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 "10:division by zero" } */
  16   /* { dg-error "3:enumerator value for 'E3' is not an integer constant" "enum error" { target *-*-* } .-1 } */
  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 "15:division by zero" } */
  20   /* { dg-error "enumerator value for 'E4' is not an integer constant" "enum error" { target *-*-* } .-1 } */
  21   E5 = INT_MAX + 1, /* { dg-warning "16:integer overflow in expression" } */
  22   /* Again, overflow in evaluated subexpression.  */
  23   E6 = 0 * (INT_MAX + 1), /* { dg-warning "21: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 "16:division by zero" } */
  31   /* { dg-error "not an integer constant" "22:integer constant" { target *-*-* } .-1 } */
  32   int : 0 * (INT_MAX + 1); /* { dg-warning "integer overflow in expression" } */
  33 };
  34
  35 void
  36 f (void)
  37 {
  38   /* This expression is not required to be a constant expression, so
  39      it should just involve undefined behavior at runtime.  */
  40   int c = INT_MAX + 1; /* { dg-warning "19:integer overflow in expression" } */
  41 }
  42
  43 /* But this expression does need to be constant.  */
  44 static int sc = INT_MAX + 1; /* { dg-warning "25:integer overflow in expression" } */
  45
  46 /* The first two of these involve overflow, so are not null pointer
  47    constants.  The third has the overflow in an unevaluated
  48    subexpression, so is a null pointer constant.  */
  49 void *p = 0 * (INT_MAX + 1); /* { dg-warning "integer overflow in expression" } */
  50 /* { dg-warning "initialization of 'void \\*' from 'int' makes pointer from integer without a cast" "null" { target *-*-* } .-1 } */
  51 void *q = 0 * (1 / 0); /* { dg-warning "division by zero" } */
  52 /* { dg-error "initializer element is not constant" "constant" { target *-*-* } .-1 } */
  53 /* { dg-warning "initialization of 'void \\*' from 'int' makes pointer from integer without a cast" "null" { target *-*-* } .-2 } */
  54 void *r = (1 ? 0 : INT_MAX+1);
  55
  56 void
  57 g (int i)
  58 {
  59   switch (i)
  60     {
  61     case 0 * (1/0): /* { dg-warning "division by zero" } */
  62       /* { dg-error "case label does not reduce to an integer constant" "constant" { target *-*-* } .-1 } */
  63       ;
  64     case 1 + 0 * (INT_MAX + 1): /* { dg-warning "integer overflow in expression" } */
  65       ;
  66     }
  67 }
  68
  69 int
  70 h (void)
  71 {
  72   return INT_MAX + 1; /* { dg-warning "integer overflow in expression" } */
  73 }
  74
  75 int
  76 h1 (void)
  77 {
  78   return INT_MAX + 1 - INT_MAX; /* { dg-warning "integer overflow in expression" } */
  79 }
  80
  81 void fuc (unsigned char);
  82 void fsc (signed char);
  83
  84 void
  85 h2 (void)
  86 {
  87   fsc (SCHAR_MAX + 1);
  88   fsc (SCHAR_MIN - 1); /* { dg-warning "overflow in conversion from .int. to .signed char. changes value " } */
  89   fsc (UCHAR_MAX);
  90   fsc (UCHAR_MAX + 1); /* { dg-warning "overflow in conversion from .int. to .signed char. changes value from " } */
  91   fuc (-1);
  92   fuc (UCHAR_MAX + 1); /* { dg-warning "unsigned conversion from .int. to .unsigned char. changes value " } */
  93   fuc (SCHAR_MIN);
  94   fuc (SCHAR_MIN - 1); /* { dg-warning "unsigned conversion from .int. to .unsigned char. changes value " } */
  95   fuc (-UCHAR_MAX); /* { dg-warning "unsigned conversion from .int. to .unsigned char. changes value " } */
  96 }
  97
  98 void fui (unsigned int);
  99 void fsi (signed int);
 100
 101 int si;
 102 unsigned ui;
 103
 104 void
 105 h2i (int x)
 106 {
 107   /* For some reason, we only give certain warnings for implicit
 108      conversions among values of the same precision with -Wconversion,
 109      while we don't give others at all.  */
 110   fsi ((unsigned)INT_MAX + 1);
 111   si = (unsigned)INT_MAX + 1;
 112   si = x ? (unsigned)INT_MAX + 1 : 1;
 113   fsi ((unsigned)INT_MAX + 2);
 114   si = (unsigned)INT_MAX + 2;
 115   si = x ? (unsigned)INT_MAX + 2 : 1;
 116   fsi (UINT_MAX);
 117   si = UINT_MAX;
 118   fui (-1);
 119   ui = -1;
 120   ui = x ? -1 : 1U;
 121   fui (INT_MIN);
 122   ui = INT_MIN;
 123   ui = x ? INT_MIN : 1U;
 124 }