Introduce [OutputAttributeHint] to allow attributes to function as known HTML attributes when used in the editor about razor

[NTaylorMullen]

@stap123 thanks for filing the issue! You're correct in ignoring the warnings; however, we should definitely make this work on our end.

We should consider adding an OutputAttributeHint to TagHelper bound attributes. This would work much like OutputElementHint but for attributes.

[rynowak]

@NTaylorMullen - should we add this as part of the 2.1 release? It will be a while before we can ship tooling for it, but if this is compelling we should probably add it to the runtime so it get adoption by the time tooling lands.

[NTaylorMullen]

@rynowak sure why not 😉 The tooling feature for this wouldn't make it until 15.8 FYI

[rynowak]

Yeah, but we don't know if there will be another runtime release for 15.8, so this is the safest bet. IMO it's ok to add this now and then light up the tooling later.

[NTaylorMullen]

Another external customer report: https://stackoverflow.com/a/49437763/1574622

[niltor]

When can we solve this issue?
vs2019 preview2 has the same issue

[timcromarty]

Still seeing this in VS2019 RTM

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[TanayParikh]

Closing this out as it was addressed via #3031.