XmlDoc required for unnamed union case field

[DedSec256]

Repro

type A =
    /// <summary>
    ///
    /// </summary>
    /// <param name="x"></param>
    | Case of int * x: int

Expected behavior

XmlDoc is not required for the parameter

[auduchinok]

This is inconsistent to other places where anonymous top-level parameters can be declared, like parameters in functions and methods, where unnamed patterns are ignored by this check.

@dsyme @vzarytovskii Would you accept a PR making the union cases behave in line with other places?

@DedSec256 Would you like to make a PR with the change? If yes, IsNameGenerated from #4225 could be useful here. Could you also check if there're other similar cases, e.g. unnamed parameters in exception declarations, needing an update too?

[dsyme]

Aside: the whole question of XML docs for union cases is a signficant piece of the F# documentation puzzle that hasn't been properly addressed. The underlying problem - like a lot of corner cases in F# - is that XML docs are a .NET standard w.r.t. the compiled representation - so what does an XML doc on a union case even refer to?

For the above case - I think the warning is actually reasonable - if some of the union cases are named and documented, all of them should be. I'd probably say the same about parameters.

But yes, for consistency we'd accept a PR for this.

[DedSec256]

Curiously, we have yet another way to specify documentation for a union case field

fsharp/tests/service/XmlDocTests.fs

Lines 1170 to 1184 in 03714a0

	type Foo =
	| Thing of
	///A1
	///A2
	a: string *
	///B1
	///B2
	bool
	"""
	(fun checkResults ->
	getFieldXml "Thing" "a" checkResults
	|> compareXml [|"A1"; "A2"|]
	getFieldXml "Thing" "Item2" checkResults
	|> compareXml [|"B1"; "B2"|])