Mercurial > hg > CbC > CbC_gcc
view gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic4.C @ 145:1830386684a0
gcc-9.2.0
author | anatofuz |
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date | Thu, 13 Feb 2020 11:34:05 +0900 |
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// PR c++/88337 - Implement P1327R1: Allow dynamic_cast/typeid in constexpr. // { dg-do compile { target c++2a } } // { dg-additional-options "-fdelete-null-pointer-checks" } // From clang's constant-expression-cxx2a.cpp. struct A2 { virtual void a2(); }; struct A : A2 { virtual void a(); }; struct B : A {}; struct C2 { virtual void c2(); }; struct C : A, C2 { A *c = dynamic_cast<A*>(static_cast<C2*>(this)); }; struct D { virtual void d(); }; struct E { virtual void e(); }; struct F : B, C, D, private E { void *f = dynamic_cast<void*>(static_cast<D*>(this)); }; struct Padding { virtual void padding(); }; struct G : Padding, F {}; constexpr G g; // During construction of C, A is unambiguous subobject of dynamic type C. static_assert(g.c == (C*)&g); // ... but in the complete object, the same is not true, so the runtime fails. static_assert(dynamic_cast<const A*>(static_cast<const C2*>(&g)) == nullptr); // dynamic_cast<void*> produces a pointer to the object of the dynamic type. static_assert(g.f == (void*)(F*)&g); static_assert(dynamic_cast<const void*>(static_cast<const D*>(&g)) == &g); constexpr int d_a = (dynamic_cast<const A&>(static_cast<const D&>(g)), 0); // { dg-error "reference .dynamic_cast. failed" } // { dg-message ".A. is an ambiguous base class of dynamic type .G." "" { target *-*-* } .-1 } // Can navigate from A2 to its A... static_assert(&dynamic_cast<A&>((A2&)(B&)g) == &(A&)(B&)g); // ... and from B to its A ... static_assert(&dynamic_cast<A&>((B&)g) == &(A&)(B&)g); // ... but not from D. static_assert(&dynamic_cast<A&>((D&)g) == &(A&)(B&)g); // { dg-error "non-constant condition for static assertion|reference .dynamic_cast. failed" } // { dg-message ".A. is an ambiguous base class of dynamic type .G." "" { target *-*-* } .-1 } // Can cast from A2 to sibling class D. static_assert(&dynamic_cast<D&>((A2&)(B&)g) == &(D&)g); // Cannot cast from private base E to derived class F. constexpr int e_f = (dynamic_cast<F&>((E&)g), 0); // { dg-error "reference .dynamic_cast. failed" } // { dg-message "static type .const E. of its operand is a non-public base class of dynamic type .G." "" { target *-*-* } .-1 } // Cannot cast from B to private sibling E. constexpr int b_e = (dynamic_cast<E&>((B&)g), 0); // { dg-error "reference .dynamic_cast. failed" } // { dg-message "dynamic type .G. of its operand does not have an unambiguous public base class .E." "" { target *-*-* } .-1 } struct Unrelated { virtual void unrelated(); }; constexpr int b_unrelated = (dynamic_cast<Unrelated&>((B&)g), 0); // { dg-error "reference .dynamic_cast. failed" } // { dg-message "dynamic type .G. of its operand does not have an unambiguous public base class .Unrelated." "" { target *-*-* } .-1 } constexpr int e_unrelated = (dynamic_cast<Unrelated&>((E&)g), 0); // { dg-error "reference .dynamic_cast. failed" } // { dg-message "static type .const E. of its operand is a non-public base class of dynamic type .G." "" { target *-*-* } .-1 }