Thread: Fw: [COMMITTERS] pgsql: Fix blatantly broken record_image_cmp() logic for pass-by-value
Fw: [COMMITTERS] pgsql: Fix blatantly broken record_image_cmp() logic for pass-by-value
From
Kevin Grittner
Date:
Forwarded to -hackers
----- Forwarded Message -----
> From: Kevin Grittner <kgrittn@ymail.com>
> To: Kevin Grittner <kgrittn@ymail.com>; Tom Lane <tgl@sss.pgh.pa.us>
> Cc: "pgsql-committers@postgresql.org" <pgsql-committers@postgresql.org>
> Sent: Friday, November 8, 2013 4:33 PM
> Subject: Re: [COMMITTERS] pgsql: Fix blatantly broken record_image_cmp() logic for pass-by-value
>
> Kevin Grittner <kgrittn@ymail.com> wrote:
>
>> I distilled it down to the simplest case I could find which
>> failed to produce the warning; attached.
>
> For a compiler which seems to like to generate warnings for really
> esoteric cases, clang falls down rather badly on uninitialized
> variables -- at least on the package for Ubuntu 12.10. It does not
> complain at all about this:
>
>
> int warning_test(int a);
> int warning_test(int a)
> {
> int result;
>
> if (a == 1)
> result = 1;
>
> return result;
> }
>
>
> I assume that everyone here agrees that merits a warning?
>
> Bug reports filed.
>
>
> --
> Kevin Grittner
> EDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>
Re: Fw: [COMMITTERS] pgsql: Fix blatantly broken record_image_cmp() logic for pass-by-value
From
Kevin Grittner
Date:
Kevin Grittner <kgrittn@ymail.com> wrote:
>> int warning_test(int a);
>> int warning_test(int a)
>> {
>> int result;
>>
>> if (a == 1)
>> result = 1;
>>
>> return result;
>> }
I had to file separate bug reports for gcc and clang. I have
already gotten a response on the clang bug report using the above
test code. It was closed with this response:
Fixed from clang 3.3
warning_test.c:8:6: warning: variable 'result' is used uninitialized whenever 'if' condition is
false [-Wsometimes-uninitialized]
if (a == 1)
^~~~~~
warning_test.c:11:9: note: uninitialized use occurs here
return result;
^~~~~~
warning_test.c:8:2: note: remove the 'if' if its condition is always true
if (a == 1)
^~~~~~~~~~~
warning_test.c:6:14: note: initialize the variable 'result' to silence this warning
int result;
^
= 0
** Changed in: clang (Ubuntu)
Status: New => Fix Released
I take that to say that the bug will be fixed in clang version 3.3,
which is not available in any production release of Ubuntu.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company