diff -r 000000000000 -r 6474c204b198 xpcom/tests/TestCOMPtrEq.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/TestCOMPtrEq.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,166 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+ /**
+  * This attempts to test all the possible variations of |operator==|
+  * used with |nsCOMPtr|s.  Currently only the tests where pointers
+  * are to the same class are enabled.  It's not clear whether we
+  * should be supporting other tests, and some of them won't work
+  * on at least some platforms.  If we add separate comparisons
+  * for nsCOMPtr<nsISupports> we'll need to add more tests for
+  * those cases.
+  */
+
+#include "nsCOMPtr.h"
+
+  // Don't test these now, since some of them won't work and it's
+  // not clear whether they should (see above).
+#undef NSCAP_EQTEST_TEST_ACROSS_TYPES
+
+#define NS_ICOMPTREQTESTFOO_IID \
+  {0x8eb5bbef, 0xd1a3, 0x4659, \
+    {0x9c, 0xf6, 0xfd, 0xf3, 0xe4, 0xd2, 0x00, 0x0e}}
+
+class nsICOMPtrEqTestFoo : public nsISupports {
+  public:
+    NS_DECLARE_STATIC_IID_ACCESSOR(NS_ICOMPTREQTESTFOO_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsICOMPtrEqTestFoo, NS_ICOMPTREQTESTFOO_IID)
+
+#ifdef NSCAP_EQTEST_TEST_ACROSS_TYPES
+
+#define NS_ICOMPTREQTESTFOO2_IID \
+  {0x6516387b, 0x36c5, 0x4036, \
+    {0x82, 0xc9, 0xa7, 0x4d, 0xd9, 0xe5, 0x92, 0x2f}}
+
+class nsICOMPtrEqTestFoo2 : public nsISupports {
+  public:
+    NS_DECLARE_STATIC_IID_ACCESSOR(NS_ICOMPTREQTESTFOO2_IID)
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsICOMPtrEqTestFoo2, NS_ICOMPTREQTESTFOO2_IID)
+
+#endif
+
+int
+main()
+  {
+    nsCOMPtr<nsICOMPtrEqTestFoo> s;
+    nsICOMPtrEqTestFoo* r = 0;
+    const nsCOMPtr<nsICOMPtrEqTestFoo> sc;
+    const nsICOMPtrEqTestFoo* rc = 0;
+    nsICOMPtrEqTestFoo* const rk = 0;
+    const nsICOMPtrEqTestFoo* const rkc = 0;
+    nsICOMPtrEqTestFoo* d = s;
+    
+#ifdef NSCAP_EQTEST_TEST_ACROSS_TYPES
+    nsCOMPtr<nsICOMPtrEqTestFoo2> s2;
+    nsICOMPtrEqTestFoo2* r2 = 0;
+    const nsCOMPtr<nsICOMPtrEqTestFoo2> sc2;
+    const nsICOMPtrEqTestFoo2* rc2 = 0;
+    nsICOMPtrEqTestFoo2* const rk2 = 0;
+    const nsICOMPtrEqTestFoo2* const rkc2 = 0;
+    nsICOMPtrEqTestFoo2* d2 = s2;
+#endif
+
+    return (!(true &&
+              (s == s) &&
+              (s == r) &&
+              (s == sc) &&
+              (s == rc) &&
+              (s == rk) &&
+              (s == rkc) &&
+              (s == d) &&
+              (r == s) &&
+              (r == sc) &&
+              (r == rc) &&
+              (r == rk) &&
+              (r == rkc) &&
+              (r == d) &&
+              (sc == s) &&
+              (sc == r) &&
+              (sc == sc) &&
+              (sc == rc) &&
+              (sc == rk) &&
+              (sc == rkc) &&
+              (sc == d) &&
+              (rc == s) &&
+              (rc == r) &&
+              (rc == sc) &&
+              (rc == rk) &&
+              (rc == rkc) &&
+              (rc == d) &&
+              (rk == s) &&
+              (rk == r) &&
+              (rk == sc) &&
+              (rk == rc) &&
+              (rk == rkc) &&
+              (rk == d) &&
+              (rkc == s) &&
+              (rkc == r) &&
+              (rkc == sc) &&
+              (rkc == rc) &&
+              (rkc == rk) &&
+              (rkc == d) &&
+              (d == s) &&
+              (d == r) &&
+              (d == sc) &&
+              (d == rc) &&
+              (d == rk) &&
+              (d == rkc) &&
+#ifdef NSCAP_EQTEST_TEST_ACROSS_TYPES
+              (s == s2) &&
+              (s == r2) &&
+              (s == sc2) &&
+              (s == rc2) &&
+              (s == rk2) &&
+              (s == rkc2) &&
+              (s == d2) &&
+              (r == s2) &&
+              (r == r2) &&
+              (r == sc2) &&
+              (r == rc2) &&
+              (r == rk2) &&
+              (r == rkc2) &&
+              (r == d2) &&
+              (sc == s2) &&
+              (sc == r2) &&
+              (sc == sc2) &&
+              (sc == rc2) &&
+              (sc == rk2) &&
+              (sc == rkc2) &&
+              (sc == d2) &&
+              (rc == s2) &&
+              (rc == r2) &&
+              (rc == sc2) &&
+              (rc == rc2) &&
+              (rc == rk2) &&
+              (rc == rkc2) &&
+              (rc == d2) &&
+              (rk == s2) &&
+              (rk == r2) &&
+              (rk == sc2) &&
+              (rk == rc2) &&
+              (rk == rk2) &&
+              (rk == rkc2) &&
+              (rk == d2) &&
+              (rkc == s2) &&
+              (rkc == r2) &&
+              (rkc == sc2) &&
+              (rkc == rc2) &&
+              (rkc == rk2) &&
+              (rkc == rkc2) &&
+              (rkc == d2) &&
+              (d == s2) &&
+              (d == r2) &&
+              (d == sc2) &&
+              (d == rc2) &&
+              (d == rk2) &&
+              (d == rkc2) &&
+              (d == d2) &&
+#endif
+              true));
+  }