Competitive TagHelpers having attributes with equal names but incompatible types cause CompilationFailedException

[IlyaKhD]

Sample: https://github.com/IlyaKhD/Competitive_TagHelpers_Issue

error   : [Microsoft.AspNet.Server.WebListener.MessagePump] ProcessRequestAsync Microsoft.AspNet.Mvc.Razor.Compilation.CompilationFailedException: One or more compilation failures occurred:
weiftboz.w0u(55,61): DNX,Version=v4.5.1 error CS0029: Cannot implicitly convert type 'string' to 'int'
  at Microsoft.AspNet.Mvc.Razor.Compilation.CompilationResult.EnsureSuccessful()
  at Microsoft.AspNet.Mvc.Razor.Compilation.CompilerCache.CreateCacheEntry(String normalizedPath, Func`2 compile)
  at Microsoft.AspNet.Mvc.Razor.Compilation.CompilerCache.GetOrAdd(String relativePath, Func`2 compile)
  at Microsoft.AspNet.Mvc.Razor.VirtualPathRazorPageFactory.CreateInstance(String relativePath)
  at Microsoft.AspNet.Mvc.Razor.RazorViewEngine.LocatePageFromViewLocations(ActionContext context, String pageName, Boolean isPartial)
  at Microsoft.AspNet.Mvc.Razor.RazorViewEngine.GetRazorPageResult(ActionContext context, String pageName, Boolean isPartial)
  at Microsoft.AspNet.Mvc.Razor.RazorViewEngine.FindView(ActionContext context, String viewName)
  at Microsoft.AspNet.Mvc.ViewEngines.CompositeViewEngine.FindView(ActionContext context, String viewName, Boolean partial)
  at Microsoft.AspNet.Mvc.ViewEngines.CompositeViewEngine.FindView(ActionContext context, String viewName)
  at Microsoft.AspNet.Mvc.ViewFeatures.ViewResultExecutor.FindView(ActionContext actionContext, ViewResult viewResult)
  at Microsoft.AspNet.Mvc.ViewResult.<ExecuteResultAsync>d__24.MoveNext()

Instead of failing with a compilation error, it would be nice to be able to select the only appropriate TagHelper in the Process method.

Note: the issue is related to #474 (comment).

[NTaylorMullen]

This is by-design. In the past we talked about detecting this case at parse-time and logging a more verbose error but came to the conclusion that the C# compilation error was verbose enough to diagnose the problem.

As for selecting which TagHelper applies in a Process method, that would not be possible. At the point that the Process method is invoked Razor has already generated the code that tries to set a string to an int.

To work around this issue I'd recommend either of the following:

• Change attribute names to be different to avoid conflict.
• Change [HtmlTargetElement] to be more explicit to limit when a TagHelper applies.