Re: BUG #16222: [[:print:]] doesn't correctly handle Emoji skin tone modifiers on MacOS

PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> On Linux heroku-18, these expressions both eval true:

> select '✌'~'\A[[:print:]]*\Z';
> select '✌🏻'~'\A[[:print:]]*\Z';

> On MacOS Catalina, the 1st evals true but the 2nd evals false.

This is entirely a function of what your operating system's
locale support does. So it could be that you chose the wrong
LC_CTYPE setting for the macOS database -- in C locale, for
example, "false" is the right answer. However, we've observed
that macOS's UTF8-based locales seem pretty brain-dead about
handling of multibyte characters :-(. So it's likely that this
boils down to being Apple's bug. I haven't detected any interest
on their part in improving their POSIX locale support, unfortunately.

regards, tom lane