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
bar(volatile int * VP,int * P,int A,_Complex double C,volatile _Complex double VC)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();
t3(int c)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.
stmt_expr(int x,int y)38 int stmt_expr(int x, int y) {
39 return ({int _a = x, _b = y; _a > _b ? _a : _b; });
40 }
41
nowarn(unsigned char * a,unsigned char * b)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
t4(int a)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));
t5()78 void t5() {
79 t5f(); // expected-warning {{ignoring return value of function declared with warn_unused_result}}
80 }
81
82
83 int fn1() __attribute__ ((warn_unused_result));
84 int fn2() __attribute__ ((pure));
85 int fn3() __attribute__ ((__const));
86 // rdar://6587766
t6()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));
t8()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);
t10()111 void t10() {
112 (void*) some_function(); //expected-warning {{expression result unused; should this cast be to 'void'?}}
113 }
114
f(int i,...)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()
t11(int i,int j)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