re PR libstdc++/37919 ([c++0x] GCC 4.4 regression r141214 of gcc c++0x stl_pair.c causes a boost 1.36 compilation to fail)

2008-10-27  Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/37919
	Revert:
	2008-10-18  Douglas Gregor  <doug.gregor@gmail.com>

	* include/bits/stl_pair.h (__may_be_null_pointer_init): New.
	(pair::pair): Eliminate the redundant pair(U1&&, U2&&) constructor.
	Add lvalue pair<U1, U2> constructor to handle non-const pair lvalues.
	Remove the old variadic constructor, and instead provide several
	variadic constructors that avoid failing when attempting to
	initialize a pointer from a null pointer constant.
	* testsuite/20_util/pair/moveable.cc (test3): Add new tests with
	initialization of pointers from the null pointer constant.

From-SVN: r141388

3 files changed, 24 insertions, 127 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index af59f63..4230bc6 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,20 @@
 2008-10-27  Paolo Carlini  <paolo.carlini@oracle.com>
 
+	PR libstdc++/37919
+	Revert:
+	2008-10-18  Douglas Gregor  <doug.gregor@gmail.com>
+
+	* include/bits/stl_pair.h (__may_be_null_pointer_init): New.
+	(pair::pair): Eliminate the redundant pair(U1&&, U2&&) constructor.
+	Add lvalue pair<U1, U2> constructor to handle non-const pair lvalues.
+	Remove the old variadic constructor, and instead provide several
+	variadic constructors that avoid failing when attempting to
+	initialize a pointer from a null pointer constant.
+	* testsuite/20_util/pair/moveable.cc (test3): Add new tests with
+	initialization of pointers from the null pointer constant.
+
+2008-10-27  Paolo Carlini  <paolo.carlini@oracle.com>
+
 	PR libstdc++/37522
 	* config/os/mingw32/os_defines.h: Define _GLIBCXX_HAVE_BROKEN_VSWPRINTF
 	* include/bits/basic_string.h: Guard string conversions with 
diff --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h
index c169275..cf61b09 100644
--- a/libstdc++-v3/include/bits/stl_pair.h
+++ b/libstdc++-v3/include/bits/stl_pair.h
@@ -65,35 +65,8 @@
 #include <bits/move.h> // for std::move / std::forward, std::decay, and
                        // std::swap
 
-#ifdef __GXX_EXPERIMENTAL_CXX0X__
-#include <type_traits>
-#endif
-
 _GLIBCXX_BEGIN_NAMESPACE(std)
 
-#ifdef __GXX_EXPERIMENTAL_CXX0X__
-// A trait that determines whether the initialization of a T from
-// arguments of type Args could possibly be the initialization of a
-// pointer from a null pointer constant.
-template<typename, typename...>
-struct __may_be_null_pointer_init 
-  : public false_type { };
-
-template<typename _Tp, typename _Up>
-struct __may_be_null_pointer_init<_Tp*, _Up>  
-  : public integral_constant<bool,
-             (is_integral<typename remove_reference<_Up>::type>::value 
-              || is_enum<typename remove_reference<_Up>::type>::value)> 
-  { };
-
-template<typename _Class, typename _Tp, typename _Up>
-struct __may_be_null_pointer_init<_Tp _Class::*, _Up>  
-  : public integral_constant<bool,
-             (is_integral<typename remove_reference<_Up>::type>::value 
-              || is_enum<typename remove_reference<_Up>::type>::value)> 
-  { };
-#endif
-
   /// pair holds two objects of arbitrary type.
   template<class _T1, class _T2>
     struct pair
@@ -116,12 +89,10 @@ struct __may_be_null_pointer_init<_Tp _Class::*, _Up>
       : first(__a), second(__b) { }
 
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
-      // Omitted the following constructor, which appears in the C++0x
-      // working paper but is redundant with the variadic constructors
-      // below.
-      //
-      //   template<class _U1, class _U2>
-      //     pair(_U1&& __x, _U2&& __y);
+      template<class _U1, class _U2>
+        pair(_U1&& __x, _U2&& __y)
+	: first(std::forward<_U1>(__x)),
+	  second(std::forward<_U2>(__y)) { }
 
       pair(pair&& __p)
       : first(std::move(__p.first)),
@@ -140,56 +111,12 @@ struct __may_be_null_pointer_init<_Tp _Class::*, _Up>
 	: first(std::move(__p.first)),
 	  second(std::move(__p.second)) { }
 
-      // This constructor is required so that lvalue pairs don't get
-      // pushed to the variadic constructor below.
-      template<class _U1, class _U2>
-        pair(pair<_U1, _U2>& __p)
-          : first(const_cast<const pair<_U1, _U2>&>(__p).first),
-  	    second(const_cast<const pair<_U1, _U2>&>(__p).second) { }
-
-      // _GLIBCXX_RESOLVE_LIB_DEFECTS
-      // 811.  pair of pointers no longer works with literal 0
-
-      // Variadic constructor. The enable_if makes sure that we won't
-      // try to initialize a pointer from an integral type, which
-      // needs to be handled by a different constructor that will
-      // convert a null pointer constant to that pointer type. See
-      // library issue 767.
-      template<class _U1, class... _Args,
-        class _Checker 
-          = typename enable_if<
-                       (!__may_be_null_pointer_init<_T1, _U1>::value
-                        && !__may_be_null_pointer_init<_T2, _Args...>::value), 
-                     void>::type>
-        pair(_U1&& __x, _Args&&... __args)
-	: first(std::forward<_U1>(__x)),
-	  second(std::forward<_Args>(__args)...) { }
-
-      // Variadic constructor. The enable_if makes sure that the
-      // second argument isn't going to try to initialize a pointer
-      // from an integral type. However, T1 may be a pointer whose
-      // argument was a null pointer constant.
-      template<class... _Args,
-        class _Checker 
-          = typename enable_if<
-                       !__may_be_null_pointer_init<_T2, _Args...>::value, 
-                     void>::type>
-        pair(const _T1& __x, _Args&&... __args)
-	: first(__x),
-	  second(std::forward<_Args>(__args)...) { }
-
-      // Constructor typically used when T2 is a pointer and the
-      // second argument was a null pointer constant. The enable_if
-      // makes sure that the first argument isn't going to try to
-      // initialize a pointer from an integral type.
-      template<class _U1,
-        class _Checker 
-          = typename enable_if<
-                     !__may_be_null_pointer_init<_T1, _U1>::value,
-                     void>::type>
-        pair(_U1&& __x, const _T2& __y)
+      // http://gcc.gnu.org/ml/libstdc++/2007-08/msg00052.html
+      template<class _U1, class _Arg0, class... _Args>
+        pair(_U1&& __x, _Arg0&& __arg0, _Args&&... __args)
 	: first(std::forward<_U1>(__x)),
-	  second(__y) { }
+	  second(std::forward<_Arg0>(__arg0),
+		 std::forward<_Args>(__args)...) { }
 
       pair&
       operator=(pair&& __p)
diff --git a/libstdc++-v3/testsuite/20_util/pair/moveable.cc b/libstdc++-v3/testsuite/20_util/pair/moveable.cc
index 4e5c535..cd5de41 100644
--- a/libstdc++-v3/testsuite/20_util/pair/moveable.cc
+++ b/libstdc++-v3/testsuite/20_util/pair/moveable.cc
@@ -64,54 +64,9 @@ test2()
          r.second.size() == 2 && p.second.size() == 0);
 }
 
-struct X { 
-  explicit X(int, int) { }
-
-private:
-  X(const X&) = delete;
-};
-
-struct move_only {
-  move_only() { }
-  move_only(move_only&&) { }
-
-private:
-  move_only(const move_only&) = delete;
-};
-
-void
-test3()
-{
-  int *ip = 0;
-  int X::*mp = 0;
-  std::pair<int*, int*> p1(0, 0);
-  std::pair<int*, int*> p2(ip, 0);
-  std::pair<int*, int*> p3(0, ip);
-  std::pair<int*, int*> p4(ip, ip);
-
-  std::pair<int X::*, int*> p5(0, 0);
-  std::pair<int X::*, int X::*> p6(mp, 0);
-  std::pair<int X::*, int X::*> p7(0, mp);
-  std::pair<int X::*, int X::*> p8(mp, mp);
-
-  std::pair<int*, X> p9(0, 1, 2);
-  std::pair<int X::*, X> p10(0, 1, 2);
-  std::pair<int*, X> p11(ip, 1, 2);
-  std::pair<int X::*, X> p12(mp, 1, 2);
-
-  std::pair<int*, move_only> p13(0);
-  std::pair<int X::*, move_only> p14(0);
-
-  std::pair<int*, move_only> p15(0, move_only());
-  std::pair<int X::*, move_only> p16(0, move_only());
-  std::pair<move_only, int*> p17(move_only(), 0);
-  std::pair<move_only, int X::*> p18(move_only(), 0);
-}
-
 int 
 main() 
 {
   test1();
   test2();
-  test3();
 }