On Mon, 8 Jun 2020 at 23:30, Gabriel Dos Reis via SG10
<sg10_at_[hidden]> wrote:
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> At the time, I think I would have thought one was not needed, but that could be wrong.
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>
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> Indeed, this sounds to be like an overkill application of feature test macros, but…

Well, this macro gives users with the use case I depicted some more choices:
1) use a work-around that is just.. ..ghastly
2) provide an ADL-only customization point if and only if it can be
written without ghastliness
3) just provide a customization point that is not ADL-only
4) do (1) or (3) if (2) is not available