Re: -Werror and --disable-werror

[Vladimir 'phcoder' Serbinenko]

address@hidden wrote:
> On Sat, Sep 19, 2009 at 9:12 AM, Vladimir 'phcoder' Serbinenko
> <address@hidden> wrote:
>   
>> Robert Millan wrote:
>>     
>>> Hi,
>>>
>>> -Werror is not in effect.  This will help ensuring that all new code is
>>> checked to be warning-free before commit (incidentally, I found a newly
>>> introduced bug thanks to this just minutes before enabling it).
>>>
>>>
>>>       
>> If you mean this change:
>>
>> +  /* Any value different than `p.offset' will satisfy the check during
>> +     first loop.  */
>> +  lastaddr = !p.offset;
>> +
>>
>> Then there was no bug here.
>>      if (labeln && lastaddr == p.offset)
>>        return grub_error (GRUB_ERR_BAD_PART_TABLE, "loop detected");
>>
>>      labeln++;
>>      if ((labeln & (labeln - 1)) == 0)
>>     
>
> This is a check for being an integral power of 2 (or 0), i.e. having a
> single bit set.  Was that the intent?  It's probably worth an
> explanatory comment for the sake of those who aren't familiar with the
> test.
>
>   
Read the code. There is a comment
>>        lastaddr = p.offset;
>>
>> labeln is 0 during first loop run and then lastaddr is set. I explicitly
>> omitted initing variables to have smaller loop detector
>>     
>
> I suspect initializing lastaddr, which takes place outside the loop,
> is less expensive than testing labeln on every iteration.
>
>   
We optimise for size, not for speed.
>>> Since -Werror may be a problem in some situations, I've added a
>>> --disable-werror switch, which does the obvious thing.
>>>
>>>
>>>       
>>
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>>
>>     
>
>
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