[boost] Compiling program_options v1.35 on msvc9.0 fix

Subject: [boost] Compiling program_options v1.35 on msvc9.0 fix
From: Okko Willeboordse (trash_at_[hidden])
Date: 2008-11-12 14:56:38

Hi All,

My co-worker Evert van de Waal noticed the following;
 
I have had some problems compiling program_options v1.35 on visual C++
9.0 (2008) Express. It seems that this compiler does not correctly
export some global variables when compiling to DLL, leading to
unresolved dependencies. I have had to make a few changes:
 
In file *options_description.hpp*, line 158:
 
Replaced
        static const unsigned m_default_line_length;
with
        BOOST_STATIC_CONSTANT (unsigned, m_default_line_length = 80);
This is an old fix that I found in the mail archives (2005), seems to
have been erroneously dropped from the base-line.
 
In file *options_description.cpp*: removed the declaration of
m_default_line_length.
 
In file *value_semantic.cpp*: a singleton variable was defined but not
properly linked by vc9.0. I changed the implementation to (line 17)

        BOOST_PROGRAM_OPTIONS_DECL string&
        arg()
        {
          static string* str=0;
          if (!str)
          {
            str = new string;
            *str = "arg";
          }
          return *str;
        }

>From line 79 (after making the change above), I changed the only use of
arg to:

        std::string
        untyped_value::name() const
        {
            return arg();
        }

In file *details/value_semantic.hpp*: I changed the declaration of the
variable arg to (line 13):

    BOOST_PROGRAM_OPTIONS_DECL std::string& arg();

After these changes, program_options links properly, and I was able to
run the demo code.
 
Please note that also the pre-compiled version of boost 1.35 for the
vc9.0 compiler from http://www.boost-consulting.com/download/windows
suffers from these problems: the program_options DLL is unlinkable due
to unresolved references to m_default_line_length  and arg.
 
Cheerio,
Evert van de Waal