gcc/testsuite/c-c++-common/builtin-offsetof-2.c

   1 // { dg-options "-Warray-bounds" }
   2 // { dg-do compile }
   3
   4 // Test case exercising pr c/67882 - surprising offsetof result
   5 //   on an invalid array member without diagnostic.
   6
   7 typedef struct A1 {
   8   char a1[1];
   9   char c;
  10 } A1;
  11
  12 typedef struct A1_x_2 {
  13   char a1[1];
  14   char a[][2];
  15 } A1_x_2;
  16
  17 typedef struct A1_1_x {
  18   char a1_1[1][1];
  19   char a[];
  20 } A1_1_x;
  21
  22 typedef struct Ax_2_3 {
  23   int i;
  24   char a_x_2_3[][2][3];
  25 } Ax_2_3;
  26
  27 typedef struct A1_1 {
  28   char a1_1[1][1];
  29   char c;
  30 } A1_1;
  31
  32 typedef struct B {
  33   A1_1 a2_3[2][3];
  34   char a1_1[3][5];
  35   char a[];
  36 } B;
  37
  38 // Structures with members that contain flexible array members are
  39 // an extension accepted by GCC.
  40 typedef struct C {
  41   A1_1_x a5_7 [5][7];
  42   int a;
  43 } C;
  44
  45 // Structs with a "fake" flexible array member (a GCC extension).
  46 typedef struct FA0 {
  47   int i;
  48   char a0 [0];
  49 } FA0;
  50
  51 typedef struct FA1 {
  52   int i;
  53   char a1 [1];
  54 } FA1;
  55
  56 typedef struct FA3 {
  57   int i;
  58   char a3 [3];
  59 } FA3;
  60
  61 // A "fake" multidimensional flexible array member.
  62 typedef struct FA5_7 {
  63   int i;
  64   char a5_7 [5][7];
  65 } FA5_7;
  66
  67 static void test (void)
  68 {
  69   // Verify that offsetof references to array elements past the end of
  70   // the array member are diagnosed.  As an extension, permit references
  71   // to the element just past-the-end of the array.
  72
  73   int a[] = {
  74     __builtin_offsetof (A1, a1),                 // valid
  75     __builtin_offsetof (A1, a1 [0]),             // valid
  76
  77     // The following expression is valid because it forms the equivalent
  78     // of an address pointing just past the last element of the array.
  79     __builtin_offsetof (A1, a1 [1]),             // valid
  80
  81     __builtin_offsetof (A1, a1 [2]),             // { dg-warning "index" }
  82
  83     __builtin_offsetof (A1_x_2, a1),             // valid
  84     __builtin_offsetof (A1_x_2, a1 [0]),         // valid
  85     __builtin_offsetof (A1_x_2, a1 [1]),         // valid
  86     __builtin_offsetof (A1_x_2, a1 [2]),         // { dg-warning "index" }
  87
  88     __builtin_offsetof (A1_x_2, a),              // valid
  89     __builtin_offsetof (A1_x_2, a [0]),          // valid
  90     __builtin_offsetof (A1_x_2, a [1]),          // valid
  91     __builtin_offsetof (A1_x_2, a [99]),         // valid
  92
  93     __builtin_offsetof (A1_x_2, a),              // valid
  94     __builtin_offsetof (A1_x_2, a [0][0]),       // valid
  95     __builtin_offsetof (A1_x_2, a [0][1]),       // valid
  96
  97     // The following expression is valid because it forms the equivalent
  98     // of an address pointing just past the last element of the first
  99     // array.
 100     __builtin_offsetof (A1_x_2, a [0][2]),       // valid
 101
 102     // Unlike the case above, this is invalid since it refers to an element
 103     // past one one just-past-the-end in A[][2].
 104     __builtin_offsetof (A1_x_2, a [0][3]),       // { dg-warning "index" }
 105
 106     __builtin_offsetof (A1_x_2, a [1][0]),       // valid
 107     __builtin_offsetof (A1_x_2, a [1][1]),       // valid
 108     __builtin_offsetof (A1_x_2, a [1][2]),       // valid
 109     __builtin_offsetof (A1_x_2, a [99][0]),      // valid
 110     __builtin_offsetof (A1_x_2, a [99][1]),      // valid
 111     __builtin_offsetof (A1_x_2, a [99][2]),      // valid
 112
 113     __builtin_offsetof (A1_1_x, a),              // valid
 114     __builtin_offsetof (A1_1_x, a [0]),          // valid
 115     __builtin_offsetof (A1_1_x, a [1]),          // valid
 116     __builtin_offsetof (A1_1_x, a [99]),         // valid
 117
 118     __builtin_offsetof (A1_1_x, a1_1 [0][0]),    // valid
 119     __builtin_offsetof (A1_1_x, a1_1 [0][1]),    // valid
 120     __builtin_offsetof (A1_1_x, a1_1 [0][2]),    // { dg-warning "index" }
 121     __builtin_offsetof (A1_1_x, a1_1 [1][0]),    // { dg-warning "index" }
 122     __builtin_offsetof (A1_1_x, a1_1 [1][1]),    // { dg-warning "index" }
 123
 124     __builtin_offsetof (Ax_2_3, a_x_2_3 [0][1][3]),  // valid
 125     __builtin_offsetof (Ax_2_3, a_x_2_3 [0][1][4]),  // { dg-warning "index" }
 126     __builtin_offsetof (Ax_2_3, a_x_2_3 [0][2]),     // valid
 127     __builtin_offsetof (Ax_2_3, a_x_2_3 [0][2][0]),  // { dg-warning "index" }
 128
 129     __builtin_offsetof (B, a2_3 [0][0].c),           // valid
 130     __builtin_offsetof (B, a2_3 [0][0].a1_1 [0][0]), // valid
 131     __builtin_offsetof (B, a2_3 [1][3]),             // valid
 132     __builtin_offsetof (B, a2_3 [1][4]),             // { dg-warning "index" }
 133     __builtin_offsetof (B, a2_3 [0][0].a1_1 [0][1]), // valid
 134     __builtin_offsetof (B, a2_3 [0][0].a1_1 [0][2]), // { dg-warning "index" }
 135
 136     __builtin_offsetof (B, a2_3 [0][0].a1_1 [1][0]), // { dg-warning "index" }
 137     __builtin_offsetof (B, a2_3 [0][0].a1_1 [1][1]), // { dg-warning "index" }
 138
 139     __builtin_offsetof (B, a2_3 [1][2].a1_1 [0][0]), // valid
 140
 141     // Forming an offset to the just-past-end element is valid.
 142     __builtin_offsetof (B, a2_3 [1][2].a1_1 [0][1]), // valid
 143     __builtin_offsetof (B, a2_3 [1][2].a1_1 [1][0]), // { dg-warning "index" }
 144     __builtin_offsetof (B, a2_3 [1][2].a1_1 [1][1]), // { dg-warning "index" }
 145
 146     // Forming an offset to the just-past-end element is valid.
 147     __builtin_offsetof (B, a2_3 [1][3]),             // valid
 148     // ...but these are diagnosed because they dereference a just-past-the-end
 149     // element.
 150     __builtin_offsetof (B, a2_3 [1][3].a1_1 [0][0]), // { dg-warning "index" }
 151     __builtin_offsetof (B, a2_3 [1][3].a1_1 [0][0]), // { dg-warning "index" }
 152     __builtin_offsetof (B, a2_3 [1][3].a1_1 [0][1]), // { dg-warning "index" }
 153     __builtin_offsetof (B, a2_3 [1][3].a1_1 [1][0]), // { dg-warning "index" }
 154     __builtin_offsetof (B, a2_3 [1][3].a1_1 [1][1]), // { dg-warning "index" }
 155
 156     // Analogous to the case above, these are both diagnosed because they
 157     // dereference just-past-the-end elements of the a2_3 array.
 158     __builtin_offsetof (B, a2_3 [1][3].c),       // { dg-warning "index" }
 159     __builtin_offsetof (B, a2_3 [1][3].c),       // { dg-warning "index" }
 160
 161     // The following are all invalid because of the reference to a2_3[2].
 162     __builtin_offsetof (B, a2_3 [2][0].a1_1 [0][0]), // { dg-warning "index" }
 163     __builtin_offsetof (B, a2_3 [2][0].a1_1 [0][1]), // { dg-warning "index" }
 164     __builtin_offsetof (B, a2_3 [2][0].a1_1 [1][0]), // { dg-warning "index" }
 165     __builtin_offsetof (B, a2_3 [2][0].a1_1 [1][1]), // { dg-warning "index" }
 166     __builtin_offsetof (B, a2_3 [2][0].c),           // { dg-warning "index" }
 167
 168     __builtin_offsetof (C, a5_7 [4][6]),
 169     __builtin_offsetof (C, a5_7 [4][6].a),
 170     __builtin_offsetof (C, a5_7 [4][6].a [0]),
 171     __builtin_offsetof (C, a5_7 [4][6].a [99]),
 172
 173     __builtin_offsetof (C, a5_7 [4][7]),             // valid
 174     // Diagnose the following even though the object whose offset is
 175     // computed is a flexible array member.
 176     __builtin_offsetof (C, a5_7 [4][7].a),           // { dg-warning "index" }
 177     __builtin_offsetof (C, a5_7 [4][7].a [0]),       // { dg-warning "index" }
 178     __builtin_offsetof (C, a5_7 [4][7].a [99]),      // { dg-warning "index" }
 179
 180     // Verify that no diagnostic is issued for offsetof expressions
 181     // involving structs where the array has a rank of 1 and is the last
 182     // member (e.g., those are treated as flexible array members).
 183     __builtin_offsetof (FA0, a0 [0]),
 184     __builtin_offsetof (FA0, a0 [1]),
 185     __builtin_offsetof (FA0, a0 [99]),
 186
 187     __builtin_offsetof (FA1, a1 [0]),
 188     __builtin_offsetof (FA1, a1 [1]),
 189     __builtin_offsetof (FA1, a1 [99]),
 190
 191     __builtin_offsetof (FA3, a3 [0]),
 192     __builtin_offsetof (FA3, a3 [3]),
 193     __builtin_offsetof (FA3, a3 [99]),
 194
 195     __builtin_offsetof (FA5_7, a5_7 [0][0]),
 196
 197     // Unlike one-dimensional arrays, verify that out-of-bounds references
 198     // to "fake" flexible arrays with rank of 2 and greater are diagnosed.
 199
 200     // The following are valid because they compute the offset of just past
 201     // the end of each of the a5_7[0] and a5_7[1] arrays.
 202     __builtin_offsetof (FA5_7, a5_7 [0][7]),         // valid
 203     __builtin_offsetof (FA5_7, a5_7 [1][7]),         // valid
 204
 205     // The following two are accepted as an extesion (because a5_7 is
 206     // treated as a flexible array member).
 207     __builtin_offsetof (FA5_7, a5_7 [5][0]),         // extension
 208     __builtin_offsetof (FA5_7, a5_7 [5][7]),         // extension
 209
 210     // The following are invalid since in both cases they denote an element
 211     // that's beyond just-past-the-end of the array.
 212     __builtin_offsetof (FA5_7, a5_7 [0][8]),        // { dg-warning "index" }
 213     __builtin_offsetof (FA5_7, a5_7 [6][8])         // { dg-warning "index" }
 214   };
 215
 216   (void)&a;
 217 }