[Bug c++/85552] New: Adding curly braces to the declaration of a std::unique_ptr to a forward declared class breaks compilation

[parker.coates at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85552

            Bug ID: 85552
           Summary: Adding curly braces to the declaration of a
                    std::unique_ptr to a forward declared class breaks
                    compilation
           Product: gcc
           Version: 7.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: parker.coates at gmail dot com
  Target Milestone: ---

Created attachment 44031
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44031&action=edit
Minimal test case

The attached sample fails to compile on GCC, despite working on Clang and MSVC.
https://godbolt.org/g/D9bHBN

To my non-expert eyes, this appears to be a bug, as there is no reason this
code should need to generate a destructor.