From b62b8c72b8132d85d39147764e7b5780e5cff5fe Mon Sep 17 00:00:00 2001
From: Alan Donovan <adonovan@google.com>
Date: Mon, 5 Jun 2017 14:04:35 -0400
Subject: [PATCH] go/gcexportdata: a command for inspecting gc export data in
 archive files

Change-Id: I2428b201c49dc441a0023053798f3287902fc370
Reviewed-on: https://go-review.googlesource.com/44861
Reviewed-by: Robert Griesemer <gri@golang.org>
---
 go/gcexportdata/main.go | 81 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 go/gcexportdata/main.go

diff --git a/go/gcexportdata/main.go b/go/gcexportdata/main.go
new file mode 100644
index 0000000000..106046c4cb
--- /dev/null
+++ b/go/gcexportdata/main.go
@@ -0,0 +1,81 @@
+// Copyright 2017 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.
+
+// +build ignore
+
+// The gcexportdata command is a diagnostic tool that displays the
+// contents of gc export data files.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"go/token"
+	"go/types"
+	"log"
+	"os"
+
+	"golang.org/x/tools/go/gcexportdata"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+func main() {
+	log.SetPrefix("gcexportdata: ")
+	log.SetFlags(0)
+	flag.Usage = func() {
+		fmt.Fprintln(os.Stderr, "usage: gcexportdata file.a")
+	}
+	flag.Parse()
+	if flag.NArg() != 1 {
+		flag.Usage()
+		os.Exit(2)
+	}
+	filename := flag.Args()[0]
+
+	f, err := os.Open(filename)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	r, err := gcexportdata.NewReader(f)
+	if err != nil {
+		log.Fatalf("%s: %s", filename, err)
+	}
+
+	// Decode the package.
+	imports := make(map[string]*types.Package)
+	fset := token.NewFileSet()
+	pkg, err := gcexportdata.Read(r, fset, imports, "dummy")
+	if err != nil {
+		log.Fatal("%s: %s", filename, err)
+	}
+
+	// Print all package-level declarations, including non-exported ones.
+	fmt.Printf("package %s\n", pkg.Name())
+	for _, imp := range pkg.Imports() {
+		fmt.Printf("import %q\n", imp.Path())
+	}
+	qual := func(p *types.Package) string {
+		if pkg == p {
+			return ""
+		}
+		return p.Name()
+	}
+	scope := pkg.Scope()
+	for _, name := range scope.Names() {
+		obj := scope.Lookup(name)
+		fmt.Printf("%s: %s\n",
+			fset.Position(obj.Pos()),
+			types.ObjectString(obj, qual))
+
+		// For types, print each method.
+		if _, ok := obj.(*types.TypeName); ok {
+			for _, method := range typeutil.IntuitiveMethodSet(obj.Type(), nil) {
+				fmt.Printf("%s: %s\n",
+					fset.Position(method.Obj().Pos()),
+					types.SelectionString(method, qual))
+			}
+		}
+	}
+}