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150
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1 // RUN: %clang_cc1 -fsyntax-only -verify %s -Wno-unreachable-code
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2
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3 int foo(int X, int Y);
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4
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5 double sqrt(double X); // implicitly const because of no -fmath-errno!
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6
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7 void bar(volatile int *VP, int *P, int A,
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8 _Complex double C, volatile _Complex double VC) {
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9
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10 VP < P; // expected-warning {{relational comparison result unused}}
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11 (void)A;
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12 (void)foo(1,2); // no warning.
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13
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14 A < foo(1, 2); // expected-warning {{relational comparison result unused}}
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15
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16 foo(1,2)+foo(4,3); // expected-warning {{expression result unused}}
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17
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18
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19 *P; // expected-warning {{expression result unused}}
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20 *VP; // no warning.
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21 P[4]; // expected-warning {{expression result unused}}
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22 VP[4]; // no warning.
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23
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24 __real__ C; // expected-warning {{expression result unused}}
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25 __real__ VC;
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26
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27 // We know this can't change errno because of no -fmath-errno.
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28 sqrt(A); // expected-warning {{ignoring return value of function declared with const attribute}}
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29 }
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30
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31 extern void t1();
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32 extern void t2();
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33 void t3(int c) {
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34 c ? t1() : t2();
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35 }
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36
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37 // This shouldn't warn: the expr at the end of the stmtexpr really is used.
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38 int stmt_expr(int x, int y) {
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39 return ({int _a = x, _b = y; _a > _b ? _a : _b; });
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40 }
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41
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42 void nowarn(unsigned char* a, unsigned char* b)
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43 {
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44 unsigned char c = 1;
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45 *a |= c, *b += c;
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46
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47
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48 // PR4633
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49 int y, x;
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50 ((void)0), y = x;
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51 }
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52
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53 void t4(int a) {
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54 int b = 0;
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55
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56 if (a)
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57 b < 1; // expected-warning{{relational comparison result unused}}
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58 else
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59 b < 2; // expected-warning{{relational comparison result unused}}
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60
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61 while (1)
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62 b < 3; // expected-warning{{relational comparison result unused}}
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63
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64 do
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65 b < 4; // expected-warning{{relational comparison result unused}}
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66 while (1);
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67
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68 for (;;)
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69 b < 5; // expected-warning{{relational comparison result unused}}
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70
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71 for (b < 1;;) {} // expected-warning{{relational comparison result unused}}
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72 for (;b < 1;) {}
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73 for (;;b < 1) {} // expected-warning{{relational comparison result unused}}
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74 }
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75
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76 // rdar://7186119
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77 int t5f(void) __attribute__((warn_unused_result));
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78 void t5() {
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79 t5f(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}}
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80 }
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81
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82
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83 int fn1() __attribute__ ((warn_unused_result));
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84 int fn2() __attribute__ ((pure));
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85 int fn3() __attribute__ ((__const));
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86 // rdar://6587766
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87 int t6() {
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88 if (fn1() < 0 || fn2(2,1) < 0 || fn3(2) < 0) // no warnings
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89 return -1;
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90
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91 fn1(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}}
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92 fn2(92, 21); // expected-warning {{ignoring return value of function declared with pure attribute}}
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93 fn3(42); // expected-warning {{ignoring return value of function declared with const attribute}}
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94 __builtin_abs(0); // expected-warning {{ignoring return value of function declared with const attribute}}
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95 (void)0, fn1(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}}
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96 return 0;
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97 }
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98
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99 int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
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100
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101 // PR4010
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102 int (*fn4)(void) __attribute__ ((warn_unused_result));
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103 void t8() {
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104 fn4(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}}
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105 }
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106
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107 void t9() __attribute__((warn_unused_result)); // expected-warning {{attribute 'warn_unused_result' cannot be applied to functions without return value}}
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108
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109 // rdar://7410924
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110 void *some_function(void);
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111 void t10() {
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112 (void*) some_function(); //expected-warning {{expression result unused; should this cast be to 'void'?}}
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113 }
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114
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115 void f(int i, ...) {
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116 __builtin_va_list ap;
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117
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118 __builtin_va_start(ap, i);
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119 __builtin_va_arg(ap, int);
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120 __builtin_va_end(ap);
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121 }
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122
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123 // PR8371
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124 int fn5() __attribute__ ((__const));
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125
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126 // Don't warn for unused expressions in macro bodies; however, do warn for
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127 // unused expressions in macro arguments. Macros below are reduced from code
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128 // found in the wild.
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129 #define NOP(a) (a)
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130 #define M1(a, b) (long)foo((a), (b))
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131 #define M2 (long)0;
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132 #define M3(a) (t3(a), fn2())
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133 #define M4(a, b) (foo((a), (b)) ? 0 : t3(a), 1)
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134 #define M5(a, b) (foo((a), (b)), 1)
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135 #define M6() fn1()
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136 #define M7() fn2()
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137 void t11(int i, int j) {
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138 M1(i, j); // no warning
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139 NOP((long)foo(i, j)); // expected-warning {{expression result unused}}
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140 M2; // no warning
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141 NOP((long)0); // expected-warning {{expression result unused}}
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142 M3(i); // no warning
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143 NOP((t3(i), fn2())); // expected-warning {{ignoring return value}}
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144 M4(i, j); // no warning
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145 NOP((foo(i, j) ? 0 : t3(i), 1)); // expected-warning {{expression result unused}}
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146 M5(i, j); // no warning
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147 NOP((foo(i, j), 1)); // expected-warning {{expression result unused}}
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148 M6(); // expected-warning {{ignoring return value}}
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149 M7(); // no warning
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150 }
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151 #undef NOP
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152 #undef M1
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153 #undef M2
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154 #undef M3
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155 #undef M4
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156 #undef M5
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157 #undef M6
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158 #undef M7
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159
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160 #define UNREFERENCED_PARAMETER(x) (x)
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161
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162 void unused_parm(int a) {
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163 // Don't warn if the warning is introduced by a macro that's spelled
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164 // UNREFERENCED_PARAMETER, as that's a commonly used macro in Windows headers.
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165 UNREFERENCED_PARAMETER(a);
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166 }
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