Bug#1074118: deal.ii: FTBFS with CGAL 6.0

[Joachim Reichel]

Source: deal.ii
Version: 9.4.1-1
Severity: normal
Tags: ftbfs
X-Debbugs-Cc: reichel at debian.org

Dear maintainer,

your package fails to build with cgal 6.0~beta1-1, which has recently been
uploaded to experimental. See [1] for the release notes with breaking changes.

[1] https://github.com/CGAL/cgal/releases/tag/v6.0-beta1

Your package seems to be affected by the changes from boost::variant/optional
to std::variant/optional.

Best regards,
  Joachim