[Bug libstdc++/71794] New: Std::array as an incomplete type in nested name specifier.

["p.bednarski at outlook dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71794

            Bug ID: 71794
           Summary: Std::array as an incomplete type in nested name
                    specifier.
           Product: gcc
           Version: 6.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: p.bednarski at outlook dot com
  Target Milestone: ---

Created attachment 38851
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38851&action=edit
Code that won't compile on GCC.

In code attached: MyContainer type works perfectly fine. std::vector works fine
as well.

Error message:
$ g++-6 -Wall -Wextra -Wpedantic --std=c++14  main.cpp 
main.cpp: In instantiation of ‘T foo() [with T = std::array<float, 4ul>]’:
main.cpp:39:31:   required from here
main.cpp:16:21: error: incomplete type ‘B<std::array<float, 4ul> >’ used in
nested name specifier
     return B<T>::bar();
            ~~~~~~~~~^~