Fix lint errs (#59)

vendor/golang.org/x/tools/go/packages/external.go

@@ -0,0 +1,68 @@
+// Copyright 2018 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.
+
+// This file enables an external tool to intercept package requests.
+// If the tool is present then its results are used in preference to
+// the go list command.
+
+package packages
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+// findExternalTool returns the file path of a tool that supplies
+// the build system package structure, or "" if not found."
+// If GOPACKAGESDRIVER is set in the environment findExternalTool returns its
+// value, otherwise it searches for a binary named gopackagesdriver on the PATH.
+func findExternalDriver(cfg *Config) driver {
+	const toolPrefix = "GOPACKAGESDRIVER="
+	tool := ""
+	for _, env := range cfg.Env {
+		if val := strings.TrimPrefix(env, toolPrefix); val != env {
+			tool = val
+		}
+	}
+	if tool != "" && tool == "off" {
+		return nil
+	}
+	if tool == "" {
+		var err error
+		tool, err = exec.LookPath("gopackagesdriver")
+		if err != nil {
+			return nil
+		}
+	}
+	return func(cfg *Config, words ...string) (*driverResponse, error) {
+		buf := new(bytes.Buffer)
+		fullargs := []string{
+			"list",
+			fmt.Sprintf("-test=%t", cfg.Tests),
+			fmt.Sprintf("-export=%t", usesExportData(cfg)),
+			fmt.Sprintf("-deps=%t", cfg.Mode >= LoadImports),
+		}
+		for _, f := range cfg.BuildFlags {
+			fullargs = append(fullargs, fmt.Sprintf("-buildflag=%v", f))
+		}
+		fullargs = append(fullargs, "--")
+		fullargs = append(fullargs, words...)
+		cmd := exec.CommandContext(cfg.Context, tool, fullargs...)
+		cmd.Env = cfg.Env
+		cmd.Dir = cfg.Dir
+		cmd.Stdout = buf
+		cmd.Stderr = new(bytes.Buffer)
+		if err := cmd.Run(); err != nil {
+			return nil, fmt.Errorf("%v: %v: %s", tool, err, cmd.Stderr)
+		}
+		var response driverResponse
+		if err := json.Unmarshal(buf.Bytes(), &response); err != nil {
+			return nil, err
+		}
+		return &response, nil
+	}
+}