[Bug c++/78948] [C++17] constexpr if instantiating too eagerly

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78948

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org
   Target Milestone|---                         |7.0

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
I seem to remember some discussion in Oulu about why it wouldn't work to call
discarded statements unevaluated, but I don't remember the reasoning.  I
suppose it's that we say a few things about unevaluated operands that we don't
want to apply: prohibiting lambdas, and allowing bare non-static data members
(DR 850).  The former is easy to handle; the latter doesn't seem worth worrying
much about.