Re: longjmp clobber warnings are utterly broken in modern gcc

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Stark <stark@mit.edu>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-01-25T20:40:10Z
Lists: pgsql-hackers
Greg Stark <stark@mit.edu> writes:
> Some Google(tm)ing does turn up plenty of other people complaining about
> similar behaviour. This report seems to have the most enlightening response:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54561

Yeah, I saw that before too.  I got an interesting response from Jakub J.
just now as well:
https://bugzilla.redhat.com/show_bug.cgi?id=1185673

It sounds like the appearance of the warning is contingent on code
generation decisions, making it even less likely to ever be useful
to us in its current form.

> Perhaps Clang has a more useful warning?

Clang, at least the version on my Mac, doesn't warn either with the
settings we normally use, and it doesn't have -Wclobber at all.
I tried turning on -Weverything, and it still didn't complain.
(It did generate incorrect code though, so it's no better than gcc
in that respect.)

			regards, tom lane