misc/cgo/testplugin: add test of -buildmode=plugin

Change-Id: Ie9fea9814c850b084562ab2349b54d9ad9fa1f4a
Reviewed-on: https://go-review.googlesource.com/27825
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

misc/cgo/testplugin/src/common/common.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package common
+
+var X int
+
+func init() {
+	X = 3
+}

misc/cgo/testplugin/src/host/host.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"plugin"
+
+	"common"
+)
+
+func init() {
+	common.X *= 5
+}
+
+func main() {
+	if got, want := common.X, 3*5; got != want {
+		log.Fatalf("before plugin load common.X=%d, want %d", got, want)
+	}
+
+	p, err := plugin.Open("plugin1.so")
+	if err != nil {
+		log.Fatalf("plugin.Open failed: %v", err)
+	}
+
+	const wantX = 3 * 5 * 7
+	if got := common.X; got != wantX {
+		log.Fatalf("after plugin load common.X=%d, want %d", got, wantX)
+	}
+
+	seven, err := p.Lookup("Seven")
+	if err != nil {
+		log.Fatalf(`Lookup("Seven") failed: %v`, err)
+	}
+	if got, want := *seven.(*int), 7; got != want {
+		log.Fatalf("via lookup plugin1.Seven=%d, want %d", got, want)
+	}
+
+	readFunc, err := p.Lookup("ReadCommonX")
+	if err != nil {
+		log.Fatalf(`Lookup("ReadCommonX") failed: %v`, err)
+	}
+	if got := readFunc.(func() int)(); got != wantX {
+		log.Fatalf("via lookup plugin1.ReadCommonX()=%d, want %d", got, wantX)
+	}
+
+	fmt.Println("PASS")
+}

misc/cgo/testplugin/src/plugin1/plugin1.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// // No C code required.
+import "C"
+
+import "common"
+
+func ReadCommonX() int {
+	return common.X
+}
+
+var Seven int
+
+func init() {
+	Seven = 7
+	common.X *= Seven
+}
+
+func main() {
+	panic("plugin1.main called")
+}

misc/cgo/testplugin/test.bash

+#!/usr/bin/env bash
+# Copyright 2016 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+set -e
+
+if [ ! -f src/host/host.go ]; then
+	cwd=$(pwd)
+	echo "misc/cgo/testplugin/test.bash is running in $cwd" 1>&2
+	exit 1
+fi
+
+goos=$(go env GOOS)
+goarch=$(go env GOARCH)
+
+function cleanup() {
+	rm -f plugin1.so host pkg
+}
+trap cleanup EXIT
+
+rm -rf pkg
+
+GOPATH=$(pwd) go build -buildmode=plugin plugin1
+GOPATH=$(pwd) go build host
+
+LD_LIBRARY_PATH=$(pwd) ./host

src/cmd/dist/test.go

@@ -540,6 +540,9 @@ func (t *tester) registerTests() {
 		if t.supportedBuildmode("shared") {
 			t.registerTest("testshared", "../misc/cgo/testshared", "go", "test")
 		}
+		if t.supportedBuildmode("plugin") {
+			t.registerTest("testplugin", "../misc/cgo/testplugin", "./test.bash")
+		}
 		if t.gohostos == "linux" && t.goarch == "amd64" {
 			t.registerTest("testasan", "../misc/cgo/testasan", "go", "run", "main.go")
 		}
@@ -724,6 +727,12 @@ func (t *tester) supportedBuildmode(mode string) bool {
 			return true
 		}
 		return false
+	case "plugin":
+		switch pair {
+		case "linux-386", "linux-amd64", "linux-arm", "linux-arm64", "linux-ppc64le", "linux-s390x":
+			return true
+		}
+		return false
 	default:
 		log.Fatalf("internal error: unknown buildmode %s", mode)
 		return false