v1.0.6 of Microsoft.CodeDom.Providers.DotNetCompilerPlatform

I had the same problem, it looks like a change in the Microsoft.CodeDom.Providers.DotNetCompilerPlatform.props file under packages\Microsoft.CodeDom.Providers.DotNetCompilerPlatform.1.0.6\build\net45

I added back in a target from the 1.0.5 version by adding back in

<Target Name="IncludeRoslynCompilerFilesToItemGroup" AfterTargets="ResolveAssemblyReferences" >
<ItemGroup>
  <None Include="@(RoslyCompilerFiles)" Condition="">
    <Link>%(RoslyCompilerFiles.Link)</Link>
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </None>
</ItemGroup>

before

<Target Name="CopyRoslynCompilerFilesToOutputDirectory" ... />

and publishing is working again.

I think it is being tracked here link

1.0.7 was released. Please give it a try. If you see any issue, go to roslyncodedomprovider github repo and file an issue there.