Unable to compile my C Extension on Windows: unresolved external link errors

[Marco Sulla]

On Sun, 14 Nov 2021 at 16:42, Barry Scott <barry at barrys-emacs.org> wrote:
>
> Sorry iPad sent the message before it was complete...
>
> > On 14 Nov 2021, at 10:38, Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
> >
> > Okay, now the problem seems to be another: I get the same "unresolved
> > external link" errors, but only for internal functions.
> >
> > This seems quite normal. The public .lib does not expose the internals
> > of Python.
> > The strange fact is: why can I compile it on Linux and MacOS? Their
> > external libraries expose the internal functions?
>
> Windows is not Linux is not macOS,
> The toolchain on each OS has its own strengths, weaknesses and quirks.
>
> On Windows DLLs only allow access to the symbols that are explicitly listed to be access.

Where are those symbols listed?

> On macOS .dynlib and Unix .so its being extern that does this.

And extern is the default. I understand now.

> Maybe you could copy the code that you want and add it to your code?
> Change any conflicting symbols of course.

It's quite hard. I have to compile dictobject.c, which needs a lot of
internal functions. And I suppose that every internal function may
require 1 or more other internal functions.

I have other two other solutions:
* compile a whole python DLL with the symbols I need and link against
it. I have to put this DLL in my code, which is ugly.
* drop the support of the C Extension for Windows users and make for
them the slow, pure py version only.

Since my interest in Windows now is near to zero, I think I'll opt for
the third for now.