workflows: setup CI for Windows (#1158)

This setups a GitHub Actions based CI for Swift APIs.

Author: compnerd

.github/workflows/windows.yml

@@ -0,0 +1,47 @@
+name: windows
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: windows-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: seanmiddleditch/gha-setup-vsdevenv@master
+
+      - name: Install swift-DEVELOPMENT-SNAPSHOT-2020-12-14-a
+        run: |
+          Install-Binary -Url "https://swift.org/builds/development/windows10/swift-DEVELOPMENT-SNAPSHOT-2020-12-14-a/swift-DEVELOPMENT-SNAPSHOT-2020-12-14-a-windows10.exe" -Name "installer.exe" -ArgumentList ("-q")
+      - name: Set Environment Variables
+        run: |
+          echo "SDKROOT=C:\Library\Developer\Platforms\Windows.platform\Developer\SDKs\Windows.sdk" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+          echo "DEVELOPER_DIR=C:\Library\Developer" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+      - name: Adjust Paths
+        run: |
+          echo "C:\Library\Swift-development\bin;C:\Library\icu-67\usr\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          echo "C:\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+      - name: Install Supporting Files
+        run: |
+          Copy-Item "$env:SDKROOT\usr\share\ucrt.modulemap" -destination "$env:UniversalCRTSdkDir\Include\$env:UCRTVersion\ucrt\module.modulemap"
+          Copy-Item "$env:SDKROOT\usr\share\visualc.modulemap" -destination "$env:VCToolsInstallDir\include\module.modulemap"
+          Copy-Item "$env:SDKROOT\usr\share\visualc.apinotes" -destination "$env:VCToolsInstallDir\include\visualc.apinotes"
+          Copy-Item "$env:SDKROOT\usr\share\winsdk.modulemap" -destination "$env:UniversalCRTSdkDir\Include\$env:UCRTVersion\um\module.modulemap"
+
+      - name: Install X10
+        run: |
+          Invoke-WebRequest -UseBasicParsing -Uri https://artprodeus21.artifacts.visualstudio.com/A8fd008a0-56bc-482c-ba46-67f9425510be/3133d6ab-80a8-4996-ac4f-03df25cd3224/_apis/artifact/cGlwZWxpbmVhcnRpZmFjdDovL2NvbXBuZXJkL3Byb2plY3RJZC8zMTMzZDZhYi04MGE4LTQ5OTYtYWM0Zi0wM2RmMjVjZDMyMjQvYnVpbGRJZC80Mzc2OC9hcnRpZmFjdE5hbWUvdGVuc29yZmxvdy13aW5kb3dzLXg2NA2/content?format=zip -OutFile tensorflow-windows-x64.zip
+          Expand-Archive -Force -Path tensorflow-windows-x64.zip -DestinationPath C:\Library\
+          Move-Item C:\Library\tensorflow-windows-x64\Library\tensorflow-2.3.0 C:\Library
+          echo "C:\Library\tensorflow-2.3.0\usr\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+
+      - name: Build
+        run: |
+          # We build twice as the first one currently fails for some unexplained
+          # reason.  This should only build once.
+          swift build -v -Xswiftc -DTENSORFLOW_USE_STANDARD_TOOLCHAIN -Xcc -IC:\Library\tensorflow-2.3.0\usr\include -Xlinker -LC:\Library\tensorflow-2.3.0\usr\lib
+          swift build -v -Xswiftc -DTENSORFLOW_USE_STANDARD_TOOLCHAIN -Xcc -IC:\Library\tensorflow-2.3.0\usr\include -Xlinker -LC:\Library\tensorflow-2.3.0\usr\lib
+    # - name: Run tests
+    #   run: swift test -v