[Bug c++/59211] init_priority doesn't work with constant expressions

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59211

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
Similar to PR 53017 (does the same +0 workaround work?). The main difference
with constructor seems to be a call to default_conversion.