return argument_pack;
}
-/* Returns true if the template argument vector ARGS contains
- any pack expansions, false otherwise. */
+/* Returns the number of pack expansions in the template argument vector
+ ARGS. */
-static bool
-any_pack_expanson_args_p (tree args)
+static int
+pack_expansion_args_count (tree args)
{
int i;
+ int count = 0;
if (args)
for (i = 0; i < TREE_VEC_LENGTH (args); ++i)
- if (PACK_EXPANSION_P (TREE_VEC_ELT (args, i)))
- return true;
- return false;
+ {
+ tree elt = TREE_VEC_ELT (args, i);
+ if (elt && PACK_EXPANSION_P (elt))
+ ++count;
+ }
+ return count;
}
/* Convert all template arguments to their appropriate types, and
subtract it from nparms to get the number of non-variadic
parameters. */
int variadic_p = 0;
+ int variadic_args_p = 0;
int post_variadic_parms = 0;
if (args == error_mark_node)
if (!post_variadic_parms)
inner_args = expand_template_argument_pack (inner_args);
+ /* Count any pack expansion args. */
+ variadic_args_p = pack_expansion_args_count (inner_args);
+
nargs = inner_args ? NUM_TMPL_ARGS (inner_args) : 0;
if ((nargs > nparms && !variadic_p)
|| (nargs < nparms - variadic_p
&& require_all_args
- && !any_pack_expanson_args_p (inner_args)
+ && !variadic_args_p
&& (!use_default_args
|| (TREE_VEC_ELT (parms, nargs) != error_mark_node
&& !TREE_PURPOSE (TREE_VEC_ELT (parms, nargs))))))
return error_mark_node;
}
+ /* We can't pass a pack expansion to a non-pack parameter of an alias
+ template (DR 1430). */
+ else if (in_decl && DECL_ALIAS_TEMPLATE_P (in_decl)
+ && variadic_args_p
+ && nargs - variadic_args_p < nparms - variadic_p)
+ {
+ if (complain & tf_error)
+ {
+ for (int i = 0; i < TREE_VEC_LENGTH (inner_args); ++i)
+ {
+ tree arg = TREE_VEC_ELT (inner_args, i);
+ tree parm = TREE_VALUE (TREE_VEC_ELT (parms, i));
+
+ if (PACK_EXPANSION_P (arg)
+ && !template_parameter_pack_p (parm))
+ {
+ error ("pack expansion argument for non-pack parameter "
+ "%qD of alias template %qD", parm, in_decl);
+ inform (DECL_SOURCE_LOCATION (parm), "declared here");
+ goto found;
+ }
+ }
+ gcc_unreachable ();
+ found:;
+ }
+ return error_mark_node;
+ }
/* We need to evaluate the template arguments, even though this
template-id may be nested within a "sizeof". */
--- /dev/null
+// PR c++/57138
+// { dg-do compile { target c++11 } }
+
+template <template <typename ... X> class T, typename ... Y>
+struct D
+{
+ template <typename ... Z>
+ using type = T <Y..., Z...>; // { dg-error "pack expansion" }
+};
+template <typename T>
+class A {};
+template <typename X, typename Y>
+struct B;
+template <typename T>
+struct B <int, T>
+{
+ typedef A <T> type;
+};
+template <typename X, typename Y>
+using C = typename B <X, Y>::type;
+struct E : public D <C> {};