fixup! ObjectListFilter filter values to target type coercion (#589)

Author: xperiandri

src/FSharp.Data.GraphQL.Server.Middleware/ObjectListFilterModule.fs

@@ -200,31 +200,49 @@ module ObjectListFilter =
         match comparer with
         | null -> ValueNone
         | :? StringComparer as sc ->
-            let mutable isOrdinalIgnoreCase = false
-
-            if StringComparer.IsWellKnownOrdinalComparer (sc, &isOrdinalIgnoreCase) then
-                if isOrdinalIgnoreCase then
-                    ValueSome StringComparison.OrdinalIgnoreCase
-                else
-                    ValueSome StringComparison.Ordinal
+            // Fast path: match well-known singletons by reference first.
+            // This is required because on Linux/Ubuntu CultureInfo.CurrentCulture and
+            // CultureInfo.InvariantCulture share the same CompareInfo, making them
+            // indistinguishable via IsWellKnownCultureAwareComparer alone.
+            if obj.ReferenceEquals (sc, StringComparer.OrdinalIgnoreCase) then
+                ValueSome StringComparison.OrdinalIgnoreCase
+            elif obj.ReferenceEquals (sc, StringComparer.InvariantCultureIgnoreCase) then
+                ValueSome StringComparison.InvariantCultureIgnoreCase
+            elif obj.ReferenceEquals (sc, StringComparer.CurrentCultureIgnoreCase) then
+                ValueSome StringComparison.CurrentCultureIgnoreCase
+            elif obj.ReferenceEquals (sc, StringComparer.Ordinal) then
+                ValueSome StringComparison.Ordinal
+            elif obj.ReferenceEquals (sc, StringComparer.InvariantCulture) then
+                ValueSome StringComparison.InvariantCulture
+            elif obj.ReferenceEquals (sc, StringComparer.CurrentCulture) then
+                ValueSome StringComparison.CurrentCulture
             else
-                let mutable compareInfo = Unchecked.defaultof<Globalization.CompareInfo>
-                let mutable compareOptions = Globalization.CompareOptions.None
-
-                if StringComparer.IsWellKnownCultureAwareComparer (sc, &compareInfo, &compareOptions) then
-                    let isInvariantCulture = compareInfo.Equals Globalization.CultureInfo.InvariantCulture.CompareInfo
-                    let isCurrentCulture = compareInfo.Equals Globalization.CultureInfo.CurrentCulture.CompareInfo
-
-                    match compareOptions with
-                    | Globalization.CompareOptions.None when isInvariantCulture -> ValueSome StringComparison.InvariantCulture
-                    | Globalization.CompareOptions.IgnoreCase when isInvariantCulture ->
-                        ValueSome StringComparison.InvariantCultureIgnoreCase
-                    | Globalization.CompareOptions.None when isCurrentCulture -> ValueSome StringComparison.CurrentCulture
-                    | Globalization.CompareOptions.IgnoreCase when isCurrentCulture ->
-                        ValueSome StringComparison.CurrentCultureIgnoreCase
-                    | _ -> ValueNone
+                // Fallback for non-singleton comparers (e.g. StringComparer.Create(...)).
+                let mutable isOrdinalIgnoreCase = false
+
+                if StringComparer.IsWellKnownOrdinalComparer (sc, &isOrdinalIgnoreCase) then
+                    if isOrdinalIgnoreCase then
+                        ValueSome StringComparison.OrdinalIgnoreCase
+                    else
+                        ValueSome StringComparison.Ordinal
                 else
-                    ValueNone
+                    let mutable compareInfo = Unchecked.defaultof<Globalization.CompareInfo>
+                    let mutable compareOptions = Globalization.CompareOptions.None
+
+                    if StringComparer.IsWellKnownCultureAwareComparer (sc, &compareInfo, &compareOptions) then
+                        let isInvariantCulture = compareInfo.Equals Globalization.CultureInfo.InvariantCulture.CompareInfo
+                        let isCurrentCulture = compareInfo.Equals Globalization.CultureInfo.CurrentCulture.CompareInfo
+
+                        match compareOptions with
+                        | Globalization.CompareOptions.None when isInvariantCulture -> ValueSome StringComparison.InvariantCulture
+                        | Globalization.CompareOptions.IgnoreCase when isInvariantCulture ->
+                            ValueSome StringComparison.InvariantCultureIgnoreCase
+                        | Globalization.CompareOptions.None when isCurrentCulture -> ValueSome StringComparison.CurrentCulture
+                        | Globalization.CompareOptions.IgnoreCase when isCurrentCulture ->
+                            ValueSome StringComparison.CurrentCultureIgnoreCase
+                        | _ -> ValueNone
+                    else
+                        ValueNone
         | _ -> ValueNone
 
      /// Gets the type from a MemberInfo (PropertyInfo or FieldInfo).

tests/FSharp.Data.GraphQL.Tests/ObjectListFilter/ObjectListFilterComparerMappingTests.fs

@@ -53,9 +53,9 @@ let ``comparerToStringComparison singleton mappings are all distinct`` () =
 
 // ─────────────────────────────────────────────────────────────────────────────
 // IsWellKnownCultureAwareComparer fallback path
-// StringComparer.Create produces a non-singleton comparer that is still
-// well-known, so it falls through the ReferenceEquals branch and hits the
-// IsWellKnownCultureAwareComparer fallback.
+// StringComparer.Create produces a non-singleton comparer; the singleton
+// ReferenceEquals fast path is skipped and IsWellKnownCultureAwareComparer
+// is used instead.
 // ─────────────────────────────────────────────────────────────────────────────
 
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