Attributes with no value don't invoke IntelliSense.

[NTaylorMullen]

If you type: <custom asp-int-attribute="" /> the document location of the generated LineMapping points to the beginning of asp-int-attribute and not inside the quotes. In order to get invoked IntelliSense we need to be mapping it correctly.

[NTaylorMullen]

7afd78b

[NTaylorMullen]

Note: IntelliSense currently does not invoke automatically, you must do ctrl => j once you've written an empty attribute. A good example of this is in the InputTagHelper in Mvc where you may expect IntelliSense to be invoked after typing <input asp-for="" for your input tag to see potential properties on the pages Model.

Another issue this solved is upon typing in an empty attribute IntelliSense will automatically invoke once it detects a potential match (just like in the C# editor).