[boost] [variant] spirit broken

Subject: [boost] [variant] spirit broken
From: Jürgen Hunold (jhunold_at_[hidden])
Date: 2016-06-03 03:30:41

Hi Antony,

according to git bisect, your commit
-----------
commit b3650685f941a0c35cadfd878a185f274e132788                                                                                                                                                                                                 
Author: Antony Polukhin <antoshkka_at_[hidden]>                                                                                                                                                                                                   
Date:   Sat May 28 01:29:52 2016 +0300                                                                                                                                                                                                          
                                                                                                                                                                                                                                                
    Variant constructors and assignment operators now do not participate in 
overload resolutions if variant can not hold the input type (trac 5871, trac 
11602)                                                                                 
------------

broke Boost.Spirit. The test failures can be seen in the regression matrix. 
For example:

http://www.boost.org/development/tests/develop/developer/output/Flast-FreeBSD10-clang-3-7-0~gnu++11-boost-bin-v2-libs-spirit-test-karma_actions-p3-test-clang-linux-3-7-0-debug.html

fails with

../boost/variant/variant.hpp:1152:7: note: while substituting deduced template 
arguments into function template 'operator=' [with T = 
boost::variant<boost::spirit::info::nil_, std::__1::basic_string<char>, 
boost::recursive_wrapper<boost::spirit::info>, 
boost::recursive_wrapper<std::__1::pair<boost::spirit::info, 
boost::spirit::info> >, 
boost::recursive_wrapper<std::__1::list<boost::spirit::info, 
std::__1::allocator<boost::spirit::info> > > >]
class variant
      ^
../boost/spirit/home/support/info.hpp:29:12: note: definition of 
'boost::spirit::info' is not complete until the closing '}'
    struct info

It seems that the commit somehow disabled support for recursive variant usage.

To reproduce this, just run the Spirit regression test.

Yours,

Jürgen
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