gcc/testsuite/gcc.dg/Wdangling-pointer-2.c

   1 /* Exercise conditional C-only uses of dangling pointers with optimization.
   2    { dg-do compile }
   3    { dg-options "-O2 -Wall" } */
   4
   5 typedef __SIZE_TYPE__ size_t;
   6
   7 extern void* memchr (const void*, int, size_t);
   8 extern char* strchr (const char*, int);
   9
  10 void sink (void*, ...);
  11
  12
  13 void nowarn_compound_literal (int i, int j)
  14 {
  15   {
  16     int *p = i ? (int[]){ 1, 2, 3 } : (int[]){ 4, 5, 6 };
  17     sink (p);
  18   }
  19   {
  20     int a[] = { 1, 2, 3 };
  21     int *q = i ? (int[]){ 4, 5, 6 } : a;
  22     int *p = &q[1];
  23     sink (p);
  24   }
  25   {
  26     int *p = i ? (int[]){ 1, 2, 3 } : (int[]){ 4, 5, 6 };
  27     int *q = __builtin_memchr (p, 2, 3 * sizeof *p);
  28     sink (q);
  29   }
  30   {
  31     int a[] = { i, i + 1, i + 2, 3 };
  32     int *p = i ? (int[]){ j, j + 1, j + 2, 3 } : a;
  33     int *q = __builtin_memchr (p, 3, 4 * sizeof *p);
  34     sink (q);
  35   }
  36 }
  37
  38
  39 void warn_maybe_compound_literal (int i, int j)
  40 {
  41   int a[] = { 1, 2, 3 }, *p;
  42   {
  43     p = i ? (int[]){ 4, 5, 6 } : a;
  44   }
  45   // When the 'p' is optimized away it's not mentioned in the warning.
  46   sink (p);         // { dg-warning "dangling pointer \('p' \)?to an unnamed temporary may be used" }
  47 }
  48
  49
  50 void warn_maybe_compound_literal_memchr (int i, int j, int x)
  51 {
  52   int a[] = { 1, 2, 3 }, *p;
  53   {
  54     int *q = i ? (int[]){ 4, 5, 6 } : a;
  55     p = memchr (q, x, 3 * sizeof *q);
  56   }
  57   sink (p);         // { dg-warning "dangling pointer 'p' to an unnamed temporary may be used" }
  58 }
  59
  60
  61 void warn_maybe_array (int i, int j)
  62 {
  63   int a[] = { 1, 2, 3 }, *p;
  64   {
  65     int b[] = { 4, 5, 6 };
  66     p = i ? a : b;
  67   }
  68   // When the 'p' is optimized away it's not mentioned in the warning.
  69   sink (p);         // { dg-warning "dangling pointer \('p' \)?to 'b' may be used" }
  70 }
  71
  72
  73 void warn_maybe_array_memchr (int i, int j, int x)
  74 {
  75   int a[] = { 1, 2, 3 }, *p;
  76   {
  77     int b[] = { 4, 5, 6 };
  78     int *q = i ? a : b;
  79     p = memchr (q, x, 3 * sizeof *q);
  80   }
  81   sink (p);         // { dg-warning "dangling pointer 'p' to 'b' may be used" }
  82 }