`open type T` when `T` is an enum is treated as unused even when it's used

[brianrourkeboll]

Repro steps

// Shows as unused; the unused opens analyzer will suggest removing it.
open type System.DayOfWeek

// …Even though it's used.
let monday = Monday

Expected behavior

The open type declaration for an enum should be considered used if any of its enum cases are used unqualified.

Actual behavior

The open type declaration for an enum is considered unused even when one or more of its enum cases are used.

Known workarounds

N/A.

Related information

.NET 8, 9.

[brianrourkeboll]

I assume the fix involves yielding the enum cases as FSharpSymbols in here:

fsharp/src/Compiler/Service/ServiceAnalysis.fs

Lines 23 to 54 in 6c96fc7

	/// Compute an indexed table of the set of symbols revealed by 'open', on-demand
	let revealedSymbols: Lazy<HashSet<FSharpSymbol>> =
	lazy
	let symbols: FSharpSymbol[] =
	[|
	for ent in entity.NestedEntities do
	ent
	if ent.IsFSharpRecord then
	for rf in ent.FSharpFields do
	rf
	if ent.IsFSharpUnion && not (ent.HasAttribute<RequireQualifiedAccessAttribute>()) then
	for unionCase in ent.UnionCases do
	unionCase
	if ent.HasAttribute<ExtensionAttribute>() then
	for fv in ent.MembersFunctionsAndValues do
	// fv.IsExtensionMember is always false for C# extension methods returning by `MembersFunctionsAndValues`,
	// so we have to check Extension attribute instead.
	// (note: fv.IsExtensionMember has proper value for symbols returning by GetAllUsesOfAllSymbolsInFile though)
	if fv.HasAttribute<ExtensionAttribute>() then
	fv
	for apCase in entity.ActivePatternCases do
	apCase
	// The IsNamespace and IsFSharpModule cases are handled by looking at DeclaringEntity below
	if not entity.IsNamespace && not entity.IsFSharpModule then
	for fv in entity.MembersFunctionsAndValues do
	fv
	|]