Improve handling of unmet protocol conformance

[compnerd]

It is unclear if this is a LSP issue or a VSCode issue, but the protocol conformance requirements are not listed in the diagnostic emitted. The hover card in VSCode is unable to emit/display the missing requirements. The VScode light bulb does however seem to be able to synthesize the missing protocol requirements.

[tristanlabelle]

@MaxDesiatov seems more like a feature request? I think this requires augmenting the textDocument/diagnostic textual content with a list of missing requirements.

[tristanlabelle]

Supporting screenshots:

Unactionable prompt in hover:

Though this is available through the light bulb:

[MaxDesiatov]

Shouldn't there be a way to reference light bulb actions (whatever they're called in LSP parlance) from diagnostics so that instead of "No quick fixes available" in the hover it was able to pick those up?

[ahoppen]

Tracked in Apple’s issue tracker as rdar://112539108

[benlangmuir]

light bulb actions (whatever they're called in LSP parlance)

"Code Action" where "QuickFix" is a specific kind.

Shouldn't there be a way to reference light bulb actions (whatever they're called in LSP parlance) from diagnostics so that instead of "No quick fixes available" in the hover it was able to pick those up?

We should already be finding quick fixes from the most recent diagnostics when looking up code actions; one issue is that diagnostic locations may not overlap where the cursor is, particularly if the diagnostic only has a single source location and not a range. Maybe we could teach that code to extend locations out to their token boundaries? Just a guess.

[ahoppen]

I’ve got a fix up: #777. We weren’t storing the diagnostics retrieved using the pull-model diagnostics.

[tristanlabelle]

Testing with latest:

Clicking on Quick Fix...:

Clicking on do you want to add protocol stubs?:

Note: the quick fix text is inconsistent with the code action:

I wonder also if @compnerd had in mind to be able to see the list of missing members in the hover popup in addition to having the fixit available?