unused-expr.c revision 634785ca8423b6dd6c15e80714a076c3aaa5a047
1// RUN: %clang_cc1 -fsyntax-only -verify -fno-math-errno %s 2 3int foo(int X, int Y); 4 5double sqrt(double X); // implicitly const because of -fno-math-errno! 6 7void bar(volatile int *VP, int *P, int A, 8 _Complex double C, volatile _Complex double VC) { 9 10 VP == P; // expected-warning {{expression result unused}} 11 (void)A; 12 (void)foo(1,2); // no warning. 13 14 A == foo(1, 2); // expected-warning {{expression 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 -fno-math-errno. 28 sqrt(A); // expected-warning {{ignoring return value of function declared with const attribute}} 29} 30 31extern void t1(); 32extern void t2(); 33void 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. 38int stmt_expr(int x, int y) { 39 return ({int _a = x, _b = y; _a > _b ? _a : _b; }); 40} 41 42void 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 53void t4(int a) { 54 int b = 0; 55 56 if (a) 57 b == 1; // expected-warning{{expression result unused}} 58 else 59 b == 2; // expected-warning{{expression result unused}} 60 61 while (1) 62 b == 3; // expected-warning{{expression result unused}} 63 64 do 65 b == 4; // expected-warning{{expression result unused}} 66 while (1); 67 68 for (;;) 69 b == 5; // expected-warning{{expression result unused}} 70 71 for (b == 1;;) {} // expected-warning{{expression result unused}} 72 for (;b == 1;) {} 73 for (;;b == 1) {} // expected-warning{{expression result unused}} 74} 75 76// rdar://7186119 77int t5f(void) __attribute__((warn_unused_result)); 78void t5() { 79 t5f(); // expected-warning {{ignoring return value of function declared with warn_unused_result}} 80} 81 82 83int fn1() __attribute__ ((warn_unused_result)); 84int fn2() __attribute__ ((pure)); 85int fn3() __attribute__ ((const)); 86// rdar://6587766 87int 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_fabsf(0); // expected-warning {{ignoring return value of function declared with const attribute}} 95 return 0; 96} 97 98int t7 __attribute__ ((warn_unused_result)); // expected-warning {{'warn_unused_result' attribute only applies to function types}} 99 100// PR4010 101int (*fn4)(void) __attribute__ ((warn_unused_result)); 102void t8() { 103 fn4(); // expected-warning {{ignoring return value of function declared with warn_unused_result attribute}} 104} 105 106void t9() __attribute__((warn_unused_result)); // expected-warning {{attribute 'warn_unused_result' cannot be applied to functions without return value}} 107