From 8be41181b4d321e62c91a008b69a8761b831be0d Mon Sep 17 00:00:00 2001
From: wrkettlitz <wrkettlitz@pm.me>
Date: Thu, 5 Mar 2020 17:50:38 +0100
Subject: [PATCH] IReadOnlyCollection<T> does not implement ICollection<T>

---
 src/libraries/System.Linq/src/System/Linq/AnyAll.cs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libraries/System.Linq/src/System/Linq/AnyAll.cs b/src/libraries/System.Linq/src/System/Linq/AnyAll.cs
index f97526a40cdff9..97f193a31429e4 100644
--- a/src/libraries/System.Linq/src/System/Linq/AnyAll.cs
+++ b/src/libraries/System.Linq/src/System/Linq/AnyAll.cs
@@ -20,6 +20,10 @@ public static bool Any<TSource>(this IEnumerable<TSource> source)
             {
                 return collectionoft.Count != 0;
             }
+            
+            if (source is IReadOnlyCollection<TSource> readOnlyCollection)
+                return readOnlyCollection.Count != 0;
+
             else if (source is IIListProvider<TSource> listProv)
             {
                 // Note that this check differs from the corresponding check in
@@ -38,6 +42,7 @@ public static bool Any<TSource>(this IEnumerable<TSource> source)
             {
                 return collection.Count != 0;
             }
+           
 
             using (IEnumerator<TSource> e = source.GetEnumerator())
             {