Re: [RFC / RFH] Re-opened C++/51213 (access control under SFINAE)

[Paolo Carlini]

On 08/02/2012 06:53 PM, Jason Merrill wrote:

On 08/02/2012 12:21 PM, Paolo Carlini wrote:

+      if (complain & tf_error)
+        recheck_decl_substitution (spec, gen_tmpl, targ_ptr);
+      else
+        return error_mark_node;

I think we want to be consistent with the end of the function about whether we return error_mark_node or the decl after giving access errors in non-SFINAE context; I don't have a strong opinion either way, but this returns the decl, and the end of the function returns error_mark_node.

I see. Then, I restarted testing with this variant.

Paolo.

/////////////////////

Index: testsuite/g++.dg/cpp0x/sfinae37.C
===================================================================
--- testsuite/g++.dg/cpp0x/sfinae37.C   (revision 190071)
+++ testsuite/g++.dg/cpp0x/sfinae37.C   (working copy)
@@ -5,6 +5,12 @@ class C {
   typedef int type;
 };
 
+template<int>
+struct I;
+
+template<>
+struct I<2> { };
+
 template<class T, class = typename T::type>
 auto f(int) -> char;
 
@@ -13,6 +19,10 @@ auto f(...) -> char (&)[2];
 
 static_assert(sizeof(f<C>(0)) == 2, "Ouch");
 
+typedef int testf[sizeof(f<C>(0)) == 2 ? 1 : -1];
+
+I<sizeof(f<C>(0))> vf;
+
 template<class T>
 auto g(int) -> decltype(typename T::type(), char());
 
@@ -20,3 +30,7 @@ template<class>
 auto g(...) -> char (&)[2];
 
 static_assert(sizeof(g<C>(0)) == 2, "Ouch");
+
+typedef int testg[sizeof(g<C>(0)) == 2 ? 1 : -1];
+
+I<sizeof(g<C>(0))> vg;
Index: cp/pt.c
===================================================================
--- cp/pt.c     (revision 190071)
+++ cp/pt.c     (working copy)
@@ -14363,8 +14363,12 @@ instantiate_template_1 (tree tmpl, tree orig_args,
 
   if (spec != NULL_TREE)
     {
-      if (FNDECL_RECHECK_ACCESS_P (spec) && (complain & tf_error))
-       recheck_decl_substitution (spec, gen_tmpl, targ_ptr);
+      if (FNDECL_HAS_ACCESS_ERRORS (spec))
+       {
+         if (complain & tf_error)
+           recheck_decl_substitution (spec, gen_tmpl, targ_ptr);
+         return error_mark_node;
+       }
       return spec;
     }
 
@@ -14426,7 +14430,7 @@ instantiate_template_1 (tree tmpl, tree orig_args,
        {
          /* Remember to reinstantiate when we're out of SFINAE so the user
             can see the errors.  */
-         FNDECL_RECHECK_ACCESS_P (fndecl) = true;
+         FNDECL_HAS_ACCESS_ERRORS (fndecl) = true;
        }
       return error_mark_node;
     }
@@ -15122,9 +15126,11 @@ type_unification_real (tree tparms,
              location_t save_loc = input_location;
              if (DECL_P (parm))
                input_location = DECL_SOURCE_LOCATION (parm);
+             push_deferring_access_checks (dk_no_deferred);
              arg = tsubst_template_arg (arg, targs, complain, NULL_TREE);
              arg = convert_template_argument (parm, arg, targs, complain,
                                               i, NULL_TREE);
+             pop_deferring_access_checks ();
              input_location = save_loc;
              if (arg == error_mark_node)
                return 1;
Index: cp/cp-tree.h
===================================================================
--- cp/cp-tree.h        (revision 190071)
+++ cp/cp-tree.h        (working copy)
@@ -729,10 +729,10 @@ DEF_VEC_ALLOC_O (qualified_typedef_usage_t,gc);
 /* Non-zero if this template specialization has access violations that
    should be rechecked when the function is instantiated outside argument
    deduction.  */
-#define TINFO_RECHECK_ACCESS_P(NODE) \
+#define TINFO_HAS_ACCESS_ERRORS(NODE) \
   (TREE_LANG_FLAG_0 (TEMPLATE_INFO_CHECK (NODE)))
-#define FNDECL_RECHECK_ACCESS_P(NODE) \
-  (TINFO_RECHECK_ACCESS_P (DECL_TEMPLATE_INFO (NODE)))
+#define FNDECL_HAS_ACCESS_ERRORS(NODE) \
+  (TINFO_HAS_ACCESS_ERRORS (DECL_TEMPLATE_INFO (NODE)))
 
 struct GTY(()) tree_template_info {
   struct tree_common common;