Package segfaults when built with -O2 but not with -O0

[Ralf Corsepius]

On 12/01/2011 07:11 PM, Paul Howarth wrote:
> On Thu, 01 Dec 2011 15:45:48 +0100
> Ralf Corsepius<rc040203 at freenet.de>  wrote:
>
>> On 12/01/2011 11:23 AM, Paul Howarth wrote:
>>> Ralf,
>>>
>>> On 11/18/2011 05:53 PM, Ralf Corsepius wrote:
>>>> On 11/18/2011 05:32 PM, Paul Howarth wrote:
>>>>> It already builds with -Wall and there are no warnings:
>>>> This doesn't mean much.
>>>>
>>>> Adding a couple of more agressive options, this is what happens to
>>>> pptp:
>>>>
>>
>>> What were the "couple of more agressive options" you used,
>>
>> This is what I did (rebased against today's git):
>>
>> diff --git a/pptp.spec b/pptp.spec
>> index 289dd08..78e36ca 100644
>> --- a/pptp.spec
>> +++ b/pptp.spec
>> @@ -86,7 +86,7 @@ tunnels.
>>    perl -pi -e 's/install -o root -m 555 pptp/install -m 755 pptp/;'
>> Makefile
>>
>>    %build
>> -make %{?_smp_mflags} CFLAGS="-Wall %{optflags}" IP=/sbin/ip
>> +make %{?_smp_mflags} CFLAGS="-Wall %{optflags} -Wextra
>> -Wstrict-aliasing -Wnested-externs -Wstrict-prototypes" IP=/sbin/ip
>>
>>    %install
>>    rm -rf %{buildroot}
>>
>>
>>> and which
>>> distro?
>>
>> Local rawhide mock.
>>
>> The result I posted was extracted from a "fedpkg mockbuild"'s
>> build.log in a local mock on fedora-16/x86_64.
>>
>>
>>> I've tried "-Wall -Wextra" and still can't provoke the strict
>>> aliasing warning locally.
>> -Wstrict-aliasing is responsible for this warning.
>>
>> Today's version looks like this:
>>
>> # grep warning: results_pptp/1.7.2/13.fc17/build.log  | grep punned
>> pptp_gre.c:92:29: warning: dereferencing type-punned pointer might
>> break strict-aliasing rules [-Wstrict-aliasing]
>> pptp_gre.c:99:28: warning: dereferencing type-punned pointer might
>> break strict-aliasing rules [-Wstrict-aliasing]
>> pptp_callmgr.c:202:48: warning: dereferencing type-punned pointer
>> might break strict-aliasing rules [-Wstrict-aliasing]
>> pptp_callmgr.c:325:29: warning: dereferencing type-punned pointer
>> might break strict-aliasing rules [-Wstrict-aliasing]
>> pptp_callmgr.c:330:28: warning: dereferencing type-punned pointer
>> might break strict-aliasing rules [-Wstrict-aliasing]
>> pptp_callmgr.c:358:25: warning: dereferencing type-punned pointer
>> might break strict-aliasing rules [-Wstrict-aliasing]
>> pptp.c:459:33: warning: dereferencing type-punned pointer might break
>> strict-aliasing rules [-Wstrict-aliasing]
>
> This is weird: I can't reproduce these either locally in mock or in
> koji:
Neither can I ;)

> http://koji.fedoraproject.org/koji/taskinfo?taskID=3555838

... mock appends build.log's from subsequent mock runs ...

... the warnings above stem from older builds.

I had not cleaned up the build.log when "git merging" your recent 
changes into my git checkout.

Ralf