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Re: [C++ PATCH] "decomposition declaration" -> "structured binding" in C++ diagnostics
- From: Jason Merrill <jason at redhat dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 3 Jul 2017 17:01:11 -0400
- Subject: Re: [C++ PATCH] "decomposition declaration" -> "structured binding" in C++ diagnostics
- Authentication-results: sourceware.org; auth=none
- References: <20170630172630.GO2123@tucnak> <CADzB+2=Dea=Pe=APhXpRhyaG4r4-ZAerabC8QWXeMvHB9SKvgw@mail.gmail.com> <20170630193550.GQ2123@tucnak> <CADzB+2=jrQsLFG5dz7+CVCxrGsAKqgk-sYf_fhQOC5rj5VXqSQ@mail.gmail.com> <20170703160202.GY2123@tucnak> <CADzB+2nB8mOtj9xq+bL22N8KaDY2Bj55B1VRGyf0Pg0fsSifNA@mail.gmail.com> <20170703195916.GA2123@tucnak>
On Mon, Jul 3, 2017 at 3:59 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Mon, Jul 03, 2017 at 03:50:06PM -0400, Jason Merrill wrote:
>> On Mon, Jul 3, 2017 at 12:02 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>> > So like this?
>>
>> Looks good, except...
>>
>> > case sc_auto:
>> > - error_at (loc, "decomposition declaration cannot be declared "
>> > + error_at (loc, "structured binding declaration cannot be "
>> > "C++98 %<auto%>");
>> > break;
>> > default:
>>
>> This case should just fall into the default gcc_unreachable, we aren't
>> going to get C++98 auto in C++17 mode.
>
> We actually support structured bindings (with a pedwarn that they are only
> available in -std=c++1z) in older std modes (of course, it doesn't make
> much sense in -std=c++98, because you always get either the above error
> or error that the type of the structured binding is not appropriate; but
> for -std=gnu++11 and above it works well).
> If I remove the above error_at and fall through into gcc_unreachable,
> we'll ICE.
Ah, OK.
Jason