Replace leftover string with the proper type in C# set typemap

This is just a mistake remaining from generalizing the old
string-specific typemap to any type.

Fix it now and update a unit test to test for sets of objects other than
strings.

1 files changed, 1 insertions, 1 deletions

diff --git a/Lib/csharp/std_set.i b/Lib/csharp/std_set.i
index 3b2492e0e..1d946e644 100644
--- a/Lib/csharp/std_set.i
+++ b/Lib/csharp/std_set.i
@@ -30,7 +30,7 @@ class set {
 
 %typemap(csinterfaces) std::set<T> "global::System.IDisposable, global::System.Collections.Generic.ISet<$typemap(cstype, T)>\n";
 %proxycode %{
-  void global::System.Collections.Generic.ICollection<$typemap(cstype, T)>.Add(string item) {
+  void global::System.Collections.Generic.ICollection<$typemap(cstype, T)>.Add($typemap(cstype, T) item) {
       ((global::System.Collections.Generic.ISet<$typemap(cstype, T)>)this).Add(item);
   }