As pointed out by @CaptainAmerica the solution is to update the CodeDom assembly from NuGet. One should point out how to do this in Visual Studio.
I found the solution here:
https://www.nuget.org/packages/Microsoft.CodeDom.Providers.DotNetCompilerPlatform/
Basically, in the Visual Studio menu select:
Tools-> Nuget Package Manager -> Package Manager Console
In the console that appears at the bottom of Visual Studio run this command:
Install-Package Microsoft.CodeDom.Providers.DotNetCompilerPlatform