Viewing file:  Wpessimizing-move1.C (2.16 KB) -rw-r--r--
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// PR c++/86981
// { dg-do compile { target c++11 } }
// { dg-options "-Wpessimizing-move" }
// Define std::move.
namespace std {
template<typename _Tp>
struct remove_reference
{ typedef _Tp type; };
template<typename _Tp>
struct remove_reference<_Tp&>
{ typedef _Tp type; };
template<typename _Tp>
struct remove_reference<_Tp&&>
{ typedef _Tp type; };
template<typename _Tp>
constexpr typename std::remove_reference<_Tp>::type&&
move(_Tp&& __t) noexcept
{ return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
}
struct T {
T() { }
T(const T&) { }
T(T&&) { }
};
struct U {
U() { }
U(const U&) { }
U(U&&) { }
U(T) { }
};
T g;
T
fn1 ()
{
T t;
return std::move (t); // { dg-warning "moving a local object in a return statement prevents copy elision" }
}
T
fn2 ()
{
// Not a local variable.
return std::move (g);
}
int
fn3 ()
{
int i = 42;
// Not a class type.
return std::move (i);
}
T
fn4 (bool b)
{
T t;
if (b)
throw std::move (t);
return std::move (t); // { dg-warning "moving a local object in a return statement prevents copy elision" }
}
T
fn5 (T t)
{
// Function parameter; std::move is redundant but not pessimizing.
return std::move (t);
}
U
fn6 (T t, U u, bool b)
{
if (b)
return std::move (t);
else
// Function parameter; std::move is redundant but not pessimizing.
return std::move (u);
}
U
fn6 (bool b)
{
T t;
U u;
if (b)
return std::move (t);
else
return std::move (u); // { dg-warning "moving a local object in a return statement prevents copy elision" }
}
T
fn7 ()
{
static T t;
// Non-local; don't warn.
return std::move (t);
}
T
fn8 ()
{
return T();
}
T
fn9 (int i)
{
T t;
switch (i)
{
case 1:
return std::move ((t)); // { dg-warning "moving a local object in a return statement prevents copy elision" }
case 2:
return (std::move (t)); // { dg-warning "moving a local object in a return statement prevents copy elision" }
default:
return (std::move ((t))); // { dg-warning "moving a local object in a return statement prevents copy elision" }
}
}
int
fn10 ()
{
return std::move (42);
}
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