go: plugin: loading plugin leads to 'fatal error: invalid runtime symbol table' with some stdlib packages

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

$ go version
go version go1.8beta1 darwin/amd64

What operating system and processor architecture are you using (go env)?

$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/mccolljr/Documents/dev/go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.8beta1/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.8beta1/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/rg/pwv319qj009dkq19ryb8x3m00000gn/T/go-build046386885=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

pg.go

attempted builds (same error for each): go build --buildmode=plugin pg.go go build --gcflags "-dynlink" --buildmode=plugin pg.go

package main

import (
	"log"
	"net/http"

	"html/template"
)

var Handler http.Handler

func init() {
	Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		p, err := template.ParseFiles("x.tpl")
		if err != nil {
			log.Fatalln(err)
		}

		p.ExecuteTemplate(w, "x.tpl", nil)
	})
}

x.tpl

TEST!

main.go

attempted builds (same error for each): go build main.go && ./main go build --gcflags "-dynlink" main.go && ./main

package main

import (
	"fmt"
	"net/http"
	"plugin"
)

func main() {
	p, err := plugin.Open("pg.so")

	if err != nil {
		panic(err)
	}

	sym, err := p.Lookup("Handler")

	if err != nil {
		panic(err)
	}

	fmt.Println("starting...")

	http.ListenAndServe(":8080", *(sym.(*http.Handler)))
}

note This program works correctly when you change pg.go to:

package main

import (
	"fmt"
	"net/http"
)

var Handler http.Handler

func init() {
	Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprint(w, "TEST!")
	})
}

What did you expect to see?

terminal:

$ ./main
starting...

browser:

TEST!

What did you see instead?

runtime: invalid pc-encoded table f=gE#?? pc=0x40d92c1 targetpc=0x53dde9d tab=[0/0]0x0
	value=-1 until pc=0x40d9290
	value=0 until pc=0x40d9290
	value=0 until pc=0x40d9290
	value=228 until pc=0x40d92c1
	value=230 until pc=0x40d92c1
fatal error: invalid runtime symbol table

runtime stack:
invalid spdelta r; runtime.sizeclass int32; runtime.large bool } 0x405b9c0 0x5329fe5 0x3f3b4 -1
r; runtime.sizeclass int32; runtime.large bool }(0x100, 0x7fff5fbfef9800, 0x534336700)
	?:0 +0x12ce625

goroutine 1 [copystack]:
invalid spdelta gE#?? 0x40d9290 0x53dde9d 0x78c52 -1
gE#??(0xc4200ce64000, 0xa00, 0xa00, 0xc42006ed9800, 0xc420014db000)
	?:0 +0x1304c0d fp=0xc420137b6f sp=0xc420137b68

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
	/usr/local/Cellar/go/1.8beta1/libexec/src/runtime/asm_amd64.s:2184 +0x1
exit status 2