Change GetHashCode for Set, MultiSet and Map

1 files changed, 17 insertions, 3 deletions

diff --git a/Binaries/DafnyRuntime.cs b/Binaries/DafnyRuntime.cs
index a682422a..2a553c81 100644
--- a/Binaries/DafnyRuntime.cs
+++ b/Binaries/DafnyRuntime.cs
@@ -75,7 +75,11 @@ namespace Dafny
       return other is Set<T> && Equals((Set<T>)other);

     }

     public override int GetHashCode() {

-      return dict.GetHashCode();

+      var hashCode = 0;

+      foreach (var t in dict.Keys) {

+        hashCode = (hashCode << 3) | (hashCode >> 29) ^ t.GetHashCode();

+      }

+      return hashCode;

     }

     public override string ToString() {

       var s = "{";

@@ -228,7 +232,12 @@ namespace Dafny
       return other is MultiSet<T> && Equals((MultiSet<T>)other);

     }

     public override int GetHashCode() {

-      return dict.GetHashCode();

+      var hashCode = 0;

+      foreach (var kv in dict) {

+        hashCode = (hashCode << 3) | (hashCode >> 29) ^ kv.Key.GetHashCode();

+        hashCode = (hashCode << 3) | (hashCode >> 29) ^ kv.Value.GetHashCode();

+      }

+      return hashCode;

     }

     public override string ToString() {

       var s = "multiset{";

@@ -392,7 +401,12 @@ namespace Dafny
       return other is Map<U, V> && Equals((Map<U, V>)other);

     }

     public override int GetHashCode() {

-      return dict.GetHashCode();

+      var hashCode = 0;

+      foreach (var kv in dict) {

+        hashCode = (hashCode << 3) | (hashCode >> 29) ^ kv.Key.GetHashCode();

+        hashCode = (hashCode << 3) | (hashCode >> 29) ^ kv.Value.GetHashCode();

+      }

+      return hashCode;

     }

     public override string ToString() {

       var s = "map[";