Hi All, Andrey Semashev <wrote:
Vicente J. Botet Escriba wrote:
Hi,
I've started to use C++11 lambda functions with Boost.Thread.
The following works with clang-3.2
boost::future<int> f1 = boost::async( []() -> int {return 123;} );
But it fails with gcc-4.6.2, 4.7.2 and 4.8.0
../example/lambda_future.cpp:25:91: erreur: conversion from ‘boost::future<void>’ to non-scalar type ‘boost::future<int>’ requested boost::future<int> f1 = boost::async( []() -> int {return 123;} );
The current implementation of boost::async uses boost::result_of to get the result type of the callable parameter.
Is this a know bug on boost::result_of or gcc compiler?
I think this is because result_of is based on decltype for clang and TR1 protocol for gcc. This is because gcc doesn't support N3276. 4.8.0 release notes state that it is supported but I saw someone on the list found some bug in it so the support is incomplete for now.
For what it's worth, there's a patch in trac[1] which would allow the previous to compile without requiring a full decltype implementation and without causing errors when using tr1::result_of would succeed. The patch was created after some discussion[2], but I haven't continued to push for its acceptance -- work happens. Some may find it useful, however. Thanks, Nate [1] https://svn.boost.org/trac/boost/ticket/7753 [2] http://boost.2283326.n4.nabble.com/Range-amp-c-0x-Lambdas-Can-this-be-done-t...