From 093e897c1b002c4e8977095399a3208885d13229 Mon Sep 17 00:00:00 2001
From: "dbaron%fas.harvard.edu" <dbaron%fas.harvard.edu>
Date: Sat, 7 Apr 2001 17:25:16 +0000
Subject: [PATCH] Fix bustage on VC++ and gcc 2.7.2.x caused by incorrect
 overload resolution.

---
 configure.in          | 45 +++++++++++++++++++++++++++++++++++++++++++
 xpcom/base/nsCOMPtr.h | 10 +++++++++-
 xpcom/glue/nsCOMPtr.h | 10 +++++++++-
 3 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/configure.in b/configure.in
index c29badbe8ef..c5b59085448 100644
--- a/configure.in
+++ b/configure.in
@@ -3487,6 +3487,51 @@ if test "$_PEDANTIC"; then
     esac
 fi
 
+dnl Autoconf test for gcc 2.7.2.x (and maybe others?) so that we don't
+dnl provide non-const forms of the operator== for comparing nsCOMPtrs to
+dnl raw pointers in nsCOMPtr.h.  (VC++ has the same bug.)
+
+AC_LANG_CPLUSPLUS
+_SAVE_CXXFLAGS=$CXXFLAGS
+CXXFLAGS="$CXXFLAGS ${_WARNINGS_CXXFLAGS}"
+
+AC_CACHE_CHECK(for correct overload resolution with const and templates,
+    ac_nscap_nonconst_opeq_bug,
+    [AC_TRY_COMPILE([
+                      template <class T>
+                      class Pointer
+                        {
+                        public:
+                          T* myPtr;
+                        };
+                      
+                      template <class T, class U>
+                      int operator==(const Pointer<T>& rhs, U* lhs)
+                        {
+                          return rhs.myPtr == lhs;
+                        }
+                      
+                      template <class T, class U>
+                      int operator==(const Pointer<T>& rhs, const U* lhs)
+                        {
+                          return rhs.myPtr == lhs;
+                        }
+                    ],
+                    [
+                      Pointer<int> foo;
+                      const int* bar;
+                      return foo == bar;
+                    ],
+                    ac_nscap_nonconst_opeq_bug="no",
+                    ac_nscap_nonconst_opeq_bug="yes")])
+
+AC_LANG_C
+CXXFLAGS="$_SAVE_CXXFLAGS"
+
+if test "$ac_nscap_nonconst_opeq_bug" = "yes" ; then
+    AC_DEFINE(NSCAP_DONT_PROVIDE_NONCONST_OPEQ)
+fi
+
 dnl pass -Wno-long-long to the compiler
 MOZ_ARG_ENABLE_BOOL(long-long-warning,
 [  --enable-long-long-warning
diff --git a/xpcom/base/nsCOMPtr.h b/xpcom/base/nsCOMPtr.h
index ab44a71634d..955f0fae459 100644
--- a/xpcom/base/nsCOMPtr.h
+++ b/xpcom/base/nsCOMPtr.h
@@ -1193,7 +1193,15 @@ operator!=( const U* lhs, const nsCOMPtr<T>& rhs )
   // better conversion for the other argument, define additional
   // |operator==| without the |const| on the raw pointer.
   // See bug 65664 for details.
-#ifndef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
+// This is defined by an autoconf test, but VC++ also has a bug that
+// prevents us from using these.  (It also, fortunately, has the bug
+// that we don't need them either.)
+#ifdef _MSC_VER
+#define NSCAP_DONT_PROVIDE_NONCONST_OPEQ
+#endif
+
+#ifndef NSCAP_DONT_PROVIDE_NONCONST_OPEQ
 template <class T, class U>
 inline
 NSCAP_BOOL
diff --git a/xpcom/glue/nsCOMPtr.h b/xpcom/glue/nsCOMPtr.h
index ab44a71634d..955f0fae459 100644
--- a/xpcom/glue/nsCOMPtr.h
+++ b/xpcom/glue/nsCOMPtr.h
@@ -1193,7 +1193,15 @@ operator!=( const U* lhs, const nsCOMPtr<T>& rhs )
   // better conversion for the other argument, define additional
   // |operator==| without the |const| on the raw pointer.
   // See bug 65664 for details.
-#ifndef CANT_RESOLVE_CPP_CONST_AMBIGUITY
+
+// This is defined by an autoconf test, but VC++ also has a bug that
+// prevents us from using these.  (It also, fortunately, has the bug
+// that we don't need them either.)
+#ifdef _MSC_VER
+#define NSCAP_DONT_PROVIDE_NONCONST_OPEQ
+#endif
+
+#ifndef NSCAP_DONT_PROVIDE_NONCONST_OPEQ
 template <class T, class U>
 inline
 NSCAP_BOOL