[Bug c++/85708] New: A corrupt fold expression passed compilation

["violetcrestfall at hotmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85708

            Bug ID: 85708
           Summary: A corrupt fold expression passed compilation
           Product: gcc
           Version: 8.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: violetcrestfall at hotmail dot com
  Target Milestone: ---

Created attachment 44095
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44095&action=edit
A corrupt fold expression example that passed compilation with GCC

The example attached has passed compilation with
GCC 8.1 (on gcc.godbolt.org) and GCC 8.0.1 (r259500).
The 5th line in the example:
    (std::cerr << "Error: " << ... << std::forward<tArgs>(vArgs)) << std::endl;

[std::cerr << "Error: "] is not a cast-expression apparently, so this
expression should not have been recognized as a fold-expression.
The code failed to be compiled with MSVC 19.14 and Clang 6.0.0, which is the
correct behavior.