D Haley writes:
Ah, perhaps a distant cousin. Hi!
> I came across this situation recently
>
> Consider the following code
>
> #include <sstream>
>
> using std::stringstream;
>
> int main()
> {
> int i;
> stringstream ss;
> }
>
> I the compiled it with
>
> gcc main.cpp -Wall -lstdc++
> >main.cpp: In function 'int main()':
> >main.cpp:7: warning: unused variable 'i'
>
> Why did this not warn me about the unused stringstream?
> Can wall only catch unused primitive types?
No, it's not that, it's ...
> Is it because the constructor is called and therefore it is not unused?
Yes.
> It seems that -Wall should pick this up from the point of view of "i
> declared it then did nothing, this is incorrect" (also i used no params
> in the constructor), but it is concievable that declaring this object
> might be sufficient for some action to be taken by the code, thus
> rendering it incorrect for -Wall to report it.
You got it in one. For example, you might see
{
lock myLock;
...
}
where the lock constructor locks memory and the destructor releases
it.
> Is this desirable behaviour by GCC or not?
Sure is.
Andrew.
