HotReload fails when building library tests

[tannergooding]

Repro

1. Clone https://github.com/dotnet/runtime
2. Run .\build.cmd -subset clr+libs+libs.tests -c Release

The build eventually fails with:

'C:\Program' is not recognized as an internal or external command,
  operable program or batch file.
C:\Users\tagoo\.nuget\packages\microsoft.dotnet.hotreload.utils.generator.buildtool\1.0.1-alpha.0.21267.1\build\Microsoft.DotNet.HotReload.Utils.Generator.BuildTool.targets(56,5): error MSB3073: The command "C:\Program Files\dotnet\dotnet.exe C:\Users\tagoo\.nuget\packages\microsoft.dotnet.hotreload.utils.generator.buildtool\1.0.1-alpha.0.21267.1\build\\..\tools\net6.0\Microsoft.DotNet.HotReload.Utils.Generator.BuildTool.dll -msbuild:C:\Users\tagoo\Source\repos\runtime\src\libraries\System.Runtime.Loader\tests\ApplyUpdate\System.Reflection.Metadata.ApplyUpdate.Test.MethodBody1\System.Reflection.Metadata.ApplyUpdate.Test.MethodBody1.csproj -script:C:\Users\tagoo\Source\repos\runtime\src\libraries\System.Runtime.Loader\tests\ApplyUpdate\System.Reflection.Metadata.ApplyUpdate.Test.MethodBody1\deltascript.json -p:Configuration=Release" exited with code 9009. [C:\Users\tagoo\Source\repos\runtime\src\libraries\System.Runtime.Loader\tests\ApplyUpdate\System.Reflection.Metadata.ApplyUpdate.Test.MethodBody1\System.Reflection.Metadata.ApplyUpdate.Test.MethodBody1.csproj]

Expected Behavior

The build should succeed and not fail because dotnet.exe is installed into the default location

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[tannergooding]

This looks to be failing because HotReload runs <Exec Command="$(_HotReloadDeltaGeneratorCommand) $(_HotReloadDeltaGeneratorArgs)" />, where <_HotReloadDeltaGeneratorCommand>$(DotNetTool) $(_HotReloadDeltaGeneratorPath)</_HotReloadDeltaGeneratorCommand>.

I'd expect that DotNetTool should be properly quoted for this to work.

[ViktorHofer]

Was fixed with dotnet/hotreload-utils#27 and the fix will be ingested with #52967. Thanks for reporting though 👍