On Sat, 20 Mar 2021 at 17:54, Phil Bouchard via Std-Proposals
<std-proposals@lists.isocpp.org> wrote:

And that's why deduction probably shouldn't happen with class members
like that. It's not a matter of whether it's possible to specify in
the standard; it's a matter of whether it's a good idea to permit it.

And there are good arguments why it shouldn't be.

So it's better to be stricter than stuck down the road with an allowance you can't revert...

See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3897.html

But my take is we should enable it for clarity because decltype(...) is quite ugly.

--

Phil Bouchard
Founder
C.: (819) 328-4743