The code generation macros are supposed to support parameter-dependent return types, but it turns out that they currently don't really do that. This commit fixes the issue.
* Add are_tagged_arguments_mp11 and is_argument_pack_mp11 metafunctions when Boost.MP11 is usable.
* Predicate requirements can be encoded as Boost.MP11-style quoted metafunctions as well as by MPL binary metafunction classes.
* Argument packs qualify as Boost.MP11-style lists as well as MPL sequences.
* Internal components and test programs use Boost.MP11 and C++11 type traits vice MPL and Boost.TypeTraits when Boost.MP11 is usable.
* Fix compiler failures showing up on regression test matrix due to void return type.
* Fix gcc-3.4 failures showing up regression test matrix due to binding string literals to non-const references to char const*.
* Update tutorial documentation to match literate tests.
* Replace calls to boost::forward with calls to std::forward.
<boost/parameter/config.hpp>
* Relax perfect forwarding requirements so that msvc-12.0 passes muster.
<boost/parameter/parameters.hpp>
* Use boost::mpl::vector if neither boost::fusion::list nor boost::fusion::deque are true variadic MPL sequences.
.travis.yml
appveyor.yml
* Remove test configurations of compilers that fail perfect forwarding requirements.
* Consolidate for fewer jobs.
1. The end of section 3.2.1 of the current home page tutorial notes "that because of the forwarding problem, parameter::parameters::operator() can't accept non-const rvalues." Add code to eliminate this problem. As a positive side effect, Boost.Parameter-enabled functions and constructors are no longer bound by BOOST_PARAMETER_MAX_ARITY on compilers that support perfect forwarding. User code can now check for this support by detecting the configuration macro BOOST_PARAMETER_HAS_PERFECT_FORWARDING, or manually turn off this support by defining the configuration macro BOOST_PARAMETER_DISABLE_PERFECT_FORWARDING. See "test/evaluate_category.cpp" and "test/preprocessor_eval_category.cpp" for example usage.
2. Add parameter category qualifiers "consume" and "move_from"(current qualifiers are "in", "out", "in_out", and "forward") based on http://www.modernescpp.com/index.php/c-core-guidelines-how-to-pass-function-parameters.
3. Update documentation to reflect the above changes.
Add parameter category qualifier "forward" (current qualifiers are "in", "out", and "in_out") based on http://www.modernescpp.com/index.php/c-core-guidelines-how-to-pass-function-parameters. Add new usage syntax BOOST_PARAMETER_NAME((object-name), namespace-name) qualifier(tag-name)) and BOOST_PARAMETER_NAME(qualifier(name)). (Existing code that uses qualifiers directly and correctly with BOOST_PARAMETER_FUNCTION and other code generation macros should remain unaffected for now, so no breaking changes.) The reason for the change in usage is to enable applying of parameter category constraints to Boost.Parameter-enabled functions and constructors invoked through argument composition. (Otherwise, it is currently possible to use argument composition to bypass parameter category constraints applied in BOOST_PARAMETER_FUNCTION et. al.) See "test/compose.cpp" for example usage.
