[dev.cmdgo] cmd: pull in x/mod on the dev.cmdgo branch

This change changes the requirement on golang.org/x/mod to require the
top of the dev.cmdgo branch of that repository. This allows the code
on this branch to use the changes on the branch on that repo for parsing
go.work files. It also vendors in those changes using go mod vendor.

Generated using:
  go get -d golang.org/x/mod@dev.cmdgo
  go mod tidy
  go mod vendor

For #45713

Change-Id: I7a20835937c13f90d17c0f39d96b435daec89fba
Reviewed-on: https://go-review.googlesource.com/c/go/+/334933
Trust: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

5 files changed, 407 insertions, 85 deletions

diff --git a/src/cmd/go.mod b/src/cmd/go.mod
index cd03968eed..21d7d8b75a 100644
--- a/src/cmd/go.mod
+++ b/src/cmd/go.mod
@@ -7,7 +7,7 @@ require (
 	github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639 // indirect
 	golang.org/x/arch v0.0.0-20210502124803-cbf565b21d1e
 	golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e // indirect
-	golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a
+	golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61
 	golang.org/x/sys v0.0.0-20210511113859-b0526f3d8744 // indirect
 	golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 	golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9
diff --git a/src/cmd/go.sum b/src/cmd/go.sum
index d728acaec9..529b152b77 100644
--- a/src/cmd/go.sum
+++ b/src/cmd/go.sum
@@ -13,8 +13,8 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e h1:8foAy0aoO5GkqCvAEJ4VC4P3zksTg4X4aJCDpZzmgQI=
 golang.org/x/crypto v0.0.0-20210503195802-e9a32991a82e/go.mod h1:P+XmwS30IXTQdn5tA2iutPOUgjI07+tq3H3K9MVA1s8=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a h1:e8qnjKz4EE6OjRki9wTadWSIogINvq10sMcuBRORxMY=
-golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
+golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61 h1:gQY3CVezomIImcWCpxp6Mhj+fXCOZ+gD8/88326LVqw=
+golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
diff --git a/src/cmd/vendor/golang.org/x/mod/modfile/rule.go b/src/cmd/vendor/golang.org/x/mod/modfile/rule.go
index 78f83fa714..d6a2d3879e 100644
--- a/src/cmd/vendor/golang.org/x/mod/modfile/rule.go
+++ b/src/cmd/vendor/golang.org/x/mod/modfile/rule.go
@@ -423,68 +423,12 @@ func (f *File) add(errs *ErrorList, block *LineBlock, line *Line, verb string, a
 		}
 
 	case "replace":
-		arrow := 2
-		if len(args) >= 2 && args[1] == "=>" {
-			arrow = 1
-		}
-		if len(args) < arrow+2 || len(args) > arrow+3 || args[arrow] != "=>" {
-			errorf("usage: %s module/path [v1.2.3] => other/module v1.4\n\t or %s module/path [v1.2.3] => ../local/directory", verb, verb)
-			return
-		}
-		s, err := parseString(&args[0])
-		if err != nil {
-			errorf("invalid quoted string: %v", err)
-			return
-		}
-		pathMajor, err := modulePathMajor(s)
-		if err != nil {
-			wrapModPathError(s, err)
-			return
-		}
-		var v string
-		if arrow == 2 {
-			v, err = parseVersion(verb, s, &args[1], fix)
-			if err != nil {
-				wrapError(err)
-				return
-			}
-			if err := module.CheckPathMajor(v, pathMajor); err != nil {
-				wrapModPathError(s, err)
-				return
-			}
-		}
-		ns, err := parseString(&args[arrow+1])
-		if err != nil {
-			errorf("invalid quoted string: %v", err)
+		replace, wrappederr := parseReplace(f.Syntax.Name, line, verb, args, fix)
+		if wrappederr != nil {
+			*errs = append(*errs, *wrappederr)
 			return
 		}
-		nv := ""
-		if len(args) == arrow+2 {
-			if !IsDirectoryPath(ns) {
-				errorf("replacement module without version must be directory path (rooted or starting with ./ or ../)")
-				return
-			}
-			if filepath.Separator == '/' && strings.Contains(ns, `\`) {
-				errorf("replacement directory appears to be Windows path (on a non-windows system)")
-				return
-			}
-		}
-		if len(args) == arrow+3 {
-			nv, err = parseVersion(verb, ns, &args[arrow+2], fix)
-			if err != nil {
-				wrapError(err)
-				return
-			}
-			if IsDirectoryPath(ns) {
-				errorf("replacement module directory path %q cannot have version", ns)
-				return
-			}
-		}
-		f.Replace = append(f.Replace, &Replace{
-			Old:    module.Version{Path: s, Version: v},
-			New:    module.Version{Path: ns, Version: nv},
-			Syntax: line,
-		})
+		f.Replace = append(f.Replace, replace)
 
 	case "retract":
 		rationale := parseDirectiveComment(block, line)
@@ -515,6 +459,83 @@ func (f *File) add(errs *ErrorList, block *LineBlock, line *Line, verb string, a
 	}
 }
 
+func parseReplace(filename string, line *Line, verb string, args []string, fix VersionFixer) (*Replace, *Error) {
+	wrapModPathError := func(modPath string, err error) *Error {
+		return &Error{
+			Filename: filename,
+			Pos:      line.Start,
+			ModPath:  modPath,
+			Verb:     verb,
+			Err:      err,
+		}
+	}
+	wrapError := func(err error) *Error {
+		return &Error{
+			Filename: filename,
+			Pos:      line.Start,
+			Err:      err,
+		}
+	}
+	errorf := func(format string, args ...interface{}) *Error {
+		return wrapError(fmt.Errorf(format, args...))
+	}
+
+	arrow := 2
+	if len(args) >= 2 && args[1] == "=>" {
+		arrow = 1
+	}
+	if len(args) < arrow+2 || len(args) > arrow+3 || args[arrow] != "=>" {
+		return nil, errorf("usage: %s module/path [v1.2.3] => other/module v1.4\n\t or %s module/path [v1.2.3] => ../local/directory", verb, verb)
+	}
+	s, err := parseString(&args[0])
+	if err != nil {
+		return nil, errorf("invalid quoted string: %v", err)
+	}
+	pathMajor, err := modulePathMajor(s)
+	if err != nil {
+		return nil, wrapModPathError(s, err)
+
+	}
+	var v string
+	if arrow == 2 {
+		v, err = parseVersion(verb, s, &args[1], fix)
+		if err != nil {
+			return nil, wrapError(err)
+		}
+		if err := module.CheckPathMajor(v, pathMajor); err != nil {
+			return nil, wrapModPathError(s, err)
+		}
+	}
+	ns, err := parseString(&args[arrow+1])
+	if err != nil {
+		return nil, errorf("invalid quoted string: %v", err)
+	}
+	nv := ""
+	if len(args) == arrow+2 {
+		if !IsDirectoryPath(ns) {
+			return nil, errorf("replacement module without version must be directory path (rooted or starting with ./ or ../)")
+		}
+		if filepath.Separator == '/' && strings.Contains(ns, `\`) {
+			return nil, errorf("replacement directory appears to be Windows path (on a non-windows system)")
+		}
+	}
+	if len(args) == arrow+3 {
+		nv, err = parseVersion(verb, ns, &args[arrow+2], fix)
+		if err != nil {
+			return nil, wrapError(err)
+		}
+		if IsDirectoryPath(ns) {
+			return nil, errorf("replacement module directory path %q cannot have version", ns)
+
+		}
+	}
+	return &Replace{
+		Old:    module.Version{Path: s, Version: v},
+		New:    module.Version{Path: ns, Version: nv},
+		Syntax: line,
+	}, nil
+}
+
 // fixRetract applies fix to each retract directive in f, appending any errors
 // to errs.
 //
@@ -556,6 +577,63 @@ func (f *File) fixRetract(fix VersionFixer, errs *ErrorList) {
 	}
 }
 
+func (f *WorkFile) add(errs *ErrorList, line *Line, verb string, args []string, fix VersionFixer) {
+	wrapError := func(err error) {
+		*errs = append(*errs, Error{
+			Filename: f.Syntax.Name,
+			Pos:      line.Start,
+			Err:      err,
+		})
+	}
+	errorf := func(format string, args ...interface{}) {
+		wrapError(fmt.Errorf(format, args...))
+	}
+
+	switch verb {
+	default:
+		errorf("unknown directive: %s", verb)
+
+	case "go":
+		if f.Go != nil {
+			errorf("repeated go statement")
+			return
+		}
+		if len(args) != 1 {
+			errorf("go directive expects exactly one argument")
+			return
+		} else if !GoVersionRE.MatchString(args[0]) {
+			errorf("invalid go version '%s': must match format 1.23", args[0])
+			return
+		}
+
+		f.Go = &Go{Syntax: line}
+		f.Go.Version = args[0]
+
+	case "directory":
+		if len(args) != 1 {
+			errorf("usage: %s local/dir", verb)
+			return
+		}
+		s, err := parseString(&args[0])
+		if err != nil {
+			errorf("invalid quoted string: %v", err)
+			return
+		}
+		f.Directory = append(f.Directory, &Directory{
+			Path:   s,
+			Syntax: line,
+		})
+
+	case "replace":
+		replace, wrappederr := parseReplace(f.Syntax.Name, line, verb, args, fix)
+		if wrappederr != nil {
+			*errs = append(*errs, *wrappederr)
+			return
+		}
+		f.Replace = append(f.Replace, replace)
+	}
+}
+
 // IsDirectoryPath reports whether the given path should be interpreted
 // as a directory path. Just like on the go command line, relative paths
 // and rooted paths are directory paths; the rest are module paths.
@@ -1165,6 +1243,10 @@ func (f *File) DropExclude(path, vers string) error {
 }
 
 func (f *File) AddReplace(oldPath, oldVers, newPath, newVers string) error {
+	return addReplace(f.Syntax, &f.Replace, oldPath, oldVers, newPath, newVers)
+}
+
+func addReplace(syntax *FileSyntax, replace *[]*Replace, oldPath, oldVers, newPath, newVers string) error {
 	need := true
 	old := module.Version{Path: oldPath, Version: oldVers}
 	new := module.Version{Path: newPath, Version: newVers}
@@ -1178,12 +1260,12 @@ func (f *File) AddReplace(oldPath, oldVers, newPath, newVers string) error {
 	}
 
 	var hint *Line
-	for _, r := range f.Replace {
+	for _, r := range *replace {
 		if r.Old.Path == oldPath && (oldVers == "" || r.Old.Version == oldVers) {
 			if need {
 				// Found replacement for old; update to use new.
 				r.New = new
-				f.Syntax.updateLine(r.Syntax, tokens...)
+				syntax.updateLine(r.Syntax, tokens...)
 				need = false
 				continue
 			}
@@ -1196,7 +1278,7 @@ func (f *File) AddReplace(oldPath, oldVers, newPath, newVers string) error {
 		}
 	}
 	if need {
-		f.Replace = append(f.Replace, &Replace{Old: old, New: new, Syntax: f.Syntax.addLine(hint, tokens...)})
+		*replace = append(*replace, &Replace{Old: old, New: new, Syntax: syntax.addLine(hint, tokens...)})
 	}
 	return nil
 }
@@ -1282,30 +1364,36 @@ func (f *File) SortBlocks() {
 // retract directives are not de-duplicated since comments are
 // meaningful, and versions may be retracted multiple times.
 func (f *File) removeDups() {
+	removeDups(f.Syntax, &f.Exclude, &f.Replace)
+}
+
+func removeDups(syntax *FileSyntax, exclude *[]*Exclude, replace *[]*Replace) {
 	kill := make(map[*Line]bool)
 
 	// Remove duplicate excludes.
-	haveExclude := make(map[module.Version]bool)
-	for _, x := range f.Exclude {
-		if haveExclude[x.Mod] {
-			kill[x.Syntax] = true
-			continue
+	if exclude != nil {
+		haveExclude := make(map[module.Version]bool)
+		for _, x := range *exclude {
+			if haveExclude[x.Mod] {
+				kill[x.Syntax] = true
+				continue
+			}
+			haveExclude[x.Mod] = true
 		}
-		haveExclude[x.Mod] = true
-	}
-	var excl []*Exclude
-	for _, x := range f.Exclude {
-		if !kill[x.Syntax] {
-			excl = append(excl, x)
+		var excl []*Exclude
+		for _, x := range *exclude {
+			if !kill[x.Syntax] {
+				excl = append(excl, x)
+			}
 		}
+		*exclude = excl
 	}
-	f.Exclude = excl
 
 	// Remove duplicate replacements.
 	// Later replacements take priority over earlier ones.
 	haveReplace := make(map[module.Version]bool)
-	for i := len(f.Replace) - 1; i >= 0; i-- {
-		x := f.Replace[i]
+	for i := len(*replace) - 1; i >= 0; i-- {
+		x := (*replace)[i]
 		if haveReplace[x.Old] {
 			kill[x.Syntax] = true
 			continue
@@ -1313,18 +1401,18 @@ func (f *File) removeDups() {
 		haveReplace[x.Old] = true
 	}
 	var repl []*Replace
-	for _, x := range f.Replace {
+	for _, x := range *replace {
 		if !kill[x.Syntax] {
 			repl = append(repl, x)
 		}
 	}
-	f.Replace = repl
+	*replace = repl
 
 	// Duplicate require and retract directives are not removed.
 
 	// Drop killed statements from the syntax tree.
 	var stmts []Expr
-	for _, stmt := range f.Syntax.Stmt {
+	for _, stmt := range syntax.Stmt {
 		switch stmt := stmt.(type) {
 		case *Line:
 			if kill[stmt] {
@@ -1344,7 +1432,7 @@ func (f *File) removeDups() {
 		}
 		stmts = append(stmts, stmt)
 	}
-	f.Syntax.Stmt = stmts
+	syntax.Stmt = stmts
 }
 
 // lineLess returns whether li should be sorted before lj. It sorts
diff --git a/src/cmd/vendor/golang.org/x/mod/modfile/work.go b/src/cmd/vendor/golang.org/x/mod/modfile/work.go
new file mode 100644
index 0000000000..b1fabff51b
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/mod/modfile/work.go
@@ -0,0 +1,234 @@
+// 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 modfile
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// A WorkFile is the parsed, interpreted form of a go.work file.
+type WorkFile struct {
+	Go        *Go
+	Directory []*Directory
+	Replace   []*Replace
+
+	Syntax *FileSyntax
+}
+
+// A Directory is a single directory statement.
+type Directory struct {
+	Path       string // Directory path of module.
+	ModulePath string // Module path in the comment.
+	Syntax     *Line
+}
+
+// ParseWork parses and returns a go.work file.
+//
+// file is the name of the file, used in positions and errors.
+//
+// data is the content of the file.
+//
+// fix is an optional function that canonicalizes module versions.
+// If fix is nil, all module versions must be canonical (module.CanonicalVersion
+// must return the same string).
+func ParseWork(file string, data []byte, fix VersionFixer) (*WorkFile, error) {
+	fs, err := parse(file, data)
+	if err != nil {
+		return nil, err
+	}
+	f := &WorkFile{
+		Syntax: fs,
+	}
+	var errs ErrorList
+
+	for _, x := range fs.Stmt {
+		switch x := x.(type) {
+		case *Line:
+			f.add(&errs, x, x.Token[0], x.Token[1:], fix)
+
+		case *LineBlock:
+			if len(x.Token) > 1 {
+				errs = append(errs, Error{
+					Filename: file,
+					Pos:      x.Start,
+					Err:      fmt.Errorf("unknown block type: %s", strings.Join(x.Token, " ")),
+				})
+				continue
+			}
+			switch x.Token[0] {
+			default:
+				errs = append(errs, Error{
+					Filename: file,
+					Pos:      x.Start,
+					Err:      fmt.Errorf("unknown block type: %s", strings.Join(x.Token, " ")),
+				})
+				continue
+			case "directory", "replace":
+				for _, l := range x.Line {
+					f.add(&errs, l, x.Token[0], l.Token, fix)
+				}
+			}
+		}
+	}
+
+	if len(errs) > 0 {
+		return nil, errs
+	}
+	return f, nil
+}
+
+// Cleanup cleans up the file f after any edit operations.
+// To avoid quadratic behavior, modifications like DropRequire
+// clear the entry but do not remove it from the slice.
+// Cleanup cleans out all the cleared entries.
+func (f *WorkFile) Cleanup() {
+	w := 0
+	for _, r := range f.Directory {
+		if r.Path != "" {
+			f.Directory[w] = r
+			w++
+		}
+	}
+	f.Directory = f.Directory[:w]
+
+	w = 0
+	for _, r := range f.Replace {
+		if r.Old.Path != "" {
+			f.Replace[w] = r
+			w++
+		}
+	}
+	f.Replace = f.Replace[:w]
+
+	f.Syntax.Cleanup()
+}
+
+func (f *WorkFile) AddGoStmt(version string) error {
+	if !GoVersionRE.MatchString(version) {
+		return fmt.Errorf("invalid language version string %q", version)
+	}
+	if f.Go == nil {
+		stmt := &Line{Token: []string{"go", version}}
+		f.Go = &Go{
+			Version: version,
+			Syntax:  stmt,
+		}
+		// Find the first non-comment-only block that's and add
+		// the go statement before it. That will keep file comments at the top.
+		i := 0
+		for i = 0; i < len(f.Syntax.Stmt); i++ {
+			if _, ok := f.Syntax.Stmt[i].(*CommentBlock); !ok {
+				break
+			}
+		}
+		f.Syntax.Stmt = append(append(f.Syntax.Stmt[:i:i], stmt), f.Syntax.Stmt[i:]...)
+	} else {
+		f.Go.Version = version
+		f.Syntax.updateLine(f.Go.Syntax, "go", version)
+	}
+	return nil
+}
+
+func (f *WorkFile) AddDirectory(diskPath, modulePath string) error {
+	need := true
+	for _, d := range f.Directory {
+		if d.Path == diskPath {
+			if need {
+				d.ModulePath = modulePath
+				f.Syntax.updateLine(d.Syntax, "directory", AutoQuote(diskPath))
+				need = false
+			} else {
+				d.Syntax.markRemoved()
+				*d = Directory{}
+			}
+		}
+	}
+
+	if need {
+		f.AddNewDirectory(diskPath, modulePath)
+	}
+	return nil
+}
+
+func (f *WorkFile) AddNewDirectory(diskPath, modulePath string) {
+	line := f.Syntax.addLine(nil, "directory", AutoQuote(diskPath))
+	f.Directory = append(f.Directory, &Directory{Path: diskPath, ModulePath: modulePath, Syntax: line})
+}
+
+func (f *WorkFile) SetDirectory(dirs []*Directory) {
+	need := make(map[string]string)
+	for _, d := range dirs {
+		need[d.Path] = d.ModulePath
+	}
+
+	for _, d := range f.Directory {
+		if modulePath, ok := need[d.Path]; ok {
+			d.ModulePath = modulePath
+		} else {
+			d.Syntax.markRemoved()
+			*d = Directory{}
+		}
+	}
+
+	// TODO(#45713): Add module path to comment.
+
+	for diskPath, modulePath := range need {
+		f.AddNewDirectory(diskPath, modulePath)
+	}
+	f.SortBlocks()
+}
+
+func (f *WorkFile) DropDirectory(path string) error {
+	for _, d := range f.Directory {
+		if d.Path == path {
+			d.Syntax.markRemoved()
+			*d = Directory{}
+		}
+	}
+	return nil
+}
+
+func (f *WorkFile) AddReplace(oldPath, oldVers, newPath, newVers string) error {
+	return addReplace(f.Syntax, &f.Replace, oldPath, oldVers, newPath, newVers)
+}
+
+func (f *WorkFile) DropReplace(oldPath, oldVers string) error {
+	for _, r := range f.Replace {
+		if r.Old.Path == oldPath && r.Old.Version == oldVers {
+			r.Syntax.markRemoved()
+			*r = Replace{}
+		}
+	}
+	return nil
+}
+
+func (f *WorkFile) SortBlocks() {
+	f.removeDups() // otherwise sorting is unsafe
+
+	for _, stmt := range f.Syntax.Stmt {
+		block, ok := stmt.(*LineBlock)
+		if !ok {
+			continue
+		}
+		sort.SliceStable(block.Line, func(i, j int) bool {
+			return lineLess(block.Line[i], block.Line[j])
+		})
+	}
+}
+
+// removeDups removes duplicate replace directives.
+//
+// Later replace directives take priority.
+//
+// require directives are not de-duplicated. That's left up to higher-level
+// logic (MVS).
+//
+// retract directives are not de-duplicated since comments are
+// meaningful, and versions may be retracted multiple times.
+func (f *WorkFile) removeDups() {
+	removeDups(f.Syntax, nil, &f.Replace)
+}
diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index 34dbdaf5dd..beceef5392 100644
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -28,7 +28,7 @@ golang.org/x/arch/x86/x86asm
 ## explicit; go 1.17
 golang.org/x/crypto/ed25519
 golang.org/x/crypto/ed25519/internal/edwards25519
-# golang.org/x/mod v0.4.3-0.20210608190319-0f08993efd8a
+# golang.org/x/mod v0.4.3-0.20210723200715-e41a6a4f3b61
 ## explicit; go 1.17
 golang.org/x/mod/internal/lazyregexp
 golang.org/x/mod/modfile