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Re: [wg14/wg21 liaison] [SG10] Feature test macro for P0306 (__VA_OPT__)

From: Barry Revzin <barry.revzin_at_[hidden]>
Date: Thu, 28 Jan 2021 09:19:54 -0600
On Thu, Jan 28, 2021 at 4:12 AM Jonathan Wakely <cxx_at_[hidden]> wrote:

> On Wed, 27 Jan 2021 at 20:54, Barry Revzin via Liaison <
> liaison_at_[hidden]> wrote:
>> Eric Niebler actually asked this on StackOverflow a few years ago:
>> https://stackoverflow.com/q/48045470/2069064
>> The accepted answer there is:
>> #define PP_THIRD_ARG(a,b,c,...) c#define VA_OPT_SUPPORTED_I(...) PP_THIRD_ARG(__VA_OPT__(,),true,false,)#define VA_OPT_SUPPORTED VA_OPT_SUPPORTED_I(?)
> Who is going to remember that without having to look it up though?
> The #ifdef __VA_OPT__ solution was my first thought, it's unfortunate we
> forbid it. If we can't have that then I think we do need a feature test
> macro. The voodoo above will make most developers wish they were using Rust.

Yeah but isn't the purpose of StackOverflow's existence to copy and paste
code from it? Just need to remember how to google the question.


Received on 2021-01-28 09:20:11