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Re: [SG10] [EXTERNAL] Macro for <coroutine>

From: Casey Carter <cartec69_at_[hidden]>
Date: Wed, 15 Jan 2020 16:29:32 -0800
On Wed, Jan 15, 2020 at 4:20 PM Barry Revzin <barry.revzin_at_[hidden]> wrote:

> On Wed, Jan 15, 2020 at 6:14 PM Casey Carter <cartec69_at_[hidden]> wrote:
>> I suppose I'm saying "it would be nice to have these two distinct
>> feature-test macros, but it may be too late now since __cpp_coroutines has
>> an established history."
>> On Wed, Jan 15, 2020 at 4:13 PM Casey Carter <cartec69_at_[hidden]> wrote:
>>> As a rule, it's useful to have distinct macros to indicate compiler and
>>> library support of a feature that has both core language and library
>>> surface. Standard libraries can then provide the library support / define
>>> the library macro only when the necessary compiler support is present. If
>>> the feature is unusable without library support, e.g., coroutines, users
>>> check only the library macro.
> How established? Just #include <coroutine> fails on latest gcc, clang
> w/libc++, and the latest msvc on godbolt - unless there are extra flags I
> need to pass in to get this to work on any of them:
> https://godbolt.org/z/oy9hzc

__cpp_coroutines has indicated support for TS coroutines for years (

Received on 2020-01-15 18:32:17