Re: [boost] [config] clang deleted functions bugged

Subject: Re: [boost] [config] clang deleted functions bugged
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2013-10-27 20:12:42

Le 28/10/13 00:47, Peter Dimov a écrit :
> Vicente J. Botet Escriba wrote:
>> Hi,
>>
>> Clang has a bug with deleted functions (see 
>> http://stackoverflow.com/questions/7754564/clang-error-message-when-using-c0x-call-to-deleted-constructor-of).
>
> This is not a clang bug. It was a bug in boost::shared_ptr, now fixed.
>
Maybe you are right, but there are other cases when the constructor is 
deleted, that is when we use explicitly = delete.
In this case the clang compiler report an error similar to the error 
reported by the preceding link.

bjam toolset=clang-3.4xl -l 300 variant=debug  -j6 ts_container
warning: mismatched versions of Boost.Build engine and core
warning: Boost.Build engine (bjam) is 2011.12.01
warning: Boost.Build core (at /Users/viboes/boost/trunk/tools/build/v2) 
is 2013.05-svn
Performing configuration checks

     - lockfree boost::atomic_flag : yes (cached)
...patience...
...patience...
...found 1416 targets...
...updating 23 targets...
clang-darwin.compile.c++ 
../../../bin.v2/libs/thread/build/clang-darwin-3.4xl/debug/link-static/threading-multi/pthread/once.o
clang-darwin.compile.c++ 
../../../bin.v2/libs/thread/build/clang-darwin-3.4xl/debug/threading-multi/pthread/once.o
clang-darwin.compile.c++ 
../../../bin.v2/libs/thread/test/container__thread_vector_p_lib.test/clang-darwin-3.4xl/debug/threading-multi/threads/container/thread_vector_pass.o
In file included from threads/container/thread_vector_pass.cpp:8:
In file included from ../../../boost/thread/thread.hpp:12:
In file included from ../../../boost/thread/thread_only.hpp:17:
In file included from ../../../boost/thread/pthread/thread_data.hpp:10:
In file included from ../../../boost/thread/exceptions.hpp:20:
In file included from /usr/include/c++/v1/string:439:
In file included from /usr/include/c++/v1/algorithm:627:
/usr/include/c++/v1/memory:1641:31: error: call to deleted constructor 
of 'boost::thread'
             ::new((void*)__p) _Up(_VSTD::forward<_Args>(__args)...);
                               ^   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/v1/memory:1568:18: note: in instantiation of function 
template specialization 
'std::__1::allocator<boost::thread>::construct<boost::thread, const 
boost::thread &>' requested here
             {__a.construct(__p, _VSTD::forward<_Args>(__args)...);}
                  ^
/usr/include/c++/v1/memory:1449:14: note: in instantiation of function 
template specialization 
'std::__1::allocator_traits<std::__1::allocator<boost::thread> 
 >::__construct<boost::thread, const boost::thread &>' requested here
             {__construct(__has_construct<allocator_type, pointer, 
_Args...>(),
              ^
/usr/include/c++/v1/memory:1531:17: note: in instantiation of function 
template specialization 
'std::__1::allocator_traits<std::__1::allocator<boost::thread> 
 >::construct<boost::thread, const boost::thread &>' requested here
                 construct(__a, _VSTD::__to_raw_pointer(__end2-1), 
_VSTD::move_if_noexcept(*--__end1));
                 ^
/usr/include/c++/v1/vector:839:21: note: in instantiation of function 
template specialization 
'std::__1::allocator_traits<std::__1::allocator<boost::thread> 
 >::__construct_backward<boost::thread *>' requested here
     __alloc_traits::__construct_backward(this->__alloc(), 
this->__begin_, this->__end_, __v.__begin_);
                     ^
/usr/include/c++/v1/vector:1488:9: note: in instantiation of member 
function 'std::__1::vector<boost::thread, 
std::__1::allocator<boost::thread> >::__swap_out_circular_buffer' 
requested here
         __swap_out_circular_buffer(__v);
         ^
threads/container/thread_vector_pass.cpp:56:13: note: in instantiation 
of member function 'std::__1::vector<boost::thread, 
std::__1::allocator<boost::thread> >::reserve' requested here
     threads.reserve(10);
             ^
../../../boost/thread/detail/thread.hpp:165:33: note: function has been 
explicitly marked deleted here
       BOOST_THREAD_MOVABLE_ONLY(thread)
                                 ^
../../../boost/thread/detail/move.hpp:240:28: note: expanded from macro 
'BOOST_THREAD_MOVABLE_ONLY'
   BOOST_THREAD_NO_COPYABLE(TYPE) \
                            ^
../../../boost/thread/detail/delete.hpp:58:35: note: expanded from macro 
'BOOST_THREAD_NO_COPYABLE'
     BOOST_THREAD_DELETE_COPY_CTOR(CLASS) \
                                   ^
../../../boost/thread/detail/delete.hpp:24:7: note: expanded from macro 
'BOOST_THREAD_DELETE_COPY_CTOR'
       CLASS(CLASS const&) = delete; \
       ^
1 error generated.

The concerned code is (compile error in lines (1) and (2))

   typedef std::vector<boost::thread> thread_vector;
   {
     thread_vector threads;
     threads.reserve(10); // (1)
     for (int i = 0; i < 10; ++i)
     {
       boost::thread th(&increment_count);
       threads.push_back(std::move(th)); // (2)
     }
     join_all(threads);
   }

Boost.Thread defines a private constructor when 
BOOST_NO_CXX11_DELETED_FUNCTIONS is defined and in this case there is no 
compiler error.
Note that libc++ doesn't make use of =delete to implement movable only 
classes, so the compiler bug is not visible when we push_back a 
std::thread on a vector of std::threads.

clang-3.4xl is the latest from svn. The same behavior for clang-3.1 and 3.2

Best,
Vicente