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Re: [PATCH] Decorate string_view members with nonnull attribute
On 14 June 2018 at 20:40, Jonathan Wakely <jwakely@redhat.com> wrote:
>> Namely "For an attribute-token (including an attribute-scoped-token)
>> not specified in this document, the behavior is
>> implementation-defined.", aka [dcl.attr.grammar]/6.
>
>
> As I said on IRC, if the user does
>
> #define gnu R"(
> ,= ,-_-. =.
> ((_/)o o(\_))
> `-'(. .)`-'
> \_/
> )"
>
> then the attribute-scoped-token isn't even valid, and so the behaviour
> of the implementation-defined gnu::nonnull attribute doesn't matter.
> The code doesn't contain such an attribute.
>
> This seems like an unnecessary discussion: we should just use the
> __attribute__ form instead.
That may well be, but deciding to handle preprocessor definitions of
vendor attributes
in a particular way doesn't make us non-conforming. The behaviour of a
gnu::nonnull
would, as far as I understand it, possibly include restrictions on
what the preprocessor
can do with it, just like the specification for standard attributes
does. The preprocessor
is part of the implementation, not a magical separate step that can do
whatever it pleases.
Conformance being a moot point, I'd prefer using the standard
attribute syntax if we can,
instead of using the gnuattribute syntax, but that's not a strong preference.