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131
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1 // PR c++/86981
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2 // { dg-do compile { target c++11 } }
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3 // { dg-options "-Wpessimizing-move" }
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4
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5 // Define std::move.
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6 namespace std {
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7 template<typename _Tp>
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8 struct remove_reference
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9 { typedef _Tp type; };
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10
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11 template<typename _Tp>
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12 struct remove_reference<_Tp&>
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13 { typedef _Tp type; };
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14
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15 template<typename _Tp>
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16 struct remove_reference<_Tp&&>
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17 { typedef _Tp type; };
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18
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19 template<typename _Tp>
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20 constexpr typename std::remove_reference<_Tp>::type&&
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21 move(_Tp&& __t) noexcept
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22 { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
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23 }
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24
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25 struct T {
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26 T() { }
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27 T(const T&) { }
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28 T(T&&) { }
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29 };
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30 struct U {
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31 U() { }
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32 U(const U&) { }
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33 U(U&&) { }
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34 U(T) { }
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35 };
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36
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37 T g;
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38
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39 T
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40 fn1 ()
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41 {
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42 T t;
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43 return std::move (t); // { dg-warning "moving a local object in a return statement prevents copy elision" }
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44 }
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45
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46 T
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47 fn2 ()
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48 {
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49 // Not a local variable.
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50 return std::move (g);
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51 }
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52
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53 int
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54 fn3 ()
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55 {
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56 int i = 42;
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57 // Not a class type.
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58 return std::move (i);
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59 }
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60
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61 T
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62 fn4 (bool b)
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63 {
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64 T t;
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65 if (b)
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66 throw std::move (t);
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67 return std::move (t); // { dg-warning "moving a local object in a return statement prevents copy elision" }
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68 }
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69
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70 T
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71 fn5 (T t)
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72 {
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73 // Function parameter; std::move is redundant but not pessimizing.
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74 return std::move (t);
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75 }
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76
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77 U
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78 fn6 (T t, U u, bool b)
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79 {
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80 if (b)
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81 return std::move (t);
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82 else
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83 // Function parameter; std::move is redundant but not pessimizing.
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84 return std::move (u);
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85 }
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86
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87 U
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88 fn6 (bool b)
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89 {
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90 T t;
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91 U u;
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92 if (b)
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93 return std::move (t);
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94 else
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95 return std::move (u); // { dg-warning "moving a local object in a return statement prevents copy elision" }
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96 }
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97
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98 T
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99 fn7 ()
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100 {
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101 static T t;
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102 // Non-local; don't warn.
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103 return std::move (t);
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104 }
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105
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106 T
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107 fn8 ()
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108 {
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109 return T();
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110 }
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111
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112 T
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113 fn9 (int i)
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114 {
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115 T t;
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116
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117 switch (i)
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118 {
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119 case 1:
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120 return std::move ((t)); // { dg-warning "moving a local object in a return statement prevents copy elision" }
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121 case 2:
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122 return (std::move (t)); // { dg-warning "moving a local object in a return statement prevents copy elision" }
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123 default:
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124 return (std::move ((t))); // { dg-warning "moving a local object in a return statement prevents copy elision" }
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125 }
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126 }
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127
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128 int
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129 fn10 ()
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130 {
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131 return std::move (42);
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132 }
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