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

[Patrick Palka <ppalka@redhat.com>]

On Tue, 20 Sep 2022, Nathan Sidwell wrote:

> On 9/19/22 09:52, Patrick Palka wrote:
> > 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.
> 
> 
> Looks good, I wonder why I missed that.  (I guess extracting a testcase out of
> the headers was too tricky?)

Many thanks.  I managed to produce a small testcase which mirrors the
format of the xtreme-header-2* testcase.  Does the following look OK?

-- >8 --

	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/testsuite/ChangeLog:

	* g++.dg/modules/pr106761.h: New test.
	* g++.dg/modules/pr106761_a.H: New test.
	* g++.dg/modules/pr106761_b.C: New test.
---
 gcc/cp/module.cc                          |  3 +++
 gcc/testsuite/g++.dg/modules/pr106761.h   | 22 ++++++++++++++++++++++
 gcc/testsuite/g++.dg/modules/pr106761_a.H |  5 +++++
 gcc/testsuite/g++.dg/modules/pr106761_b.C |  7 +++++++
 4 files changed, 37 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/modules/pr106761.h
 create mode 100644 gcc/testsuite/g++.dg/modules/pr106761_a.H
 create mode 100644 gcc/testsuite/g++.dg/modules/pr106761_b.C

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;
 		}
diff --git a/gcc/testsuite/g++.dg/modules/pr106761.h b/gcc/testsuite/g++.dg/modules/pr106761.h
new file mode 100644
index 00000000000..9f22a22a45d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr106761.h
@@ -0,0 +1,22 @@
+// PR c++/106761
+
+template<class...>
+struct __and_;
+
+template<class, class>
+struct is_convertible;
+
+template<class... Ts>
+struct _TupleConstraints {
+  template<class... Us>
+  using __constructible = __and_<is_convertible<Ts, Us>...>;
+};
+
+template<class... Ts>
+struct tuple {
+  template<class... Us>
+  using __constructible
+    = typename _TupleConstraints<Ts...>::template __constructible<Us...>;
+};
+
+tuple<int, int> t;
diff --git a/gcc/testsuite/g++.dg/modules/pr106761_a.H b/gcc/testsuite/g++.dg/modules/pr106761_a.H
new file mode 100644
index 00000000000..8ad116412af
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr106761_a.H
@@ -0,0 +1,5 @@
+// PR c++/106761
+// { dg-additional-options -fmodule-header }
+
+// { dg-module-cmi {} }
+#include "pr106761.h"
diff --git a/gcc/testsuite/g++.dg/modules/pr106761_b.C b/gcc/testsuite/g++.dg/modules/pr106761_b.C
new file mode 100644
index 00000000000..336cb12757e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr106761_b.C
@@ -0,0 +1,7 @@
+// PR c++/106761
+// { dg-additional-options -fmodules-ts }
+
+#include "pr106761.h"
+import "pr106761_a.H";
+
+tuple<int, int> u = t;
-- 
2.38.0.rc0.52.gdda7228a83