Re: bug: return doesn't accept negative numbers

[Eric Blake]

On 08/08/2011 08:14 PM, Chet Ramey wrote:
> On 8/8/11 9:42 PM, Mike Frysinger wrote:
> > On Monday, August 08, 2011 21:20:29 Chet Ramey wrote:
> > > On 8/8/11 8:53 AM, Eric Blake wrote:
> > > > However, you are on to something - since bash allows 'exit -1' as an
> > > > extension, it should similarly allow 'return -1' as the same sort of
> > > > extension.  The fact that bash accepts 'exit -1' and 'exit -- -1', but
> > > > only 'return -- -1', is the real point that you are complaining about.
> > >
> > > That's a reasonable extension to consider for the next release of bash.
> >
> > i posted a patch for this quite a while ago.  not that it's hard to code.
>
> Sure.  It's just removing the three lines of code that were added
> between bash-3.2 and bash-4.0.  The question was always whether that's
> the right thing to do, and whether the result will behave as Posix
> requires.

Yes, the result will behave as POSIX requires.  POSIX requires that 
'return' and 'exit' need not support '--' (since they are special 
builtins that do not specifically require compliance with the generic 
rules on option parsing), that they need not support options, and that 
if their optional argument is present, it need not be supported if it is 
not a non-negative integer no greater than 255.  But they are _not_ 
required to reject any input outside the above constraints - therefore, 
an extension that supports '--', an extension that parses '-- -1' as 
255, and an extension that parses any option that looks like a negative 
number such as 'exit -1', are ALL valid extensions permitted by POSIX, 
and need not be disabled by --posix, but can be available always.  ksh 
does just that: 'return -1' and 'return -- -1' are always accepted and 
both result in the same behavior as the POSIX-mandated 'return 255'; ksh 
also has an extension where 'return --help' prints help, although bash 
uses 'help return' for this purpose.

--
Eric Blake   eblake@redhat.com    +1-801-349-2682
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