From 930cf98bb2b6de4d1813eea7f451b5f231a968da Mon Sep 17 00:00:00 2001
From: Brian Rourke Boll <brianrourkeboll@gmail.com>
Date: Wed, 28 Aug 2024 15:01:12 -0400
Subject: [PATCH 1/2] Detect `open type` use correctly for enums

* Consider `open type` used when the type is an enum and any of
  the enum cases is used unqualified.
---
 src/Compiler/Service/ServiceAnalysis.fs          |  5 +++++
 .../ProjectAnalysisTests.fs                      | 16 +++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/Compiler/Service/ServiceAnalysis.fs b/src/Compiler/Service/ServiceAnalysis.fs
index 29df63b1194..26b2ea1f7a2 100644
--- a/src/Compiler/Service/ServiceAnalysis.fs
+++ b/src/Compiler/Service/ServiceAnalysis.fs
@@ -51,6 +51,11 @@ module UnusedOpens =
                         if not entity.IsNamespace && not entity.IsFSharpModule then
                             for fv in entity.MembersFunctionsAndValues do
                                 fv
+
+                            if entity.IsEnum then
+                                for field in entity.FSharpFields do
+                                    if field.IsStatic && field.IsLiteral then
+                                        field
                     |]
 
                 HashSet<_>(symbols, symbolHash)
diff --git a/tests/FSharp.Compiler.Service.Tests/ProjectAnalysisTests.fs b/tests/FSharp.Compiler.Service.Tests/ProjectAnalysisTests.fs
index e14a3ae1e52..bbaac72bb56 100644
--- a/tests/FSharp.Compiler.Service.Tests/ProjectAnalysisTests.fs
+++ b/tests/FSharp.Compiler.Service.Tests/ProjectAnalysisTests.fs
@@ -5603,6 +5603,14 @@ open SomeUsedModuleContainingFunction
 open SomeUsedModuleContainingExtensionMember
 open SomeUsedModuleContainingActivePattern
 open SomeUsedModuleContainingUnion
+open type System.DayOfWeek // Used, should not appear.
+open type System.DateTimeKind // Unused, should appear.
+
+type FSharpEnum1 = X = 1 | Y = (1 <<< 1) | Z = (1 <<< 2)
+type FSharpEnum2 = H = 1 | I = (1 <<< 1) | J = (1 <<< 2)
+
+open type FSharpEnum1 // Used, should not appear.
+open type FSharpEnum2 // Unused, should appear.
 
 type UseTheThings(i:int) =
     member x.Value = Dictionary<int,int>() // use something from System.Collections.Generic, as a constructor
@@ -5610,6 +5618,10 @@ type UseTheThings(i:int) =
     member x.UseSomeUsedModuleContainingActivePattern(ActivePattern g) = g
     member x.UseSomeUsedModuleContainingExtensionMember() = (3).Q
     member x.UseSomeUsedModuleContainingUnion() = A
+    member x.UseEnumCase = Monday // Use an enum case from System.DayOfWeek.
+    member x.UseEnumCaseQualified = System.DateTimeKind.Utc // Use a qualified enum case.
+    member x.UseFSharpEnumCase = Y // Use an enum case from FSharpEnum1.
+    member x.UseFSharpEnumCaseQualified = FSharpEnum2.J // Use a qualified enum case.
 """
     let fileSource1 = SourceText.ofString fileSource1Text
     FileSystem.OpenFileForWriteShim(fileName1).Write(fileSource1Text)
@@ -5637,7 +5649,9 @@ type UseTheThings(i:int) =
            (((6, 5), (6, 19)), "open FSharp.Control // unused");
            (((7, 5), (7, 16)), "open FSharp.Data // unused");
            (((8, 5), (8, 25)), "open System.Globalization // unused");
-           (((25, 5), (25, 21)), "open SomeUnusedModule")]
+           (((25, 5), (25, 21)), "open SomeUnusedModule");
+           (((31, 10), (31, 29)), "open type System.DateTimeKind // Unused, should appear.")
+           (((37, 10), (37, 21)), "open type FSharpEnum2 // Unused, should appear.")]
     unusedOpensData |> shouldEqual expected
 
 [<Theory>]

From 6461ad8fed35c6b8250eb1eca1ea1fa504de1d6b Mon Sep 17 00:00:00 2001
From: Brian Rourke Boll <brianrourkeboll@gmail.com>
Date: Wed, 28 Aug 2024 15:04:57 -0400
Subject: [PATCH 2/2] Update release notes

---
 docs/release-notes/.FSharp.Compiler.Service/9.0.100.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/release-notes/.FSharp.Compiler.Service/9.0.100.md b/docs/release-notes/.FSharp.Compiler.Service/9.0.100.md
index 12adae55598..91751ba27df 100644
--- a/docs/release-notes/.FSharp.Compiler.Service/9.0.100.md
+++ b/docs/release-notes/.FSharp.Compiler.Service/9.0.100.md
@@ -13,6 +13,7 @@
 * Fixed checking failure when `global` namespace is involved with enabled GraphBasedChecking ([PR #17553](https://github.com/dotnet/fsharp/pull/17553))
 * Add missing byte chars notations, enforce limits in decimal notation in byte char & string (Issues [#15867](https://github.com/dotnet/fsharp/issues/15867), [#15868](https://github.com/dotnet/fsharp/issues/15868), [#15869](https://github.com/dotnet/fsharp/issues/15869), [PR #15898](https://github.com/dotnet/fsharp/pull/15898))
 * Parentheses analysis: keep extra parentheses around unit & tuples in method definitions. ([PR #17618](https://github.com/dotnet/fsharp/pull/17618))
+* Consider `open type` used when the type is an enum and any of the enum cases is used unqualified. ([PR #17628](https://github.com/dotnet/fsharp/pull/17628))
 
 ### Added