I was reading subsection 18.2 Constructors and Destructors of section 18 exception handling in C++17 standard draft where there is an example(page 384). I tried to understand where destruction of object A returned inside the try block happens but couldn't find. So I copied the example, added some prints and see that dtor of that object is never called. What am I missing here? Someone please explain what's happening here.
#include <stdio.h>
struct A {
int a_;
explicit A(int a):a_(a) {
printf("A(%d)'s ctor\n", a_);
}
~A() {
printf("A(%d)'s dtor\n", a_);
}
};
struct Y { ~Y() noexcept(false) {
printf("y's dtor\n");
throw 0; } };
A f() {
try {
A a(23);
Y y;
A b(56);
return A(100); // #1 who destructs this ??
} catch (...) {
printf("handling exception..\n");
}
printf("At line %d now..\n", __LINE__);
return A(200); // #2
}
int main() {
auto ret = f();
printf("f returned A(%d) object\n", ret.a_);
return 0;
}
Above code outputs following:
A(23)'s ctor
A(56)'s ctor
A(100)'s ctor
A(56)'s dtor
y's dtor
A(23)'s dtor
handling exception..
At line 34 now..
A(200)'s ctor
f returned A(200) object
A(200)'s dtor
...Program finished with exit code 0
