Fix for LWG Issue 2059: C++0x ambiguity problem with map::erase

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@236950 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/associative/set/erase_iter.pass.cpp

@@ -18,6 +18,14 @@
 
 #include "min_allocator.h"
 
+struct TemplateConstructor
+{
+    template<typename T>
+    TemplateConstructor (const T&) {}
+};
+
+bool operator<(const TemplateConstructor&, const TemplateConstructor&) { return false; }
+
 int main()
 {
     {
@@ -178,4 +186,18 @@ int main()
         assert(i == m.end());
     }
 #endif
+#if __cplusplus >= 201402L
+    {
+    //  This is LWG #2059
+        typedef TemplateConstructor T;
+        typedef std::set<T> C;
+        typedef C::iterator I;
+
+        C c;
+        T a{0};
+        I it = c.find(a);
+        if (it != c.end())
+            c.erase(it);
+    }
+#endif
 }