re PR c++/55220 ([c++11] ICE when doing partial template specialization on variadic template)

PR c++/55220 * pt.c (unify): A pack expansion that is not the last template argument makes the entire template argument list non-deduced. From-SVN: r196068

re PR c++/55220 ([c++11] ICE when doing partial template specialization on variadic template)
PR c++/55220 * pt.c (unify): A pack expansion that is not the last template argument makes the entire template argument list non-deduced. From-SVN: r196068
d132b74a · Jason Merrill · Jason Merrill · 06449b40 · d132b74a · d132b74a
Commit d132b74a authored Feb 14, 2013 by Jason Merrill Committed by Jason Merrill Feb 14, 2013
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gcc/cp/ChangeLog
+4 -0

gcc/cp/pt.c
+8 -0

gcc/testsuite/g++.dg/cpp0x/variadic-nondeduce2.C
+25 -0

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--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
 2013-02-14  Jason Merrill  <jason@redhat.com>

+	PR c++/55220
+	* pt.c (unify): A pack expansion that is not the last template
+	argument makes the entire template argument list non-deduced.
+
 	PR c++/56323
 	* name-lookup.c (do_class_using_decl): Handle typedefs with
 	inheriting constructors.

--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -16548,6 +16548,14 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
                && PACK_EXPANSION_P (TREE_VEC_ELT (parmvec, len - 1)))
              parm_variadic_p = 1;
            
+             for (i = 0; i < len - parm_variadic_p; ++i)
+	       /* If the template argument list of P contains a pack
+		  expansion that is not the last template argument, the
+		  entire template argument list is a non-deduced
+		  context.  */
+	       if (PACK_EXPANSION_P (TREE_VEC_ELT (parmvec, i)))
+		 return unify_success (explain_p);
+
            if (TREE_VEC_LENGTH (argvec) < len - parm_variadic_p)
              return unify_too_few_arguments (explain_p,
 					      TREE_VEC_LENGTH (argvec), len);

--- a/gcc/testsuite/g++.dg/cpp0x/variadic-nondeduce2.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic-nondeduce2.C
+// PR c++/55220
+// { dg-do compile { target c++11 } }
+
+template <typename ...> struct something_like_tuple
+{
+
+};
+
+template <typename, typename> struct is_last
+{
+  static const bool value = false;
+};
+
+// Head is non-deducible, so this can't work as the user intended
+template <typename T, template <typename ...> class Tuple, typename ... Head>
+struct is_last<T, Tuple<Head ..., T>>
+{
+  static const bool value = true;
+};
+
+#define SA(X) static_assert (X, #X)
+
+typedef something_like_tuple<char, int, float> something_like_tuple_t;
+SA ((is_last<float, something_like_tuple_t>::value == false));
+SA ((is_last<int, something_like_tuple_t>::value == false));