C++程序  |  27行  |  708 B

// RUN: %clang_cc1 -emit-llvm %s -verify -fno-rtti -triple %itanium_abi_triple -o - | FileCheck %s
// expected-no-diagnostics

struct A {
  virtual ~A(){};
};

struct B : public A {
  B() : A() {}
};

// An upcast can be resolved statically and can be used with -fno-rtti, iff it
// does not use runtime support.
A *upcast(B *b) {
  return dynamic_cast<A *>(b);
// CHECK-LABEL: define {{.*}}%struct.A* @_Z6upcastP1B
// CHECK-NOT: call {{.*}}i8* @__dynamic_cast
}

// A NoOp dynamic_cast can be used with -fno-rtti iff it does not use
// runtime support.
B *samecast(B *b) {
  return dynamic_cast<B *>(b);
// CHECK-LABEL: define {{.*}}%struct.B* @_Z8samecastP1B
// CHECK-NOT: call {{.*}}i8* @__dynamic_cast
}