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Re: [PATCH] Decorate string_view members with nonnull attribute
On 14 June 2018 at 20:21, Ville Voutilainen <ville.voutilainen@gmail.com> wrote:
> On 14 June 2018 at 20:08, Jonathan Wakely <jwakely@redhat.com> wrote:
>>> Oops, indeed. But for gnu-attributes, surely we can decide whatever we
>>> want about what's
>>> valid and what's not?
>>
>>
>> We could say that #defining 'nonnull' and/or 'gnu' as a macro is
>> undefined, but then programs that the standard says are valid would
>> fail to compile, and we'd be a non-conforming implementation.
>>
>> We can use __attribute__(__nonnull__)) so that we accept those
>> programs (and be a conforming implementation). Why would we choose to
>> be non-conforming when we don't have to?
>
> I can read the specification liberally enough that it might give us
> the freedom to disallow programs
> that #define names that our implementation uses for vendor attributes.
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.