On Tue, 2014-03-04 at 23:54 -0300, Fernando Pelliccioni wrote: > > We still have the problem of dangling references. > > > Any decent compiler can deal with this problem, and according to the > Standard the implementations are encouraged to issue a warning in such > a case. > I don't know implementations that don't do it. > > > GCC: > In function 'int& dangling()': > warning: reference to local variable 'i' returned > [-Wreturn-local-addr] > int i = 1234; > ^ > Clang > warning: reference to stack memory associated with local variable > 'i' returned [-Wreturn-stack-address] > return i; > ^ > > > The same happens with MSVC. > > > Do you think that the Warning is not much? > Well, you can use a compiler option > > > -Werror > Or in this case.... > -Werror-return-stack-address > > > ...and... voilà, the problem is over, we now have errors instead of > warnings. > What is the advantage of Rust now? I think it's insignificant. >
I usually find myself defending C++ in most discussion but it's not
ideal (although from what I heard about article it is much less horrible
then presented).
#include <iostream>
class Test {
public:
Test(int &i) : i(i) {}
int get_i() const {
i++
return i;
}
private:
int &i;
};
Test foo(int i) {
return Test(i);
}
int main() {
Test a = foo(1);
Test b = foo(2);
std::cout << a.get_i() << " " << b.get_i() << std::endl;
return 0;
}
No warnings on -Wall -Wextra -O1. Of course -O1 and -O0 have different
results as we are happy to write somewhere on stack and in first case
the valgrind does not report any errors. Add more code, foo begin a bit
longer (or getting itself a reference) multiple files, Cheshire Cats...
Once you get any structure more complicated then tree you'll need to use
pointers. You can use std::shared_pointer as long as your structure is
DAG - once it isn't you are on your own. 'Rust' have similar problem -
but it has compile error instead of potentially a warning (potentially
as C++ needs to have 'sufficient' knowledge).
(Not mentioning the reference invalidation mentioned earlier)
Best regards
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