[Bug libstdc++/85184] New: Remove __glibcxx_assert uses from std::variant

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85184

            Bug ID: 85184
           Summary: Remove __glibcxx_assert uses from std::variant
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

These assertions are being used to verify that the implementation works
correctly, i.e. to catch logic errors. Users should not be paying for those
checks at runtime.

The assertions should be removed before we declare our C++17 support
non-experimental.