Use clang GNU frontend for Windows SYCL CI

Author: allnes

.github/actions/setup-sycl-toolchain/action.yml

@@ -130,12 +130,21 @@ runs:
       if (-not $clangClPath) {
         $clangClPath = $clangCl.FullName
       }
-      $clangClShortPath = Get-ShortPath $clangClPath
       $clangBin = Split-Path $clangClPath -Parent
+      $clangPath = Join-Path $clangBin 'clang.exe'
+      $clangCxxPath = Join-Path $clangBin 'clang++.exe'
+      if (-not (Test-Path $clangPath)) {
+        throw "clang.exe was not found next to $clangClPath. Install the Visual Studio LLVM/Clang toolset on the Windows runner."
+      }
+      if (-not (Test-Path $clangCxxPath)) {
+        throw "clang++.exe was not found next to $clangClPath. Install the Visual Studio LLVM/Clang toolset on the Windows runner."
+      }
+      $clangShortPath = Get-ShortPath $clangPath
+      $clangCxxShortPath = Get-ShortPath $clangCxxPath
 
-      "ITLABAI_CC=$clangClShortPath" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
-      "ITLABAI_CXX=$clangClShortPath" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
-      "ITLABAI_ACPP_CPU_CXX=$clangClShortPath" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+      "ITLABAI_CC=$clangShortPath" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+      "ITLABAI_CXX=$clangCxxShortPath" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+      "ITLABAI_ACPP_CPU_CXX=$clangCxxShortPath" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
       "$clangBin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
 
   - name: Configure Windows toolchain environment