problem compiling X3 example

I've simply created a VS project to test the X3.rexpr_full example. 
Compiling just 
"C:\cpp\boost_1_63\libs\spirit\example\x3\rexpr\rexpr_full\src\rexpr.cpp" 
and I get error C2995(function template has already been defined). I see 
no circular includes. I have not modified anything in these folders. 
Also showing the warnings.
I'm suspecting this is about Microsoft, and the likes have been seen 
before. But I can up empty on searching it.
Thanks, Dan.

1>  rexpr.cpp
1>c:\cpp\boost_1_63\boost\spirit\home\x3\support\ast\variant.hpp(223): 
warning C4521: 
'boost::spirit::x3::variant<std::string,boost::spirit::x3::forward_ast<rexpr::ast::rexpr>>': 
multiple copy constructors specified
1> 
c:\cpp\boost_1_63\libs\spirit\example\x3\rexpr\rexpr_full\rexpr\ast.hpp(28): 
note: see reference to class template instantiation 
'boost::spirit::x3::variant<std::string,boost::spirit::x3::forward_ast<rexpr::ast::rexpr>>' 
being compiled
1>c:\cpp\boost_1_63\libs\spirit\example\x3\rexpr\rexpr_full\rexpr\rexpr_def.hpp(70): 
error C2995: 'bool rexpr::parser::parse_rule(unknown-type,Iterator 
&,const Iterator &,const Context &,Attribute &)': function template has 
already been defined
1> 
c:\cpp\boost_1_63\libs\spirit\example\x3\rexpr\rexpr_full\rexpr\rexpr_def.hpp(70): 
note: see declaration of 'rexpr::parser::parse_rule'




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