Refactor and expand the CI workflows

- For each OS, builds of the default compiler plus the
  latest-supported compilers are run. When multiple operating systems
  are supported (such as Ubuntu 16.04 and latest), a build on
  the oldest OS using its default compiler is also performed.

- Debug builds are used because they often are more thorough at
  detecting coding issues (debug warning counts are higher).

- Runtime dynamic sanitizers are added and serialized per-compiler.
  Their build and runtime log-files are xz-compressed, and then
  GitHub's asset upload Zips the log directory.

- Each workflow now holds the maximum allowed compiler warnings
  per-build, so we can have tighter control of when new warnings
  are introduced (that would otherwise pass if still below the
  maximum)

- Use of github's new 'cache' feature has been leveraged to restore
  the brew, macports, and msys2 environments to eliminate the
  lenghthy setup times for those environments.  If a new cache
  is needed, then we simply increment the cache `key:` value and
  the next CI run will archive new caches. (Note that GitHub has a
  400MB limit on cache size however they have already said they
  are raising it - so we might be able to cache out longest running
  job which is MSYS+Clang)

- Where it makes sense, multi-line workflow statements have been
  broken out into .github/scripts as files to make the workflow YAML
  leaner and more readable, while giving us a richer environment in
  the scripts.

.github/workflows/analysis.yml

@@ -1,4 +1,4 @@
-name: Static code analysis
+name: Code analysis
 on: push
 jobs:
 
@@ -9,7 +9,7 @@ jobs:
       - uses: actions/checkout@v1
       - run:  sudo apt-get update
       - name: Install pylint
-        run: |
+        run:  |
           sudo apt-get install python3-setuptools
           sudo pip3 install pylint beautifulsoup4 html5lib
       - name: Run pylint
@@ -23,15 +23,15 @@ jobs:
     needs: run_linters
     steps:
       - uses: actions/checkout@v1
-      - name: Log environment
-        run:  ./scripts/log-env.sh
       - run:  sudo apt-get update
-      - name: Install dependencies
-        run:  sudo apt-get install python3-setuptools $(./scripts/list-build-dependencies.sh -p apt)
+      - name: Install C++ compiler and libraries
+        run:  sudo apt-get install python3-setuptools $(./scripts/list-build-dependencies.sh -m apt -c gcc)
       - name: Install scan-build (Python version)
         run:  sudo pip3 install scan-build beautifulsoup4 html5lib
+      - name: Log environment
+        run:  ./scripts/log-env.sh
       - name: Build
-        run: |
+        run:  |
           # build steps
           set -x
           g++ --version
@@ -40,7 +40,8 @@ jobs:
           intercept-build make -j "$(nproc)"
       - name: Analyze
         run:  analyze-build -v -o report --html-title="dosbox-staging (${GITHUB_SHA:0:8})"
-      - uses: actions/upload-artifact@master
+      - name: Upload report
+        uses: actions/upload-artifact@master
         with:
           name: report
           path: report
@@ -49,4 +50,40 @@ jobs:
           # summary
           echo "Full report is included in build Artifacts"
           echo
-          ./scripts/count-bugs.py report/*/index.html
+          ./scripts/count-bugs.py -m 92 report/*/index.html
+
+  dynamic_matrix:
+    name: ${{ matrix.compiler }} dynamic sanitizers
+    needs: run_linters
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        compiler: [Clang, GCC]
+    steps:
+      - uses: actions/checkout@v1
+      - run:  sudo apt-get update
+      - name: Install C++ compiler and libraries
+        env:
+          VERSION_GCC: 9
+          VERSION_Clang: 8
+        run:  >
+          sudo apt-get install -y $(./scripts/list-build-dependencies.sh -m apt
+          -c ${{ matrix.compiler }} -v $VERSION_${{ matrix.compiler }})
+      - name: Log environment
+        run:  ./scripts/log-env.sh
+      - name: Build and run sanitizers
+        env:
+          VERSION_GCC: 9
+          VERSION_Clang: 8
+          SANITIZERS_GCC: UASAN USAN TSAN
+          SANITIZERS_Clang: USAN MSAN
+        run: |
+          ./.github/scripts/build-and-run-sanitizers.sh \
+          ${{ matrix.compiler }} \
+          $VERSION_${{ matrix.compiler }} \
+          $SANITIZERS_${{ matrix.compiler }}
+      - name: Upload logs
+        uses: actions/upload-artifact@master
+        with:
+          name: ${{ matrix.compiler }}-logs
+          path: ${{ matrix.compiler }}-logs

.github/workflows/dormant/linux.yml

@@ -0,0 +1,46 @@
+name: Linux builds
+on: push
+env:
+  MAX_WARNINGS_GCC_6_Debug:     378
+  MAX_WARNINGS_GCC_6_Release:   661
+  MAX_WARNINGS_GCC_7_Debug:     380
+  MAX_WARNINGS_GCC_7_Release:   329
+  MAX_WARNINGS_GCC_8_Debug:     380
+  MAX_WARNINGS_GCC_8_Release:   330
+  MAX_WARNINGS_GCC_9_Debug:     403
+  MAX_WARNINGS_GCC_9_Release:   358
+  MAX_WARNINGS_Clang_7_Debug:   193
+  MAX_WARNINGS_Clang_7_Release: 193
+  MAX_WARNINGS_Clang_8_Debug:   193
+  MAX_WARNINGS_Clang_8_Release: 193
+
+jobs:
+
+  build_matrix:
+    name: ${{ matrix.compiler }}-${{ matrix.compiler_version }}
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        compiler: [Clang, GCC]
+        compiler_version: [6, 7, 8, 9]
+        # build_type: [Debug, Release]
+        exclude:
+          - compiler: Clang
+            compiler_version: 6
+          - compiler: Clang
+            compiler_version: 9
+    steps:
+      - uses: actions/checkout@v1
+      - run:  sudo apt-get update
+      - name: Install C++ compiler and libraries
+        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -m apt -c ${{ matrix.compiler }} -v ${{ matrix.compiler_version }})
+      - name: Log environment
+        run:  ./scripts/log-env.sh
+      - name: Release build
+        run:  ./scripts/build.sh --compiler ${{ matrix.compiler }} --version-postfix ${{ matrix.compiler_version }} --build-type Release
+      - name: Release warnings
+        run:  ./scripts/count-warnings.py -m $MAX_WARNINGS_${{ matrix.compiler }}_${{ matrix.compiler_version }}_Release build.log
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler ${{ matrix.compiler }} --version-postfix ${{ matrix.compiler_version }} --build-type Debug
+      - name: Debug warnings
+        run:  ./scripts/count-warnings.py -m $MAX_WARNINGS_${{ matrix.compiler }}_${{ matrix.compiler_version }}_Debug build.log

.github/workflows/dormant/macos-gcc.yml

@@ -0,0 +1,76 @@
+name: macOS builds
+on: push
+env:
+  MAX_WARNINGS_GCC_9_Debug:   361
+  MAX_WARNINGS_GCC_9_Release: 321
+  PATH: "${GITHUB_WORKSPACE}/.github/scripts:${PATH}"
+
+jobs:
+  build_macos_gcc_brew:
+    name: GCC-${{ matrix.compiler_version }} (HomeBrew)
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        compiler_version: [9]
+    steps:
+      - uses: actions/checkout@v1
+      - name: Prepare tar-zstd for the cache
+        run:  |
+          brew install zstd gnu-tar
+          cp .github/scripts/tar /usr/local/bin/tar
+      - uses: actions/cache@v1
+        id:   cache-brew
+        with: {path: /usr/local, key: brew-gcc-2019-v18}
+      - name: Install C++ compiler and libraries
+        if:   steps.cache-brew.outputs.cache-hit != 'true'
+        run:  |
+          ./.github/scripts/reset-brew.sh
+          brew install $(./scripts/list-build-dependencies.sh -m brew -c gcc -v ${{ matrix.compiler_version }})
+          sudo ./.github/scripts/shrink-brew.sh
+      - name: Log environment
+        run:  ./scripts/log-env.sh
+      - name: Release build
+        run: ./scripts/build.sh --compiler gcc --version-postfix ${CC_PREFIX}${{ matrix.compiler_version }} --build-type Release
+      - name: Release warnings
+        run:  python3 ./scripts/count-warnings.py -m $MAX_WARNINGS_GCC_${{ matrix.compiler_version }}_Release build.log
+      - name: Debug build
+        run: ./scripts/build.sh --compiler gcc --version-postfix ${CC_PREFIX}${{ matrix.compiler_version }} --build-type Debug
+      - name: Debug warnings
+        run:  python3 ./scripts/count-warnings.py -m $MAX_WARNINGS_GCC_${{ matrix.compiler_version }}_Debug build.log
+
+  build_macos_gcc_macports:
+    name: GCC-${{ matrix.compiler_version }} (MacPorts)
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        compiler_version: [9]
+    steps:
+      - uses: actions/checkout@v1
+      - name: Prepare tar-zstd and /opt/local for the cache
+        run:  |
+          brew install zstd gnu-tar
+          cp .github/scripts/tar /usr/local/bin/tar
+          sudo ./.github/scripts/prepare-for-macports-cachehit.sh
+      - uses: actions/cache@v1
+        id:   cache-macports
+        with: {path: /opt/local, key: macports-gcc-2019-v14}
+      - name: Install MacPorts, C++ compiler, and libraries
+        if:   steps.cache-macports.outputs.cache-hit != 'true'
+        run:  |
+          ./.github/scripts/download-and-build-macports.sh
+          sudo ./.github/scripts/install-and-update-macports.sh
+          sudo /opt/local/bin/port -q -f install $(./scripts/list-build-dependencies.sh -m macports -c gcc -v ${{ matrix.compiler_version }})
+      - name: Log environment
+        run:  ./scripts/log-env.sh
+      - name: Release build
+        run:  ./scripts/build.sh --compiler gcc --version-postfix mp-${{ matrix.compiler_version }} --build-type Release --bin-path /opt/local/bin
+      - name: Release warnings
+        run:  python3 ./scripts/count-warnings.py $MAX_WARNINGS_GCC_${{ matrix.compiler_version }}_Release build.log
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler gcc --version-postfix mp-${{ matrix.compiler_version }} --build-type Debug --bin-path /opt/local/bin
+      - name: Debug warnings
+        run:  python3 ./scripts/count-warnings.py $MAX_WARNINGS_GCC_${{ matrix.compiler_version }}_Debug build.log
+
+      - name: Shrink MacPorts for cache
+        if:   steps.cache-macports.outputs.cache-hit != 'true'
+        run:  sudo ./.github/scripts/shrink-macports.sh

.github/workflows/dormant/windows.yml

@@ -0,0 +1,84 @@
+name: Windows builds
+on: push
+env:
+  MAX_WARNINGS_GCC_32bit_Debug:     320
+  MAX_WARNINGS_GCC_32bit_Release:   284
+  MAX_WARNINGS_GCC_64bit_Debug:     405
+  MAX_WARNINGS_GCC_64bit_Release:   369
+  MAX_WARNINGS_Clang_32bit_Debug:   129
+  MAX_WARNINGS_Clang_32bit_Release: 129
+  MAX_WARNINGS_Clang_64bit_Debug:   190
+  MAX_WARNINGS_Clang_64bit_Release: 190
+
+jobs:
+
+  build_msvc_matrix:
+    name: MSVC 32-bit
+    runs-on: windows-latest
+    steps:
+      - uses:  actions/checkout@v1
+      - name:  Install packages
+        shell: pwsh
+        run: |
+          vcpkg install libpng sdl1 sdl1-net opusfile
+          vcpkg integrate install
+      - name:  Log environment
+        shell: pwsh
+        run:   .\scripts\log-env.ps1
+      - name:  Release build
+        shell: pwsh
+        env:
+          PATH: '${env:PATH};C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Current\Bin\amd64'
+        run: |
+          cd visualc_net
+          MSBuild -m dosbox.sln -p:Configuration=Release
+      - name:  Debug build
+        shell: pwsh
+        env:
+          PATH: '${env:PATH};C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Current\Bin\amd64'
+        run: |
+          cd visualc_net
+          MSBuild -m dosbox.sln -p:Configuration=Debug
+
+
+  build_msys2_matrix:
+    name: ${{ matrix.compiler }} ${{ matrix.bits }}-bit
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        compiler: [GCC, Clang]
+        bits:     [32, 64]
+    env:
+      CHERE_INVOKING: yes
+    steps:
+      - uses:  actions/checkout@v1
+      - uses:  actions/cache@v1
+        id:    cache-msys2
+        if:    matrix.compiler == 'GCC'
+        with:
+          path: 'C:/tools/msys64'
+          key: msys2-${{ matrix.compiler }}-${{ matrix.bits }}-2019-v11}
+      - name:  Install MSYS2
+        if:    steps.cache-msys2.outputs.cache-hit != 'true'
+        run:   choco install msys2 --no-progress
+      - name:  Install C++ compiler and libraries
+        if:    steps.cache-msys2.outputs.cache-hit != 'true'
+        shell: python scripts\msys-bash.py {0}
+        run:   ./scripts/list-build-dependencies.sh -m msys2 -c ${{ matrix.compiler }} -b ${{ matrix.bits }} | xargs pacman -S --noconfirm
+      - name:  Shrink MSYS2 for cache
+        if:    matrix.compiler == 'GCC' && steps.cache-msys2.outputs.cache-hit != 'true'
+        shell: python scripts\msys-bash.py {0}
+        run:   ./.github/scripts/shrink-msys2.sh
+      - name:  Log environment
+        shell: python scripts\msys-bash.py {0}
+        run:  ./scripts/log-env.sh
+      - name:  Release build
+        shell: python scripts\msys-bash.py {0}
+        run:   ./scripts/build.sh --compiler ${{ matrix.compiler }} --build-type Release --bin-path /mingw${{ matrix.bits }}/bin
+      - name:  Release warnings
+        run:   '.\scripts\count-warnings.py -m $env:MAX_WARNINGS_${{ matrix.compiler }}_${{ matrix.bits }}bit_Release build.log'
+      - name:  Debug build
+        shell: python scripts\msys-bash.py {0}
+        run:   ./scripts/build.sh --compiler ${{ matrix.compiler }} --build-type Debug --bin-path /mingw${{ matrix.bits }}/bin
+      - name:  Debug warnings
+        run:   '.\scripts\count-warnings.py -m $env:MAX_WARNINGS_${{ matrix.compiler }}_${{ matrix.bits }}bit_Debug build.log'

.github/workflows/linux.yml

@@ -1,51 +1,80 @@
 name: Linux builds
 on: push
+env:
+  MAX_WARNINGS_GCC_5_Debug:     373
+  MAX_WARNINGS_GCC_5_Release:    -1
+  MAX_WARNINGS_GCC_6_Debug:     378
+  MAX_WARNINGS_GCC_6_Release:   661
+  MAX_WARNINGS_GCC_7_Debug:     380
+  MAX_WARNINGS_GCC_7_Release:   329
+  MAX_WARNINGS_GCC_8_Debug:     380
+  MAX_WARNINGS_GCC_8_Release:   330
+  MAX_WARNINGS_GCC_9_Debug:     403
+  MAX_WARNINGS_GCC_9_Release:   358
+  MAX_WARNINGS_Clang_7_Debug:   193
+  MAX_WARNINGS_Clang_7_Release: 193
+  MAX_WARNINGS_Clang_8_Debug:   193
+  MAX_WARNINGS_Clang_8_Release: 193
+
 jobs:
 
-  build_ubuntu_clang_8:
-    name: Clang 8 (ubuntu-18.04)
-    runs-on: ubuntu-18.04
+  gcc-5_1604:
+    name: GCC-5 (Ubuntu 16.04)
+    runs-on: ubuntu-16.04
     steps:
       - uses: actions/checkout@v1
+      - run:  sudo apt-get update
+      - name: Install C++ compiler and libraries
+        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -m apt -c gcc)
       - name: Log environment
         run:  ./scripts/log-env.sh
-      - run:  sudo apt-get update
-      - name: Install dependencies
-        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -p apt --compiler clang --compiler-version 8)
-      - name: Build
-        run:  ./scripts/build.sh --compiler clang --compiler-version 8 --lto
-      - name: Summarize warnings
-        run:  ./scripts/count-warnings.py build.log
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler gcc --build-type Debug
+      - name: Debug warnings
+        run:  ./scripts/count-warnings.py -m $MAX_WARNINGS_GCC_5_Debug build.log
 
-  build_ubuntu_matrix_gcc:
-    name: GCC
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: [ubuntu-18.04, ubuntu-16.04]
+  gcc-7_latest:
+    name: GCC-7 (Ubuntu-latest)
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v1
+      - run:  sudo apt-get update
+      - name: Install C++ compiler and libraries
+        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -m apt -c gcc)
       - name: Log environment
         run:  ./scripts/log-env.sh
-      - run:  sudo apt-get update
-      - name: Install dependencies
-        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -p apt)
-      - name: Build
-        run:  ./scripts/build.sh
-      - name: Summarize warnings
-        run:  ./scripts/count-warnings.py build.log
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler gcc --build-type Debug
+      - name: Debug warnings
+        run:  ./scripts/count-warnings.py -m $MAX_WARNINGS_GCC_7_Debug build.log
 
-  build_ubuntu_gcc9:
-    name: GCC 9 (ubuntu-18.04)
-    runs-on: ubuntu-18.04
+  gcc-9_latest:
+    name: GCC-9 (Ubuntu-latest)
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v1
+      - run:  sudo apt-get update
+      - name: Install C++ compiler and libraries
+        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -m apt -c gcc -v 9)
       - name: Log environment
         run:  ./scripts/log-env.sh
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler gcc --version-postfix 9 --build-type Debug
+      - name: Debug warnings
+        run:  ./scripts/count-warnings.py -m $MAX_WARNINGS_GCC_9_Debug build.log
+
+  clang-8_latest:
+    name: Clang-8 (Ubuntu-latest)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
       - run:  sudo apt-get update
-      - name: Install dependencies
-        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -p apt --compiler-version 9)
-      - name: Build
-        run:  ./scripts/build.sh --compiler-version 9 --lto
-      - name: Summarize warnings
-        run:  ./scripts/count-warnings.py build.log
+      - name: Install C++ compiler and libraries
+        run:  sudo apt-get install -y $(./scripts/list-build-dependencies.sh -m apt -c clang -v 8)
+      - name: Log environment
+        run:  ./scripts/log-env.sh
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler clang --version-postfix 8 --build-type Debug
+      - name: Debug warnings
+        run:  ./scripts/count-warnings.py -m $MAX_WARNINGS_Clang_8_Debug build.log
+

.github/workflows/macos.yml

@@ -1,60 +1,51 @@
 name: macOS builds
 on: push
-jobs:
+env:
+  MAX_WARNINGS_Clang_Debug:   245
+  MAX_WARNINGS_Clang_Release: 245
+  MAX_WARNINGS_GCC_9_Debug:   361
+  MAX_WARNINGS_GCC_9_Release: 321
 
-  build_macos_xcode_clang:
+jobs:
+  clang_xcode:
     name: Clang (Xcode)
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@v1
+      - name: Install C++ compiler and libraries
+        run:  brew install $(./scripts/list-build-dependencies.sh -m brew -c clang)
       - name: Log environment
         run:  ./scripts/log-env.sh
-      - name: Install dependencies
-        run:  brew install $(./scripts/list-build-dependencies.sh -p brew --compiler clang)
-      - name: Build
-        run:  ./scripts/build.sh --compiler clang --lto
-      - name: Summarize warnings
-        run:  python3 ./scripts/count-warnings.py build.log
+      - name: Debug build
+        run:  ./scripts/build.sh --compiler clang --build-type Debug
+      - name: Debug warnings
+        run:  python3 ./scripts/count-warnings.py -m $MAX_WARNINGS_Clang_Debug build.log
 
-
-#  build_macos_brew_gcc9:
-#    name: GCC 9 (Homebrew)
-#    runs-on: macos-latest
-#    steps:
-#      - uses: actions/checkout@v1
-#      - name: Log environment
-#        run:  ./scripts/log-env.sh
-#      - name: Install dependencies
-#        run:  brew install $(./scripts/list-build-dependencies.sh -p brew --compiler-version 9)
-#      - name: Build
-#        run:  echo ./scripts/build.sh --compiler-version 9 --lto
-#      - name: Summarize warnings
-#        run:  echo python3 ./scripts/count-warnings.py build.log
-
-
-#  build_macos_macports_gcc9:
-#    name: GCC 9 (MacPorts)
-#    runs-on: macos-latest
-#    steps:
-#      - uses: actions/checkout@v1
-#      - name: Install MacPorts
-#        run: |
-#          # xcode-select --install || true
-#          # sudo xcodebuild -license || true
-#          git clone --quiet --depth=1 https://github.com/macports/macports-base.git
-#          cd macports-base
-#          ./configure
-#          make -j"$(sysctl -n hw.physicalcpu || echo 4)"
-#          sudo make install
-#
-#      - name: Install dependencies
-#        run: |
-#          PATH="/opt/local/sbin:/opt/local/bin:${PATH}"
-#          sudo port -q selfupdate || true
-#          sudo port -q install $(./scripts/list-build-dependencies.sh -p macports --compiler-version 9)
-#
-#      - name: Build
-#        run:  echo ./scripts/build.sh --compiler-version mp-9 --bin-path /opt/local/bin
-#      - name: Summarize warnings
-#        run:  echo python3 ./scripts/count-warnings.py build.log
+  gcc_brew:
+    name: GCC-${{ matrix.compiler_version }} (HomeBrew)
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        compiler_version: [9]
+    steps:
+      - uses: actions/checkout@v1
+      - name: Prepare tar-zstd for the cache
+        run:  |
+          brew install zstd gnu-tar
+          cp .github/scripts/tar /usr/local/bin/tar
+      - uses: actions/cache@v1
+        id:   cache-brew
+        with: {path: /usr/local, key: brew-gcc-2019-v18}
+      - name: Install C++ compiler and libraries
+        if:   steps.cache-brew.outputs.cache-hit != 'true'
+        run:  |
+          ./.github/scripts/reset-brew.sh
+          brew install $(./scripts/list-build-dependencies.sh -m brew -c gcc -v ${{ matrix.compiler_version }})
+          sudo ./.github/scripts/shrink-brew.sh
+      - name: Log environment
+        run:  ./scripts/log-env.sh
+      - name: Debug build
+        run: ./scripts/build.sh --compiler gcc --version-postfix ${CC_PREFIX}${{ matrix.compiler_version }} --build-type Debug
+      - name: Debug warnings
+        run:  python3 ./scripts/count-warnings.py -m $MAX_WARNINGS_GCC_${{ matrix.compiler_version }}_Debug build.log
 

.github/workflows/windows.yml

@@ -1,132 +1,75 @@
 name: Windows builds
 on: push
+env:
+  MAX_WARNINGS_GCC_32bit_Debug:     320
+  MAX_WARNINGS_GCC_32bit_Release:   284
+  MAX_WARNINGS_GCC_64bit_Debug:     405
+  MAX_WARNINGS_GCC_64bit_Release:   369
+  MAX_WARNINGS_Clang_32bit_Debug:   129
+  MAX_WARNINGS_Clang_32bit_Release: 129
+  MAX_WARNINGS_Clang_64bit_Debug:   190
+  MAX_WARNINGS_Clang_64bit_Release: 190
+
 jobs:
 
-  build_msys2_clang_32:
-    name: Clang 8 i686 (MSYS2)
+  build_msvc_matrix:
+    name: MSVC 32-bit (${{ matrix.type }})
     runs-on: windows-latest
-    env:
-      CHERE_INVOKING: yes
+    strategy:
+      matrix:
+        type: [Release, Debug]
     steps:
       - uses:  actions/checkout@v1
-      - name:  Install msys2 environment
-        run:   choco install msys2 --no-progress
-      - name:  Log environment
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/log-env.sh
-      - name:  Install dependencies
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/list-build-dependencies.sh -p msys2 --compiler clang --bit-depth 32 | xargs pacman -S --noconfirm
-      - name:  Build
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/build.sh --compiler clang --bit-depth 32 --bin-path /mingw32/bin
-      - name:  Summarize warnings
-        run:   .\scripts\count-warnings.py build.log
-
-  build_msys2_clang_64:
-    name: Clang 8 x86_64 (MSYS2)
-    runs-on: windows-latest
-    env:
-      CHERE_INVOKING: yes
-    steps:
-      - uses:  actions/checkout@v1
-      - name:  Install msys2 environment
-        run:   choco install msys2 --no-progress
-      - name:  Log environment
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/log-env.sh
-      - name:  Install dependencies
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/list-build-dependencies.sh -p msys2 --compiler clang | xargs pacman -S --noconfirm
-      - name:  Build
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/build.sh --compiler clang --bin-path /mingw64/bin
-      - name:  Summarize warnings
-        run:   .\scripts\count-warnings.py build.log
-
-  build_msys2_gcc_32:
-    name: GCC 9 i686 (MSYS2)
-    runs-on: windows-latest
-    env:
-      CHERE_INVOKING: yes
-    steps:
-      - uses:  actions/checkout@v1
-      - name:  Install msys2 environment
-        run:   choco install msys2 --no-progress
-      - name:  Log environment
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/log-env.sh
-      - name:  Install dependencies
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/list-build-dependencies.sh -p msys2 --bit-depth 32 | xargs pacman -S --noconfirm
-      - name:  Build
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/build.sh --bit-depth 32 --bin-path /mingw32/bin
-      - name:  Summarize warnings
-        run:   .\scripts\count-warnings.py build.log
-
-
-  build_msys2_gcc_64:
-    name: GCC 9 x86_64 (MSYS2)
-    runs-on: windows-latest
-    env:
-      CHERE_INVOKING: yes
-    steps:
-      - uses:  actions/checkout@v1
-      - name:  Install msys2 environment
-        run:   choco install msys2 --no-progress
-      - name:  Log environment
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/log-env.sh
-      - name:  Install dependencies
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/list-build-dependencies.sh -p msys2 | xargs pacman -S --noconfirm
-      - name:  Build
-        shell: python scripts\msys-bash.py {0}
-        run:   ./scripts/build.sh --bin-path /mingw64/bin
-      - name:  Summarize warnings
-        run:   .\scripts\count-warnings.py build.log
-
-  build_msvc_debug:
-    name: MSVC Debug x86
-    runs-on: windows-latest
-    steps:
-      - uses:  actions/checkout@v1
-      - name:  Log environment
-        shell: pwsh
-        run:   .\scripts\log-env.ps1
       - name:  Install packages
         shell: pwsh
         run: |
           vcpkg install libpng sdl1 sdl1-net opusfile
           vcpkg integrate install
-      - name:  Build
-        shell: pwsh
-        env:
-          PATH: '${env:PATH};C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Current\Bin\amd64'
-        run: |
-          # build steps
-          cd visualc_net
-          MSBuild -m dosbox.sln -p:Configuration=Debug
-
-  build_msvc_release:
-    name: MSVC Release x86
-    runs-on: windows-latest
-    steps:
-      - uses:  actions/checkout@v1
       - name:  Log environment
         shell: pwsh
         run:   .\scripts\log-env.ps1
-      - name:  Install packages
-        shell: pwsh
-        run: |
-          vcpkg install libpng sdl1 sdl1-net opusfile
-          vcpkg integrate install
-      - name:  Build
+      - name:  ${{ matrix.type }} build
         shell: pwsh
         env:
           PATH: '${env:PATH};C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Current\Bin\amd64'
         run: |
-          # build steps
           cd visualc_net
-          MSBuild -m dosbox.sln -p:Configuration=Release
+          MSBuild -m dosbox.sln -p:Configuration=${{ matrix.type }}
+
+
+  build_msys2_matrix:
+    name: ${{ matrix.compiler }} ${{ matrix.bits }}-bit
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        compiler: [GCC, Clang]
+        bits:     [32, 64]
+    env:
+      CHERE_INVOKING: yes
+    steps:
+      - uses:  actions/checkout@v1
+      - uses:  actions/cache@v1
+        id:    cache-msys2
+        if:    matrix.compiler == 'GCC'
+        with:
+          path: 'C:/tools/msys64'
+          key: msys2-${{ matrix.compiler }}-${{ matrix.bits }}-2019-v11}
+      - name:  Install MSYS2
+        if:    steps.cache-msys2.outputs.cache-hit != 'true'
+        run:   choco install msys2 --no-progress
+      - name:  Install C++ compiler and libraries
+        if:    steps.cache-msys2.outputs.cache-hit != 'true'
+        shell: python scripts\msys-bash.py {0}
+        run:   ./scripts/list-build-dependencies.sh -m msys2 -c ${{ matrix.compiler }} -b ${{ matrix.bits }} | xargs pacman -S --noconfirm
+      - name:  Shrink MSYS2 for cache
+        if:    matrix.compiler == 'GCC' && steps.cache-msys2.outputs.cache-hit != 'true'
+        shell: python scripts\msys-bash.py {0}
+        run:   ./.github/scripts/shrink-msys2.sh
+      - name:  Log environment
+        shell: python scripts\msys-bash.py {0}
+        run:  ./scripts/log-env.sh
+      - name:  Debug Build
+        shell: python scripts\msys-bash.py {0}
+        run:   ./scripts/build.sh --compiler ${{ matrix.compiler }} --build-type Debug --bin-path /mingw${{ matrix.bits }}/bin
+      - name:  Debug Warnings
+        run:   '.\scripts\count-warnings.py -m $env:MAX_WARNINGS_${{ matrix.compiler }}_${{ matrix.bits }}bit_Debug build.log'