This is the mail archive of the
libstdc++@gcc.gnu.org
mailing list for the libstdc++ project.
[v3] libstdc++/37919
- From: Paolo Carlini <paolo dot carlini at oracle dot com>
- To: Gcc Patch List <gcc-patches at gcc dot gnu dot org>
- Cc: libstdc++ <libstdc++ at gcc dot gnu dot org>
- Date: Mon, 27 Oct 2008 17:51:22 +0100
- Subject: [v3] libstdc++/37919
Hi,
tested x86_64-linux, committed to mainline.
Paolo.
//////////////////
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.
Index: include/bits/stl_pair.h
===================================================================
*** include/bits/stl_pair.h (revision 141384)
--- include/bits/stl_pair.h (working copy)
***************
*** 65,99 ****
#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
--- 65,72 ----
*************** struct __may_be_null_pointer_init<_Tp _C
*** 116,127 ****
: 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);
pair(pair&& __p)
: first(std::move(__p.first)),
--- 89,98 ----
: first(__a), second(__b) { }
#ifdef __GXX_EXPERIMENTAL_CXX0X__
! 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)),
*************** struct __may_be_null_pointer_init<_Tp _C
*** 140,195 ****
: 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)
: first(std::forward<_U1>(__x)),
! second(__y) { }
pair&
operator=(pair&& __p)
--- 111,122 ----
: first(std::move(__p.first)),
second(std::move(__p.second)) { }
! // 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(std::forward<_Arg0>(__arg0),
! std::forward<_Args>(__args)...) { }
pair&
operator=(pair&& __p)
Index: testsuite/20_util/pair/moveable.cc
===================================================================
*** testsuite/20_util/pair/moveable.cc (revision 141384)
--- testsuite/20_util/pair/moveable.cc (working copy)
*************** test2()
*** 64,117 ****
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();
}
--- 64,72 ----