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145
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1 // PR c++/88337 - Implement P1327R1: Allow dynamic_cast/typeid in constexpr.
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2 // { dg-do compile { target c++2a } }
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3 // { dg-additional-options "-fdelete-null-pointer-checks" }
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4
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5 // From clang's constant-expression-cxx2a.cpp.
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6
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7 struct A2 { virtual void a2(); };
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8 struct A : A2 { virtual void a(); };
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9 struct B : A {};
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10 struct C2 { virtual void c2(); };
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11 struct C : A, C2 { A *c = dynamic_cast<A*>(static_cast<C2*>(this)); };
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12 struct D { virtual void d(); };
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13 struct E { virtual void e(); };
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14 struct F : B, C, D, private E { void *f = dynamic_cast<void*>(static_cast<D*>(this)); };
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15 struct Padding { virtual void padding(); };
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16 struct G : Padding, F {};
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17
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18 constexpr G g;
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19
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20 // During construction of C, A is unambiguous subobject of dynamic type C.
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21 static_assert(g.c == (C*)&g);
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22 // ... but in the complete object, the same is not true, so the runtime fails.
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23 static_assert(dynamic_cast<const A*>(static_cast<const C2*>(&g)) == nullptr);
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24
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25 // dynamic_cast<void*> produces a pointer to the object of the dynamic type.
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26 static_assert(g.f == (void*)(F*)&g);
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27 static_assert(dynamic_cast<const void*>(static_cast<const D*>(&g)) == &g);
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28
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29 constexpr int d_a = (dynamic_cast<const A&>(static_cast<const D&>(g)), 0); // { dg-error "reference .dynamic_cast. failed" }
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30 // { dg-message ".A. is an ambiguous base class of dynamic type .G." "" { target *-*-* } .-1 }
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31
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32 // Can navigate from A2 to its A...
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33 static_assert(&dynamic_cast<A&>((A2&)(B&)g) == &(A&)(B&)g);
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34 // ... and from B to its A ...
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35 static_assert(&dynamic_cast<A&>((B&)g) == &(A&)(B&)g);
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36 // ... but not from D.
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37 static_assert(&dynamic_cast<A&>((D&)g) == &(A&)(B&)g); // { dg-error "non-constant condition for static assertion|reference .dynamic_cast. failed" }
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38 // { dg-message ".A. is an ambiguous base class of dynamic type .G." "" { target *-*-* } .-1 }
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39
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40 // Can cast from A2 to sibling class D.
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41 static_assert(&dynamic_cast<D&>((A2&)(B&)g) == &(D&)g);
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42
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43 // Cannot cast from private base E to derived class F.
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44 constexpr int e_f = (dynamic_cast<F&>((E&)g), 0); // { dg-error "reference .dynamic_cast. failed" }
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45 // { dg-message "static type .const E. of its operand is a non-public base class of dynamic type .G." "" { target *-*-* } .-1 }
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46
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47 // Cannot cast from B to private sibling E.
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48 constexpr int b_e = (dynamic_cast<E&>((B&)g), 0); // { dg-error "reference .dynamic_cast. failed" }
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49 // { dg-message "dynamic type .G. of its operand does not have an unambiguous public base class .E." "" { target *-*-* } .-1 }
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50
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51 struct Unrelated { virtual void unrelated(); };
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52
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53 constexpr int b_unrelated = (dynamic_cast<Unrelated&>((B&)g), 0); // { dg-error "reference .dynamic_cast. failed" }
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54 // { dg-message "dynamic type .G. of its operand does not have an unambiguous public base class .Unrelated." "" { target *-*-* } .-1 }
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55 constexpr int e_unrelated = (dynamic_cast<Unrelated&>((E&)g), 0); // { dg-error "reference .dynamic_cast. failed" }
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56 // { dg-message "static type .const E. of its operand is a non-public base class of dynamic type .G." "" { target *-*-* } .-1 }
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