From: Vladimir Prus (vladimir_at_[hidden])
Date: 2008-06-19 01:11:19
Ovanes Markarian wrote:
> Sorry for the double post. I had to patch Source of the Program
> Options to solve this issue. Here the organization of the project
> which produced Linking errors:
>
>
> BoostProgramOptions.LIB (we link against DLL version of LIB)
> ^
> |
> Lib with PO retriever (static lib)
> ^
> |
> +------------------------------------------------------------+
> | |
> Lib A Lib B
> ^ ^
> | |
> +------------------------------------------------------------+
> ^
> |
> DLL which links with A & B
>
> Lib A & Lib B rely on the same program options reader.
>
>
> Initial problem was as described below. To solve this issue I had to
> remove the arg definition in the value_semantic.cpp file and
> initialize it in the header file detail/value_semantic.hpp with MS
> specific __declspec(selectany) which causes to ignore multiple defined
> linker symbol. Here the linke in the value_semantic.hpp
>
> extern BOOST_PROGRAM_OPTIONS_DECL __declspec(selectany)
> std::string arg("arg");
So, what is the *reason* for the original linker error?
>
> I hope you can reproduce this behaviour and apply this patch to next
> boost destributions.
>
>
> With Kind Regards,
> Ovanes
>
>
> P.S. I don't know if the entire fix is worth doing it when the arg's
> value is copied in the source anyway. Just a small example:
>
> template<class T, class charT>
> std::string
> typed_value<T, charT>::name() const
> {
> if (!m_default_value.empty() && !m_default_value_as_text.empty()) {
> return arg + " (=" + m_default_value_as_text + ")";
Well, this will rely on compiler/linker ability to merge duplicate strings.
- Volodya