clang/test/Sema/warn-tautological-compare.c

   1 // RUN: %clang_cc1 -triple x86_64-apple-darwin -fsyntax-only -verify  %s
   2
   3 extern int a[] __attribute__((weak));
   4 int b[] = {8,13,21};
   5 struct {
   6   int x[10];
   7 } c;
   8 const char str[] = "text";
   9
  10 void ignore(void) {
  11   if (!a) {}
  12 }
  13 void test(void) {
  14   if (!b) {} // expected-warning {{address of array 'b' will always evaluate to 'true'}}
  15   if (b == 0) {} // expected-warning {{comparison of array 'b' equal to a null pointer is always false}}
  16   if (!c.x) {} // expected-warning {{address of array 'c.x' will always evaluate to 'true'}}
  17   if (c.x == 0) {} // expected-warning {{comparison of array 'c.x' equal to a null pointer is always false}}
  18   if (!str) {} // expected-warning {{address of array 'str' will always evaluate to 'true'}}
  19   if (0 == str) {} // expected-warning {{comparison of array 'str' equal to a null pointer is always false}}
  20 }
  21
  22 int array[2];
  23 int test1(void)
  24 {
  25   if (!array) { // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  26     return array[0];
  27   } else if (array != 0) { // expected-warning {{comparison of array 'array' not equal to a null pointer is always true}}
  28     return array[1];
  29   }
  30   if (array == 0) // expected-warning {{comparison of array 'array' equal to a null pointer is always false}}
  31     return 1;
  32   return 0;
  33 }
  34
  35 #define NULL (void*)0
  36
  37 int test2(int* pointer, char ch, void * pv) {
  38    if (!&pointer) {  // expected-warning {{address of 'pointer' will always evaluate to 'true'}}
  39      return 0;
  40    }
  41
  42    if (&pointer) {  // expected-warning {{address of 'pointer' will always evaluate to 'true'}}
  43      return 0;
  44    }
  45
  46    if (&pointer == NULL) {} // expected-warning {{comparison of address of 'pointer' equal to a null pointer is always false}}
  47
  48    if (&pointer != NULL) {} // expected-warning {{comparison of address of 'pointer' not equal to a null pointer is always true}}
  49
  50    return 1;
  51 }
  52
  53 void test3(void) {
  54    if (array) { } // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  55    if (array != 0) {} // expected-warning {{comparison of array 'array' not equal to a null pointer is always true}}
  56    if (!array) { } // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  57    if (array == 0) {} // expected-warning {{comparison of array 'array' equal to a null pointer is always false}}
  58
  59    if (array[0] &&
  60        array) {} // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  61
  62    if (array[0] ||
  63        array) {} // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  64
  65    if (array[0] &&
  66        !array) {} // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  67    if (array[0] ||
  68        !array) {} // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  69
  70    if (array && // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  71        array[0]) {}
  72    if (!array || // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  73        array[0]) {}
  74
  75    if (array ||  // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  76        (!array && array[0])) {} // expected-warning {{address of array 'array' will always evaluate to 'true'}}
  77  }
  78
  79 #define SAVE_READ(PTR) if( (PTR) && (&result) ) *result=*PTR;
  80 void _HTTPClientErrorHandler(int me)
  81 {
  82   int *result;
  83   SAVE_READ(&me);
  84 }
  85
  86 void test_conditional_operator(void) {
  87   int x;
  88   x = b ? 1 : 0;     // expected-warning {{address of array}}
  89   x = c.x ? 1 : 0;   // expected-warning {{address of array}}
  90   x = str ? 1 : 0;   // expected-warning {{address of array}}
  91   x = array ? 1 : 0; // expected-warning {{address of array}}
  92   x = &x ? 1 : 0;    // expected-warning {{address of 'x'}}
  93 }
  94
  95 void test4(void) {
  96   int *a = (void *) 0;
  97   int b = (&a) == ((void *) 0); // expected-warning {{comparison of address of 'a' equal to a null pointer is always false}}
  98 }