Hi,
Consider simple code below which results in Foo::Call method to be actually
called for _deleted instance_:
class Foo : public sigc::trackable {
public:
void Call() { printf("Foo call\n"); }
};
Foo* inst = new Foo();
auto fun = sigc::mem_fun(inst, &Foo::Call); // <-- bad
//sigc::slot<void> fun = sigc::mem_fun(inst, &Foo::Call); // <-- good
delete inst;
fun(); // <--- ooops!
The documentation for mem_fun says that "...only if the object type
inherits from sigc::trackable
<https://developer.gnome.org/libsigc++/stable/structsigc_1_1trackable.html> is
the slot automatically cleared...", but the problem is that result of mem_fun
is not a slot, but a bound_mem_fun which for some reason doesn't track
referenced object lifetime even if it inherits from trackable. If result of
mem_fun is put explicitly into a slot, then everything works fine and Call()
method is not called after instance is freed.
For me it looks like a typical "shoot in the foot" for C++11 programs and
should be indeed fixed. Just in case - issue is reproducible in current master
too.
BR, Andrey
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