[PATCH] c++: stream PACK_EXPANSION_EXTRA_ARGS [PR106761]

[Patrick Palka <ppalka@redhat.com>]

It looks like some xtreme-header-* tests are failing after the libstdc++
change r13-2158-g02f6b405f0e9dc ultimately because we're neglecting
to stream PACK_EXPANSION_EXTRA_ARGS, which leads to false equivalences
of different partial instantiations of _TupleConstraints::__constructible.

Tested on x86_64-pc-linux-gnu, does this look OK for trunk?

	PR c++/106761

gcc/cp/ChangeLog:

	* module.cc (trees_out::type_node) <case TYPE_PACK_EXPANSION>:
	Stream PACK_EXPANSION_EXTRA_ARGS.
	(trees_in::tree_node) <case TYPE_PACK_EXPANSION>: Likewise.
---
 gcc/cp/module.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 1a1ff5be574..9a9ef4e3332 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -8922,6 +8922,7 @@ trees_out::type_node (tree type)
       if (streaming_p ())
 	u (PACK_EXPANSION_LOCAL_P (type));
       tree_node (PACK_EXPANSION_PARAMETER_PACKS (type));
+      tree_node (PACK_EXPANSION_EXTRA_ARGS (type));
       break;
 
     case TYPENAME_TYPE:
@@ -9455,12 +9456,14 @@ trees_in::tree_node (bool is_use)
 	    {
 	      bool local = u ();
 	      tree param_packs = tree_node ();
+	      tree extra_args = tree_node ();
 	      if (!get_overrun ())
 		{
 		  tree expn = cxx_make_type (TYPE_PACK_EXPANSION);
 		  SET_TYPE_STRUCTURAL_EQUALITY (expn);
 		  PACK_EXPANSION_PATTERN (expn) = res;
 		  PACK_EXPANSION_PARAMETER_PACKS (expn) = param_packs;
+		  PACK_EXPANSION_EXTRA_ARGS (expn) = extra_args;
 		  PACK_EXPANSION_LOCAL_P (expn) = local;
 		  res = expn;
 		}
-- 
2.38.0.rc0