[patch] test failure on sparc64 due to undefined division by zero behaviour

Hello PostgreSQL hackers,

I recently got the following bug report about a test suite failure on
sparc64:

----- Forwarded message from Aurelien Jarno <aurel32@debian.org> -----

Date: Wed, 02 Mar 2011 23:49:05 +0100
From: Aurelien Jarno <aurel32@debian.org>
To: Debian Bug Tracking System <submit@bugs.debian.org>
Subject: Bug#616180: postgresql-9.0: FTBFS on sparc64, testsuite issues with int8

postgresql-9.0 fails to build on sparc64 due to testsuite errors with
int8. The division by 0 is not trapped and a SIGFPE is issued instead of
an error.

Postgresql people claims it's a gcc bug, while gcc people says the code
is incorrect [1]. Whatever the real issue is, the fix is very simple
(actually taken in another part from the very same file), so it's
probably the best to simply apply it.

[1] http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29968

----- End forwarded message -----


The C99 standard [2], section 6.5.5 paragraph 5 actually says:

  "The result of the / operator is the quotient from the division of
  the first operand by the second; the result of the % operator is the
  remainder. In both operations, if the value of the second operand is
  zero, the behavior is undefined."

so the gcc folk's claim that this isn't a gcc bug looks justified.

Aurelien sent a straightforward patch for this, I updated it to apply
to current git head, updated the comments, and git-formatted it.

Thanks for considering!

Martin

[2] http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf
--
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)