From 7819b3c5ef37220dc5e5d2f877921740b67d676c Mon Sep 17 00:00:00 2001
From: Florian Greinacher <fgreinacher@users.noreply.github.com>
Date: Mon, 16 Jan 2017 21:45:43 +0100
Subject: [PATCH] Handle F# lists that implement IReadOnlyCollection<T> (F# 4.1
 and above) (#1181)

Fixes #1180
---
 .../Serialization/JsonArrayContract.cs        | 22 ++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs b/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs
index 3a301647..96afac5b 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs
@@ -191,6 +191,11 @@ namespace Newtonsoft.Json.Serialization
 
                 _genericCollectionDefinitionType = typeof(List<>).MakeGenericType(CollectionItemType);
                 _parameterizedConstructor = CollectionUtils.ResolveEnumerableCollectionConstructor(CreatedType, CollectionItemType);
+
+#if HAVE_FSHARP_TYPES
+                StoreFSharpListCreatorIfNecessary(underlyingType);
+#endif
+
                 IsReadOnlyOrFixedSize = true;
                 canDeserialize = HasParameterizedCreatorInternal;
             }
@@ -207,11 +212,7 @@ namespace Newtonsoft.Json.Serialization
                 _parameterizedConstructor = CollectionUtils.ResolveEnumerableCollectionConstructor(underlyingType, CollectionItemType);
 
 #if HAVE_FSHARP_TYPES
-                if (!HasParameterizedCreatorInternal && underlyingType.Name == FSharpUtils.FSharpListTypeName)
-                {
-                    FSharpUtils.EnsureInitialized(underlyingType.Assembly());
-                    _parameterizedCreator = FSharpUtils.CreateSeq(CollectionItemType);
-                }
+                StoreFSharpListCreatorIfNecessary(underlyingType);
 #endif
 
                 if (underlyingType.IsGenericType() && underlyingType.GetGenericTypeDefinition() == typeof(IEnumerable<>))
@@ -306,5 +307,16 @@ namespace Newtonsoft.Json.Serialization
 
             return (IList)_genericTemporaryCollectionCreator();
         }
+
+#if HAVE_FSHARP_TYPES
+        private void StoreFSharpListCreatorIfNecessary(Type underlyingType)
+        {
+            if (!HasParameterizedCreatorInternal && underlyingType.Name == FSharpUtils.FSharpListTypeName)
+            {
+                FSharpUtils.EnsureInitialized(underlyingType.Assembly());
+                _parameterizedCreator = FSharpUtils.CreateSeq(CollectionItemType);
+            }
+        }
+#endif
     }
 }
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