diff --git a/mozilla/configure.in b/mozilla/configure.in
index db1bd5dbdf4..d1286c65ac8 100644
--- a/mozilla/configure.in
+++ b/mozilla/configure.in
@@ -2643,6 +2643,19 @@ if test "$ac_cv_need_cpp_template_cast_to_base" = yes ; then
   AC_DEFINE(NEED_CPP_TEMPLATE_CAST_TO_BASE)
 fi
 
+dnl Some compilers have trouble resolving the ambiguity between two
+dnl functions whose arguments differ only by cv-qualifications.
+AC_CACHE_CHECK(whether the compiler cannot resolve const ambiguities correctly,
+               ac_cv_cant_resolve_const_ambiguity,
+               [AC_TRY_COMPILE([int a(int *i) { return *i; }
+                                const int a(const int *i) { return *i; } ],
+                               [ int i; a(&i); ],
+                               ac_cv_cant_resolve_const_ambiguity=no,
+                               ac_cv_cant_resolve_const_ambiguity=yes)])
+if test "$ac_cv_cant_resolve_const_ambiguity" = yes ; then
+  AC_DEFINE(CANT_RESOLVE_CPP_CONST_AMBIGUITY)
+fi
+
 dnl
 dnl We dont do exceptions on unix.  The only reason this used to be here
 dnl is that mozilla/xpcom/tests/TestCOMPtr.cpp has a test which uses 
diff --git a/mozilla/xpcom/base/nsCOMPtr.h b/mozilla/xpcom/base/nsCOMPtr.h
index 68b811b9dfb..b4df3f7f053 100644
--- a/mozilla/xpcom/base/nsCOMPtr.h
+++ b/mozilla/xpcom/base/nsCOMPtr.h
@@ -649,6 +649,17 @@ class nsCOMPtr
           return get();
         }
 
+#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+  // broken version for IRIX
+
+      nsCOMPtr<T>*
+      get_address() const
+        {
+          return NS_CONST_CAST(nsCOMPtr<T>*, this);
+        }
+
+#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       nsCOMPtr<T>*
       get_address()
         {
@@ -661,6 +672,8 @@ class nsCOMPtr
           return this;
         }
 
+#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       // This is going to become private soon, once all users of
       // nsCOMPtr stop using it.  It may even become:
       // void operator&() const {}
@@ -851,6 +864,17 @@ class nsCOMPtr<nsISupports>
           return get();
         }
 
+#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+  // broken version for IRIX
+
+      nsCOMPtr<nsISupports>*
+      get_address() const
+        {
+          return NS_CONST_CAST(nsCOMPtr<nsISupports>*, this);
+        }
+
+#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       nsCOMPtr<nsISupports>*
       get_address()
         {
@@ -863,6 +887,8 @@ class nsCOMPtr<nsISupports>
           return this;
         }
 
+#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       // This is going to become private soon, once all users of
       // nsCOMPtr stop using it.  It may even become:
       // void operator&() const {}
@@ -943,6 +969,20 @@ nsCOMPtr<T>::begin_assignment()
   }
 #endif
 
+#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
+// This is the broken version for IRIX, which can't handle the version below.
+
+template <class T>
+inline
+nsCOMPtr<T>*
+address_of( const nsCOMPtr<T>& aPtr )
+  {
+    return aPtr.get_address();
+  }
+
+#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
 template <class T>
 inline
 nsCOMPtr<T>*
@@ -959,6 +999,8 @@ address_of( const nsCOMPtr<T>& aPtr )
     return aPtr.get_address();
   }
 
+#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
 template <class T>
 class nsGetterAddRefs
     /*
diff --git a/mozilla/xpcom/glue/nsCOMPtr.h b/mozilla/xpcom/glue/nsCOMPtr.h
index 68b811b9dfb..b4df3f7f053 100644
--- a/mozilla/xpcom/glue/nsCOMPtr.h
+++ b/mozilla/xpcom/glue/nsCOMPtr.h
@@ -649,6 +649,17 @@ class nsCOMPtr
           return get();
         }
 
+#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+  // broken version for IRIX
+
+      nsCOMPtr<T>*
+      get_address() const
+        {
+          return NS_CONST_CAST(nsCOMPtr<T>*, this);
+        }
+
+#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       nsCOMPtr<T>*
       get_address()
         {
@@ -661,6 +672,8 @@ class nsCOMPtr
           return this;
         }
 
+#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       // This is going to become private soon, once all users of
       // nsCOMPtr stop using it.  It may even become:
       // void operator&() const {}
@@ -851,6 +864,17 @@ class nsCOMPtr<nsISupports>
           return get();
         }
 
+#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+  // broken version for IRIX
+
+      nsCOMPtr<nsISupports>*
+      get_address() const
+        {
+          return NS_CONST_CAST(nsCOMPtr<nsISupports>*, this);
+        }
+
+#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       nsCOMPtr<nsISupports>*
       get_address()
         {
@@ -863,6 +887,8 @@ class nsCOMPtr<nsISupports>
           return this;
         }
 
+#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
       // This is going to become private soon, once all users of
       // nsCOMPtr stop using it.  It may even become:
       // void operator&() const {}
@@ -943,6 +969,20 @@ nsCOMPtr<T>::begin_assignment()
   }
 #endif
 
+#ifdef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
+// This is the broken version for IRIX, which can't handle the version below.
+
+template <class T>
+inline
+nsCOMPtr<T>*
+address_of( const nsCOMPtr<T>& aPtr )
+  {
+    return aPtr.get_address();
+  }
+
+#else // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
 template <class T>
 inline
 nsCOMPtr<T>*
@@ -959,6 +999,8 @@ address_of( const nsCOMPtr<T>& aPtr )
     return aPtr.get_address();
   }
 
+#endif // CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
 template <class T>
 class nsGetterAddRefs
     /*