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      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 {{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 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{{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
     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}}
     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_fabsf(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