Re: remove obsolete NULL casts - Mailing list pgsql-patches

From Neil Conway
Subject Re: remove obsolete NULL casts
Date
Msg-id 87vfnpov2t.fsf@mailbox.samurai.com
Whole thread Raw
In response to Re: remove obsolete NULL casts  (Kurt Roeckx <Q@ping.be>)
Responses Re: remove obsolete NULL casts  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-patches
Kurt Roeckx <Q@ping.be> writes:
> In src/backend/port/darwin/system.c you replaced:
>
> execl(_PATH_BSHELL, "sh", "-c", command, (char *) NULL);
>
> By:
> execl(_PATH_BSHELL, "sh", "-c", command, NULL);
>
> I think that is one of the exceptions where you do have to cast it,
> because the type is unknown.  You can only remove the cast when you
> actually know what pointer type it is.

Ah, good catch! Upon further investigation, you're completely correct:
technically, you need to cast the NULL literal to a pointer type in a
function call if (a) there is no prototype for the function, or (b)
the function is a varargs function (which execl() is).

I'd imagine it would only make a difference on a machine where the
null pointer is represented by a non-zero bit pattern (i.e. it
shouldn't make a difference on any modern machine), but we should do
this correctly, of course. Interesting -- you learn something new
every day :-)

I won't bother posting an updated patch, but I'll include your fix in
the patch when I apply it. Thanks again.

-Neil


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