On Wednesday, 16 December 2020 at 04:45:34 UTC, Dave P. wrote:
Oh interesting, so I only need extern(C) for declaring symbols
I’m linking to and
for symbols I want to export to C. I had sort of assumed that D
might have
different calling conventions for different things, but that
makes things a lot easier.
Not so fast! :-)
extern(C) does affect the calling convention on Windows x86.
There's also extern(Windows), which changes a function to the
stdcall calling convention used by the Win32 API (and OpenGL
implementations on Windows, and a handful of other libraries).
And there's no guarantee that as D moves to new platforms that
there won't be other exceptions joining x86 Windows.
That's why I said I'm not sure I'd ever pass a templated function
pointer to C. It isn't going to work on 32-bit Windows, or with
any stdcall C function, right now, and possibly other platforms
in the future.
So as a default, you should always be explicit with your
extern(x) linkage attributes on functions even when you aren't
actually linking with C, and only break that rule when it's
necessary.
