cmd/go: -buildmode=c-shared should work on windows

[chai2010]

[ianlancetaylor]

It would help to be more specific: different -buildmode options are, and always will be, supported on different systems. Which -buildmode options are you specifically interested in?

[mattn]

Probably, most of windows users are looking for a way to generate dlls.:

--buildmode=c-shared

or

--buildmode=dll

[chai2010]

I only need -buildmode=c-shared, to generate DLL for other C/C++ user.
If Go can generate DLL, i can say byebye to C++.

PS: Also hope fix #9510 in Go1.5!

[mewmew]

I would also like to see this happen. Is anyone currently working on this issue? Any CL's which may be reviewed?

[minux]

Unfortunately, I'm not aware of anyone working on this issue right now.

[nadiasvertex]

I also need this. If I had some idea how much work was involved I might be willing to contribute an implementation. I know that Windows DLLs are fairly different from ELF style shared libraries, so if this is an enormous task it won't be something I can commit to.

Is there any way to find out how much/what kind of work would be involved?

[ianlancetaylor]

@nadiasvertex The main thing is to make the function hostlink in cmd/link/internal/ld/lb.go do the right thing on Windows. On Darwin it invokes theC linker with -dynamiclib. On GNU/Linux it invokes the C linker with -Wl,-Bsymbolic -Wl,-z,relro -shared -Wl,-z,nodelete.

Basically, if you produce a list of commands that will turn a Windows object file into a Windows DLL, change hostlink to invokes those commands.

That said, it's possible that Windows needs to know the list of symbols that are callable from outside the DLL. It used to need to know that, but it's been many years since I looked at it. If you need that list of symbols, it's available by looping over the symbol table and looking for the Cgoexport field having a CgoExportStatic flag.

[nadiasvertex]

Great! I'll look at it. I suspect that the challenge is mostly in knowing
where the linker is on Windows.

On Mon, Dec 7, 2015 at 10:58 AM Ian Lance Taylor notifications@github.com
wrote:

@nadiasvertex https://github.com/nadiasvertex The main thing is to make
the function hostlink in cmd/link/internal/ld/lb.go do the right thing on
Windows. On Darwin it invokes theC linker with -dynamiclib. On GNU/Linux it
invokes the C linker with -Wl,-Bsymbolic -Wl,-z,relro -shared
-Wl,-z,nodelete.

Basically, if you produce a list of commands that will turn a Windows
object file into a Windows DLL, change hostlink to invokes those commands.

That said, it's possible that Windows needs to know the list of symbols
that are callable from outside the DLL. It used to need to know that, but
it's been many years since I looked at it. If you need that list of
symbols, it's available by looping over the symbol table and looking for
the Cgoexport field having a CgoExportStatic flag.

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