libstdc++-v3/testsuite/25_algorithms/fill/109150.cc

   1 // { dg-do run }
   2
   3 // Test the problematic cases identified in PR libstdc++/109150
   4 // where the previous std::fill was non-conforming.
   5
   6 #include <algorithm>
   7 #include <testsuite_hooks.h>
   8
   9 const int global = 0;
  10
  11 struct X {
  12   void operator=(const int& i) { VERIFY(&i == &global); }
  13 };
  14
  15 void
  16 test_identity_matters()
  17 {
  18   X x;
  19   // Assigning int to X has non-trivial side effects, so we cannot
  20   // hoist the load outside the loop, we have to do exactly what the
  21   // standard says to do.
  22   std::fill(&x, &x+1, global);
  23 }
  24
  25 struct Y {
  26   int i;
  27   void operator=(int ii) { i = ii + 1; }
  28 };
  29
  30 void
  31 test_self_aliasing()
  32 {
  33   Y y[2] = { };
  34   // Assigning int to X has non-trivial side effects, altering the value
  35   // used to fill the later elements. Must not load it outside the loop.
  36   std::fill(y, y+2, y[0].i);
  37   VERIFY(y[1].i == 2);
  38 }
  39
  40 struct Z
  41 {
  42   Z() { }
  43 #if __cplusplus >= 201103L
  44   explicit Z(const Z&) = default;
  45 #endif
  46 };
  47
  48 void
  49 test_explicit_copy_ctor()
  50 {
  51   Z z;
  52   // The optimization that copies the fill value must use direct-initialization
  53   // otherwise this case would be ill-formed due to the explicit constructor.
  54   std::fill(&z, &z, z);
  55 }
  56
  57 int main()
  58 {
  59   test_identity_matters();
  60   test_self_aliasing();
  61   test_explicit_copy_ctor();
  62 }