[cfe-users] Is there a way to make clang warn on this code?

[Richard Trieu]

Quentin,

Clang does not have a warning for uninitialized fields in class methods.
 I've looked before to add a warning to flag any unused fields at the end
of the a constructor.  However, there were good reasons to have
uninitialized fields, such as having an Init() method later that
initializes the fields, or a guard variable to protect against
uninitialized use.  Also, -Wuninitialized typically warns on the use of an
uninitialized variable, not the mere presence of one.

The other idea is to do cross method analysis, either using the control
flow of a program to determine which methods are used in which order, or
testing methods against constructors.  Such an analysis would likely be too
expensive, and would be more suited for static analysis.

So there's no warning for this yet, and probably won't be unless we find a
better way to detect it.

Richard


On Fri, Mar 14, 2014 at 5:15 PM, Eric Christopher <echristo at gmail.com>wrote:

> Adding Richard explicitly here. :)
> On Mar 14, 2014 4:32 PM, "Quentin Colombet" <qcolombet at apple.com> wrote:
>
>> Hi,
>>
>> I recently found a non-deterministic behavior in my application that was
>> due to a missing field initialization.
>> Here is a snippet of the actual problem:
>>
>> struct foo {
>>   foo() {}; // <— bar is not initialized here.
>>   int getBar() const {
>>     return bar; // <— this returns an uninitialized value.
>>   }
>> private:
>>   int bar;
>> };
>>
>> I’ve compiled the attached cpp file that contains this snippet with -Wall
>> -Wextra -Wuninitialized, but no warning is issued (trunk 203678).
>> Is there an option to make clang warn about that?
>>
>> If not, should I file a PR?
>>
>> Thanks,
>>  -Quentin
>>
>>
>> _______________________________________________
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>> cfe-users at cs.uiuc.edu
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>>
>>
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