Support msvc compiler (be able to produce Node.js native addons)

[anurbol]

Summary

Generated c/c++ code should not contain GCC-specific stuff (e.g. attribute).

Description

I wanted to write a node addon in Nim, but unfortunately without success. I managed to do everything needed (getting generated .cpp files from nimcache folder, exporting nim symbols with .exportc.), but failed at the last stage.
Turns out that Node addons binaries (Windows ones) are built exclusively by msvc (via node-gyp), and the compiler does not understand Nim-generated c/c++ code, since the code is GCC specific. To be more specific, Nim generates __attribute__ things that's OK for GCC, but not for msvc, and msvc produces c3646 unknown override specifier errors.

Alternatives

Well, I have to stick with c++ for now (I wanted to switch to Nim so badly)

[nc-x]

Use --cc:vcc for MSVC compiler. See https://nim-lang.org/docs/nimc.html#compiler-selection and https://nim-lang.org/faq.html (How do I use a different C compiler than the default one?).

[anurbol]

@nc-x Lol what 😄 Oh my God, I almost learned the contents of nim --fullhelp by heart (there is no --cc option, unless I am blind), when I just should have looked at FAQ? LOL. Thanks!!! I'll try that!

[nc-x]

Yeah, i just checked, it is not there in --help or --fullhelp.

[anurbol]

Yeah, i just checked, it is not there in --help or --fullhelp.

That's a material for another issue 😃

[anurbol]

Seems to work perfectly... Are Nim creators even Humans? I mean everything seems so good... I'll close this for now, but will reopen if something pops out.

[ohenepee]

@anurbol Did it work (I mean making the nodejs native addon thingy)? Any repo or tuts?