[Boost-users] [variant] forward declarations

Subject: [Boost-users] [variant] forward declarations
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2014-07-18 15:21:34

Hello,

I've got some structs in a AST of sorts which the main player in the
mix is a node. In at least one of the use cases, one of the variant
types must be forward declared at the time the node can be declared.
Possibly one or two other similar use cases.

Error 2 error C2139: 'xml::xelement' : an undefined class is not
allowed as an argument to compiler intrinsic type trait
'__is_nothrow_constructible'
i:\installs\development\boost.org\1.55.0\boost_1_55_0\stage\include\boost\type_traits\has_nothrow_constructor.hpp
24 1 xml

However, I am bumping into C2139, above.

Is there any way for variant to work with forward declared structs (or
classes, etc)? Or am I just asking too much from C++?

I am building against Visual Studio 2013, Boost 1.55.

Thank you...

Best regards,

Michael Powell