[dev.cmdgo] cmd: update x/tools and remove copy of txtar

golang.org/x/tools/txtar is the main location for this package. We
don't need our own copy.

Also, update cmd/vet tests for compatibility with CL 301949.

For golang/go#47193

Change-Id: I480eb591f57a0d05b433a657653e2021e39354eb
Reviewed-on: https://go-review.googlesource.com/c/go/+/337352
Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

16 files changed, 249 insertions, 96 deletions

diff --git a/src/cmd/go.mod b/src/cmd/go.mod
index 21d7d8b75a..b0a3f48045 100644
--- a/src/cmd/go.mod
+++ b/src/cmd/go.mod
@@ -10,6 +10,6 @@ require (
 	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
+	golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 )
diff --git a/src/cmd/go.sum b/src/cmd/go.sum
index 529b152b77..bf237d40bc 100644
--- a/src/cmd/go.sum
+++ b/src/cmd/go.sum
@@ -36,8 +36,8 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9 h1:2XlR/j4I4xz5GQZI7zBjqTfezYyRIE2jD5IMousB2rg=
-golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6 h1:er++nfKy5Irv8JPDfJ68QzoVKQ6MBF7cf5xC15O4Zy0=
+golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
diff --git a/src/cmd/go/internal/fsys/fsys_test.go b/src/cmd/go/internal/fsys/fsys_test.go
index 7f175c7031..c080c14987 100644
--- a/src/cmd/go/internal/fsys/fsys_test.go
+++ b/src/cmd/go/internal/fsys/fsys_test.go
@@ -1,7 +1,6 @@
 package fsys
 
 import (
-	"cmd/go/internal/txtar"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -12,6 +11,8 @@ import (
 	"path/filepath"
 	"reflect"
 	"testing"
+
+	"golang.org/x/tools/txtar"
 )
 
 // initOverlay resets the overlay state to reflect the config.
diff --git a/src/cmd/go/internal/txtar/archive_test.go b/src/cmd/go/internal/txtar/archive_test.go
deleted file mode 100644
index 3f734f6762..0000000000
--- a/src/cmd/go/internal/txtar/archive_test.go
+++ /dev/null
@@ -1,67 +0,0 @@
-// 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.
-
-package txtar
-
-import (
-	"bytes"
-	"fmt"
-	"reflect"
-	"testing"
-)
-
-var tests = []struct {
-	name   string
-	text   string
-	parsed *Archive
-}{
-	{
-		name: "basic",
-		text: `comment1
-comment2
--- file1 --
-File 1 text.
--- foo ---
-More file 1 text.
--- file 2 --
-File 2 text.
--- empty --
--- noNL --
-hello world`,
-		parsed: &Archive{
-			Comment: []byte("comment1\ncomment2\n"),
-			Files: []File{
-				{"file1", []byte("File 1 text.\n-- foo ---\nMore file 1 text.\n")},
-				{"file 2", []byte("File 2 text.\n")},
-				{"empty", []byte{}},
-				{"noNL", []byte("hello world\n")},
-			},
-		},
-	},
-}
-
-func Test(t *testing.T) {
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			a := Parse([]byte(tt.text))
-			if !reflect.DeepEqual(a, tt.parsed) {
-				t.Fatalf("Parse: wrong output:\nhave:\n%s\nwant:\n%s", shortArchive(a), shortArchive(tt.parsed))
-			}
-			text := Format(a)
-			a = Parse(text)
-			if !reflect.DeepEqual(a, tt.parsed) {
-				t.Fatalf("Parse after Format: wrong output:\nhave:\n%s\nwant:\n%s", shortArchive(a), shortArchive(tt.parsed))
-			}
-		})
-	}
-}
-
-func shortArchive(a *Archive) string {
-	var buf bytes.Buffer
-	fmt.Fprintf(&buf, "comment: %q\n", a.Comment)
-	for _, f := range a.Files {
-		fmt.Fprintf(&buf, "file %q: %q\n", f.Name, f.Data)
-	}
-	return buf.String()
-}
diff --git a/src/cmd/go/proxy_test.go b/src/cmd/go/proxy_test.go
index 74bfecc08d..a387fe67db 100644
--- a/src/cmd/go/proxy_test.go
+++ b/src/cmd/go/proxy_test.go
@@ -25,12 +25,12 @@ import (
 
 	"cmd/go/internal/modfetch/codehost"
 	"cmd/go/internal/par"
-	"cmd/go/internal/txtar"
 
 	"golang.org/x/mod/module"
 	"golang.org/x/mod/semver"
 	"golang.org/x/mod/sumdb"
 	"golang.org/x/mod/sumdb/dirhash"
+	"golang.org/x/tools/txtar"
 )
 
 var (
diff --git a/src/cmd/go/script_test.go b/src/cmd/go/script_test.go
index 8a7c77a46f..3c5855bd6f 100644
--- a/src/cmd/go/script_test.go
+++ b/src/cmd/go/script_test.go
@@ -31,9 +31,10 @@ import (
 	"cmd/go/internal/imports"
 	"cmd/go/internal/par"
 	"cmd/go/internal/robustio"
-	"cmd/go/internal/txtar"
 	"cmd/go/internal/work"
 	"cmd/internal/sys"
+
+	"golang.org/x/tools/txtar"
 )
 
 var testSum = flag.String("testsum", "", `may be tidy, listm, or listall. If set, TestScript generates a go.sum file at the beginning of each test and updates test files if they pass.`)
diff --git a/src/cmd/go/testdata/addmod.go b/src/cmd/go/testdata/addmod.go
index 03869e68de..a1ace4ce59 100644
--- a/src/cmd/go/testdata/addmod.go
+++ b/src/cmd/go/testdata/addmod.go
@@ -29,7 +29,7 @@ import (
 	"path/filepath"
 	"strings"
 
-	"cmd/go/internal/txtar"
+	"golang.org/x/tools/txtar"
 )
 
 func usage() {
diff --git a/src/cmd/go/testdata/savedir.go b/src/cmd/go/testdata/savedir.go
index d469c31a91..6a8a232702 100644
--- a/src/cmd/go/testdata/savedir.go
+++ b/src/cmd/go/testdata/savedir.go
@@ -24,7 +24,7 @@ import (
 	"strings"
 	"unicode/utf8"
 
-	"../internal/txtar"
+	"golang.org/x/tools/txtar"
 )
 
 func usage() {
diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go
index 822820f06e..6589478af0 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go
@@ -555,7 +555,7 @@ func checkPrintf(pass *analysis.Pass, kind Kind, call *ast.CallExpr, fn *types.F
 	format, idx := formatString(pass, call)
 	if idx < 0 {
 		if false {
-			pass.Reportf(call.Lparen, "can't check non-constant format in call to %s", fn.Name())
+			pass.Reportf(call.Lparen, "can't check non-constant format in call to %s", fn.FullName())
 		}
 		return
 	}
@@ -563,7 +563,7 @@ func checkPrintf(pass *analysis.Pass, kind Kind, call *ast.CallExpr, fn *types.F
 	firstArg := idx + 1 // Arguments are immediately after format string.
 	if !strings.Contains(format, "%") {
 		if len(call.Args) > firstArg {
-			pass.Reportf(call.Lparen, "%s call has arguments but no formatting directives", fn.Name())
+			pass.Reportf(call.Lparen, "%s call has arguments but no formatting directives", fn.FullName())
 		}
 		return
 	}
@@ -577,7 +577,7 @@ func checkPrintf(pass *analysis.Pass, kind Kind, call *ast.CallExpr, fn *types.F
 		if format[i] != '%' {
 			continue
 		}
-		state := parsePrintfVerb(pass, call, fn.Name(), format[i:], firstArg, argNum)
+		state := parsePrintfVerb(pass, call, fn.FullName(), format[i:], firstArg, argNum)
 		if state == nil {
 			return
 		}
@@ -589,8 +589,12 @@ func checkPrintf(pass *analysis.Pass, kind Kind, call *ast.CallExpr, fn *types.F
 			anyIndex = true
 		}
 		if state.verb == 'w' {
-			if kind != KindErrorf {
-				pass.Reportf(call.Pos(), "%s call has error-wrapping directive %%w, which is only supported by Errorf", state.name)
+			switch kind {
+			case KindNone, KindPrint:
+				pass.Reportf(call.Pos(), "%s does not support error-wrapping directive %%w", state.name)
+				return
+			case KindPrintf:
+				pass.Reportf(call.Pos(), "%s call has error-wrapping directive %%w, which is only supported for functions backed by fmt.Errorf", state.name)
 				return
 			}
 			if anyW {
@@ -621,7 +625,7 @@ func checkPrintf(pass *analysis.Pass, kind Kind, call *ast.CallExpr, fn *types.F
 	if maxArgNum != len(call.Args) {
 		expect := maxArgNum - firstArg
 		numArgs := len(call.Args) - firstArg
-		pass.ReportRangef(call, "%s call needs %v but has %v", fn.Name(), count(expect, "arg"), count(numArgs, "arg"))
+		pass.ReportRangef(call, "%s call needs %v but has %v", fn.FullName(), count(expect, "arg"), count(numArgs, "arg"))
 	}
 }
 
@@ -949,7 +953,7 @@ func recursiveStringer(pass *analysis.Pass, e ast.Expr) (string, bool) {
 	}
 	if id, ok := e.(*ast.Ident); ok {
 		if pass.TypesInfo.Uses[id] == sig.Recv() {
-			return method.Name(), true
+			return method.FullName(), true
 		}
 	}
 	return "", false
@@ -1044,7 +1048,7 @@ func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
 		if sel, ok := call.Args[0].(*ast.SelectorExpr); ok {
 			if x, ok := sel.X.(*ast.Ident); ok {
 				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
-					pass.ReportRangef(call, "%s does not take io.Writer but has first arg %s", fn.Name(), analysisutil.Format(pass.Fset, call.Args[0]))
+					pass.ReportRangef(call, "%s does not take io.Writer but has first arg %s", fn.FullName(), analysisutil.Format(pass.Fset, call.Args[0]))
 				}
 			}
 		}
@@ -1058,7 +1062,7 @@ func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
 		if strings.Contains(s, "%") {
 			m := printFormatRE.FindStringSubmatch(s)
 			if m != nil {
-				pass.ReportRangef(call, "%s call has possible formatting directive %s", fn.Name(), m[0])
+				pass.ReportRangef(call, "%s call has possible formatting directive %s", fn.FullName(), m[0])
 			}
 		}
 	}
@@ -1068,16 +1072,16 @@ func checkPrint(pass *analysis.Pass, call *ast.CallExpr, fn *types.Func) {
 		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
 			str, _ := strconv.Unquote(lit.Value)
 			if strings.HasSuffix(str, "\n") {
-				pass.ReportRangef(call, "%s arg list ends with redundant newline", fn.Name())
+				pass.ReportRangef(call, "%s arg list ends with redundant newline", fn.FullName())
 			}
 		}
 	}
 	for _, arg := range args {
 		if isFunctionValue(pass, arg) {
-			pass.ReportRangef(call, "%s arg %s is a func value, not called", fn.Name(), analysisutil.Format(pass.Fset, arg))
+			pass.ReportRangef(call, "%s arg %s is a func value, not called", fn.FullName(), analysisutil.Format(pass.Fset, arg))
 		}
 		if methodName, ok := recursiveStringer(pass, arg); ok {
-			pass.ReportRangef(call, "%s arg %s causes recursive call to %s method", fn.Name(), analysisutil.Format(pass.Fset, arg), methodName)
+			pass.ReportRangef(call, "%s arg %s causes recursive call to %s method", fn.FullName(), analysisutil.Format(pass.Fset, arg), methodName)
 		}
 	}
 }
diff --git a/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go b/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
index cf72ea990b..b949fc8407 100644
--- a/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
+++ b/src/cmd/vendor/golang.org/x/tools/go/ast/astutil/rewrite.go
@@ -9,6 +9,8 @@ import (
 	"go/ast"
 	"reflect"
 	"sort"
+
+	"golang.org/x/tools/internal/typeparams"
 )
 
 // An ApplyFunc is invoked by Apply for each node n, even if n is nil,
@@ -437,7 +439,11 @@ func (a *application) apply(parent ast.Node, name string, iter *iterator, n ast.
 		}
 
 	default:
-		panic(fmt.Sprintf("Apply: unexpected node type %T", n))
+		if typeparams.IsListExpr(n) {
+			a.applyList(n, "ElemList")
+		} else {
+			panic(fmt.Sprintf("Apply: unexpected node type %T", n))
+		}
 	}
 
 	if a.post != nil && !a.post(&a.cursor) {
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/doc.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/doc.go
new file mode 100644
index 0000000000..5583947e21
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/doc.go
@@ -0,0 +1,11 @@
+// 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 typeparams provides functions to work indirectly with type parameter
+// data stored in go/ast and go/types objects, while these API are guarded by a
+// build constraint.
+//
+// This package exists to make it easier for tools to work with generic code,
+// while also compiling against older Go versions.
+package typeparams
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
new file mode 100644
index 0000000000..3a0abc7c18
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/notypeparams.go
@@ -0,0 +1,90 @@
+// 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.
+
+//go:build !typeparams || !go1.17
+// +build !typeparams !go1.17
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// NOTE: doc comments must be kept in sync with typeparams.go.
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = false
+
+// UnpackIndex extracts all index expressions from e. For non-generic code this
+// is always one expression: e.Index, but may be more than one expression for
+// generic type instantiation.
+func UnpackIndex(e *ast.IndexExpr) []ast.Expr {
+	return []ast.Expr{e.Index}
+}
+
+// IsListExpr reports whether n is an *ast.ListExpr, which is a new node type
+// introduced to hold type arguments for generic type instantiation.
+func IsListExpr(n ast.Node) bool {
+	return false
+}
+
+// ForTypeDecl extracts the (possibly nil) type parameter node list from n.
+func ForTypeDecl(*ast.TypeSpec) *ast.FieldList {
+	return nil
+}
+
+// ForFuncDecl extracts the (possibly nil) type parameter node list from n.
+func ForFuncDecl(*ast.FuncDecl) *ast.FieldList {
+	return nil
+}
+
+// ForSignature extracts the (possibly empty) type parameter object list from
+// sig.
+func ForSignature(*types.Signature) []*types.TypeName {
+	return nil
+}
+
+// HasTypeSet reports if iface has a type set.
+func HasTypeSet(*types.Interface) bool {
+	return false
+}
+
+// IsComparable reports if iface is the comparable interface.
+func IsComparable(*types.Interface) bool {
+	return false
+}
+
+// IsConstraint reports whether iface may only be used as a type parameter
+// constraint (i.e. has a type set or is the comparable interface).
+func IsConstraint(*types.Interface) bool {
+	return false
+}
+
+// ForNamed extracts the (possibly empty) type parameter object list from
+// named.
+func ForNamed(*types.Named) []*types.TypeName {
+	return nil
+}
+
+// NamedTArgs extracts the (possibly empty) type argument list from named.
+func NamedTArgs(*types.Named) []types.Type {
+	return nil
+}
+
+// InitInferred initializes info to record inferred type information.
+func InitInferred(*types.Info) {
+}
+
+// GetInferred extracts inferred type information from info for e.
+//
+// The expression e may have an inferred type if it is an *ast.IndexExpr
+// representing partial instantiation of a generic function type for which type
+// arguments have been inferred using constraint type inference, or if it is an
+// *ast.CallExpr for which type type arguments have be inferred using both
+// constraint type inference and function argument inference.
+func GetInferred(*types.Info, ast.Expr) ([]types.Type, *types.Signature) {
+	return nil, nil
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
new file mode 100644
index 0000000000..6b7958af06
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
@@ -0,0 +1,105 @@
+// 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.
+
+//go:build typeparams && go1.17
+// +build typeparams,go1.17
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// NOTE: doc comments must be kept in sync with notypeparams.go.
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = true
+
+// UnpackIndex extracts all index expressions from e. For non-generic code this
+// is always one expression: e.Index, but may be more than one expression for
+// generic type instantiation.
+func UnpackIndex(e *ast.IndexExpr) []ast.Expr {
+	if x, _ := e.Index.(*ast.ListExpr); x != nil {
+		return x.ElemList
+	}
+	if e.Index != nil {
+		return []ast.Expr{e.Index}
+	}
+	return nil
+}
+
+// IsListExpr reports whether n is an *ast.ListExpr, which is a new node type
+// introduced to hold type arguments for generic type instantiation.
+func IsListExpr(n ast.Node) bool {
+	_, ok := n.(*ast.ListExpr)
+	return ok
+}
+
+// ForTypeDecl extracts the (possibly nil) type parameter node list from n.
+func ForTypeDecl(n *ast.TypeSpec) *ast.FieldList {
+	return n.TParams
+}
+
+// ForFuncDecl extracts the (possibly nil) type parameter node list from n.
+func ForFuncDecl(n *ast.FuncDecl) *ast.FieldList {
+	if n.Type != nil {
+		return n.Type.TParams
+	}
+	return nil
+}
+
+// ForSignature extracts the (possibly empty) type parameter object list from
+// sig.
+func ForSignature(sig *types.Signature) []*types.TypeName {
+	return sig.TParams()
+}
+
+// HasTypeSet reports if iface has a type set.
+func HasTypeSet(iface *types.Interface) bool {
+	return iface.HasTypeList()
+}
+
+// IsComparable reports if iface is the comparable interface.
+func IsComparable(iface *types.Interface) bool {
+	return iface.IsComparable()
+}
+
+// IsConstraint reports whether iface may only be used as a type parameter
+// constraint (i.e. has a type set or is the comparable interface).
+func IsConstraint(iface *types.Interface) bool {
+	return iface.IsConstraint()
+}
+
+// ForNamed extracts the (possibly empty) type parameter object list from
+// named.
+func ForNamed(named *types.Named) []*types.TypeName {
+	return named.TParams()
+}
+
+// NamedTArgs extracts the (possibly empty) type argument list from named.
+func NamedTArgs(named *types.Named) []types.Type {
+	return named.TArgs()
+}
+
+// InitInferred initializes info to record inferred type information.
+func InitInferred(info *types.Info) {
+	info.Inferred = make(map[ast.Expr]types.Inferred)
+}
+
+// GetInferred extracts inferred type information from info for e.
+//
+// The expression e may have an inferred type if it is an *ast.IndexExpr
+// representing partial instantiation of a generic function type for which type
+// arguments have been inferred using constraint type inference, or if it is an
+// *ast.CallExpr for which type type arguments have be inferred using both
+// constraint type inference and function argument inference.
+func GetInferred(info *types.Info, e ast.Expr) ([]types.Type, *types.Signature) {
+	if info.Inferred == nil {
+		return nil, nil
+	}
+	inf := info.Inferred[e]
+	return inf.TArgs, inf.Sig
+}
diff --git a/src/cmd/go/internal/txtar/archive.go b/src/cmd/vendor/golang.org/x/tools/txtar/archive.go
index 1796684877..214256617b 100644
--- a/src/cmd/go/internal/txtar/archive.go
+++ b/src/cmd/vendor/golang.org/x/tools/txtar/archive.go
@@ -34,7 +34,7 @@ package txtar
 import (
 	"bytes"
 	"fmt"
-	"os"
+	"io/ioutil"
 	"strings"
 )
 
@@ -66,7 +66,7 @@ func Format(a *Archive) []byte {
 
 // ParseFile parses the named file as an archive.
 func ParseFile(file string) (*Archive, error) {
-	data, err := os.ReadFile(file)
+	data, err := ioutil.ReadFile(file)
 	if err != nil {
 		return nil, err
 	}
@@ -121,7 +121,7 @@ func isMarker(data []byte) (name string, after []byte) {
 	if i := bytes.IndexByte(data, '\n'); i >= 0 {
 		data, after = data[:i], data[i+1:]
 	}
-	if !bytes.HasSuffix(data, markerEnd) {
+	if !(bytes.HasSuffix(data, markerEnd) && len(data) >= len(marker)+len(markerEnd)) {
 		return "", nil
 	}
 	return strings.TrimSpace(string(data[len(marker) : len(data)-len(markerEnd)])), after
diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index beceef5392..e032ccc2c7 100644
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -48,7 +48,7 @@ golang.org/x/sys/windows
 # golang.org/x/term v0.0.0-20210503060354-a79de5458b56
 ## explicit; go 1.17
 golang.org/x/term
-# golang.org/x/tools v0.1.2-0.20210519160823-49064d2332f9
+# golang.org/x/tools v0.1.6-0.20210726171848-ebce39e5e3d6
 ## explicit; go 1.17
 golang.org/x/tools/cover
 golang.org/x/tools/go/analysis
@@ -92,6 +92,8 @@ golang.org/x/tools/go/types/objectpath
 golang.org/x/tools/go/types/typeutil
 golang.org/x/tools/internal/analysisinternal
 golang.org/x/tools/internal/lsp/fuzzy
+golang.org/x/tools/internal/typeparams
+golang.org/x/tools/txtar
 # golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1
 ## explicit; go 1.11
 golang.org/x/xerrors
diff --git a/src/cmd/vet/testdata/print/print.go b/src/cmd/vet/testdata/print/print.go
index fca594925f..be42a37717 100644
--- a/src/cmd/vet/testdata/print/print.go
+++ b/src/cmd/vet/testdata/print/print.go
@@ -491,10 +491,10 @@ type recursiveStringer int
 func (s recursiveStringer) String() string {
 	_ = fmt.Sprintf("%d", s)
 	_ = fmt.Sprintf("%#v", s)
-	_ = fmt.Sprintf("%v", s)  // ERROR "Sprintf format %v with arg s causes recursive String method call"
-	_ = fmt.Sprintf("%v", &s) // ERROR "Sprintf format %v with arg &s causes recursive String method call"
+	_ = fmt.Sprintf("%v", s)  // ERROR "Sprintf format %v with arg s causes recursive \(cmd/vet/testdata/print\.recursiveStringer\)\.String method call"
+	_ = fmt.Sprintf("%v", &s) // ERROR "Sprintf format %v with arg &s causes recursive \(cmd/vet/testdata/print\.recursiveStringer\)\.String method call"
 	_ = fmt.Sprintf("%T", s)  // ok; does not recursively call String
-	return fmt.Sprintln(s)    // ERROR "Sprintln arg s causes recursive call to String method"
+	return fmt.Sprintln(s)    // ERROR "Sprintln arg s causes recursive call to \(cmd/vet/testdata/print\.recursiveStringer\)\.String method"
 }
 
 type recursivePtrStringer int
@@ -502,7 +502,7 @@ type recursivePtrStringer int
 func (p *recursivePtrStringer) String() string {
 	_ = fmt.Sprintf("%v", *p)
 	_ = fmt.Sprint(&p)     // ok; prints address
-	return fmt.Sprintln(p) // ERROR "Sprintln arg p causes recursive call to String method"
+	return fmt.Sprintln(p) // ERROR "Sprintln arg p causes recursive call to \(\*cmd/vet/testdata/print\.recursivePtrStringer\)\.String method"
 }
 
 type BoolFormatter bool