Tag Helpers: Generation for ModelExpression is incorrect when indexing

[dougbu]

When indexing into an Array or List model, MvcTagHelperAttributeValueCodeRenderer generates incorrect code. For example with a List<User> model and <textarea for="[index].Blurb" /> in the Razor source, the generated C# is:

__Microsoft_AspNet_Mvc_TagHelpers_TextAreaTagHelper.For =
  CreateModelExpression(__model => __model.[index].Blurb);

Note the extra . before [index]. This effectively limits tag helpers to simple property access.

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Need to change MvcTagHelperAttributeValueCodeRenderer to leave out the . when the passed Action will write an initial [. (Can't special-case TModel to avoid breaking model => model.Count and similar expressions.)
@ escaping (issue #1253) won't help without IntelliSense. Users can't see the generated code to understand the problem.

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Side note: If the user is debugging or has error pages enabled, the compilation error references a line number past the end of the .cshtml file e.g.

C:\dd\k\Mvc.1\samples\TagHelperSample.Web\Views\Home\Index.cshtml(90,112): error CS1001: Identifier expected

In my test Index.cshtml has 37 lines.

[dougbu]

not exact the same problem as #1253 (and #1408) but the same solution. e.g. <input asp-for="@Model[index].Blurb" /> will work once #1253 is fixed. treating this one as a duplicate...