re PR c++/88986 (ICE: tree check: expected tree that contains 'decl minimal' structure, have 'error_mark' in member_vec_binary_search, at cp/name-lookup.c:1136)

/cp
2019-02-13  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/88986
	* decl.c (make_typename_type): Allow for TYPE_PACK_EXPANSION as
	context (the first argument).
	* pt.c (tsubst, case TYPENAME_TYPE): Handle TYPE_PACK_EXPANSION
	as context.

/testsuite
2019-02-13  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/88986
	* g++.dg/cpp1z/using4.C: New.
	* g++.dg/cpp1z/using5.C: Likewise.
	* g++.dg/cpp1z/using6.C: Likewise.

From-SVN: r268839

7 files changed, 73 insertions, 3 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index cb74761..b423f7c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2019-02-13  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/88986
+	* decl.c (make_typename_type): Allow for TYPE_PACK_EXPANSION as
+	context (the first argument).
+	* pt.c (tsubst, case TYPENAME_TYPE): Handle TYPE_PACK_EXPANSION
+	as context.
+
 2019-02-12  Jason Merrill  <jason@redhat.com>
 
 	PR c++/89144 - link error with constexpr initializer_list.
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 4038197..31d7dc5 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -3816,7 +3816,9 @@ make_typename_type (tree context, tree name, enum tag_types tag_type,
   gcc_assert (identifier_p (name));
   gcc_assert (TYPE_P (context));
 
-  if (!MAYBE_CLASS_TYPE_P (context))
+  if (TREE_CODE (context) == TYPE_PACK_EXPANSION)
+    /* This can happen for C++17 variadic using (c++/88986).  */;
+  else if (!MAYBE_CLASS_TYPE_P (context))
     {
       if (complain & tf_error)
 	error ("%q#T is not a class", context);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b96e3aa..e6782fe 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14928,8 +14928,25 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 
     case TYPENAME_TYPE:
       {
-	tree ctx = tsubst_aggr_type (TYPE_CONTEXT (t), args, complain,
-				     in_decl, /*entering_scope=*/1);
+	tree ctx = TYPE_CONTEXT (t);
+	if (TREE_CODE (ctx) == TYPE_PACK_EXPANSION)
+	  {
+	    ctx = tsubst_pack_expansion (ctx, args, complain, in_decl);
+	    if (ctx == error_mark_node
+		|| TREE_VEC_LENGTH (ctx) > 1)
+	      return error_mark_node;
+	    if (TREE_VEC_LENGTH (ctx) == 0)
+	      {
+		if (complain & tf_error)
+		  error ("%qD is instantiated for an empty pack",
+			 TYPENAME_TYPE_FULLNAME (t));
+		return error_mark_node;
+	      }
+	    ctx = TREE_VEC_ELT (ctx, 0);
+	  }
+	else
+	  ctx = tsubst_aggr_type (ctx, args, complain, in_decl,
+				  /*entering_scope=*/1);
 	if (ctx == error_mark_node)
 	  return error_mark_node;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index bf9d01c..d221495 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2019-02-13  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/88986
+	* g++.dg/cpp1z/using4.C: New.
+	* g++.dg/cpp1z/using5.C: Likewise.
+	* g++.dg/cpp1z/using6.C: Likewise.
+
 2019-02-13  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/89290
diff --git a/gcc/testsuite/g++.dg/cpp1z/using4.C b/gcc/testsuite/g++.dg/cpp1z/using4.C
new file mode 100644
index 0000000..2c133d9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/using4.C
@@ -0,0 +1,12 @@
+// PR c++/88986
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct B { typedef int type; };
+
+template<typename ...T> struct C : T... {
+  using typename T::type ...;  // { dg-warning "pack expansion" "" { target c++14_down } }
+  void f() { type value; }
+};
+
+template struct C<B>;
diff --git a/gcc/testsuite/g++.dg/cpp1z/using5.C b/gcc/testsuite/g++.dg/cpp1z/using5.C
new file mode 100644
index 0000000..90f37cc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/using5.C
@@ -0,0 +1,10 @@
+// PR c++/88986
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+template<typename ...T> struct C : T... {
+  using typename T::type ...;  // { dg-warning "pack expansion" "" { target c++14_down } }
+  void f() { type value; }  // { dg-error "empty pack" }
+};
+
+template struct C<>;
diff --git a/gcc/testsuite/g++.dg/cpp1z/using6.C b/gcc/testsuite/g++.dg/cpp1z/using6.C
new file mode 100644
index 0000000..af78d6d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/using6.C
@@ -0,0 +1,14 @@
+// PR c++/88986
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct B1 { typedef int type; };
+struct B2 { typedef double type; };
+
+template<typename ...T> struct C : T... {
+  using typename T::type ...;  // { dg-warning "pack expansion" "" { target c++14_down } }
+  // { dg-error "redeclaration" "" { target *-*-* } .-1 }
+  void f() { type value; }
+};
+
+template struct C<B1, B2>;