Explicitly reference Roslyn compiler toolset version that will ship i…

…n preview 7

- see also dotnet/efcore#16370 and dotnet/efcore#16385 discussions
- grab latest from the '.NET Core 3 Release' channel

Directory.Build.targets

@@ -37,6 +37,14 @@
     <HasReferenceAssembly Condition="'$(HasReferenceAssembly)' == ''">false</HasReferenceAssembly>
   </PropertyGroup>
 
+  <ItemGroup>
+    <!-- Track compiler separately from Arcade.-->
+    <PackageReference Include="Microsoft.Net.Compilers.Toolset"
+        Version="$(MicrosoftNetCompilersToolsetVersion)"
+        PrivateAssets="all"
+        IsImplicitlyDefined="true" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(Language)' == 'C#' AND '$(IsReferenceAssemblyProject)' == 'true'">
     <Compile Include="$(SharedSourceRoot)ReferenceAssemblyInfo.cs" LinkBase="Properties" />
   </ItemGroup>

eng/Version.Details.xml

@@ -62,7 +62,7 @@
       <Uri>https://github.com/dotnet/core-setup</Uri>
       <Sha>df2b1489de5d4b8211c5e132d299a83523ce742a</Sha>
     </Dependency>
-    <!-- 
+    <!--
          Win-x64 is used here because we have picked an arbitrary runtime identifier to flow the version of the latest NETCore.App runtime.
          All Runtime.$rid packages should have the same version.
     -->
@@ -92,5 +92,9 @@
       <Uri>https://github.com/dotnet/corefx</Uri>
       <Sha>9e3278936912fc413891926f3789689cb05fd3c3</Sha>
     </Dependency>
+    <Dependency Name="Microsoft.Net.Compilers.Toolset" Version="3.3.0-beta1-19351-01">
+      <Uri>https://github.com/dotnet/roslyn</Uri>
+      <Sha>c91adff42c488aef2c2c532a7b053fb55e0c16ea</Sha>
+    </Dependency>
   </ToolsetDependencies>
 </Dependencies>

eng/Versions.props

@@ -25,8 +25,6 @@
     <PreviousExtensionsReleaseVersion Condition=" '$(PatchVersion)' != '0' ">$(MajorVersion).$(MinorVersion).$([MSBuild]::Subtract($(PatchVersion), 1))</PreviousExtensionsReleaseVersion>
   </PropertyGroup>
   <PropertyGroup Label="Arcade settings">
-    <!-- Opt-in to using the version of the Roslyn compiler bundled with Arcade. -->
-    <UsingToolMicrosoftNetCompilers>true</UsingToolMicrosoftNetCompilers>
     <!-- Disable Arcade's Xliff tools -->
     <UsingToolXliff>false</UsingToolXliff>
     <!-- Using .NET framework assemblies from a package. -->
@@ -64,6 +62,8 @@
     <MicrosoftNETCorePlatformsPackageVersion>3.0.0-preview7.19329.3</MicrosoftNETCorePlatformsPackageVersion>
     <!-- Packages from dotnet/arcade -->
     <MicrosoftDotNetGenAPIPackageVersion>1.0.0-beta.19330.1</MicrosoftDotNetGenAPIPackageVersion>
+    <!-- Packages from dotnet/roslyn -->
+    <MicrosoftNetCompilersToolsetVersion>3.3.0-beta1-19351-01</MicrosoftNetCompilersToolsetVersion>
   </PropertyGroup>
   <PropertyGroup Label="Dependency version settings">
     <!--
@@ -102,5 +102,9 @@
       $(RestoreSources);
       https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json;
     </RestoreSources>
+    <RestoreSources Condition="'$(DotNetBuildOffline)' != 'true' AND $(MicrosoftNetCompilersToolsetVersion.Contains('-')) ">
+      $(RestoreSources);
+      https://dotnet.myget.org/F/roslyn/api/v3/index.json;
+    </RestoreSources>
   </PropertyGroup>
 </Project>