[Bug c++/86862] New: Segfault using extern template on class deriving from streambuf

["jessemaurais at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86862

            Bug ID: 86862
           Summary: Segfault using extern template on class deriving from
                    streambuf
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jessemaurais at gmail dot com
  Target Milestone: ---

Created attachment 44505
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44505&action=edit
Source code with system info and command line using -v -save-temps added as
comments

Using GCC 8.2.0-1 in Debian testing the code

template <class Char, template <class> class Traits>
class base : public std::basic_streambuf<Char, Traits<Char>>
{};
template <class Char, template <class> class Traits = std::char_traits>
class derived : public base<Char, Traits>
{};
extern template class derived<char>;

segfaults apparently on parsing the base class for the extern template. No
special command line arguments are given. See the attachment for the full info
given by -v -save-temps