From f39c54f71e8e9f053b7efb6e69b1429944badba4 Mon Sep 17 00:00:00 2001
From: Peter Dettman <peter.dettman@bouncycastle.org>
Date: Tue, 11 Apr 2023 14:47:22 +0700
Subject: Platform guards for ReadOnlySet<T>

---
 crypto/src/util/collections/CollectionUtilities.cs | 2 ++
 crypto/src/util/collections/ReadOnlySet.cs         | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/crypto/src/util/collections/CollectionUtilities.cs b/crypto/src/util/collections/CollectionUtilities.cs
index a1fb0e949..6f94c4409 100644
--- a/crypto/src/util/collections/CollectionUtilities.cs
+++ b/crypto/src/util/collections/CollectionUtilities.cs
@@ -75,10 +75,12 @@ namespace Org.BouncyCastle.Utilities.Collections
             return new ReadOnlyListProxy<T>(l);
         }
 
+#if NETCOREAPP1_0_OR_GREATER || NET40_OR_GREATER || NETSTANDARD1_0_OR_GREATER
         public static ISet<T> ReadOnly<T>(ISet<T> s)
         {
             return new ReadOnlySetProxy<T>(s);
         }
+#endif
 
         public static bool Remove<K, V>(IDictionary<K, V> d, K k, out V v)
         {
diff --git a/crypto/src/util/collections/ReadOnlySet.cs b/crypto/src/util/collections/ReadOnlySet.cs
index 36c198f07..d77494847 100644
--- a/crypto/src/util/collections/ReadOnlySet.cs
+++ b/crypto/src/util/collections/ReadOnlySet.cs
@@ -1,10 +1,15 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 
 namespace Org.BouncyCastle.Utilities.Collections
 {
     internal abstract class ReadOnlySet<T>
+#if NETCOREAPP1_0_OR_GREATER || NET40_OR_GREATER || NETSTANDARD1_0_OR_GREATER
         : ISet<T>
+#else
+        : ICollection<T>, IEnumerable<T>, IEnumerable
+#endif
     {
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
         {
@@ -35,6 +40,7 @@ namespace Org.BouncyCastle.Utilities.Collections
         public abstract bool Overlaps(IEnumerable<T> other);
     }
 
+#if NETCOREAPP1_0_OR_GREATER || NET40_OR_GREATER || NETSTANDARD1_0_OR_GREATER
     internal class ReadOnlySetProxy<T>
         : ReadOnlySet<T>
     {
@@ -58,4 +64,5 @@ namespace Org.BouncyCastle.Utilities.Collections
         public override bool IsSupersetOf(IEnumerable<T> other) => m_target.IsSupersetOf(other);
         public override bool Overlaps(IEnumerable<T> other) => m_target.Overlaps(other);
     }
+#endif
 }
-- 
cgit 1.4.1