Re: C++ PATCH for c++/70778 (ICE with member template template parameter)

[Jason Merrill]

On Sat, Jul 23, 2016 at 10:50 PM, Jason Merrill <ja...@redhat.com> wrote:
> Here when we partially instantiated the declaration of the AddToFront
> partial specialization, which meant substituting into
> "Holder<Indexs>", we weren't replacing KeyType in the template
> parameter list of Holder, leading to confusion when we encounter it
> later and try to substitute in 0.
>
> Tested x86_64-pc-linux-gnu, applying to trunk.

commit fa7e4de043897f89467887f84e705cdd3a0cfb79
Author: Jason Merrill <ja...@redhat.com>
Date:   Fri Jul 22 16:42:52 2016 -0400

        PR c++/70778 - member template template parameter
    
        * pt.c (tsubst): Also substitute into the template of a
        BOUND_TEMPLATE_TEMPLATE_PARM.

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index a44bead..65fa982 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13232,13 +13232,20 @@ tsubst (tree t, tree args, tsubst_flags_t complain, 
tree in_decl)
 
                if (code == BOUND_TEMPLATE_TEMPLATE_PARM)
                  {
-                   tree argvec = tsubst (TYPE_TI_ARGS (t), args,
+                   tree tinfo = TYPE_TEMPLATE_INFO (t);
+                   /* We might need to substitute into the types of non-type
+                      template parameters.  */
+                   tree tmpl = tsubst (TI_TEMPLATE (tinfo), args,
+                                       complain, in_decl);
+                   if (tmpl == error_mark_node)
+                     return error_mark_node;
+                   tree argvec = tsubst (TI_ARGS (tinfo), args,
                                          complain, in_decl);
                    if (argvec == error_mark_node)
                      return error_mark_node;
 
                    TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (r)
-                     = build_template_info (TYPE_TI_TEMPLATE (t), argvec);
+                     = build_template_info (tmpl, argvec);
                  }
              }
            break;
diff --git a/gcc/testsuite/g++.dg/template/ttp29.C 
b/gcc/testsuite/g++.dg/template/ttp29.C
new file mode 100644
index 0000000..7d4e03a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/ttp29.C
@@ -0,0 +1,21 @@
+// PR c++/70778
+
+template <class KeyType>
+struct Stuff
+{
+  template <KeyType, class>
+  struct AddToFront;
+
+  template <KeyType ToAdd, template<KeyType> class Holder, KeyType Indexs>
+  struct AddToFront<ToAdd, Holder<Indexs> >
+  {
+  };
+};
+
+template <unsigned>
+struct Holder {};
+
+int main()
+{
+  Stuff<unsigned>::AddToFront<0, Holder<24> > t;
+}