go/types, types2: use strings.Builder instead of bytes.Buffer where possible

Also, consistently use declaration: var buf strings.Builder.
We don't change exported signatures to match go/types (where we
can't change the exported signatures for backward-compatibility).

Change-Id: I75350886aa231889ae2fd5c4008dd4be9ed6e09f
Reviewed-on: https://go-review.googlesource.com/c/go/+/428094
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>

21 files changed, 58 insertions, 69 deletions

diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index ef1db13fb9..0793948838 100644
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -24,10 +24,10 @@
 package types2
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"go/constant"
+	"strings"
 )
 
 // An Error describes a type-checking error; it implements the error interface.
@@ -388,7 +388,7 @@ type Initializer struct {
 }
 
 func (init *Initializer) String() string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for i, lhs := range init.Lhs {
 		if i > 0 {
 			buf.WriteString(", ")
diff --git a/src/cmd/compile/internal/types2/api_test.go b/src/cmd/compile/internal/types2/api_test.go
index 9367e5f3f2..ac81d31fb2 100644
--- a/src/cmd/compile/internal/types2/api_test.go
+++ b/src/cmd/compile/internal/types2/api_test.go
@@ -5,7 +5,6 @@
 package types2_test
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"errors"
 	"fmt"
@@ -894,7 +893,7 @@ func TestImplicitsInfo(t *testing.T) {
 }
 
 func predString(tv TypeAndValue) string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	pred := func(b bool, s string) {
 		if b {
 			if buf.Len() > 0 {
diff --git a/src/cmd/compile/internal/types2/errors.go b/src/cmd/compile/internal/types2/errors.go
index 61d8953014..3734db5910 100644
--- a/src/cmd/compile/internal/types2/errors.go
+++ b/src/cmd/compile/internal/types2/errors.go
@@ -7,7 +7,6 @@
 package types2
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"runtime"
@@ -64,7 +63,7 @@ func (err *error_) msg(qf Qualifier) string {
 	if err.empty() {
 		return "no error"
 	}
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for i := range err.desc {
 		p := &err.desc[i]
 		if i > 0 {
@@ -106,7 +105,7 @@ func sprintf(qf Qualifier, debug bool, format string, args ...interface{}) strin
 		case syntax.Expr:
 			arg = syntax.String(a)
 		case []syntax.Expr:
-			var buf bytes.Buffer
+			var buf strings.Builder
 			buf.WriteByte('[')
 			for i, x := range a {
 				if i > 0 {
@@ -121,7 +120,7 @@ func sprintf(qf Qualifier, debug bool, format string, args ...interface{}) strin
 		case Type:
 			arg = typeString(a, qf, debug)
 		case []Type:
-			var buf bytes.Buffer
+			var buf strings.Builder
 			buf.WriteByte('[')
 			for i, x := range a {
 				if i > 0 {
@@ -132,7 +131,7 @@ func sprintf(qf Qualifier, debug bool, format string, args ...interface{}) strin
 			buf.WriteByte(']')
 			arg = buf.String()
 		case []*TypeParam:
-			var buf bytes.Buffer
+			var buf strings.Builder
 			buf.WriteByte('[')
 			for i, x := range a {
 				if i > 0 {
@@ -300,15 +299,15 @@ func posFor(at poser) syntax.Pos {
 
 // stripAnnotations removes internal (type) annotations from s.
 func stripAnnotations(s string) string {
-	var b strings.Builder
+	var buf strings.Builder
 	for _, r := range s {
 		// strip #'s and subscript digits
 		if r < '₀' || '₀'+10 <= r { // '₀' == U+2080
-			b.WriteRune(r)
+			buf.WriteRune(r)
 		}
 	}
-	if b.Len() < len(s) {
-		return b.String()
+	if buf.Len() < len(s) {
+		return buf.String()
 	}
 	return s
 }
diff --git a/src/cmd/compile/internal/types2/example_test.go b/src/cmd/compile/internal/types2/example_test.go
index 4edaad580e..ad0f22fcec 100644
--- a/src/cmd/compile/internal/types2/example_test.go
+++ b/src/cmd/compile/internal/types2/example_test.go
@@ -17,7 +17,6 @@ package types2_test
 // from source, use golang.org/x/tools/go/loader.
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/types2"
 	"fmt"
@@ -68,7 +67,7 @@ func Unused() { {}; {{ var x int; _ = x }} } // make sure empty block scopes get
 
 	// Print the tree of scopes.
 	// For determinism, we redact addresses.
-	var buf bytes.Buffer
+	var buf strings.Builder
 	pkg.Scope().WriteTo(&buf, 0, true)
 	rx := regexp.MustCompile(` 0x[a-fA-F0-9]*`)
 	fmt.Println(rx.ReplaceAllString(buf.String(), ""))
@@ -173,7 +172,7 @@ func fib(x int) int {
 	// fmt.Println("Types and Values of each expression:")
 	// items = nil
 	// for expr, tv := range info.Types {
-	// 	var buf bytes.Buffer
+	// 	var buf strings.Builder
 	// 	posn := expr.Pos()
 	// 	tvstr := tv.Type.String()
 	// 	if tv.Value != nil {
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index d88eef640a..26e01e9ae5 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -338,16 +338,16 @@ func typeParamsString(list []*TypeParam) string {
 	}
 
 	// general case (n > 2)
-	var b strings.Builder
+	var buf strings.Builder
 	for i, tname := range list[:n-1] {
 		if i > 0 {
-			b.WriteString(", ")
+			buf.WriteString(", ")
 		}
-		b.WriteString(tname.obj.name)
+		buf.WriteString(tname.obj.name)
 	}
-	b.WriteString(", and ")
-	b.WriteString(list[n-1].obj.name)
-	return b.String()
+	buf.WriteString(", and ")
+	buf.WriteString(list[n-1].obj.name)
+	return buf.String()
 }
 
 // isParameterized reports whether typ contains any of the type parameters of tparams.
diff --git a/src/cmd/compile/internal/types2/instantiate_test.go b/src/cmd/compile/internal/types2/instantiate_test.go
index 591b467a2e..3c897869fc 100644
--- a/src/cmd/compile/internal/types2/instantiate_test.go
+++ b/src/cmd/compile/internal/types2/instantiate_test.go
@@ -233,15 +233,15 @@ var _ T[int]
 
 // Copied from errors.go.
 func stripAnnotations(s string) string {
-	var b strings.Builder
+	var buf strings.Builder
 	for _, r := range s {
 		// strip #'s and subscript digits
 		if r < '₀' || '₀'+10 <= r { // '₀' == U+2080
-			b.WriteRune(r)
+			buf.WriteRune(r)
 		}
 	}
-	if b.Len() < len(s) {
-		return b.String()
+	if buf.Len() < len(s) {
+		return buf.String()
 	}
 	return s
 }
diff --git a/src/cmd/compile/internal/types2/issues_test.go b/src/cmd/compile/internal/types2/issues_test.go
index 697a73525c..8588687803 100644
--- a/src/cmd/compile/internal/types2/issues_test.go
+++ b/src/cmd/compile/internal/types2/issues_test.go
@@ -7,7 +7,6 @@
 package types2_test
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"internal/testenv"
@@ -427,7 +426,7 @@ func TestIssue29029(t *testing.T) {
 
 	// printInfo prints the *Func definitions recorded in info, one *Func per line.
 	printInfo := func(info *Info) string {
-		var buf bytes.Buffer
+		var buf strings.Builder
 		for _, obj := range info.Defs {
 			if fn, ok := obj.(*Func); ok {
 				fmt.Fprintln(&buf, fn)
diff --git a/src/cmd/compile/internal/types2/mono_test.go b/src/cmd/compile/internal/types2/mono_test.go
index 4511110691..890099207c 100644
--- a/src/cmd/compile/internal/types2/mono_test.go
+++ b/src/cmd/compile/internal/types2/mono_test.go
@@ -5,7 +5,6 @@
 package types2_test
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"cmd/compile/internal/types2"
 	"errors"
@@ -22,7 +21,7 @@ func checkMono(t *testing.T, body string) error {
 	}
 	files := []*syntax.File{file}
 
-	var buf bytes.Buffer
+	var buf strings.Builder
 	conf := types2.Config{
 		Error:    func(err error) { fmt.Fprintln(&buf, err) },
 		Importer: defaultImporter(),
diff --git a/src/cmd/compile/internal/types2/scope.go b/src/cmd/compile/internal/types2/scope.go
index 095875d94b..a679a3d954 100644
--- a/src/cmd/compile/internal/types2/scope.go
+++ b/src/cmd/compile/internal/types2/scope.go
@@ -7,7 +7,6 @@
 package types2
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"io"
@@ -233,7 +232,7 @@ func (s *Scope) WriteTo(w io.Writer, n int, recurse bool) {
 
 // String returns a string representation of the scope, for debugging.
 func (s *Scope) String() string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	s.WriteTo(&buf, 0, false)
 	return buf.String()
 }
diff --git a/src/cmd/compile/internal/types2/termlist.go b/src/cmd/compile/internal/types2/termlist.go
index 8e1f290b2b..196f8abf72 100644
--- a/src/cmd/compile/internal/types2/termlist.go
+++ b/src/cmd/compile/internal/types2/termlist.go
@@ -4,7 +4,7 @@
 
 package types2
 
-import "bytes"
+import "strings"
 
 // A termlist represents the type set represented by the union
 // t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
@@ -25,7 +25,7 @@ func (xl termlist) String() string {
 	if len(xl) == 0 {
 		return "∅"
 	}
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for i, x := range xl {
 		if i > 0 {
 			buf.WriteString(termSep)
diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go
index 328c5029e7..9ac3b6349c 100644
--- a/src/cmd/compile/internal/types2/typeset.go
+++ b/src/cmd/compile/internal/types2/typeset.go
@@ -5,10 +5,10 @@
 package types2
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"sort"
+	"strings"
 )
 
 // ----------------------------------------------------------------------------
@@ -71,7 +71,7 @@ func (s *_TypeSet) String() string {
 	hasMethods := len(s.methods) > 0
 	hasTerms := s.hasTerms()
 
-	var buf bytes.Buffer
+	var buf strings.Builder
 	buf.WriteByte('{')
 	if s.comparable {
 		buf.WriteString("comparable")
diff --git a/src/go/types/api_test.go b/src/go/types/api_test.go
index 8dd30a6ed5..2367f3ab93 100644
--- a/src/go/types/api_test.go
+++ b/src/go/types/api_test.go
@@ -5,7 +5,6 @@
 package types_test
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 	"go/ast"
@@ -896,7 +895,7 @@ func TestImplicitsInfo(t *testing.T) {
 }
 
 func predString(tv TypeAndValue) string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	pred := func(b bool, s string) {
 		if b {
 			if buf.Len() > 0 {
diff --git a/src/go/types/errors.go b/src/go/types/errors.go
index 964f377984..4148287601 100644
--- a/src/go/types/errors.go
+++ b/src/go/types/errors.go
@@ -62,7 +62,7 @@ func (err *error_) msg(fset *token.FileSet, qf Qualifier) string {
 	if err.empty() {
 		return "no error"
 	}
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for i := range err.desc {
 		p := &err.desc[i]
 		if i > 0 {
@@ -164,7 +164,7 @@ func sprintf(fset *token.FileSet, qf Qualifier, debug bool, format string, args
 		case Type:
 			arg = typeString(a, qf, debug)
 		case []Type:
-			var buf bytes.Buffer
+			var buf strings.Builder
 			buf.WriteByte('[')
 			for i, x := range a {
 				if i > 0 {
@@ -175,7 +175,7 @@ func sprintf(fset *token.FileSet, qf Qualifier, debug bool, format string, args
 			buf.WriteByte(']')
 			arg = buf.String()
 		case []*TypeParam:
-			var buf bytes.Buffer
+			var buf strings.Builder
 			buf.WriteByte('[')
 			for i, x := range a {
 				if i > 0 {
@@ -370,15 +370,15 @@ func spanOf(at positioner) posSpan {
 
 // stripAnnotations removes internal (type) annotations from s.
 func stripAnnotations(s string) string {
-	var b strings.Builder
+	var buf strings.Builder
 	for _, r := range s {
 		// strip #'s and subscript digits
 		if r < '₀' || '₀'+10 <= r { // '₀' == U+2080
-			b.WriteRune(r)
+			buf.WriteRune(r)
 		}
 	}
-	if b.Len() < len(s) {
-		return b.String()
+	if buf.Len() < len(s) {
+		return buf.String()
 	}
 	return s
 }
diff --git a/src/go/types/example_test.go b/src/go/types/example_test.go
index 3c1bdb58c3..e752a77881 100644
--- a/src/go/types/example_test.go
+++ b/src/go/types/example_test.go
@@ -16,7 +16,6 @@ package types_test
 // from source, use golang.org/x/tools/go/loader.
 
 import (
-	"bytes"
 	"fmt"
 	"go/ast"
 	"go/format"
@@ -72,7 +71,7 @@ func Unused() { {}; {{ var x int; _ = x }} } // make sure empty block scopes get
 
 	// Print the tree of scopes.
 	// For determinism, we redact addresses.
-	var buf bytes.Buffer
+	var buf strings.Builder
 	pkg.Scope().WriteTo(&buf, 0, true)
 	rx := regexp.MustCompile(` 0x[a-fA-F0-9]*`)
 	fmt.Println(rx.ReplaceAllString(buf.String(), ""))
@@ -233,7 +232,7 @@ func fib(x int) int {
 	fmt.Println("Types and Values of each expression:")
 	items = nil
 	for expr, tv := range info.Types {
-		var buf bytes.Buffer
+		var buf strings.Builder
 		posn := fset.Position(expr.Pos())
 		tvstr := tv.Type.String()
 		if tv.Value != nil {
@@ -328,7 +327,7 @@ func mode(tv types.TypeAndValue) string {
 }
 
 func exprString(fset *token.FileSet, expr ast.Expr) string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	format.Node(&buf, fset, expr)
 	return buf.String()
 }
diff --git a/src/go/types/infer.go b/src/go/types/infer.go
index 768efbf73b..f9a855bd1c 100644
--- a/src/go/types/infer.go
+++ b/src/go/types/infer.go
@@ -339,16 +339,16 @@ func typeParamsString(list []*TypeParam) string {
 	}
 
 	// general case (n > 2)
-	var b strings.Builder
+	var buf strings.Builder
 	for i, tname := range list[:n-1] {
 		if i > 0 {
-			b.WriteString(", ")
+			buf.WriteString(", ")
 		}
-		b.WriteString(tname.obj.name)
+		buf.WriteString(tname.obj.name)
 	}
-	b.WriteString(", and ")
-	b.WriteString(list[n-1].obj.name)
-	return b.String()
+	buf.WriteString(", and ")
+	buf.WriteString(list[n-1].obj.name)
+	return buf.String()
 }
 
 // isParameterized reports whether typ contains any of the type parameters of tparams.
diff --git a/src/go/types/instantiate_test.go b/src/go/types/instantiate_test.go
index 281c8bbcad..91dae734c1 100644
--- a/src/go/types/instantiate_test.go
+++ b/src/go/types/instantiate_test.go
@@ -239,15 +239,15 @@ var _ T[int]
 
 // Copied from errors.go.
 func stripAnnotations(s string) string {
-	var b strings.Builder
+	var buf strings.Builder
 	for _, r := range s {
 		// strip #'s and subscript digits
 		if r < '₀' || '₀'+10 <= r { // '₀' == U+2080
-			b.WriteRune(r)
+			buf.WriteRune(r)
 		}
 	}
-	if b.Len() < len(s) {
-		return b.String()
+	if buf.Len() < len(s) {
+		return buf.String()
 	}
 	return s
 }
diff --git a/src/go/types/issues_test.go b/src/go/types/issues_test.go
index bd98f48177..d46d085ba8 100644
--- a/src/go/types/issues_test.go
+++ b/src/go/types/issues_test.go
@@ -7,7 +7,6 @@
 package types_test
 
 import (
-	"bytes"
 	"fmt"
 	"go/ast"
 	"go/importer"
@@ -429,7 +428,7 @@ func TestIssue29029(t *testing.T) {
 
 	// printInfo prints the *Func definitions recorded in info, one *Func per line.
 	printInfo := func(info *Info) string {
-		var buf bytes.Buffer
+		var buf strings.Builder
 		for _, obj := range info.Defs {
 			if fn, ok := obj.(*Func); ok {
 				fmt.Fprintln(&buf, fn)
diff --git a/src/go/types/mono_test.go b/src/go/types/mono_test.go
index 5df3d493f8..02daa4fdc6 100644
--- a/src/go/types/mono_test.go
+++ b/src/go/types/mono_test.go
@@ -5,7 +5,6 @@
 package types_test
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 	"go/ast"
@@ -25,7 +24,7 @@ func checkMono(t *testing.T, body string) error {
 	}
 	files := []*ast.File{file}
 
-	var buf bytes.Buffer
+	var buf strings.Builder
 	conf := types.Config{
 		Error:    func(err error) { fmt.Fprintln(&buf, err) },
 		Importer: importer.Default(),
diff --git a/src/go/types/scope.go b/src/go/types/scope.go
index 010727eb72..fc42ce6524 100644
--- a/src/go/types/scope.go
+++ b/src/go/types/scope.go
@@ -7,7 +7,6 @@
 package types
 
 import (
-	"bytes"
 	"fmt"
 	"go/token"
 	"io"
@@ -233,7 +232,7 @@ func (s *Scope) WriteTo(w io.Writer, n int, recurse bool) {
 
 // String returns a string representation of the scope, for debugging.
 func (s *Scope) String() string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	s.WriteTo(&buf, 0, false)
 	return buf.String()
 }
diff --git a/src/go/types/termlist.go b/src/go/types/termlist.go
index d65c172ba1..83a02eefac 100644
--- a/src/go/types/termlist.go
+++ b/src/go/types/termlist.go
@@ -4,7 +4,7 @@
 
 package types
 
-import "bytes"
+import "strings"
 
 // A termlist represents the type set represented by the union
 // t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
@@ -25,7 +25,7 @@ func (xl termlist) String() string {
 	if len(xl) == 0 {
 		return "∅"
 	}
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for i, x := range xl {
 		if i > 0 {
 			buf.WriteString(termSep)
diff --git a/src/go/types/typeset.go b/src/go/types/typeset.go
index 08ff191f2e..fc4647e850 100644
--- a/src/go/types/typeset.go
+++ b/src/go/types/typeset.go
@@ -5,10 +5,10 @@
 package types
 
 import (
-	"bytes"
 	"fmt"
 	"go/token"
 	"sort"
+	"strings"
 )
 
 // ----------------------------------------------------------------------------
@@ -71,7 +71,7 @@ func (s *_TypeSet) String() string {
 	hasMethods := len(s.methods) > 0
 	hasTerms := s.hasTerms()
 
-	var buf bytes.Buffer
+	var buf strings.Builder
 	buf.WriteByte('{')
 	if s.comparable {
 		buf.WriteString("comparable")