Re: [PATCH] Remove useless if-before-free tests.

From: Jim Meyering <jim@meyering.net>
Date: Feb 18, 2008, 09:18 UTC
Message-ID: <87pruuy64v.fsf@rho.meyering.net>
In-Reply-To: <ee77f5c20802171409k2dee2c87v8d84eba111c3d506@mail.gmail.com>

"David Symonds" <dsymonds@gmail.com> wrote:

Show 19 quoted lines

> On Feb 17, 2008 1:58 PM, Jim Meyering <jim@meyering.net> wrote:
>> This change removes all useless if-before-free tests.
>> E.g., it replace code like this
>>
>>         if (some_expression)
>>                 free (some_expression);
>>
>> with the now-equivalent
>>
>>         free (some_expression);
>>
>> It is equivalent not just because POSIX has required free(NULL)
>> to work for a long time, but simply because it has worked for
>> so long that no reasonable porting target fails the test.
>> Here's some evidence from nearly 1.5 years ago:
>>
>>     http://www.winehq.org/pipermail/wine-patches/2006-October/031544.html
>
> That's not great evidence. It only tests 9 systems, and misses several

If you mean mingw, cygwin, and M$-based ones, they're all ok. As far as I know, you have to go back to SunOS4 to find a system on which free(NULL) fails. That OS stopped being a reasonable porting target a couple years ago.

> targets that Git already runs on. It seems like a fairly minor cleanup
> for a definite loss of portability.

It's a definite loss of portability if you can find a reasonable porting target for which free(NULL) fails. But even if you do, the fix is not to reject the clean-up, but to amend it with a wrapper function. That encapsulates the work-around in one place rather than polluting all of those files.