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c++windowsvisual-c++boostdll

"Mixing a dll boost library with a static runtime is a really bad idea..."

I have two projects in a Visual Studio solution. One builds a static LIB, the other builds a dynamic DLL. Both use static runtime linking (/MT and /MTd), and both use Boost. Boost was not my decision - I wanted to chuck it but I was overruled by committee.

The LIB builds fine, but the DLL coughs up an error from auto_link.hpp (line 354): "Mixing a dll boost library with a static runtime is a really bad idea...".

#if (defined(_DLL) || defined(_RTLDLL)) && defined(BOOST_DYN_LINK)
#  define BOOST_LIB_PREFIX
#elif defined(BOOST_DYN_LINK)
#  error "Mixing a dll boost library with a static runtime is a really bad idea..."
#else
#  define BOOST_LIB_PREFIX "lib"
#endif

I did not define BOOST_DYN_LINK. It seems Boost is making a leap that since I am building a DLL (_USRDLL and _WINDLL are defined), I must want dynamic runtime linking (/MD or /MDd, which defines _DLL) or DLL linking against Boost. This is incorrect as I specifically asked for static linking (/MT or /MTd).

I filed a bug report against Boost for its incorrect assumptions, but that does not help me with using the library. In the report, the Boost maintainers insist that I am setting it (despite the fact that an audit showed I am not; and Boost manipulates it in at least 30 files). I found one answer on the Boost mailing list, which essentially states to change my project settings to accomodate Boost.

Changing to Dynamic Runtime Linking (/MD and /MDd) is not feasible since static linking was chosen (1) due to security considerations, and (2) another library uses static linking. This is non-negotiable - we have no choice.

To summarize for clarity (TLDR): I want to use static linking for everything, while my output program is a DLL (not a static LIB, not an EXE). Everything is linked statically within the DLL.

Does anyone know how to use this library on Windows to build a DLL with static linking?

Solution

  • This issue is indeed a fault with boosts settings. For some unknown reason (that I cannot determine to be logical - as it has not effect). Boost Python will force dynamic linking of boost, regardless of user options

    In short, if you have boost-python in your project, boost incorrectly prevents static-linking of boost with the /MT switch.

    This problem is resolved easily by defining BOOST_PYTHON_STATIC_LIB before including the boost headers.