cmd/ld: unsupported relocation for dynamic symbol

[sbinet]

• What version of Go are you using (go version)?
  go version go1.4.2 darwin/amd64
  MacOSX-10.6.8
• What did you do?

$ cd $GOPATH/src/github.com/sbinet
$ git clone git://github.com/sbinet/test-cgo
$ cd test-cgo
$ make
/bin/rm -f pkg/my/*.so
(cd pkg/my && cc -shared -o libmy.so lib.c)
# github.com/sbinet/test-cgo/pcgo
github.com/sbinet/test-cgo/pkg._Cvar_Global: unsupported relocation for dynamic symbol Global (type=1 stype=32)
github.com/sbinet/test-cgo/pkg._Cvar_Global: unhandled relocation for Global (type 32 rtype 1)
make: *** [install] Error 2

note that if, in test-cgo/pkg/my/lib.h I change:

#define API_DATA(RTYPE) extern RTYPE
//#define API_DATA(RTYPE) RTYPE

to:

//#define API_DATA(RTYPE) extern RTYPE
#define API_DATA(RTYPE) RTYPE

everything compiles and runs:

$ make && (cd ./pkg/my && pcgo)
/bin/rm -f pkg/my/*.so
(cd pkg/my && cc -shared -o libmy.so lib.c)
>>>
Global: 42
Global: 42
<<<

Note that on master, I get instead:

$ go version devel +48469a2 Mon Feb 23 07:54:13 2015 +0000 darwin/amd64
$ make && (cd ./pkg/my && pcgo)
>>>
Global: 42
fatal error: unexpected signal during runtime execution
[signal 0xb code=0x1 addr=0xb01dfacedebac1e pc=0x1dbf23]

runtime stack:
runtime.throw(0x126e70, 0x2a)
    /Users/binet/dev/go/root/go/src/runtime/panic.go:511 +0xa0
runtime.sigpanic()
    /Users/binet/dev/go/root/go/src/runtime/sigpanic_unix.go:12 +0x62

goroutine 1 [syscall, locked to thread]:
runtime.cgocall_errno(0xac120, 0xc208037ed0, 0xc200000000)
    /Users/binet/dev/go/root/go/src/runtime/cgocall.go:130 +0x10c fp=0xc208037eb0 sp=0xc208037e88
github.com/sbinet/test-cgo/pkg._Cfunc_Get(0x25ff0000077a25ff, 0x0)
    /Users/binet/dev/go/root/path/src/github.com/sbinet/test-cgo/pkg/:24 +0x3c fp=0xc208037ed0 sp=0xc208037eb0
github.com/sbinet/test-cgo/pkg.Print()
    /Users/binet/dev/go/root/path/src/github.com/sbinet/test-cgo/pkg/pkg.go:14 +0x10c fp=0xc208037f58 sp=0xc208037ed0
main.main()
    /Users/binet/dev/go/root/path/src/github.com/sbinet/test-cgo/pcgo/main.go:11 +0x4e fp=0xc208037fa0 sp=0xc208037f58
runtime.main()
    /Users/binet/dev/go/root/go/src/runtime/proc.go:88 +0x1d2 fp=0xc208037fe0 sp=0xc208037fa0
runtime.goexit()
    /Users/binet/dev/go/root/go/src/runtime/asm_amd64.s:2466 +0x1 fp=0xc208037fe8 sp=0xc208037fe0

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /Users/binet/dev/go/root/go/src/runtime/asm_amd64.s:2466 +0x1
zsh: exit 2     (; cd pkg/my && pcgo; )

Such extern global symbols are heavily used in e.g. the CPython API.

To recap: the pkg builds fine, it's when somebody uses that cgo-based package that all hell breaks loose.

[rsc]

I suspect this is a duplicate of #8009.

Issue #9511 talks about dropping support for OS X 10.6 officially. If we do that we can close this bug and #8009 and maybe a few others.

[sbinet]

yes, most probably the same underlying issue.

I just upgraded my old (2008) macbook-pro from 10.6 to 10.10 (yosemite) and everything works fine (master and 1.4.2)

[rsc]

Per #9511, we will not be making any further bug fixes specific to 10.6.

[rsc]

Per #9511, we will not be making any further bug fixes specific to 10.6.