Opened 8 years ago
Last modified 8 years ago
#10340 closed Bugs
No boost::promise<T>::set_value(const T&) overload present in C++03 mode — at Version 7
Reported by: | Owned by: | Anthony Williams | |
---|---|---|---|
Milestone: | Boost 1.57.0 | Component: | thread |
Version: | Boost 1.54.0 | Severity: | Problem |
Keywords: | Cc: |
Description (last modified by )
When compiling in C++03 mode I am unable to use anything but a primitive type in a promise, and therefore also the dependent types in Boost.Thread
Minimal testcase:
#include <boost/thread/future.hpp> struct foo { foo(int i_): i(i_) {} int i; }; int main() { // Clearly a const future ref isn't much use, but I needed to // prove the problem wasn't me trying to copy a unique_future const boost::unique_future<foo>& fut = boost::make_ready_future( foo(42) ); }
Output from g++ 4.8.2 with Boost 1.55 and -DBOOST_THREAD_USES_MOVE:
In file included from ../../deps/boost/include/boost/tuple/tuple.hpp:33:0,
from ../../deps/boost/include/boost/thread/detail/async_func.hpp:37, from ../../deps/boost/include/boost/thread/future.hpp:22, from t.cpp:2:
../../deps/boost/include/boost/tuple/detail/tuple_basic.hpp: In function ‘typename boost::tuples::access_traits<typename boost::tuples::element<N, boost::tuples::cons<HT, TT> >::type>::const_type boost::tuples::get(const boost::tuples::cons<HT, TT>&)’: ../../deps/boost/include/boost/tuple/detail/tuple_basic.hpp:228:45: warning: typedef ‘cons_element’ locally defined but not used [-Wunused-local-typedefs]
typedef BOOST_DEDUCED_TYPENAME impl::type cons_element;
In file included from ../../deps/boost/include/boost/bind/bind.hpp:29:0,
from ../../deps/boost/include/boost/bind.hpp:22, from ../../deps/boost/include/boost/thread/future.hpp:41, from t.cpp:2:
../../deps/boost/include/boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ../../deps/boost/include/boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs]
typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ];
t.cpp: In function ‘int main()’: t.cpp:12:78: error: expected primary-expression before ‘f’
const boost::unique_future<foo>& fut = boost::make_ready_future( foo f(42) );
t.cpp:12:42: warning: unused variable ‘fut’ [-Wunused-variable]
const boost::unique_future<foo>& fut = boost::make_ready_future( foo f(42) );
In file included from ../../deps/boost/include/boost/system/system_error.hpp:14:0,
from ../../deps/boost/include/boost/thread/exceptions.hpp:22, from ../../deps/boost/include/boost/thread/pthread/mutex.hpp:12, from ../../deps/boost/include/boost/thread/mutex.hpp:16, from ../../deps/boost/include/boost/thread/future.hpp:24, from t.cpp:2:
../../deps/boost/include/boost/system/error_code.hpp: At global scope: ../../deps/boost/include/boost/system/error_code.hpp:222:36: warning: ‘boost::system::posix_category’ defined but not used [-Wunused-variable]
static const error_category & posix_category = generic_category();
../../deps/boost/include/boost/system/error_code.hpp:223:36: warning: ‘boost::system::errno_ecat’ defined but not used [-Wunused-variable]
static const error_category & errno_ecat = generic_category();
../../deps/boost/include/boost/system/error_code.hpp:224:36: warning: ‘boost::system::native_ecat’ defined but not used [-Wunused-variable]
static const error_category & native_ecat = system_category();
I have replicated this with Clang 3.4, also with Boost 1.54 on both compilers, and without -DBOOST_THREAD_USES_MOVE too. From the boost-users mailing list it looks like it has been replicated with 1.56 too.
Change History (7)
comment:1 by , 8 years ago
comment:2 by , 8 years ago
Simpler test case:
#include <boost/thread/future.hpp> struct foo { foo(int i_) { } }; int main() { boost::promise<foo> p; const foo f(42); p.set_value(f); }
This fails with -DBOOST_THREAD_USES_MOVE but compiles OK without.
comment:3 by , 8 years ago
Agh, apologies for the brainfail there. Problem hopefully clear from the bug title, but for completeness here is the compile error with 1.55, g++ 4.8.2, and -DBOOST_THREAD_USES_MOVE:
In file included from t.cpp:1:0: ../deps/boost/include/boost/thread/future.hpp: In instantiation of ‘boost::unique_future<typename boost::decay<T>::type> boost::make_ready_future(const T&) [with T = foo; typename boost::decay<T>::type = foo]’: t.cpp:14:35: required from here ../deps/boost/include/boost/thread/future.hpp:3634:5: error: no matching function for call to ‘boost::promise<foo>::set_value(const foo&)’ p.set_value(boost::forward<future_value_type>(value)); ^ ../deps/boost/include/boost/thread/future.hpp:3634:5: note: candidates are: In file included from t.cpp:1:0: ../deps/boost/include/boost/thread/future.hpp:2052:14: note: void boost::promise<R>::set_value(typename boost::detail::future_traits<T>::source_reference_type) [with R = foo; typename boost::detail::future_traits<T>::source_reference_type = foo&] void set_value(typename detail::future_traits<R>::source_reference_type r) ^ ../deps/boost/include/boost/thread/future.hpp:2052:14: note: no known conversion for argument 1 from ‘const foo’ to ‘boost::detail::future_traits<foo>::source_reference_type {aka foo&}’ ../deps/boost/include/boost/thread/future.hpp:2064:14: note: void boost::promise<R>::set_value(typename boost::detail::future_traits<T>::rvalue_source_type) [with R = foo; typename boost::detail::future_traits<T>::rvalue_source_type = boost::rv<foo>&] void set_value(typename detail::future_traits<R>::rvalue_source_type r) ^ ../deps/boost/include/boost/thread/future.hpp:2064:14: note: no known conversion for argument 1 from ‘const foo’ to ‘boost::detail::future_traits<foo>::rvalue_source_type {aka boost::rv<foo>&}’
comment:5 by , 8 years ago
Replying to viboes:
IIUC you need to make
foo
movable in C++98 compilers.
Forget this comment, please :(
comment:6 by , 8 years ago
Description: | modified (diff) |
---|
comment:7 by , 8 years ago
Description: | modified (diff) |
---|
The error you pasted is due to a syntax error and doesn't match the code you pasted:
(Also the output would be a lot more useful with
-Wno-unused-local-typedefs
)