re-generate with Go 1.16.4

Fairly minor changes since the last time we re-vendored, with Go 1.15.x.

And test with Go 1.16.x too.

.github/workflows/test.yml

@@ -4,7 +4,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.14.x, 1.15.x]
+        go-version: [1.15.x, 1.16.x]
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:

gen.go

@@ -1,6 +1,7 @@
 // Copyright (c) 2019, Daniel Martí <mvdan@mvdan.cc>
 // See LICENSE for licensing information
 
+//go:build ignore
 // +build ignore
 
 package main
@@ -22,7 +23,8 @@ func main() {
 	pkgs, err := listPackages(context.TODO(), nil,
 		"cmd/gofmt",
 
-		// These are internal cmd dependencies. Copy them.
+		// These are internal dependencies. Copy them.
+		"internal/execabs",
 		"cmd/internal/diff",
 	)
 	if err != nil {
@@ -32,8 +34,11 @@ func main() {
 		if pkg.ImportPath == "cmd/gofmt" {
 			copyGofmt(pkg)
 		} else {
-			parts := strings.Split(pkg.ImportPath, "/")
-			copyInternal(pkg, filepath.Join(parts[1:]...))
+			dir := pkg.ImportPath
+			if strings.HasPrefix(dir, "cmd/internal") {
+				dir = dir[len("cmd/"):]
+			}
+			copyInternal(pkg, filepath.FromSlash(dir))
 		}
 	}
 }
@@ -280,5 +285,9 @@ func fixImports(body string) string {
 		"cmd/internal/",
 		"mvdan.cc/gofumpt/internal/",
 		-1)
+	body = strings.Replace(body,
+		`"internal/`,
+		`"mvdan.cc/gofumpt/internal/`,
+		-1)
 	return body
 }

gofmt.go

@@ -14,7 +14,7 @@ import (
 	"go/scanner"
 	"go/token"
 	"io"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -75,15 +75,15 @@ func initParserMode() {
 	}
 }
 
-func isGoFile(f os.FileInfo) bool {
+func isGoFile(f fs.DirEntry) bool {
 	// ignore non-Go files
 	name := f.Name()
 	return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")
 }
 
 // If in == nil, the source is the contents of the file with the given filename.
 func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error {
-	var perm os.FileMode = 0o644
+	var perm fs.FileMode = 0o644
 	if in == nil {
 		f, err := os.Open(filename)
 		if err != nil {
@@ -98,7 +98,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 		perm = fi.Mode().Perm()
 	}
 
-	src, err := ioutil.ReadAll(in)
+	src, err := io.ReadAll(in)
 	if err != nil {
 		return err
 	}
@@ -153,7 +153,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 			if err != nil {
 				return err
 			}
-			err = ioutil.WriteFile(filename, res, perm)
+			err = os.WriteFile(filename, res, perm)
 			if err != nil {
 				os.Rename(bakname, filename)
 				return err
@@ -180,7 +180,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 	return err
 }
 
-func visitFile(path string, f os.FileInfo, err error) error {
+func visitFile(path string, f fs.DirEntry, err error) error {
 	if err == nil && isGoFile(f) {
 		err = processFile(path, nil, os.Stdout, false)
 	}
@@ -193,7 +193,7 @@ func visitFile(path string, f os.FileInfo, err error) error {
 }
 
 func walkDir(path string) {
-	filepath.Walk(path, visitFile)
+	filepath.WalkDir(path, visitFile)
 }
 
 func main() {
@@ -298,9 +298,9 @@ const chmodSupported = runtime.GOOS != "windows"
 // backupFile writes data to a new file named filename<number> with permissions perm,
 // with <number randomly chosen such that the file name is unique. backupFile returns
 // the chosen file name.
-func backupFile(filename string, data []byte, perm os.FileMode) (string, error) {
+func backupFile(filename string, data []byte, perm fs.FileMode) (string, error) {
 	// create backup file
-	f, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename))
+	f, err := os.CreateTemp(filepath.Dir(filename), filepath.Base(filename))
 	if err != nil {
 		return "", err
 	}

internal/diff/diff.go

@@ -9,8 +9,9 @@ package diff
 import (
 	"io/ioutil"
 	"os"
-	"os/exec"
 	"runtime"
+
+	exec "mvdan.cc/gofumpt/internal/execabs"
 )
 
 // Returns diff of two arrays of bytes in diff tool format.

internal/execabs/execabs.go

@@ -0,0 +1,69 @@
+// Copyright 2021 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 execabs is a drop-in replacement for os/exec
+// that requires PATH lookups to find absolute paths.
+// That is, execabs.Command("cmd") runs the same PATH lookup
+// as exec.Command("cmd"), but if the result is a path
+// which is relative, the Run and Start methods will report
+// an error instead of running the executable.
+package execabs
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"path/filepath"
+	"reflect"
+	"unsafe"
+)
+
+var ErrNotFound = exec.ErrNotFound
+
+type (
+	Cmd       = exec.Cmd
+	Error     = exec.Error
+	ExitError = exec.ExitError
+)
+
+func relError(file, path string) error {
+	return fmt.Errorf("%s resolves to executable relative to current directory (.%c%s)", file, filepath.Separator, path)
+}
+
+func LookPath(file string) (string, error) {
+	path, err := exec.LookPath(file)
+	if err != nil {
+		return "", err
+	}
+	if filepath.Base(file) == file && !filepath.IsAbs(path) {
+		return "", relError(file, path)
+	}
+	return path, nil
+}
+
+func fixCmd(name string, cmd *exec.Cmd) {
+	if filepath.Base(name) == name && !filepath.IsAbs(cmd.Path) {
+		// exec.Command was called with a bare binary name and
+		// exec.LookPath returned a path which is not absolute.
+		// Set cmd.lookPathErr and clear cmd.Path so that it
+		// cannot be run.
+		lookPathErr := (*error)(unsafe.Pointer(reflect.ValueOf(cmd).Elem().FieldByName("lookPathErr").Addr().Pointer()))
+		if *lookPathErr == nil {
+			*lookPathErr = relError(name, cmd.Path)
+		}
+		cmd.Path = ""
+	}
+}
+
+func CommandContext(ctx context.Context, name string, arg ...string) *exec.Cmd {
+	cmd := exec.CommandContext(ctx, name, arg...)
+	fixCmd(name, cmd)
+	return cmd
+}
+
+func Command(name string, arg ...string) *exec.Cmd {
+	cmd := exec.Command(name, arg...)
+	fixCmd(name, cmd)
+	return cmd
+}