Re: C++ PATCH for c++/42329, P0522 and other template template parm issues

[Jason Merrill]

On Wed, Dec 21, 2016 at 4:06 PM, Jason Merrill <ja...@redhat.com> wrote:
> The fourth patch fixes 42329, where we were failing to bind a template
> template-parameter to a base class of the argument type.

We need to make sure that the argument is a class before we try this.

Tested x86_64-pc-linux-gnu, applied to trunk.

commit 9c6ba5bf60d35afce20f8bee7e2bb2ac2efe37a4
Author: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Thu Dec 22 15:19:54 2016 +0000

            PR c++/78898 - ICE on constructor with TTP
    
            PR c++/42329
            * pt.c (unify): Don't look for a class template from a non-class.
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@243890 
138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 301eb52..7711546 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -20292,7 +20292,8 @@ unify (tree tparms, tree targs, tree parm, tree arg, 
int strict,
 
       if (TREE_CODE (parm) == BOUND_TEMPLATE_TEMPLATE_PARM)
        {
-         if (strict_in & UNIFY_ALLOW_DERIVED)
+         if ((strict_in & UNIFY_ALLOW_DERIVED)
+             && CLASS_TYPE_P (arg))
            {
              /* First try to match ARG directly.  */
              tree t = try_class_unification (tparms, targs, parm, arg,
diff --git a/gcc/testsuite/g++.dg/template/ttp30.C 
b/gcc/testsuite/g++.dg/template/ttp30.C
new file mode 100644
index 0000000..f7b9ce7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/ttp30.C
@@ -0,0 +1,6 @@
+// PR c++/78898
+
+struct A {
+  template <class T> A(T);
+  template <template <typename> class SmartPtr> A(SmartPtr<int>) { A(0); }
+};