1 // RUN: %clang_cc1 -fsyntax-only -verify %s -Wno-unreachable-code 2 3 int foo(int X, int Y); 4 5 double sqrt(double X); // implicitly const because of no -fmath-errno! 6 7 void bar(volatile int *VP, int *P, int A, 8 _Complex double C, volatile _Complex double VC) { 9 10 VP < P; // expected-warning {{relational comparison result unused}} 11 (void)A; 12 (void)foo(1,2); // no warning. 13 14 A < foo(1, 2); // expected-warning {{relational comparison result unused}} 15 16 foo(1,2)+foo(4,3); // expected-warning {{expression result unused}} 17 18 19 *P; // expected-warning {{expression result unused}} 20 *VP; // no warning. 21 P[4]; // expected-warning {{expression result unused}} 22 VP[4]; // no warning. 23 24 __real__ C; // expected-warning {{expression result unused}} 25 __real__ VC; 26 27 // We know this can't change errno because of no -fmath-errno. 28 sqrt(A); // expected-warning {{ignoring return value of function declared with const attribute}} 29 } 30 31 extern void t1(); 32 extern void t2(); 33 void t3(int c) { 34 c ? t1() : t2(); 35 } 36 37 // This shouldn't warn: the expr at the end of the stmtexpr really is used. 38 int stmt_expr(int x, int y) { 39 return ({int _a = x, _b = y; _a > _b ? _a : _b; }); 40 } 41 42 void nowarn(unsigned char* a, unsigned char* b) 43 { 44 unsigned char c = 1; 45 *a |= c, *b += c; 46 47 48 // PR4633 49 int y, x; 50 ((void)0), y = x; 51 } 52 53 void t4(int a) { 54 int b = 0; 55 56 if (a) 57 b < 1; // expected-warning{{relational comparison result unused}} 58 else 59 b < 2; // expected-warning{{relational comparison result unused}} 60 61 while (1) 62 b < 3; // expected-warning{{relational comparison result unused}} 63 64 do 65 b < 4; // expected-warning{{relational comparison result unused}} 66 while (1); 67 68 for (;;) 69 b < 5; // expected-warning{{relational comparison result unused}} 70 71 for (b < 1;;) {} // expected-warning{{relational comparison result unused}} 72 for (;b < 1;) {} 73 for (;;b < 1) {} // expected-warning{{relational comparison result unused}} 74 } 75 76 // rdar://7186119 77 int t5f(void) __attribute__((warn_unused_result)); 78 void t5() { 79 t5f(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}} 80 } 81 82 83 int fn1() __attribute__ ((warn_unused_result)); 84 int fn2() __attribute__ ((pure)); 85 int fn3() __attribute__ ((__const)); 86 // rdar://6587766 87 int t6() { 88 if (fn1() < 0 || fn2(2,1) < 0 || fn3(2) < 0) // no warnings 89 return -1; 90 91 fn1(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}} 92 fn2(92, 21); // expected-warning {{ignoring return value of function declared with pure attribute}} 93 fn3(42); // expected-warning {{ignoring return value of function declared with const attribute}} 94 __builtin_abs(0); // expected-warning {{ignoring return value of function declared with const attribute}} 95 (void)0, fn1(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}} 96 return 0; 97 } 98 99 int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to functions}} 100 101 // PR4010 102 int (*fn4)(void) __attribute__ ((warn_unused_result)); 103 void t8() { 104 fn4(); // expected-warning {{ignoring return value of function declared with 'warn_unused_result' attribute}} 105 } 106 107 void t9() __attribute__((warn_unused_result)); // expected-warning {{attribute 'warn_unused_result' cannot be applied to functions without return value}} 108 109 // rdar://7410924 110 void *some_function(void); 111 void t10() { 112 (void*) some_function(); //expected-warning {{expression result unused; should this cast be to 'void'?}} 113 } 114 115 void f(int i, ...) { 116 __builtin_va_list ap; 117 118 __builtin_va_start(ap, i); 119 __builtin_va_arg(ap, int); 120 __builtin_va_end(ap); 121 } 122 123 // PR8371 124 int fn5() __attribute__ ((__const)); 125 126 // Don't warn for unused expressions in macro bodies; however, do warn for 127 // unused expressions in macro arguments. Macros below are reduced from code 128 // found in the wild. 129 #define NOP(a) (a) 130 #define M1(a, b) (long)foo((a), (b)) 131 #define M2 (long)0; 132 #define M3(a) (t3(a), fn2()) 133 #define M4(a, b) (foo((a), (b)) ? 0 : t3(a), 1) 134 #define M5(a, b) (foo((a), (b)), 1) 135 #define M6() fn1() 136 #define M7() fn2() 137 void t11(int i, int j) { 138 M1(i, j); // no warning 139 NOP((long)foo(i, j)); // expected-warning {{expression result unused}} 140 M2; // no warning 141 NOP((long)0); // expected-warning {{expression result unused}} 142 M3(i); // no warning 143 NOP((t3(i), fn2())); // expected-warning {{ignoring return value}} 144 M4(i, j); // no warning 145 NOP((foo(i, j) ? 0 : t3(i), 1)); // expected-warning {{expression result unused}} 146 M5(i, j); // no warning 147 NOP((foo(i, j), 1)); // expected-warning {{expression result unused}} 148 M6(); // expected-warning {{ignoring return value}} 149 M7(); // no warning 150 } 151 #undef NOP 152 #undef M1 153 #undef M2 154 #undef M3 155 #undef M4 156 #undef M5 157 #undef M6 158 #undef M7 159 160 #define UNREFERENCED_PARAMETER(x) (x) 161 162 void unused_parm(int a) { 163 // Don't warn if the warning is introduced by a macro that's spelled 164 // UNREFERENCED_PARAMETER, as that's a commonly used macro in Windows headers. 165 UNREFERENCED_PARAMETER(a); 166 } 167
