From patchwork Fri Feb 22 19:16:11 2013
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Subject: C++ PATCH for c++/56359 (wrong access error with function template)
Date: Fri, 22 Feb 2013 09:16:11 -0000
From: Jason Merrill <jason@redhat.com>
X-Patchwork-Id: 222678
Message-Id: <5127C3FB.1030405@redhat.com>
To: gcc-patches List <gcc-patches@gcc.gnu.org>

We need to be careful not to do any access checking on the actual 
arguments to the function when we're pushed into the context of the 
function being instantiated.

Tested x86_64-pc-linux-gnu, applying to trunk.


commit 7498f299d97da75ce3ab30d0626818a143fbaab9
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Feb 22 10:44:03 2013 -0500

    	PR c++/56359
    	* call.c (can_convert_arg): Discard access checks.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 25dfd51..7c41421 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -8765,11 +8765,18 @@ can_convert_arg (tree to, tree from, tree arg, int flags,
 
   /* Get the high-water mark for the CONVERSION_OBSTACK.  */
   p = conversion_obstack_alloc (0);
+  /* We want to discard any access checks done for this test,
+     as we might not be in the appropriate access context and
+     we'll do the check again when we actually perform the
+     conversion.  */
+  push_deferring_access_checks (dk_deferred);
 
   t  = implicit_conversion (to, from, arg, /*c_cast_p=*/false,
 			    flags, complain);
   ok_p = (t && !t->bad_p);
 
+  /* Discard the access checks now.  */
+  pop_deferring_access_checks ();
   /* Free all the conversions we allocated.  */
   obstack_free (&conversion_obstack, p);
 
diff --git a/gcc/testsuite/g++.dg/template/access25.C b/gcc/testsuite/g++.dg/template/access25.C
new file mode 100644
index 0000000..e882a70
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/access25.C
@@ -0,0 +1,20 @@
+// PR c++/56359
+
+typedef int (*InvocationCallback) (const int &);
+
+template < typename target_t >
+void SetPrototypeMethod (target_t, const char *, InvocationCallback);
+
+class A
+{
+    void Initialize ();
+protected:
+    static int Stop (const int &);
+    void Stop ();  // comment out to make the bug disappear.
+};
+
+void
+A::Initialize ()
+{
+    SetPrototypeMethod (0, "stop", A::Stop);
+}