libstdc++-v3/testsuite/25_algorithms/copy_n/108846.cc

   1 // { dg-do run { target c++11 } }
   2
   3 #include <algorithm>
   4 #include <testsuite_hooks.h>
   5
   6 // PR libstdc++/108846 std::copy, std::copy_n and std::copy_backward
   7 // on potentially overlapping subobjects
   8
   9 struct B {
  10     B(int i, short j) : i(i), j(j) {}
  11     int i;
  12     short j;
  13 };
  14 struct D : B {
  15     D(int i, short j, short x) : B(i, j), x(x) {}
  16     short x; // Stored in tail padding of B
  17 };
  18
  19 void
  20 test_pr108846()
  21 {
  22     D ddst(1, 2, 3);
  23     D dsrc(4, 5, 6);
  24     B *dst = &ddst;
  25     B *src = &dsrc;
  26     // If this is optimized to memmove it will overwrite tail padding.
  27     std::copy_n(src, 1, dst);
  28     // Check tail padding is unchanged:
  29     VERIFY(ddst.x == 3);
  30     // Check B subobject was copied:
  31     VERIFY(ddst.i == 4 && ddst.j == 5);
  32 #if __cpp_lib_ranges >= 201911L
  33     ddst.i = ddst.j = 99;
  34     std::ranges::copy_n(src, 1, dst);
  35     VERIFY(ddst.x == 3);
  36     VERIFY(ddst.i == 4 && ddst.j == 5);
  37 #endif
  38 }
  39
  40 struct B2 {
  41     B2(int i, short j) : i(i), j(j) {}
  42     B2& operator=(B2& b) { i = b.i; j = b.j; return *this; }
  43     int i;
  44     short j;
  45 };
  46 struct D2 : B2 {
  47     D2(int i, short j, short x) : B2(i, j), x(x) {}
  48     short x; // Stored in tail padding of B2
  49 };
  50
  51 void
  52 test_non_const_copy_assign()
  53 {
  54     D2 ddst(1, 2, 3);
  55     D2 dsrc(4, 5, 6);
  56     B2 *dst = &ddst;
  57     B2 *src = &dsrc;
  58     // Ensure the not-taken trivial copy path works for this type.
  59     std::copy_n(src, 1, dst);
  60     // Check tail padding is unchanged:
  61     VERIFY(ddst.x == 3);
  62     // Check B subobject was copied:
  63     VERIFY(ddst.i == 4 && ddst.j == 5);
  64 #if __cpp_lib_ranges >= 201911L
  65     ddst.i = ddst.j = 99;
  66     std::ranges::copy_n(src, 1, dst);
  67     VERIFY(ddst.x == 3);
  68     VERIFY(ddst.i == 4 && ddst.j == 5);
  69 #endif
  70 }
  71
  72 struct B3 {
  73     B3(int i, short j) : i(i), j(j) {}
  74     B3& operator=(B3& b) = default;
  75     int i;
  76     short j;
  77 };
  78 struct D3 : B3 {
  79     D3(int i, short j, short x) : B3(i, j), x(x) {}
  80     short x; // Stored in tail padding of B3
  81 };
  82
  83 void
  84 test_non_const_copy_assign_trivial()
  85 {
  86     D3 ddst(1, 2, 3);
  87     D3 dsrc(4, 5, 6);
  88     B3 *dst = &ddst;
  89     B3 *src = &dsrc;
  90     // If this is optimized to memmove it will overwrite tail padding.
  91     std::copy_n(src, 1, dst);
  92     // Check tail padding is unchanged:
  93     VERIFY(ddst.x == 3);
  94     // Check B subobject was copied:
  95     VERIFY(ddst.i == 4 && ddst.j == 5);
  96 #if __cpp_lib_ranges >= 201911L
  97     ddst.i = ddst.j = 99;
  98     std::ranges::copy_n(src, 1, dst);
  99     VERIFY(ddst.x == 3);
 100     VERIFY(ddst.i == 4 && ddst.j == 5);
 101 #endif
 102 }
 103
 104 int main()
 105 {
 106   test_pr108846();
 107   test_non_const_copy_assign();
 108   test_non_const_copy_assign_trivial();
 109 }