Go 1.14: how to -linkshared to a library produced by -buildmode=shared?

[mi...@ridge.co]

Hello.

I'm trying to build a shared library using `-buildmode=shared` and make a binary link to this shared library.

The packages are:

github.com/misha-ridge/splitlib/a (-> c)

github.com/misha-ridge/splitlib/b (-> c)

github.com/misha-ridge/splitlib/c

github.com/misha-ridge/splitlib (-> a, b, c)

I'd like to package `a` and `c` into the shared library, and put `b` and `splitlib` into the binary.

I've tried the following:

$ go install -buildmode=shared std

$ go install -buildmode=shared -linkshared  -gcflags='-N -l' ./a

This produced `libgithub.com-misha-ridge-splitlib-a.so` in the current directory

Then

$ go build -o main -linkshared  -gcflags='-N -l' .

This produced `main` in the current directory that only links to a shared libstd, but not to

the freshly built lib...splitlib-a.so:

$ ldd main

linux-vdso.so.1 (0x00007ffea3bfe000)

libstd.so => /usr/local/go/pkg/linux_amd64_dynlink/libstd.so (0x00007f7ea27f6000)

libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f7ea2631000)

libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f7ea262c000)

libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f7ea260b000)

/lib64/ld-linux-x86-64.so.2 (0x00007f7ea4f23000)

$

The shared library does not contain symbols from splitlib/a or splitlib/b:

$ go tool nm libgithub.com-misha-ridge-splitlib-a.so  | grep splitlib

  104cd0 D go.link.abihash.libgithub.com-misha-ridge-splitlib-a.so

Only the final binary does:

$ go tool nm main  | grep splitlib

    2180 T github.com/misha-ridge/splitlib/a.SetC

    2190 T github.com/misha-ridge/splitlib/b.SetC

    2170 T github.com/misha-ridge/splitlib/c.Get

    5210 D github.com/misha-ridge/splitlib/c.i

    2180 t local.github.com/misha-ridge/splitlib/a.SetC

    2190 t local.github.com/misha-ridge/splitlib/b.SetC

    2170 t local.github.com/misha-ridge/splitlib/c.Get

Am I missing some step?

The repository with reproducer is at https://github.com/misha-ridge/splitlib

-- 

Best,

Misha.

[Bryan C. Mills]

Did this work in 1.13?

https://golang.org/issue/35759 is probably related; see especially the TODO here.

Please file an issue so we don't lose track of it.

[Mikhail Gusarov]

Hi Bryan,

On 4 Mar 2020, at 2:27, 'Bryan C. Mills' via golang-nuts wrote:

> Did this work in 1.13?

Actually, no. In 1.13 it triggers the panic as described in this bug:

> https://golang.org/issue/35759 is probably related; see especially the
> TODO
> here

> <https://github.com/golang/go/blob/5a61de3fe160cc8b327ee893cd74c4d0ce9dc13d/src/cmd/go/internal/load/pkg.go#L1612-L1616>
> .

> Please file an issue <https://golang.org/issue/new> so we don't lose
> track
> of it.

Sure filed as #37675.

--
Misha