
+  # cuda:
+  #   runs-on: ubuntu-latest
+  #   name: "🐍 3.8 • CUDA 11 • Ubuntu 20.04"
+  #   container: nvidia/cuda:11.0-devel-ubuntu20.04
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   # tzdata will try to ask for the timezone, so set the DEBIAN_FRONTEND
+  #   - name: Install 🐍 3
+  #     run: apt-get update && DEBIAN_FRONTEND="noninteractive" apt-get install -y cmake git python3-dev python3-pytest python3-numpy
+
+  #   - name: Configure
+  #     run: cmake -S . -B build -DPYBIND11_CUDA_TESTS=ON -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON
+
+  #   - name: Build
+  #     run: cmake --build build -j2 --verbose
+
+  #   - name: Python tests
+  #     run: cmake --build build --target pytest
+
+
+# TODO: Internal compiler error - report to NVidia
+#  # Testing CentOS 8 + PGI compilers
+#  centos-nvhpc8:
+#    runs-on: ubuntu-latest
+#    name: "🐍 3 • CentOS8 / PGI 20.11 • x64"
+#    container: centos:8
+#
+#    steps:
+#    - uses: actions/checkout@v2
+#
+#    - name: Add Python 3 and a few requirements
+#      run: yum update -y && yum install -y git python3-devel python3-numpy python3-pytest make environment-modules
+#
+#    - name: Install CMake with pip
+#      run: |
+#        python3 -m pip install --upgrade pip
+#        python3 -m pip install cmake --prefer-binary
+#
+#    - name: Install NVidia HPC SDK
+#      run: >
+#        yum -y install
+#        https://developer.download.nvidia.com/hpc-sdk/20.11/nvhpc-20-11-20.11-1.x86_64.rpm
+#        https://developer.download.nvidia.com/hpc-sdk/20.11/nvhpc-2020-20.11-1.x86_64.rpm
+#
+#    - name: Configure
+#      shell: bash
+#      run: |
+#        source /etc/profile.d/modules.sh
+#        module load /opt/nvidia/hpc_sdk/modulefiles/nvhpc/20.11
+#        cmake -S . -B build -DDOWNLOAD_CATCH=ON -DCMAKE_CXX_STANDARD=14 -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
+#
+#    - name: Build
+#      run: cmake --build build -j 2 --verbose
+#
+#    - name: Python tests
+#      run: cmake --build build --target pytest
+#
+#    - name: C++ tests
+#      run: cmake --build build --target cpptest
+#
+#    - name: Interface test
+#      run: cmake --build build --target test_cmake_build
+
+
+  # # Testing on CentOS 7 + PGI compilers, which seems to require more workarounds
+  # centos-nvhpc7:
+  #   runs-on: ubuntu-latest
+  #   name: "🐍 3 • CentOS7 / PGI 20.9 • x64"
+  #   container: centos:7
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   - name: Add Python 3 and a few requirements
+  #     run: yum update -y && yum install -y epel-release && yum install -y git python3-devel make environment-modules cmake3
+
+  #   - name: Install NVidia HPC SDK
+  #     run:  yum -y install https://developer.download.nvidia.com/hpc-sdk/20.9/nvhpc-20-9-20.9-1.x86_64.rpm https://developer.download.nvidia.com/hpc-sdk/20.9/nvhpc-2020-20.9-1.x86_64.rpm
+
+  #   # On CentOS 7, we have to filter a few tests (compiler internal error)
+  #   # and allow deeper templete recursion (not needed on CentOS 8 with a newer
+  #   # standard library). On some systems, you many need further workarounds:
+  #   # https://github.com/pybind/pybind11/pull/2475
+  #   - name: Configure
+  #     shell: bash
+  #     run: |
+  #       source /etc/profile.d/modules.sh
+  #       module load /opt/nvidia/hpc_sdk/modulefiles/nvhpc/20.9
+  #       cmake3 -S . -B build -DDOWNLOAD_CATCH=ON \
+  #                           -DCMAKE_CXX_STANDARD=11 \
+  #                           -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)") \
+  #                           -DCMAKE_CXX_FLAGS="-Wc,--pending_instantiations=0" \
+  #                           -DPYBIND11_TEST_FILTER="test_smart_ptr.cpp;test_virtual_functions.cpp"
+
+  #   # Building before installing Pip should produce a warning but not an error
+  #   - name: Build
+  #     run: cmake3 --build build -j 2 --verbose
+
+  #   - name: Install CMake with pip
+  #     run: |
+  #       python3 -m pip install --upgrade pip
+  #       python3 -m pip install pytest
+
+  #   - name: Python tests
+  #     run: cmake3 --build build --target pytest
+
+  #   - name: C++ tests
+  #     run: cmake3 --build build --target cpptest
+
+  #   - name: Interface test
+  #     run: cmake3 --build build --target test_cmake_build
+
+
+  # Testing on GCC using the GCC docker images (only recent images supported)
   gcc:
     runs-on: ubuntu-latest
     strategy:
@@ -187,8 +423,13 @@ jobs:
         gcc:
           - 7
           - latest
+        std:
+          - 11
+        include:
+          - gcc: 10
+            std: 20
 
-    name: "🐍 3 • GCC ${{ matrix.gcc }} • x64"
+    name: "🐍 3 • GCC ${{ matrix.gcc }} • C++${{ matrix.std }}• x64"
     container: "gcc:${{ matrix.gcc }}"
 
     steps:
@@ -200,10 +441,8 @@ jobs:
     - name: Update pip
       run: python3 -m pip install --upgrade pip
 
-    - name: Setup CMake 3.18
-      uses: jwlawson/actions-setup-cmake@v1.3
-      with:
-        cmake-version: 3.18
+    - name: Update CMake
+      uses: jwlawson/actions-setup-cmake@v1.8
 
     - name: Configure
       shell: bash
@@ -211,7 +450,7 @@ jobs:
         cmake -S . -B build
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
-        -DCMAKE_CXX_STANDARD=11
+        -DCMAKE_CXX_STANDARD=${{ matrix.std }}
         -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
     - name: Build
@@ -226,6 +465,106 @@ jobs:
     - name: Interface test
       run: cmake --build build --target test_cmake_build
 
+
+  # # Testing on ICC using the oneAPI apt repo
+  # icc:
+  #   runs-on: ubuntu-20.04
+  #   strategy:
+  #     fail-fast: false
+
+  #   name: "🐍 3 • ICC latest • x64"
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   - name: Add apt repo
+  #     run: |
+  #       sudo apt-get update
+  #       sudo apt-get install -y wget build-essential pkg-config cmake ca-certificates gnupg
+  #       wget https://apt.repos.intel.com/intel-gpg-keys/GPG-PUB-KEY-INTEL-SW-PRODUCTS-2023.PUB
+  #       sudo apt-key add GPG-PUB-KEY-INTEL-SW-PRODUCTS-2023.PUB
+  #       echo "deb https://apt.repos.intel.com/oneapi all main" | sudo tee /etc/apt/sources.list.d/oneAPI.list
+
+  #   - name: Add ICC & Python 3
+  #     run: sudo apt-get update; sudo apt-get install -y intel-oneapi-compiler-dpcpp-cpp-and-cpp-classic cmake python3-dev python3-numpy python3-pytest python3-pip
+
+  #   - name: Update pip
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       python3 -m pip install --upgrade pip
+
+  #   - name: Install dependencies
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       python3 -m pip install -r tests/requirements.txt --prefer-binary
+
+  #   - name: Configure C++11
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake -S . -B build-11     \
+  #       -DPYBIND11_WERROR=ON    \
+  #       -DDOWNLOAD_CATCH=ON     \
+  #       -DDOWNLOAD_EIGEN=OFF    \
+  #       -DCMAKE_CXX_STANDARD=11             \
+  #       -DCMAKE_CXX_COMPILER=$(which icpc)  \
+  #       -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
+
+  #   - name: Build C++11
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake --build build-11 -j 2 -v
+
+  #   - name: Python tests C++11
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       sudo service apport stop
+  #       cmake --build build-11 --target check
+
+  #   - name: C++ tests C++11
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake --build build-11 --target cpptest
+
+  #   - name: Interface test C++11
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake --build build-11 --target test_cmake_build
+
+  #   - name: Configure C++17
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake -S . -B build-17     \
+  #       -DPYBIND11_WERROR=ON    \
+  #       -DDOWNLOAD_CATCH=ON     \
+  #       -DDOWNLOAD_EIGEN=OFF    \
+  #       -DCMAKE_CXX_STANDARD=17             \
+  #       -DCMAKE_CXX_COMPILER=$(which icpc)  \
+  #       -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
+
+  #   - name: Build C++17
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake --build build-17 -j 2 -v
+
+  #   - name: Python tests C++17
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       sudo service apport stop
+  #       cmake --build build-17 --target check
+
+  #   - name: C++ tests C++17
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake --build build-17 --target cpptest
+
+  #   - name: Interface test C++17
+  #     run: |
+  #       set +e; source /opt/intel/oneapi/setvars.sh; set -e
+  #       cmake --build build-17 --target test_cmake_build
+
+
+  # # Testing on CentOS (manylinux uses a centos base, and this is an easy way
+  # # to get GCC 4.8, which is the manylinux1 compiler).
   # centos:
   #   runs-on: ubuntu-latest
   #   strategy:
@@ -248,7 +587,7 @@ jobs:
   #     run: python3 -m pip install --upgrade pip
 
   #   - name: Install dependencies
-  #     run: python3 -m pip install cmake -r tests/requirements.txt
+  #     run: python3 -m pip install cmake -r tests/requirements.txt --prefer-binary
 
   #   - name: Configure
   #     shell: bash
@@ -272,65 +611,237 @@ jobs:
   #   - name: Interface test
   #     run: cmake --build build --target test_cmake_build
 
-  install-classic:
-    name: "🐍 3.5 • Debian • x86 •  Install"
-    runs-on: ubuntu-latest
-    container: i386/debian:stretch
 
-    steps:
-    - uses: actions/checkout@v1
+  # # This tests an "install" with the CMake tools
+  # install-classic:
+  #   name: "🐍 3.5 • Debian • x86 •  Install"
+  #   runs-on: ubuntu-latest
+  #   container: i386/debian:stretch
 
-    - name: Install requirements
-      run: |
-        apt-get update
-        apt-get install -y git make cmake g++ libeigen3-dev python3-dev python3-pip python3-pytest
+  #   steps:
+  #   - uses: actions/checkout@v1
+
+  #   - name: Install requirements
+  #     run: |
+  #       apt-get update
+  #       apt-get install -y git make cmake g++ libeigen3-dev python3-dev python3-pip
+  #       pip3 install "pytest==3.1.*"
+
+  #   - name: Configure for install
+  #     run: >
+  #       cmake .
+  #       -DPYBIND11_INSTALL=1 -DPYBIND11_TEST=0
+  #       -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
 
-    - name: Configure for install
-      run: cmake -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)") -DPYBIND11_INSTALL=1 -DPYBIND11_TEST=0 .
+  #   - name: Make and install
+  #     run: make install
 
-    - name: Make and install
-      run: make install
+  #   - name: Copy tests to new directory
+  #     run: cp -a tests /pybind11-tests
 
-    - name: Copy tests to new directory
-      run: cp -a tests /pybind11-tests
+  #   - name: Make a new test directory
+  #     run: mkdir /build-tests
 
-    - name: Make a new test directory
-      run: mkdir /build-tests
+  #   - name: Configure tests
+  #     run: >
+  #       cmake ../pybind11-tests
+  #       -DDOWNLOAD_CATCH=ON
+  #       -DPYBIND11_WERROR=ON
+  #       -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)")
+  #     working-directory: /build-tests
 
-    - name: Configure tests
-      run: cmake -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)") ../pybind11-tests -DPYBIND11_WERROR=ON
-      working-directory: /build-tests
+  #   - name: Run tests
+  #     run: make pytest -j 2
+  #     working-directory: /build-tests
 
-    - name: Run tests
-      run: make pytest -j 2
-      working-directory: /build-tests
 
+  # # This verifies that the documentation is not horribly broken, and does a
+  # # basic sanity check on the SDist.
+  # doxygen:
+  #   name: "Documentation build test"
+  #   runs-on: ubuntu-latest
 
-  doxygen:
-    name: "Documentation build test"
-    runs-on: ubuntu-latest
-    container: alpine:3.12
+  #   steps:
+  #   - uses: actions/checkout@v2
 
-    steps:
-    - uses: actions/checkout@v2
+  #   - uses: actions/setup-python@v2
 
-    - name: Install requirements
-      run: apk add doxygen python3-dev
+  #   - name: Install Doxygen
+  #     run: sudo apt-get install -y doxygen librsvg2-bin # Changed to rsvg-convert in 20.04
 
-    - name: Ensure pip
-      run: python3 -m ensurepip
+  #   - name: Install docs & setup requirements
+  #     run: python3 -m pip install -r docs/requirements.txt
 
-    - name: Install python docs requirements
-      run: python3 -m pip install "sphinx<3" sphinx_rtd_theme breathe==4.13.1 pytest setuptools
+  #   - name: Build docs
+  #     run: python3 -m sphinx -W -b html docs docs/.build
 
-    - name: Build docs
-      run: python3 -m sphinx -W -b html docs docs/.build
+  #   - name: Make SDist
+  #     run: python3 setup.py sdist
 
-    - name: Make SDist
-      run: python3 setup.py sdist
+  #   - run: git status --ignored
 
-    - name: Compare Dists (headers only)
-      run: |
-        python3 -m pip install --user -U ./dist/*
-        installed=$(python3 -c "import pybind11; print(pybind11.get_include(True) + '/pybind11')")
-        diff -rq $installed ./include/pybind11
+  #   - name: Check local include dir
+  #     run: >
+  #       ls pybind11;
+  #       python3 -c "import pybind11, pathlib; assert (a := pybind11.get_include()) == (b := str(pathlib.Path('include').resolve())), f'{a} != {b}'"
+
+  #   - name: Compare Dists (headers only)
+  #     working-directory: include
+  #     run: |
+  #       python3 -m pip install --user -U ../dist/*
+  #       installed=$(python3 -c "import pybind11; print(pybind11.get_include() + '/pybind11')")
+  #       diff -rq $installed ./pybind11
+
+  # win32:
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       python:
+  #       - 3.5
+  #       - 3.6
+  #       - 3.7
+  #       - 3.8
+  #       - 3.9
+  #       - pypy3
+  #       # TODO: fix hang on pypy2
+
+  #       include:
+  #         - python: 3.9
+  #           args: -DCMAKE_CXX_STANDARD=20 -DDOWNLOAD_EIGEN=OFF
+  #         - python: 3.8
+  #           args: -DCMAKE_CXX_STANDARD=17
+
+  #   name: "🐍 ${{ matrix.python }} • MSVC 2019 • x86 ${{ matrix.args }}"
+  #   runs-on: windows-latest
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   - name: Setup Python ${{ matrix.python }}
+  #     uses: actions/setup-python@v2
+  #     with:
+  #       python-version: ${{ matrix.python }}
+  #       architecture: x86
+
+  #   - name: Update CMake
+  #     uses: jwlawson/actions-setup-cmake@v1.7
+
+  #   - name: Prepare MSVC
+  #     uses: ilammy/msvc-dev-cmd@v1
+  #     with:
+  #       arch: x86
+
+  #   - name: Prepare env
+  #     run: python -m pip install -r tests/requirements.txt --prefer-binary
+
+  #   # First build - C++11 mode and inplace
+  #   - name: Configure ${{ matrix.args }}
+  #     run: >
+  #       cmake -S . -B build
+  #       -G "Visual Studio 16 2019" -A Win32
+  #       -DPYBIND11_WERROR=ON
+  #       -DDOWNLOAD_CATCH=ON
+  #       -DDOWNLOAD_EIGEN=ON
+  #       ${{ matrix.args }}
+  #   - name: Build C++11
+  #     run: cmake --build build -j 2
+
+  #   - name: Run tests
+  #     run: cmake --build build -t pytest
+
+  # win32-msvc2015:
+  #   name: "🐍 ${{ matrix.python }} • MSVC 2015 • x64"
+  #   runs-on: windows-latest
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       python:
+  #         - 2.7
+  #         - 3.6
+  #         - 3.7
+  #         # todo: check/cpptest does not support 3.8+ yet
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   - name: Setup 🐍 ${{ matrix.python }}
+  #     uses: actions/setup-python@v2
+  #     with:
+  #       python-version: ${{ matrix.python }}
+
+  #   - name: Update CMake
+  #     uses: jwlawson/actions-setup-cmake@v1.7
+
+  #   - name: Prepare MSVC
+  #     uses: ilammy/msvc-dev-cmd@v1
+  #     with:
+  #       toolset: 14.0
+
+  #   - name: Prepare env
+  #     run: python -m pip install -r tests/requirements.txt --prefer-binary
+
+  #   # First build - C++11 mode and inplace
+  #   - name: Configure
+  #     run: >
+  #       cmake -S . -B build
+  #       -G "Visual Studio 14 2015" -A x64
+  #       -DPYBIND11_WERROR=ON
+  #       -DDOWNLOAD_CATCH=ON
+  #       -DDOWNLOAD_EIGEN=ON
+
+  #   - name: Build C++14
+  #     run: cmake --build build -j 2
+
+  #   - name: Run all checks
+  #     run: cmake --build build -t check
+
+
+  # win32-msvc2017:
+  #   name: "🐍 ${{ matrix.python }} • MSVC 2017 • x64"
+  #   runs-on: windows-2016
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       python:
+  #         - 2.7
+  #         - 3.5
+  #         - 3.7
+  #       std:
+  #         - 14
+
+  #       include:
+  #         - python: 2.7
+  #           std: 17
+  #           args: >
+  #             -DCMAKE_CXX_FLAGS="/permissive- /EHsc /GR"
+
+  #   steps:
+  #   - uses: actions/checkout@v2
+
+  #   - name: Setup 🐍 ${{ matrix.python }}
+  #     uses: actions/setup-python@v2
+  #     with:
+  #       python-version: ${{ matrix.python }}
+
+  #   - name: Update CMake
+  #     uses: jwlawson/actions-setup-cmake@v1.7
+
+  #   - name: Prepare env
+  #     run: python -m pip install -r tests/requirements.txt --prefer-binary
+
+  #   # First build - C++11 mode and inplace
+  #   - name: Configure
+  #     run: >
+  #       cmake -S . -B build
+  #       -G "Visual Studio 15 2017" -A x64
+  #       -DPYBIND11_WERROR=ON
+  #       -DDOWNLOAD_CATCH=ON
+  #       -DDOWNLOAD_EIGEN=ON
+  #       -DCMAKE_CXX_STANDARD=${{ matrix.std }}
+  #       ${{ matrix.args }}
+
+  #   - name: Build ${{ matrix.std }}
+  #     run: cmake --build build -j 2
+
+  #   - name: Run all checks
+  #     run: cmake --build build -t check
diff --git a/.github/workflows/configure.yml b/.github/workflows/configure.yml
index 96904341de..77ee8cad8c 100644
--- a/.github/workflows/configure.yml
+++ b/.github/workflows/configure.yml
@@ -1,78 +1,82 @@
-name: Configure
+name: Config
 
 on:
   workflow_dispatch:
   pull_request:
   push:
     branches:
-      - master
-      - stable
-      - v*
+      - drake
 
 jobs:
+  # This tests various versions of CMake in various combinations, to make sure
+  # the configure step passes.
   cmake:
     strategy:
       fail-fast: false
       matrix:
-        python:
-        - 2.7
-        - 3.8
+        runs-on: [ubuntu-latest, macos-latest, windows-latest]
+        arch: [x64]
+        cmake: [3.18]
 
-    name: CMake ${{ matrix.cmake }} Python ${{ matrix.python }} on ubuntu
-    runs-on: ubuntu-latest
+        include:
+        - runs-on: ubuntu-latest
+          arch: x64
+          cmake: 3.4
+
+        - runs-on: macos-latest
+          arch: x64
+          cmake: 3.7
+
+        - runs-on: windows-2016
+          arch: x86
+          cmake: 3.8
+
+        - runs-on: windows-2016
+          arch: x86
+          cmake: 3.18
+
+    name: 🐍 3.7 • CMake ${{ matrix.cmake }} • ${{ matrix.runs-on }}
+    runs-on: ${{ matrix.runs-on }}
 
     steps:
     - uses: actions/checkout@v2
 
-    - name: Setup Python ${{ matrix.python }}
+    - name: Setup Python 3.7
       uses: actions/setup-python@v2
       with:
-        python-version: ${{ matrix.python }}
+        python-version: 3.7
+        architecture: ${{ matrix.arch }}
 
     - name: Prepare env
       run: python -m pip install -r tests/requirements.txt
 
-    - name: Make build directories
-      run: |
-        mkdir build3.7
-        mkdir build3.11
-        mkdir build3.18
-
-    - name: Setup CMake 3.7
-      uses: jwlawson/actions-setup-cmake@v1.3
+    # An action for adding a specific version of CMake:
+    #   https://github.com/jwlawson/actions-setup-cmake
+    - name: Setup CMake ${{ matrix.cmake }}
+      uses: jwlawson/actions-setup-cmake@v1.8
       with:
-        cmake-version: 3.7
-
-    - name: Configure 3.7
-      working-directory: build3.7
-      run: >
-        cmake ..
-        -DPYBIND11_WERROR=ON
-        -DDOWNLOAD_CATCH=ON
-        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+        cmake-version: ${{ matrix.cmake }}
 
-    - name: Setup CMake 3.11
-      uses: jwlawson/actions-setup-cmake@v1.3
-      with:
-        cmake-version: 3.11
+    # These steps use a directory with a space in it intentionally
+    - name: Make build directories
+      run: mkdir "build dir"
 
-    - name: Configure 3.11
-      working-directory: build3.11
+    - name: Configure
+      working-directory: build dir
+      shell: bash
       run: >
         cmake ..
         -DPYBIND11_WERROR=ON
         -DDOWNLOAD_CATCH=ON
         -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
 
-    - name: Setup CMake 3.18
-      uses: jwlawson/actions-setup-cmake@v1.3
-      with:
-        cmake-version: 3.18
+    # Only build and test if this was manually triggered in the GitHub UI
+    - name: Build
+      working-directory: build dir
+      if: github.event_name == 'workflow_dispatch'
+      run: cmake --build . --config Release
 
-    - name: Configure 3.18
-      working-directory: build3.18
-      run: >
-        cmake ..
-        -DPYBIND11_WERROR=ON
-        -DDOWNLOAD_CATCH=ON
-        -DPYTHON_EXECUTABLE=$(python -c "import sys; print(sys.executable)")
+    - name: Test
+      working-directory: build dir
+      if: github.event_name == 'workflow_dispatch'
+      run: cmake --build . --config Release --target check
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index e92f96e6ef..1fb9a4e18a 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -1,19 +1,45 @@
-name: Format
+# # This is a format job. Pre-commit has a first-party GitHub action, so we use
+# # that: https://github.com/pre-commit/action
 
-on:
-  workflow_dispatch:
-  pull_request:
-  push:
-    branches:
-    - master
-    - stable
-    - "v*"
+# name: Format
 
-jobs:
-  pre-commit:
-    name: Format
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - uses: actions/setup-python@v2
-    - uses: pre-commit/action@v2.0.0
+# on:
+#   workflow_dispatch:
+#   pull_request:
+#   push:
+#     branches:
+#       - drake
+
+# jobs:
+#   pre-commit:
+#     name: Format
+#     runs-on: ubuntu-latest
+#     steps:
+#     - uses: actions/checkout@v2
+#     - uses: actions/setup-python@v2
+#     - uses: pre-commit/action@v2.0.0
+#       with:
+#         # Slow hooks are marked with manual - slow is okay here, run them too
+#         extra_args: --hook-stage manual --all-files
+
+#   # TODO(eric.cousineau): This currently breaks current source code.
+#   clang-tidy:
+#     name: Clang-Tidy
+#     runs-on: ubuntu-latest
+#     container: silkeh/clang:10
+#     steps:
+#     - uses: actions/checkout@v2
+
+#     - name: Install requirements
+#       run: apt-get update && apt-get install -y python3-dev python3-pytest
+
+#     - name: Configure
+#       run: >
+#         cmake -S . -B build
+#         -DCMAKE_CXX_CLANG_TIDY="$(which clang-tidy);--warnings-as-errors=*"
+#         -DDOWNLOAD_EIGEN=ON
+#         -DDOWNLOAD_CATCH=ON
+#         -DCMAKE_CXX_STANDARD=17
+
+#     - name: Build
+#       run: cmake --build build -j 2