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' attribute}}
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 Objective-C methods, enums, structs, unions, classes, functions, and function pointers}}
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 
160 #define UNREFERENCED_PARAMETER(x) (x)
161 
unused_parm(int a)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