Viewing file:  constexpr-dynamic11.C (1.13 KB) -rw-r--r--
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// PR c++/88337 - Implement P1327R1: Allow dynamic_cast/typeid in constexpr.
// { dg-do compile { target c++20 } }
// { dg-additional-options "-fdelete-null-pointer-checks" }
// dynamic_cast in a constructor.
// [class.cdtor]#6: "If the operand of the dynamic_cast refers to the object
// under construction or destruction and the static type of the operand is not
// a pointer to or object of the constructor or destructor's own class or one
// of its bases, the dynamic_cast results in undefined behavior.
struct V {
virtual void f();
};
struct A : V { };
struct B : V {
constexpr B(V*, A*);
};
struct D : A, B {
constexpr D() : B((A*)this, this) { } // { dg-message "in 'constexpr' expansion of" }
};
constexpr B::B(V* v, A* a)
{
// well-defined: v of type V*, V base of B results in B*
B* b = dynamic_cast<B*>(v);
if (b != nullptr)
__builtin_abort ();
B& br = dynamic_cast<B&>(*v); // { dg-error "reference .dynamic_cast. failed" }
// { dg-message "dynamic type .A. of its operand does not have an unambiguous public base class .B." "" { target *-*-* } .-1 }
}
constexpr D d; // { dg-message "in 'constexpr' expansion of" }
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