> On Nov 13, 2019, at 6:56 PM, Richard Smith via Core <core@lists.isocpp.org> wrote:
>
> Hi core and SG10!
>
> (Noticed by Jens when reviewing the merge of CWG motion 8.)
>
> P1907R1 made significant changes to the behavior of non-type template parameters. It should have affected some feature-test macro, but didn't. Should we bump the version of __cpp_nontype_template_args or __cpp_nontype_template_parameter_class?
A bump in __cpp_nontype_template_parameter_class seems appropriate to me.
Daveed
I agree. This is the one introduced by P0732. I'd emailed Jens on Friday to say the same but he missed the email.
Maybe we should bump both macros? P1907 also allows more kinds of NTTP argument (eg, pointers/references to subobjects) and more kinds of parameter (eg, floating-point parameters), not just classes.
That said... I'm actually more inclined to say we should remove __cpp_nontype_template_parameter_class entirely and just bump __cpp_nontype_template_args. No-one ever fully implemented __cpp_nontype_template_parameter_class as far as I'm aware, and the feature we ended up with isn't class-type-specific (what we have now is "anything fully constant other than non-public subobjects or rvalue references").
Is this editorial or does this need to go through a paper/issue?
If there's no objection from either CWG or SG10, I'd be prepared to make a change editorially. (We bump __cplusplus editorially, and this seems to be in a somewhat similar bucket.)