gcc/testsuite/gcc.dg/overflow-warn-1.c

   1 /* Test for diagnostics for constant overflow.  */
   2 /* Origin: Joseph Myers <joseph@codesourcery.com> */
   3 /* { dg-do compile } */
   4 /* { dg-options "-std=c99" } */
   5
   6 #include <limits.h>
   7
   8 enum e {
   9   E0 = INT_MAX,
  10   /* Unsigned overflow wraps around.  */
  11   E1 = UINT_MAX + 1,
  12   /* Overflow in an unevaluated part of an expression is OK (example
  13      in the standard).  */
  14   E2 = 2 || 1 / 0,
  15   E3 = 1 / 0, /* { dg-warning "warning: division by zero" } */
  16   /* { dg-error "error: enumerator value for 'E3' is not an integer constant" "enum error" { target *-*-* } 15 } */
  17   /* But as in DR#031, the 1/0 in an evaluated subexpression means the
  18      whole expression violates the constraints.  */
  19   E4 = 0 * (1 / 0), /* { dg-warning "warning: division by zero" } */
  20   /* { dg-error "error: enumerator value for 'E4' is not an integer constant" "enum error" { xfail *-*-* } 19 } */
  21   E5 = INT_MAX + 1, /* { dg-warning "warning: integer overflow in expression" } */
  22   /* Again, overflow in evaluated subexpression.  */
  23   E6 = 0 * (INT_MAX + 1), /* { dg-warning "warning: integer overflow in expression" } */
  24   /* A cast does not constitute overflow in conversion.  */
  25   E7 = (char) INT_MAX
  26 };
  27
  28 struct s {
  29   int a;
  30   int : 0 * (1 / 0); /* { dg-warning "warning: division by zero" } */
  31   int : 0 * (INT_MAX + 1); /* { dg-warning "warning: integer overflow in expression" } */
  32 };
  33
  34 void
  35 f (void)
  36 {
  37   /* This expression is not required to be a constant expression, so
  38      it should just involve undefined behavior at runtime.  */
  39   int c = INT_MAX + 1; /* { dg-warning "warning: integer overflow in expression" } */
  40 }
  41
  42 /* But this expression does need to be constant.  */
  43 static int sc = INT_MAX + 1; /* { dg-warning "warning: integer overflow in expression" } */
  44
  45 /* The first two of these involve overflow, so are not null pointer
  46    constants.  The third has the overflow in an unevaluated
  47    subexpression, so is a null pointer constant.  */
  48 void *p = 0 * (INT_MAX + 1); /* { dg-warning "warning: integer overflow in expression" } */
  49 /* { dg-warning "warning: initialization makes pointer from integer without a cast" "null" { target *-*-* } 48 } */
  50 void *q = 0 * (1 / 0); /* { dg-warning "warning: division by zero" } */
  51 /* { dg-warning "warning: initialization makes pointer from integer without a cast" "null" { xfail *-*-* } 50 } */
  52 void *r = (1 ? 0 : INT_MAX+1);
  53
  54 void
  55 g (int i)
  56 {
  57   switch (i)
  58     {
  59     case 0 * (1/0): /* { dg-warning "warning: division by zero" } */
  60       ;
  61     case 1 + 0 * (INT_MAX + 1): /* { dg-warning "warning: integer overflow in expression" } */
  62       ;
  63     }
  64 }
  65
  66 int
  67 h (void)
  68 {
  69   return INT_MAX + 1; /* { dg-warning "warning: integer overflow in expression" } */
  70 }
  71
  72 int
  73 h1 (void)
  74 {
  75   return INT_MAX + 1 - INT_MAX; /* { dg-warning "warning: integer overflow in expression" } */
  76 }
  77
  78 void fuc (unsigned char);
  79 void fsc (signed char);
  80
  81 void
  82 h2 (void)
  83 {
  84   fsc (SCHAR_MAX + 1);
  85   fsc (SCHAR_MIN - 1); /* { dg-warning "warning: overflow in implicit constant conversion" } */
  86   fsc (UCHAR_MAX);
  87   fsc (UCHAR_MAX + 1); /* { dg-warning "warning: overflow in implicit constant conversion" } */
  88   fuc (-1);
  89   fuc (UCHAR_MAX + 1); /* { dg-warning "warning: large integer implicitly truncated to unsigned type" } */
  90   fuc (SCHAR_MIN);
  91   fuc (SCHAR_MIN - 1); /* { dg-warning "warning: large integer implicitly truncated to unsigned type" } */
  92   fuc (-UCHAR_MAX); /* { dg-warning "warning: large integer implicitly truncated to unsigned type" } */
  93 }
  94
  95 void fui (unsigned int);
  96 void fsi (signed int);
  97
  98 int si;
  99 unsigned ui;
 100
 101 void
 102 h2i (int x)
 103 {
 104   /* For some reason, we only give certain warnings for implicit
 105      conversions among values of the same precision with -Wconversion,
 106      while we don't give others at all.  */
 107   fsi ((unsigned)INT_MAX + 1);
 108   si = (unsigned)INT_MAX + 1;
 109   si = x ? (unsigned)INT_MAX + 1 : 1;
 110   fsi ((unsigned)INT_MAX + 2);
 111   si = (unsigned)INT_MAX + 2;
 112   si = x ? (unsigned)INT_MAX + 2 : 1;
 113   fsi (UINT_MAX);
 114   si = UINT_MAX;
 115   fui (-1);
 116   ui = -1;
 117   ui = x ? -1 : 1U;
 118   fui (INT_MIN);
 119   ui = INT_MIN;
 120   ui = x ? INT_MIN : 1U;
 121 }