c++: unifying equal NONTYPE_ARGUMENT_PACKs [PR102547]

Here during partial ordering of the two partial specializations we end
up in unify with parm=arg=NONTYPE_ARGUMENT_PACK<V0, V1>, and crash shortly
thereafter because uses_template_parms(parms) calls potential_const_expr
which doesn't handle NONTYPE_ARGUMENT_PACK.

This patch fixes this by extending potential_constant_expression to handle
NONTYPE_ARGUMENT_PACK appropriately.

	PR c++/102547

gcc/cp/ChangeLog:

	* constexpr.c (potential_constant_expression_1): Handle
	NONTYPE_ARGUMENT_PACK.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/variadic-partial2.C: New test.
	* g++.dg/cpp0x/variadic-partial2a.C: New test.

(cherry picked from commit d4c470c376b4cb82c9a0b7e8a4b88c44d5e4289d)

diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 31facd274e9a02dc45a48f0a7b256170f70382a3..3da7a2461673e701fa64e3ad39bff040db6130a9 100644 (file)
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -8940,6 +8940,16 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
     case CO_RETURN_EXPR:
       return false;
 
+    case NONTYPE_ARGUMENT_PACK:
+      {
+       tree args = ARGUMENT_PACK_ARGS (t);
+       int len = TREE_VEC_LENGTH (args);
+       for (int i = 0; i < len; ++i)
+         if (!RECUR (TREE_VEC_ELT (args, i), any))
+           return false;
+       return true;
+      }
+
     default:
       if (objc_non_constant_expr_p (t))
        return false;

diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic-partial2.C b/gcc/testsuite/g++.dg/cpp0x/variadic-partial2.C
new file mode 100644 (file)
index 0000000..df61f26
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic-partial2.C
@@ -0,0 +1,16 @@
+// PR c++/102547
+// { dg-do compile { target c++11 } }
+
+template<int... Vs>
+struct vals { };
+
+template<class V, class T>
+struct vals_client { };
+
+template<int V0, int V1, class T>
+struct vals_client<vals<V0, V1>, T> { };
+
+template<int V0, int V1>
+struct vals_client<vals<V0, V1>, void> { };
+
+template struct vals_client<vals<1, 2>, void>; //- "sorry, unimplemented..., ICE"

diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic-partial2a.C b/gcc/testsuite/g++.dg/cpp0x/variadic-partial2a.C
new file mode 100644 (file)
index 0000000..e98bdbb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic-partial2a.C
@@ -0,0 +1,22 @@
+// PR c++/102547
+// { dg-do compile { target c++11 } }
+// A version of variadic-partial2.C where partial ordering is performed
+// on function templates instead of class templates.
+
+template<int... Vs>
+struct vals { };
+
+template<class V, class T>
+void f(V, T) { };
+
+template<int V0, int V1, class T>
+void f(vals<V0, V1>, T) { };
+
+template<int V0, int V1>
+void f(vals<V0, V1>, char) { };
+
+template void f(vals<1, 2>, char); //- "sorry, unimplemented..., ICE"
+
+int main() {
+  f(vals<1, 3>{}, 'a'); //- "sorry, unimplemented..., ICE"
+}