When is the destructor of a constinit object called?

Question

Generally it is said that the destructors of static objects are called in the reverse order of the constructors. As I understand, constinit objects are initialized at compile time, so their destructors should be called after the destructors of "normal" static objects.

The program

struct A
{
  constexpr A(const char* t): t_(t) {}
  ~A() {std::cout << "~A(" << t_ << ")\n";} 
  const char* t_;
};  

static A a1("static");  

int main () {
   static constinit A a2("constinit");  
   return 0;
}

(using GCC 10), however, gives the output

~A(constinit)
~A(static)

i.e. the constinit object is destroyed before the "normal" static object (although it was constructed earlier). Is the "reverse order" rule no longer valid for constinit objects?

I had to revisit the standard, this is not a compiler bug, constant initialized object are destroyed as if they were dynamicaly initialized, this is specified in the standard. Violation of the reverse order rule is standard compliant. — Oliv, Jul 16 '20 at 15:57

Oliv · Accepted Answer · 2020-07-16T15:55:58.400

Both a1 and a2 are constant-initialized. The constinit specifier only asserts that the variable being defined is constant-initialized. So here a1 is initialized before a2 so a2 is destroyed before a1 as expected.

Is the "reverse order" rule no longer valid for constinit objects? The reverse order rule does not between constant initialized object and dynamicaly initialized object: even if construction of constant initialized object happens before construction of dynamicaly initialized object, destruction of constant initialized object is sequenced as if they had been dynamicaly initialized: [basic.start.term]/3

If an object is initialized statically, the object is destroyed in the same order as if the object was dynamically initialized.

When is the destructor of a constinit object called?

1 Answers1