[PATCH 11/18] mark EXPR_PACK_EXPANSION as typed only

[Nathan Froyd <froydnj at codesourcery dot com>]

EXPR_PACK_EXPANSION nodes store things in TREE_CHAIN, for symmetry with
TYPE_PACK_EXPANSIONs.  In the interest of expendiency towards slimming
tree_exp, this patch moves EXPR_PACK_EXPANSION's use of TREE_CHAIN into
a local TREE_OPERAND.  I suppose the conditional would be needed in any
event later on...

The odd case in mangle.c is needed to avoid mangling
PACK_EXPANSION_PARAMETER_PACKS; doing so would lead to an ICE.

-Nathan

gcc/cp/
	* cp-tree.def (EXPR_PACK_EXPANSION): Add an operand.
	* cp-objcp-common.c (cp_common_init_ts): Mark it as TS_TYPED.
	* cp-tree.h (PACK_EXPANSION_PARAMETER_PACKS): Use the new operand
	of EXPR_PACK_EXPANSION.
	* mangle.c (write_expression): Don't mangle all of EXPR_PACK_EXPANSION.

diff --git a/gcc/cp/cp-objcp-common.c b/gcc/cp/cp-objcp-common.c
index 57358b1..90a4a9b 100644
--- a/gcc/cp/cp-objcp-common.c
+++ b/gcc/cp/cp-objcp-common.c
@@ -238,11 +238,11 @@ cp_common_init_ts (void)
   MARK_TS_COMMON (TYPEOF_TYPE);
   MARK_TS_COMMON (BASELINK);
   MARK_TS_COMMON (TYPE_PACK_EXPANSION);
-  MARK_TS_COMMON (EXPR_PACK_EXPANSION);
   MARK_TS_COMMON (DECLTYPE_TYPE);
   MARK_TS_COMMON (BOUND_TEMPLATE_TEMPLATE_PARM);
   MARK_TS_COMMON (UNBOUND_CLASS_TEMPLATE);
 
+  MARK_TS_TYPED (EXPR_PACK_EXPANSION);
   MARK_TS_TYPED (SWITCH_STMT);
   MARK_TS_TYPED (IF_STMT);
   MARK_TS_TYPED (FOR_STMT);
diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def
index 42840a8..366013a 100644
--- a/gcc/cp/cp-tree.def
+++ b/gcc/cp/cp-tree.def
@@ -413,7 +413,7 @@ DEFTREECODE (TYPE_PACK_EXPANSION, "type_pack_expansion", tcc_type, 0)
 
    EXPR_PACK_EXPANSION plays precisely the same role as TYPE_PACK_EXPANSION,
    but will be used for expressions.  */
-DEFTREECODE (EXPR_PACK_EXPANSION, "expr_pack_expansion", tcc_expression, 1)
+DEFTREECODE (EXPR_PACK_EXPANSION, "expr_pack_expansion", tcc_expression, 2)
 
 /* Selects the Ith parameter out of an argument pack. This node will
    be used when instantiating pack expansions; see
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 3249ef0..7bdf9e0 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -2713,7 +2713,10 @@ extern void decl_shadowed_for_var_insert (tree, tree);
 
 /* The list of parameter packs used in the PACK_EXPANSION_* node. The
    TREE_VALUE of each TREE_LIST contains the parameter packs.  */
-#define PACK_EXPANSION_PARAMETER_PACKS(NODE) TREE_CHAIN (NODE)
+#define PACK_EXPANSION_PARAMETER_PACKS(NODE)		\
+  *(TREE_CODE (NODE) == EXPR_PACK_EXPANSION		\
+    ? &TREE_OPERAND (NODE, 1)				\
+    : &TREE_CHAIN (TYPE_PACK_EXPANSION_CHECK (NODE)))
 
 /* Determine if this is an argument pack.  */
 #define ARGUMENT_PACK_P(NODE)                          \
diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index 4d2ace6..e4d53c5 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -2653,6 +2653,10 @@ write_expression (tree expr)
 	      len = 2;
 	      break;
 
+	    case EXPR_PACK_EXPANSION:
+	      len = 1;
+	      break;
+
 	    default:
 	      len = TREE_OPERAND_LENGTH (expr);
 	      break;