1 files changed, 47 insertions, 0 deletions
diff --git a/clang/test/SemaCXX/libstdcxx_pair_swap_hack.cpp b/clang/test/SemaCXX/libstdcxx_pair_swap_hack.cpp
new file mode 100644
index 00000000000..8c7c782c32b
--- /dev/null
+++ b/clang/test/SemaCXX/libstdcxx_pair_swap_hack.cpp
@@ -0,0 +1,47 @@
+// RUN: %clang_cc1 -fsyntax-only %s -std=c++11 -verify -fexceptions -fcxx-exceptions
+
+// This is a test for an egregious hack in Clang that works around
+// an issue with GCC's <utility> implementation. std::pair::swap
+// has an exception specification that makes an unqualified call to
+// swap. This is invalid, because it ends up calling itself with
+// the wrong number of arguments.
+
+#ifdef BE_THE_HEADER
+
+#pragma GCC system_header
+namespace std {
+  template<typename T> void swap(T &, T &);
+
+  template<typename A, typename B> struct pair {
+    void swap(pair &other) noexcept(noexcept(swap(*this, other)));
+  };
+}
+
+#else
+
+#define BE_THE_HEADER
+#include __FILE__
+
+struct X {};
+using PX = std::pair<X, X>;
+using PI = std::pair<int, int>;
+void swap(PX &, PX &) noexcept;
+PX px;
+PI pi;
+
+static_assert(noexcept(px.swap(px)), "");
+static_assert(!noexcept(pi.swap(pi)), "");
+
+namespace sad {
+  template<typename T> void swap(T &, T &);
+
+  template<typename A, typename B> struct pair {
+    void swap(pair &other) noexcept(noexcept(swap(*this, other))); // expected-error {{too many arguments}} expected-note {{declared here}}
+  };
+
+  pair<int, int> pi;
+
+  static_assert(!noexcept(pi.swap(pi)), ""); // expected-note {{in instantiation of}}
+}
+
+#endif