Re: [PATCH] Fix an unitialized pointer in merge-recursive.c

From: David Kastrup <dak@gnu.org>
Date: Aug 16, 2007, 09:07 UTC
Message-ID: <86643f4zlf.fsf@lola.quinscape.zz>
In-Reply-To: <7vodh7khuo.fsf@gitster.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 27 quoted lines

> "Marco Costalba" <mcostalba@gmail.com> writes:
>
>> On 8/16/07, Junio C Hamano <gitster@pobox.com> wrote:
>>> "Marco Costalba" <mcostalba@gmail.com> writes:
>>>
>>> > Indeed &mrtree is passed to merge_trees() that not always
>>> > seems to set the value, so on some paths mrtree could
>>> > return uninitialized.
>>> >
>>> > Spotted by a gcc 4.2.1 warning
>>>
>>> Are you sure that gcc is correctly seeing the codeflow?
>>>
>>> In merge(), mrtree is used only under index_only, and
>>> merge_trees() always sets *result under index_only.
>>
>> Ok ;-)
>>
>> Now two options:
>>
>> - discard the patch
>>
>> - change the title in 'silence a gcc bougus warning'
>
> Third option.  Change the assignment from "mrtree = NULL" to
> "mrtree = mtree".  It is a standard idiom to work around stupid
> gcc warnings.

I think it is more efficient to write mrtree = NULL: For the computer, it makes a minuscule difference, and it can save programmers a bit of confusion and worrying times. Time that may be better spent improving things elsewhere.

I don't think that we have a contest running for least redundancy in code layout, have we? Why then require the programmer to do a complete call trace analysis before he can feel comfortable about the code? And what if callers change at some point of time?

-- 
David Kastrup