gcc/testsuite/gcc.dg/overflow-warn-4.c

   1 /* Test for diagnostics for constant overflow.  Test with -pedantic-errors.  */
   2 /* Origin: Joseph Myers <joseph@codesourcery.com> */
   3 /* { dg-do compile } */
   4 /* { dg-options "-std=c99 -pedantic-errors" } */
   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 "division by zero" } */
  16   /* { dg-error "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 "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 "integer overflow in expression" } */
  22   /* { dg-error "overflow in constant expression" "constant" { target *-*-* } .-1 } */
  23   /* Again, overflow in evaluated subexpression.  */
  24   E6 = 0 * (INT_MAX + 1), /* { dg-warning "integer overflow in expression of type .int. results in .-\[0-9\]+." } */
  25   /* { dg-error "overflow in constant expression" "constant" { target *-*-* } .-1 } */
  26   /* A cast does not constitute overflow in conversion.  */
  27   E7 = (char) INT_MAX
  28 };
  29
  30 struct s {
  31   int a;
  32   int : 0 * (1 / 0); /* { dg-warning "division by zero" } */
  33   /* { dg-error "not an integer constant" "integer constant" { target *-*-* } .-1 } */
  34   int : 0 * (INT_MAX + 1); /* { dg-warning "integer overflow in expression" } */
  35   /* { dg-error "overflow in constant expression" "constant" { target *-*-* } .-1 } */
  36 };
  37
  38 void
  39 f (void)
  40 {
  41   /* This expression is not required to be a constant expression, so
  42      it should just involve undefined behavior at runtime.  */
  43   int c = INT_MAX + 1; /* { dg-warning "integer overflow in expression" } */
  44
  45 }
  46
  47 /* But this expression does need to be constant.  */
  48 static int sc = INT_MAX + 1; /* { dg-warning "integer overflow in expression" } */
  49 /* { dg-error "overflow in constant expression" "constant" { target *-*-* } .-1 } */
  50
  51 /* The first two of these involve overflow, so are not null pointer
  52    constants.  The third has the overflow in an unevaluated
  53    subexpression, so is a null pointer constant.  */
  54 void *p = 0 * (INT_MAX + 1); /* { dg-warning "integer overflow in expression" } */
  55 /* { dg-error "overflow in constant expression" "constant" { target *-*-* } .-1 } */
  56 /* { dg-error "initialization of 'void \\*' from 'int' makes pointer from integer without a cast" "null" { target *-*-* } .-2 } */
  57 void *q = 0 * (1 / 0); /* { dg-warning "division by zero" } */
  58 /* { dg-error "initializer element is not constant" "constant" { target *-*-* } .-1 } */
  59 /* { dg-error "initialization of 'void \\*' from 'int' makes pointer from integer without a cast" "null" { target *-*-* } .-2 } */
  60 void *r = (1 ? 0 : INT_MAX+1);
  61
  62 void
  63 g (int i)
  64 {
  65   switch (i)
  66     {
  67     case 0 * (1/0): /* { dg-warning "division by zero" } */
  68       /* { dg-error "case label does not reduce to an integer constant" "constant" { target *-*-* } .-1 } */
  69       ;
  70     case 1 + 0 * (INT_MAX + 1): /* { dg-warning "integer overflow in expression" } */
  71       /* { dg-error "overflow in constant expression" "constant" { target *-*-* } .-1 } */
  72       ;
  73     }
  74 }
  75
  76 int
  77 h (void)
  78 {
  79   return INT_MAX + 1; /* { dg-warning "integer overflow in expression" } */
  80 }
  81
  82 int
  83 h1 (void)
  84 {
  85   return INT_MAX + 1 - INT_MAX; /* { dg-warning "integer overflow in expression" } */
  86 }
  87
  88 void fuc (unsigned char);
  89 void fsc (signed char);
  90
  91 void
  92 h2 (void)
  93 {
  94   fsc (SCHAR_MAX + 1); /* { dg-warning "overflow in conversion from .int. to .signed char. changes value" } */
  95   fsc (SCHAR_MIN - 1); /* { dg-warning "overflow in conversion" } */
  96   fsc (UCHAR_MAX); /* { dg-warning "overflow in conversion" } */
  97   fsc (UCHAR_MAX + 1); /* { dg-warning "overflow in conversion" } */
  98   fuc (-1);
  99   fuc (UCHAR_MAX + 1); /* { dg-warning "unsigned conversion from .int. to .unsigned char. changes value" } */
 100   fuc (SCHAR_MIN);
 101   fuc (SCHAR_MIN - 1); /* { dg-warning "unsigned conversion" } */
 102   fuc (-UCHAR_MAX); /* { dg-warning "unsigned conversion" } */
 103 }
 104
 105 void fui (unsigned int);
 106 void fsi (signed int);
 107
 108 int si;
 109 unsigned ui;
 110
 111 void
 112 h2i (int x)
 113 {
 114   /* For some reason, we only give certain warnings for implicit
 115      conversions among values of the same precision with -Wconversion,
 116      while we don't give others at all.  */
 117   fsi ((unsigned)INT_MAX + 1);
 118   si = (unsigned)INT_MAX + 1;
 119   si = x ? (unsigned)INT_MAX + 1 : 1;
 120   fsi ((unsigned)INT_MAX + 2);
 121   si = (unsigned)INT_MAX + 2;
 122   si = x ? (unsigned)INT_MAX + 2 : 1;
 123   fsi (UINT_MAX);
 124   si = UINT_MAX;
 125   fui (-1);
 126   ui = -1;
 127   ui = x ? -1 : 1U;
 128   fui (INT_MIN);
 129   ui = INT_MIN;
 130   ui = x ? INT_MIN : 1U;
 131 }