[boost] [config] Does it work with compilers in C mode ?

Is there any guarantee that the configuration files will work with a C compiler or a C++ compiler in C mode ? Is there anything in the configuration files which is C++ specific ? I am working on bringing my variadic macro data library into Boost PP, and I wanted to use the BOOST_NO_VARIADIC_MACROS in config, but Paul Mensonides was concerned that Boost PP should work with a C compiler and that config could have something that is C++ specific, and therefore be unusable for Boost PP. I would rather not reduplicate the logic of BOOST_NO_VARIADIC_MACROS in Boost PP, even though I was the one to add it to config, because it puts the same code in two different places.