libstdc++: Apply the move_iterator changes described in P1207R4

These changes are needed for some of the tests in the constrained algorithm
patch, because they use move_iterator with an uncopyable output_iterator.  The
other changes described in the paper are already applied, it seems.

libstdc++-v3/ChangeLog:

	* include/bits/stl_iterator.h (move_iterator::move_iterator): Move __i
	when initializing _M_current.
	(move_iterator::base): Split into two overloads differing in
	ref-qualifiers as in P1207R4 for C++20.

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index d925a0b..b54f1f6 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2020-02-05  Patrick Palka  <ppalka@redhat.com>
+
+       * include/bits/stl_iterator.h (move_iterator::move_iterator): Move __i
+       when initializing _M_current.
+       (move_iterator::base): Split into two overloads differing in
+       ref-qualifiers as in P1207R4 for C++20.
+
 2020-02-04  Jonathan Wakely  <jwakely@redhat.com>
 
        * include/std/functional (_GLIBCXX_NOT_FN_CALL_OP): Un-define after

diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index 784d200..c200f7a 100644 (file)
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -1166,16 +1166,29 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       explicit _GLIBCXX17_CONSTEXPR
       move_iterator(iterator_type __i)
-      : _M_current(__i) { }
+      : _M_current(std::move(__i)) { }
 
       template<typename _Iter>
        _GLIBCXX17_CONSTEXPR
        move_iterator(const move_iterator<_Iter>& __i)
        : _M_current(__i.base()) { }
 
+#if __cplusplus <= 201703L
       _GLIBCXX17_CONSTEXPR iterator_type
       base() const
       { return _M_current; }
+#else
+      constexpr iterator_type
+      base() const &
+#if __cpp_lib_concepts
+       requires copy_constructible<iterator_type>
+#endif
+      { return _M_current; }
+
+      constexpr iterator_type
+      base() &&
+      { return std::move(_M_current); }
+#endif
 
       _GLIBCXX17_CONSTEXPR reference
       operator*() const