Summary:
Throughout the libc++ headers, there are a few instances where
_VSTD::move() is used to return a local variable. Howard commented in
r189039 that these were there "for non-obvious reasons such as to help
things limp along in C++03 language mode".
However, when compiling these headers with warnings on, and in C++11 or
higher mode (like we do in FreeBSD), they cause the following complaints
about pessimizing moves:
In file included from tests.cpp:26:
In file included from tests.hpp:29:
/usr/include/c++/v1/map:1368:12: error: moving a local object in a return statement prevents copy elision [-Werror,-Wpessimizing-move]
return _VSTD::move(__h); // explicitly moved for C++03
^
/usr/include/c++/v1/__config:368:15: note: expanded from macro '_VSTD'
#define _VSTD std::_LIBCPP_NAMESPACE
^
Attempt to fix this by adding a _LIBCPP_EXPLICIT_MOVE() macro to
__config, which gets defined to _VSTD::move for pre-C++11, and to
nothing for C++11 and later.
I am not completely satisfied with the macro name (I also considered
_LIBCPP_COMPAT_MOVE and some other variants), so suggestions are
welcome. :)
Reviewers: mclow.lists, howard.hinnant, EricWF
Subscribers: arthur.j.odwyer, cfe-commits
Differential Revision: http://reviews.llvm.org/D11394
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@245421 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: Currently we only enable the use of __is_final(...) with Clang. GCC also provides __is_final(...) since 4.7 in all standard modes. This patch creates the macro _LIBCPP_HAS_IS_FINAL to note the availability of `__is_final`.
Reviewers: danalbert, mclow.lists
Reviewed By: mclow.lists
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D8795
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@239664 91177308-0d34-0410-b5e6-96231b3b80d8
are two motivations for this.
First, this allows users who are specializing __gnu_ext::hash to
continue doing so without changing their code.
Second, SGI specifies hash overloads for char* and const char* that
perform a hash of the string, not of the pointer.
In order to support this, the hashing code for string is factored out.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@136539 91177308-0d34-0410-b5e6-96231b3b80d8
the type name 'data_type', which is specified by the SGI spec as being
the correct type name for the mapped type. The second is an overload of
insert found in standard containers, taking an iterator as a 'hint'
(which we ignore in the standard containers as well). libstdc++'s
implementation includes these overloads, and they are needed to make
insert_iterator work (which I suspect is the real motivation for
including them in the standard containers).
The motivation for including these overloads of insert and leaving the
mapped_type typedef is to make it easier for clients to migrate to the
standard containers.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@136538 91177308-0d34-0410-b5e6-96231b3b80d8
