bug#15483: POSIXLY_CORRECT documentation vis a vis some simple EREs

[Paul Eggert]

On 10/07/13 09:53, Glenn Golden wrote:
> grep, when considered as an 'application'

There is no requirement that grep must
be implemented as a POSIX application.
'grep' can be written entirely in machine code.
As far as POSIX is concerned,
'grep' could even be a mechanical Turk,
i.e., not implemented via computer at all.

As a practical matter, users generally prefer
implementations that support useful extensions
to POSIX to implementations that support
only POSIX and nothing more.  Supporting a strict-POSIX
option for 'grep' sounds like it wouldn't be worth the
hassle for us.  Perhaps I'm wrong, and I could be
proven wrong if someone wrote an easy-to-maintain
patch that implements strict-POSIX behavior for 'grep'.

At any rate, it's not an urgent matter, as there's
no POSIX-conformance issue here, and little practical
benefit to any such change.