2017-03-11 21:23 GMT+01:00 Tim Song <t.canens....@gmail.com>: > On Sat, Mar 11, 2017 at 1:32 PM, Daniel Krügler > <daniel.krueg...@gmail.com> wrote: >> This patch applies inline to all namespace scope const variables >> according to options A and B2 voted in during the Kona meeting, see: >> >> http://wiki.edg.com/pub/Wg21kona2017/StrawPolls/p0607r0.html >> >> During that work it has been found that std::ignore was not declared >> constexpr (http://cplusplus.github.io/LWG/lwg-defects.html#2773), >> which was fixed as well. > > Just adding constexpr to std::ignore does ~nothing. The assignment > operator needs to be made constexpr too; there is really no other > reason to use std::ignore.
There is nothing in the resolution of the issue (Nor in the discussion that argues for the change) that says so. Yes, I considered to make the assignment function template constexpr, but decided against it, because the wording of the issue doesn't have this requirement). I'm also aware of a test-case which would show the difference, but again: This was not what the issue said. In fact I'm in the process to open a new library issue that should impose that additional requirement. - Daniel
