On 27/03/21 10:07 pm, Jonathan Wakely wrote:
On 26/03/21 21:41 +0100, François Dumont via Libstdc++ wrote:
I review the allocator aware move constructors of _GLIBCXX_DEBUG
containers.
I think the recently added __gnu_debug basic_string one is also
missing the rvalue reference, no ?
You mean is_nothrow_constructible<Base, Base&&, const Alloc&> instead
of is_nothrow_constructible<Base,Base, const Alloc&>?
No, it's not missing. They mean the exact same thing: Base is an
rvalue, Base&& is an rvalue, and Base& is an lvalue. Writing Base&&
instead of Base is just extra noise that adds no value.
Ok, noted.
libstdc++: _GLIBCXX_DEBUG Fix allocator aware move constructor
The correct term is "allocator-extended move constructor". And is it
really a "fix"? The standard doesn't require a noexcept-specifier on
those constructors, so what we have now is not incorrect, just
suboptimal.
For the debug list it is a fix because we were missing the _Safe base
class call. For the vector it is also a fix even if a minor one.
Fix several allocator aware move construtor in _GLIBCXX_DEBUG
containers.
libstdc++-v3/ChangeLog:
* include/debug/forward_list
(forward_list(forward_list&&, const allocator_type&)):
Add noexcept qualification.
* include/debug/list (list(list&&, const
allocator_type&)): Likewise and add
call to safe container allocator aware move constructor.
* include/debug/string (basic_string(basic_string&&,
const _Allocator&)):
Check base type allocator aware more constructor.
* include/debug/vector (vector(vector&&, const
allocator_type&)):
Fix noexcept qualification.
*
testsuite/23_containers/forward_list/cons/noexcept_move_construct.cc:
Add allocator aware move constructor noexceot
qualification check.
*
testsuite/23_containers/list/cons/noexcept_move_construct.cc: Likewise.
Tested under linux x86_64.
Ok to commit ?
OK, thanks.
I eventually committed the attached patch.
If you are still interested by _GLIBCXX_DEBUG fixes there is still this one:
https://gcc.gnu.org/pipermail/libstdc++/2021-March/052176.html
Thanks,
François
diff --git a/libstdc++-v3/include/debug/forward_list b/libstdc++-v3/include/debug/forward_list
index db46705cc71..16f0531dce7 100644
--- a/libstdc++-v3/include/debug/forward_list
+++ b/libstdc++-v3/include/debug/forward_list
@@ -239,8 +239,11 @@ namespace __debug
{ }
forward_list(forward_list&& __list, const allocator_type& __al)
- : _Safe(std::move(__list._M_safe()), __al),
- _Base(std::move(__list._M_base()), __al)
+ noexcept(
+ std::is_nothrow_constructible<_Base,
+ _Base, const allocator_type&>::value )
+ : _Safe(std::move(__list._M_safe()), __al),
+ _Base(std::move(__list._M_base()), __al)
{ }
explicit
diff --git a/libstdc++-v3/include/debug/list b/libstdc++-v3/include/debug/list
index 06938899253..01fe43fc7df 100644
--- a/libstdc++-v3/include/debug/list
+++ b/libstdc++-v3/include/debug/list
@@ -119,7 +119,11 @@ namespace __debug
: _Base(__x, __a) { }
list(list&& __x, const allocator_type& __a)
- : _Base(std::move(__x), __a) { }
+ noexcept(
+ std::is_nothrow_constructible<_Base,
+ _Base, const allocator_type&>::value )
+ : _Safe(std::move(__x._M_safe()), __a),
+ _Base(std::move(__x._M_base()), __a) { }
#endif
explicit
diff --git a/libstdc++-v3/include/debug/vector b/libstdc++-v3/include/debug/vector
index df179cbbfea..987bba17c2b 100644
--- a/libstdc++-v3/include/debug/vector
+++ b/libstdc++-v3/include/debug/vector
@@ -217,8 +217,9 @@ namespace __debug
: _Base(__x, __a) { }
vector(vector&& __x, const allocator_type& __a)
- noexcept(noexcept(
- _Base(std::declval<_Base&&>()), std::declval<const allocator_type&>()))
+ noexcept(
+ std::is_nothrow_constructible<_Base,
+ _Base, const allocator_type&>::value )
: _Safe(std::move(__x._M_safe()), __a),
_Base(std::move(__x._M_base()), __a),
_Safe_vector(std::move(__x)) { }
diff --git a/libstdc++-v3/testsuite/23_containers/forward_list/cons/noexcept_move_construct.cc b/libstdc++-v3/testsuite/23_containers/forward_list/cons/noexcept_move_construct.cc
index 96f3876e4f6..0eb5a5cdbba 100644
--- a/libstdc++-v3/testsuite/23_containers/forward_list/cons/noexcept_move_construct.cc
+++ b/libstdc++-v3/testsuite/23_containers/forward_list/cons/noexcept_move_construct.cc
@@ -23,4 +23,8 @@
typedef std::forward_list<int> fltype;
-static_assert(std::is_nothrow_move_constructible<fltype>::value, "Error");
+static_assert( std::is_nothrow_move_constructible<fltype>::value,
+ "noexcept move constructor" );
+static_assert( std::is_nothrow_constructible<fltype,
+ fltype, const typename fltype::allocator_type&>::value,
+ "noexcept move constructor with allocator" );
diff --git a/libstdc++-v3/testsuite/23_containers/list/cons/noexcept_move_construct.cc b/libstdc++-v3/testsuite/23_containers/list/cons/noexcept_move_construct.cc
index 5a2de10cf09..858a0d76333 100644
--- a/libstdc++-v3/testsuite/23_containers/list/cons/noexcept_move_construct.cc
+++ b/libstdc++-v3/testsuite/23_containers/list/cons/noexcept_move_construct.cc
@@ -23,4 +23,8 @@
typedef std::list<int> ltype;
-static_assert(std::is_nothrow_move_constructible<ltype>::value, "Error");
+static_assert( std::is_nothrow_move_constructible<ltype>::value,
+ "noexcept move constructor" );
+static_assert( std::is_nothrow_constructible<ltype,
+ ltype, const typename ltype::allocator_type&>::value,
+ "noexcept move constructor with allocator" );
