[cfe-dev] new -Wuninitialized implementation in Clang

[jahanian]

On Feb 4, 2011, at 6:02 AM, Michael Price - Dev wrote:

> On Feb 4, 2011, at 12:32 AM, "John N. Lehner" <jlehner at apple.com> wrote:
> 
>> On Feb 3, 2011, at 8:27 PM, Johannes Schaub (litb) wrote:
>> 
>>> Ted Kremenek wrote:
> 
> <snip>
> 
>>> 
>>> Hmm, I would personally like to not initialize variables that I  
>>> know are not
>>> read from, as in your above code example. I personally regard it as  
>>> bad
>>> coding style to initialize variables with values not really used by  
>>> the
>>> code.
>> 
>> I follow this philosophy as well (but my coworkers think I'm  
>> crazy).  While blindly initializing all variables to, say, zero will  
>> decrease the likelihood of nondeterministic runtime behavior, it  
>> doesn't necessarily contribute to program correctness.  What if the  
>> above example was "fixed" to suppress a spurious warning, but is  
>> then extended during maintenance:
>> 
>> int x = 0;
>> ...
>> if (flag)
>> x = ...
>> ...
>> if (flag)
>> use(x);
>> ...
>> use(x);
>> 
>> and use(0) is wrong.  While that may seem contrived, I saw it happen  
>> in a loop once, and use(0) turned out to be expensive.
> 
> I strongly disagree. How can use(0); be worse than use(garbage that  
> can potentially be zero or that can potentially crash your app causing  
> data corruption);

It is worse because it masks a logical bug which which is masked out by this initialization.
Better to have an occasional crash than something which seems to 'work'.

- fariborz

> 
>> John
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