The problem in this testcase is that when we first parse C<T> we look
up the canonical instantiation of C<T> which doesn't see inside A<T>
because it happens at global scope, but then in strip_typedefs we are
in the context of A<T>, so the call to make_typename_type in
strip_typedefs was finding the error and causing trouble, because we
don't expect strip_typedefs to change anything.
This is an oddity with the current semi-specification of alias
templates that I hope to address in the standard soon, but for now
this patch addresses the issue by rebuilding a TYPENAME_TYPE in
strip_typedefs, even if we could resolve it in the current scope.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 9ab225e01a4aad9a95b6a744196cd03bce9c6e28
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Jun 27 15:25:30 2017 -0400
PR c++/72764 - ICE with invalid template typename.
* decl.c (build_typename_type): No longer static.
* tree.c (strip_typedefs): Use it instead of make_typename_type.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index f82b1b6..946a916 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6087,6 +6087,7 @@ extern tree define_label (location_t,
tree);
extern void check_goto (tree);
extern bool check_omp_return (void);
extern tree make_typename_type (tree, tree, enum tag_types,
tsubst_flags_t);
+extern tree build_typename_type (tree, tree, tree,
tag_types);
extern tree make_unbound_class_template (tree, tree, tree,
tsubst_flags_t);
extern tree build_library_fn_ptr (const char *, tree, int);
extern tree build_cp_library_fn_ptr (const char *, tree, int);
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 93e24fc..3d96a3e 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -3594,7 +3594,7 @@ struct typename_hasher : ggc_ptr_hash<tree_node>
static GTY (()) hash_table<typename_hasher> *typename_htab;
-static tree
+tree
build_typename_type (tree context, tree name, tree fullname,
enum tag_types tag_type)
{
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index bb17278..4535af6 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -1503,13 +1503,13 @@ strip_typedefs (tree t, bool *remove_attributes)
break;
case TYPENAME_TYPE:
{
+ bool changed = false;
tree fullname = TYPENAME_TYPE_FULLNAME (t);
if (TREE_CODE (fullname) == TEMPLATE_ID_EXPR
&& TREE_OPERAND (fullname, 1))
{
tree args = TREE_OPERAND (fullname, 1);
tree new_args = copy_node (args);
- bool changed = false;
for (int i = 0; i < TREE_VEC_LENGTH (args); ++i)
{
tree arg = TREE_VEC_ELT (args, i);
@@ -1533,12 +1533,15 @@ strip_typedefs (tree t, bool *remove_attributes)
else
ggc_free (new_args);
}
- result = make_typename_type (strip_typedefs (TYPE_CONTEXT (t),
- remove_attributes),
- fullname, typename_type, tf_none);
- /* Handle 'typedef typename A::N N;' */
- if (typedef_variant_p (result))
- result = TYPE_MAIN_VARIANT (DECL_ORIGINAL_TYPE (TYPE_NAME (result)));
+ tree ctx = strip_typedefs (TYPE_CONTEXT (t), remove_attributes);
+ if (!changed && ctx == TYPE_CONTEXT (t) && !typedef_variant_p (t))
+ return t;
+ tree name = fullname;
+ if (TREE_CODE (fullname) == TEMPLATE_ID_EXPR)
+ name = TREE_OPERAND (fullname, 0);
+ /* Use build_typename_type rather than make_typename_type because we
+ don't want to resolve it here, just strip typedefs. */
+ result = build_typename_type (ctx, name, fullname, typename_type);
}
break;
case DECLTYPE_TYPE:
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-60.C
b/gcc/testsuite/g++.dg/cpp0x/alias-decl-60.C
new file mode 100644
index 0000000..6bf9b7b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-60.C
@@ -0,0 +1,16 @@
+// PR c++/72764
+// { dg-do compile { target c++11 } }
+
+template < typename > struct A;
+template < typename > struct B {};
+
+template < typename T >
+using C = typename A < T >::template D < T >;
+
+template < typename T > struct A
+{
+ // should be: template < typename > struct D : B < C < T > > {};
+ struct D : B < C < T > > {}; // { dg-error "not a class template" }
+};
+
+A < int >::D a; // { dg-message "required" }
