Re: master 37889523278: Add new `swap` macro and use it

[Po Lu <luangruo@yahoo.com>]

Eli Zaretskii <eliz@gnu.org> writes:

> Instead of reverting, the swap macro could have used __typeof__ where
> typeof is not available.  This has been pointed out several times
> already, so I don't understand why you keep raising this non-issue.

__typeof__ is not Standard C, and our declared objective is to be
"portable to C99 or later".  Invoking non-standard syntactic features
such as __typeof__ without a check is an issue in itself, regardless of
the number of systems it affects, not least when it is not invoked from
code that can reasonably be expected to only compile on machines with
well-established compilers (i.e. w32*.c, android*.c), but from code that
must compile everywhere.

Further proving my point, neither variant of typeof compiles with Sun C
5.8, a C99 compiler that does presently produce working Emacs builds.

> The only breakage we know of was with a compiler that does support
> __typeof__, AFAIU, so again: why do you keep insisting on your
> absolute rejection of the macro, when all the real problems have been
> addressed?

If Gnulib doesn't require __typeof__, why should we?  Generally
speaking, Emacs is portable to more systems and compilers than Gnulib
officially is; departing from this policy for no good reason will
frustrate users and future porting efforts alike.