libstdc++-v3/testsuite/25_algorithms/move_backward/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::move_backward(src, src+1, dst+1);
  28     VERIFY(ddst.x == 3);
  29 #if __cpp_lib_ranges >= 201911L
  30     std::ranges::move_backward(src, src+1, dst+1);
  31     VERIFY(ddst.x == 3);
  32 #endif
  33 }
  34
  35 struct B2 {
  36     B2(int i, short j) : i(i), j(j) {}
  37     B2& operator=(B2&& b) { i = b.i; j = b.j; return *this; }
  38     int i;
  39     short j;
  40 };
  41 struct D2 : B2 {
  42     D2(int i, short j, short x) : B2(i, j), x(x) {}
  43     short x; // Stored in tail padding of B2
  44 };
  45
  46 void
  47 test_move_only()
  48 {
  49     D2 ddst(1, 2, 3);
  50     D2 dsrc(4, 5, 6);
  51     B2 *dst = &ddst;
  52     B2 *src = &dsrc;
  53     // Ensure the not-taken trivial copy path works for this type.
  54     std::move_backward(src, src+1, dst+1);
  55     VERIFY(ddst.x == 3);
  56 #if __cpp_lib_ranges >= 201911L
  57     std::ranges::move_backward(src, src+1, dst+1);
  58     VERIFY(ddst.x == 3);
  59 #endif
  60 }
  61
  62 struct B3 {
  63     B3(int i, short j) : i(i), j(j) {}
  64     B3& operator=(B3&&) = default;
  65     int i;
  66     short j;
  67 };
  68 struct D3 : B3 {
  69     D3(int i, short j, short x) : B3(i, j), x(x) {}
  70     short x; // Stored in tail padding of B3
  71 };
  72
  73 void
  74 test_move_only_trivial()
  75 {
  76     D3 ddst(1, 2, 3);
  77     D3 dsrc(4, 5, 6);
  78     B3 *dst = &ddst;
  79     B3 *src = &dsrc;
  80     // Ensure the not-taken trivial copy path works for this type.
  81     std::move_backward(src, src+1, dst+1);
  82     VERIFY(ddst.x == 3);
  83 #if __cpp_lib_ranges >= 201911L
  84     std::ranges::move_backward(src, src+1, dst+1);
  85     VERIFY(ddst.x == 3);
  86 #endif
  87 }
  88
  89 int main()
  90 {
  91   test_pr108846();
  92   test_move_only();
  93   test_move_only_trivial();
  94 }