I've just built a Haskell dll on Windows. As part of the process it generated an 14Mb foo.dll, and a 40Mb foo.dll.a. Looking at the flags passed to ld I see --out-implib=foo.dll.a. What is the purpose of the .a file? What might it be needed for? Is it possible to suppress it?
It looks like what you're getting is an import lib that also contains a full copy of all the code.
Yes, that seems likely. My guess is it's just a cat of the .o's, with header tables etc.
I think it's possible to have minimal .lib files that do not contain any code and only refer to the corresponding dll. Further, I think recent gnu ld versions can link directly against dlls without using an import lib (though you may still need the import lib if you want to use MSVC to link to your dll).
I don't, although having that option wouldn't be a bad thing - having a minimal .lib is perfectly reasonable as a default. Having a massive .lib seems crazy. (The fact that .lib is named .dll.a isn't too much of an issue)
So my suggestion is remove it, if you're linking using gcc it should work.
I'm not linking the .dll at all, only using dynamic linking, which works without the .lib. But I don't really want to start removing files - doing that in a build system seems like a bad idea. Thanks Neil