lccwin32's import library function..

[copx]

I build DLLs using MS VC6 to shield tmy programs from the uglyness that is
Windows/C++ (DLL offers C interface to C++ Windows stuff like SAPI 5). I can
use these DLLs with mingw after importing the related import library.
However, it did not work with lccwin32 - unresolved references (compiler
cannot find any DLL functions). After a lot of head scratching I attempted
to actually use my DLLs with VC6 (instead of just using that compiler to
build them): same problem.
I eventually figured out that the problem could be fixed by specifing the
calling convention in the header file. I use the __stdcall convention for
the DLLs.
Now I wonder: why can mingw figure out the calling convention of the DLL
without any compiler specific dressing but VC6/lcc cannot?
Isn't the calling convention info stored in the lib? Do I need to turn on
some special switches to built MS import libs which work even without
specifying the calling convention in the header?
I ask because I want to use the same header for all compilers I use and
stuff like "__stdcall" breaks GCC (uses different syntax for specifying
calling conventions).