Viewing file:  constexpr-82218.C (3.07 KB) -rw-r--r--
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// PR c++/82218
// { dg-do compile { target c++14 } }
// { dg-options "-fdelete-null-pointer-checks" }
template<typename _Tp>
struct identity
{
typedef _Tp type;
};
template<typename _Tp>
inline _Tp&&
forward(typename identity<_Tp>::type&& __t)
{ return __t; }
template < typename T >
class delegate;
template < typename R, typename... Params >
class delegate< R(Params...) > final
{
private:
using CallbackType = R (*)(void*, Params...);
using FunctionPtr = R (*)(Params...);
template < typename Object >
using MethodPtr = R (Object::*)(Params...);
template < typename Object >
using ConstMethodPtr = R (Object::*)(Params...) const;
void* obj_;
CallbackType cb_;
template < typename Object, MethodPtr< Object > Mptr >
constexpr static R invoke_method(void* obj, Params... params) noexcept(
noexcept((static_cast< Object* >(obj)->*Mptr)(params...)))
{
return (static_cast< Object* >(obj)->*Mptr)(params...);
}
template < typename Object, ConstMethodPtr< Object > Mptr >
constexpr static R invoke_method(void* obj, Params... params) noexcept(
noexcept((static_cast< Object* >(obj)->*Mptr)(params...)))
{
return (static_cast< Object* >(obj)->*Mptr)(params...);
}
template < FunctionPtr Fptr >
constexpr static R invoke_function(void*, Params... params) noexcept(
noexcept((*Fptr)(params...)))
{
return (*Fptr)(params...);
}
constexpr delegate(void* obj, CallbackType callback) noexcept : obj_(obj),
cb_(callback)
{
}
constexpr static R error_function(Params...)
{
while(1);
}
public:
using base_type = delegate< R(Params...) >;
delegate()
{
*this = from< error_function >();
}
delegate(const base_type&) = default;
delegate(base_type&&) = default;
base_type& operator=(const base_type&) = default;
base_type& operator=(base_type&&) = default;
template < typename Object, MethodPtr< Object > Mptr >
constexpr static auto from(Object& obj) noexcept
{
return delegate(&obj, &invoke_method< Object, Mptr >);
}
template < typename Object, ConstMethodPtr< Object > Mptr >
constexpr static auto from(Object& obj) noexcept
{
return delegate(&obj, &invoke_method< Object, Mptr >);
}
template < FunctionPtr Fptr >
constexpr static auto from() noexcept
{
static_assert(Fptr != nullptr, "Function pointer must not be null");
return delegate(nullptr, &invoke_function< Fptr >);
}
template < typename... Args >
constexpr auto operator()(Args&&... params) const
noexcept(noexcept((*cb_)(obj_, forward< Args >(params)...)))
{
return (*cb_)(obj_, forward< Args >(params)...);
}
constexpr bool valid() const noexcept
{
return (cb_ != &invoke_function< error_function >);
}
constexpr bool operator==(const delegate& other) const noexcept
{
return (obj_ == other.obj_) && (cb_ == other.cb_);
}
constexpr bool operator!=(const delegate& other) const noexcept
{
return (obj_ != other.obj_) || (cb_ != other.cb_);
}
};
delegate< void(void) > a;
void test()
{
a();
}
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