Add test for ROOT-6124.

test/CodeGeneration/Symbols.C

@@ -0,0 +1,39 @@
+//------------------------------------------------------------------------------
+// CLING - the C++ LLVM-based InterpreterG :)
+//
+// This file is dual-licensed: you can choose to license it under the University
+// of Illinois Open Source License or the GNU Lesser General Public License. See
+// LICENSE.TXT for details.
+//------------------------------------------------------------------------------
+
+// RUN: clang -shared -fPIC -DBUILD_SHARED %s -o%T/libSymbols%shlibext
+// RUN: %cling --nologo -L%T -lSymbols  %s | FileCheck %s
+
+// Check that weak symbols do not get re-emitted (ROOT-6124)
+extern "C" int printf(const char*,...);
+
+template <class T>
+struct StaticStuff {
+  static T s_data;
+};
+template <class T>
+T StaticStuff<T>::s_data = 42;
+
+int compareAddr(int* there);
+#ifdef BUILD_SHARED
+int compareAddr(int* there) {
+  if (there != &StaticStuff<int>::s_data) {
+    printf("Wrong address, %ld here, %ld there!",
+           (long)&StaticStuff<int>::s_data,
+           (long)there);
+    // CHECK-NOT: Wrong address
+    return 1;
+  }
+  return 0;
+}
+#else
+int Symbols() {
+  return compareAddr(&StaticStuff<int>::s_data);
+}
+#endif
+