Compilation of derived class from boost::spirit::qi::grammar failed with __declspec( dllexport )

Clang-cl.
I am trying to implement a class that inherits from boost::spirit::qi::grammar and make it exportable in dynamic library:
```
#pragma once
#include
#include
#include

using boost::spirit::ascii::space_type;
struct EXPORT_DLLCLASS Grammar : boost::spirit::qi::grammar< char const*, space_type >
{
Grammar()
: Grammar::base_type( expr )
{
}
boost::spirit::qi::rule< char const*, space_type > expr, term;
};
```
I'm using `EXPORT_DLLCLASS` to specify `__attribute__( ( visibility( "default" ) ) )` or `__declspec( dllexport )` depending on the platform. Build succeeds under Linux platform, but I have problems with compilation under Windows platform with the following errors:
```
C:\.conan\oq2odq\1\include\boost/proto/extends.hpp(536,17): error: call to implicitly-deleted default constructor of 'boost::proto::exprns_::expr >, 0>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, 0>'
: proto_expr_()
^
C:\.conan\oq2odq\1\include\boost/proto/proto_fwd.hpp(377,16): note: in instantiation of member function 'boost::proto::exprns_::extends >, 0>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, 0>, boost::spirit::qi::grammar >, 0>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type>, boost::proto::domainns_::default_domain, 0>::extends' requested here
struct extends;
^
C:\.conan\oq2odq\1\include\boost/proto/detail/preprocessed/expr_variadic.hpp(50,49): note: default constructor of 'expr >, 0>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, 0>' is implicitly deleted because field 'child0' has no default constructor
typedef Arg0 proto_child0; proto_child0 child0;
```
Build succeeds if `EXPORT_DLLCLASS` is not specified.
https://stackoverflow.com/questions/75744429/compilation-of-derived-class-from-boostspiritqigrammar-failed-with-decls