AppVeyor: Also build with clang from MSYS2

.appveyor.yml

@@ -7,20 +7,34 @@ clone_folder: C:\projects\cquery
 install:
   - git submodule update --init
 
+environment:
+  CLICOLOR_FORCE: 1
+  matrix:
+    - MSYSTEM: MINGW64
+    - MSYSTEM: MSVC
+
 build_script:
-  - cd C:\projects\cquery
-  - python waf configure --msvc_version="msvc 15.0"
-  - python waf build
   - ps: |
-      $dir = "cquery-${env:appveyor_build_version}-win64"
+      If ($Env:MSYSTEM -Eq "MSVC") {
-      cd C:\projects\cquery
+        $dir = "cquery-${env:appveyor_build_version}-win64"
-      mkdir "${dir}\build\release\bin" -ea 0
+        cd C:\projects\cquery
-      mkdir "${dir}\build\release\lib\LLVM-5.0.1-win64\lib\clang\5.0.1\"
+        python waf configure --msvc_version="msvc 15.0"
-      copy "build\release\bin\*" "${dir}\build\release\bin"
+        python waf build
-      copy -recurse "build\LLVM-5.0.1-win64\lib\clang\5.0.1\include" "${dir}\build\release\lib\LLVM-5.0.1-win64\lib\clang\5.0.1\"
+        mkdir "${dir}\build\release\bin" -ea 0
-      7z a -tzip "C:\projects\cquery\${dir}.zip" "${dir}"
+        mkdir "${dir}\build\release\lib\LLVM-5.0.1-win64\lib\clang\5.0.1\"
+        copy "build\release\bin\*" "${dir}\build\release\bin"
+        copy -recurse "build\LLVM-5.0.1-win64\lib\clang\5.0.1\include" "${dir}\build\release\lib\LLVM-5.0.1-win64\lib\clang\5.0.1\"
+        7z a -tzip "C:\projects\cquery\${dir}.zip" "${dir}"
+      } Else {
+        C:\msys64\usr\bin\bash -lc @'
+        pacman -S --needed --noconfirm mingw-w64-x86_64-clang python
+        cd /c/projects/cquery
+        CXXFLAGS=-Wall /usr/bin/python waf configure build --use-system-clang 2>&1
+      '@
+      }
+  - set PATH=%PATH%;C:\msys64\%MSYSTEM%\bin
   - build\release\bin\cquery --ci --log-all-to-stderr --test-unit
-  - build\release\bin\cquery --ci --log-all-to-stderr --test-index
+  - IF "%MSYSTEM%"=="MSVC" build\release\bin\cquery --ci --log-all-to-stderr --test-index
 
 artifacts:
   - path: 'cquery-*.zip'