plugin: darwin support is still fragile

[hirochachacha]

Please answer these questions before submitting your issue. Thanks!

What did you do?

If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is best.

a.go

package main

func F() {
	b := make([]byte, 10000)
	_ = b
}

z.go

package main

import "plugin"

type A struct {
	a string
}

func NewA() *A {
	return &A{a: "a"}
}

func (a *A) Lookup() (plugin.Symbol, error) {
	so, err := plugin.Open("a.so")
	if err != nil {
		return nil, err
	}
	return so.Lookup("F")
}

func main() {
	a := NewA()

	sym, err := a.Lookup()
	if err != nil {
		panic(err)
	}

	(sym.(func()))()
}

Then,

$ go build -buildmode=plugin a.go
$ go run z.go

What did you expect to see?

no errors.

What did you see instead?

runtime: bad pointer in frame main.main at 0xc4200a5f70: 0x1
fatal error: invalid pointer found on stack

runtime stack:
runtime.throw(0x44625c6, 0x1e)
	/Users/hiro/go/src/runtime/panic.go:616 +0x81 fp=0x7ffeefbfef10 sp=0x7ffeefbfeef0 pc=0x441df81
runtime.adjustpointers(0xc4200a5f70, 0x7ffeefbff008, 0x7ffeefbff3b8, 0x40b4c48, 0x40b6a40)
	/Users/hiro/go/src/runtime/stack.go:592 +0x23e fp=0x7ffeefbfef80 sp=0x7ffeefbfef10 pc=0x443061e
runtime.adjustframe(0x7ffeefbff2c8, 0x7ffeefbff3b8, 0x40b6a40)
	/Users/hiro/go/src/runtime/stack.go:663 +0x32c fp=0x7ffeefbff038 sp=0x7ffeefbfef80 pc=0x443096c
runtime.gentraceback(0xffffffffffffffff, 0xffffffffffffffff, 0x0, 0xc420000180, 0x0, 0x0, 0x7fffffff, 0x4463e68, 0x7ffeefbff3b8, 0x0, ...)
	/Users/hiro/go/src/runtime/traceback.go:339 +0x1334 fp=0x7ffeefbff330 sp=0x7ffeefbff038 pc=0x44372a4
runtime.copystack(0xc420000180, 0x4000, 0x7ffeefbff501)
	/Users/hiro/go/src/runtime/stack.go:891 +0x26e fp=0x7ffeefbff4e8 sp=0x7ffeefbff330 pc=0x443145e
runtime.newstack()
	/Users/hiro/go/src/runtime/stack.go:1063 +0x310 fp=0x7ffeefbff678 sp=0x7ffeefbff4e8 pc=0x4431870
runtime.morestack()
	/Users/hiro/go/src/runtime/asm_amd64.s:480 +0x89 fp=0x7ffeefbff680 sp=0x7ffeefbff678 pc=0x443c6d9

goroutine 1 [copystack]:
plugin/unnamed-a6bc9850fd4dfe51568f68acc0d0e4139a9ff822.F()
	/Users/hiro/a.go:3 +0x63 fp=0xc4200a5f40 sp=0xc4200a5f38 pc=0x44436a3
main.main()
	/Users/hiro/z.go:29 +0x7a fp=0xc4200a5f88 sp=0xc4200a5f40 pc=0x40554ba
runtime.main()
	/Users/hiro/go/src/runtime/proc.go:198 +0x212 fp=0xc4200a5fe0 sp=0xc4200a5f88 pc=0x4028582
runtime.goexit()
	/Users/hiro/go/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc4200a5fe8 sp=0xc4200a5fe0 pc=0x404c3e1

goroutine 2 [force gc (idle)]:
runtime.gopark(0x407b828, 0x40b8cb0, 0x40773e6, 0xf, 0x407b714, 0x1)
	/Users/hiro/go/src/runtime/proc.go:291 +0x11a fp=0xc420036768 sp=0xc420036748 pc=0x40289ca
runtime.goparkunlock(0x40b8cb0, 0x40773e6, 0xf, 0x14, 0x1)
	/Users/hiro/go/src/runtime/proc.go:297 +0x5e fp=0xc4200367a8 sp=0xc420036768 pc=0x4028a7e
runtime.forcegchelper()
	/Users/hiro/go/src/runtime/proc.go:248 +0xcc fp=0xc4200367e0 sp=0xc4200367a8 pc=0x402880c
runtime.goexit()
	/Users/hiro/go/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc4200367e8 sp=0xc4200367e0 pc=0x404c3e1
created by runtime.init.4
	/Users/hiro/go/src/runtime/proc.go:237 +0x35

goroutine 3 [GC sweep wait]:
runtime.gopark(0x407b828, 0x40b8da0, 0x40770e3, 0xd, 0x401c714, 0x1)
	/Users/hiro/go/src/runtime/proc.go:291 +0x11a fp=0xc420036f60 sp=0xc420036f40 pc=0x40289ca
runtime.goparkunlock(0x40b8da0, 0x40770e3, 0xd, 0x14, 0x1)
	/Users/hiro/go/src/runtime/proc.go:297 +0x5e fp=0xc420036fa0 sp=0xc420036f60 pc=0x4028a7e
runtime.bgsweep(0xc420020070)
	/Users/hiro/go/src/runtime/mgcsweep.go:52 +0xa3 fp=0xc420036fd8 sp=0xc420036fa0 pc=0x401c813
runtime.goexit()
	/Users/hiro/go/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc420036fe0 sp=0xc420036fd8 pc=0x404c3e1
created by runtime.gcenable
	/Users/hiro/go/src/runtime/mgc.go:216 +0x58
exit status 2

Does this issue reproduce with the latest release (go1.9.2)?

System details

go version devel +46850212af Sat Jan 6 18:23:45 2018 +0900 darwin/amd64
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/hiro/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/hiro/.go"
GORACE=""
GOROOT="/Users/hiro/go"
GOTMPDIR=""
GOTOOLDIR="/Users/hiro/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/wq/dwn8hs0x7njbzty9f68y61700000gn/T/go-build520323770=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version devel +46850212af Sat Jan 6 18:23:45 2018 +0900 darwin/amd64
GOROOT/bin/go tool compile -V: compile version devel +46850212af Sat Jan 6 18:23:45 2018 +0900
uname -v: Darwin Kernel Version 17.3.0: Thu Nov  9 18:09:22 PST 2017; root:xnu-4570.31.3~1/RELEASE_X86_64
ProductName:	Mac OS X
ProductVersion:	10.13.2
BuildVersion:	17C88
lldb --version: lldb-900.0.64
  Swift-4.0
gdb --version: GNU gdb (GDB) 8.0.1

[hirochachacha]

Fixed by 08304e8

[akamensky]

Works on the tip, but will it be cherry-picked to 1.10.2? Currently impossible to to debug plugins that are meant for Linux on macOS.

[randall77]

I've started the backport to 1.9 and 1.10.
Issues #26202 and #26203