I was a little bit too confident below. After review of all _M_singular
usages I found another necessary fix.
After this one for sure we will be able to define
__cpp_lib_null_iterators even in Debug mode.
libstdc++: Fix N3344 behavior on _Safe_iterator::_M_can_advance
We shall be able to advance from a 0 offset a value-initialized
iterator.
libstdc++-v3/ChangeLog:
* include/debug/safe_iterator.tcc
(_Safe_iterator<>::_M_can_advance):
Accept 0 offset advance on value-initialized iterator.
* testsuite/23_containers/vector/debug/n3644.cc: New test case.
Ok to commit ?
François
On 17/03/2024 17:52, François Dumont wrote:
OK for trunk, thanks!
I think this is OK to backport to 13 too.
Maybe after this we can define the __cpp_lib_null_itetators macro for
debug mode?
After this fix of local_iterator I think we can indeed.
In fact the added 11316.cc was already passing for
unordered_set<>::local_iterator but simply because we were missing the
singular check. Both issues solved with this patch.
I found the version.def file to cleanup but no idea how to regenerate
version.h from it so I'll let you do it, ok ?
libstdc++: Fix _Safe_local_iterator<>::_M_valid_range
Unordered container local_iterator range shall not contain any
singular
iterator unless both iterators are value-initialized.
libstdc++-v3/ChangeLog:
* include/debug/safe_local_iterator.tcc
(_Safe_local_iterator::_M_valid_range): Add
_M_value_initialized and
_M_singular checks.
* testsuite/23_containers/unordered_set/debug/114316.cc:
New test case.
Ok to commit ?
François
diff --git a/libstdc++-v3/include/debug/safe_iterator.tcc
b/libstdc++-v3/include/debug/safe_iterator.tcc
index 4b2baf2980e..deaa84d0a1f 100644
--- a/libstdc++-v3/include/debug/safe_iterator.tcc
+++ b/libstdc++-v3/include/debug/safe_iterator.tcc
@@ -86,6 +86,9 @@ namespace __gnu_debug
_Safe_iterator<_Iterator, _Sequence, _Category>::
_M_can_advance(difference_type __n, bool __strict) const
{
+ if (this->_M_value_initialized() && __n == 0)
+ return true;
+
if (this->_M_singular())
return false;
diff --git a/libstdc++-v3/testsuite/23_containers/vector/debug/n3644.cc
b/libstdc++-v3/testsuite/23_containers/vector/debug/n3644.cc
new file mode 100644
index 00000000000..052c52f26b7
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/debug/n3644.cc
@@ -0,0 +1,16 @@
+// { dg-do run { target c++11 } }
+// { dg-require-debug-mode "" }
+
+#include <vector>
+#include <algorithm>
+
+#include <testsuite_hooks.h>
+
+int main()
+{
+ std::vector<int>::iterator it{};
+ auto cpy = it;
+ std::advance(it, 0);
+ VERIFY( it == cpy );
+ return 0;
+}
