Running into this issue when I publish to IIS. I created a new feature module in my habitat/helix sitecore solution. Everything builds correctly in my gulp tasks but when the site is publish out to IIS it gets the following error.
Server Error in '/' Application. Compilation Error Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. Compiler Error Message: The compiler failed with error code 255. Show Detailed Compiler Output: c:\windows\system32\inetsrv>C:\websites\SiteName\Website\bin\roslyn\csc.exe