libstdc++: Implement N3644 on _Safe_iterator<> [PR114316]

Consider range of value-initialized iterators as valid and empty.

libstdc++-v3/ChangeLog:

	PR libstdc++/114316
	* include/debug/safe_iterator.tcc (_Safe_iterator<>::_M_valid_range):
	First check if both iterators are value-initialized before checking if
	singular.
	* testsuite/23_containers/set/debug/114316.cc: New test case.
	* testsuite/23_containers/vector/debug/114316.cc: New test case.

(cherry picked from commit 07fad7a7fc245369989e9ca746728ea78b924715)

diff --git a/libstdc++-v3/include/debug/safe_iterator.tcc b/libstdc++-v3/include/debug/safe_iterator.tcc
index 170229ad2f1037d1153fe1b0af779992d81e1943..2640fc8a473d3d8604345434e4a278a3b00bd9d5 100644 (file)
--- a/libstdc++-v3/include/debug/safe_iterator.tcc
+++ b/libstdc++-v3/include/debug/safe_iterator.tcc
@@ -194,6 +194,12 @@ namespace __gnu_debug
                   std::pair<difference_type, _Distance_precision>& __dist,
                   bool __check_dereferenceable) const
     {
+      if (_M_value_initialized() && __rhs._M_value_initialized())
+       {
+         __dist = std::make_pair(0, __dp_exact);
+         return true;
+       }
+
       if (_M_singular() || __rhs._M_singular() || !_M_can_compare(__rhs))
        return false;
 
@@ -218,6 +224,12 @@ namespace __gnu_debug
                   std::pair<difference_type,
                             _Distance_precision>& __dist) const
     {
+      if (this->_M_value_initialized() && __rhs._M_value_initialized())
+       {
+         __dist = std::make_pair(0, __dp_exact);
+         return true;
+       }
+
       if (this->_M_singular() || __rhs._M_singular()
          || !this->_M_can_compare(__rhs))
        return false;

diff --git a/libstdc++-v3/testsuite/23_containers/set/debug/114316.cc b/libstdc++-v3/testsuite/23_containers/set/debug/114316.cc
new file mode 100644 (file)
index 0000000..126ec89
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/set/debug/114316.cc
@@ -0,0 +1,16 @@
+// { dg-do run { target c++11 } }
+// { dg-require-debug-mode "" }
+
+// PR libstdc++/114316
+
+#include <set>
+#include <algorithm>
+
+#include <testsuite_hooks.h>
+
+int main()
+{
+  std::set<int>::iterator it{};
+  VERIFY( std::find(it, it, 0) == it );
+  return 0;
+}

diff --git a/libstdc++-v3/testsuite/23_containers/vector/debug/114316.cc b/libstdc++-v3/testsuite/23_containers/vector/debug/114316.cc
new file mode 100644 (file)
index 0000000..f211cf6
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/debug/114316.cc
@@ -0,0 +1,16 @@
+// { dg-do run { target c++11 } }
+// { dg-require-debug-mode "" }
+
+// PR libstdc++/114316
+
+#include <vector>
+#include <algorithm>
+
+#include <testsuite_hooks.h>
+
+int main()
+{
+  std::vector<int>::iterator it{};
+  VERIFY( std::find(it, it, 0) == it );
+  return 0;
+}