cmd/asm: use strings.Builder

Change-Id: I2ec419f475f9c5d5ef1d4557cb5862a55a699d9c
Reviewed-on: https://go-review.googlesource.com/c/go/+/428284
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/asm/internal/asm/asm.go

@@ -5,9 +5,9 @@
 package asm
 
 import (
-	"bytes"
 	"fmt"
 	"strconv"
+	"strings"
 	"text/scanner"
 
 	"cmd/asm/internal/arch"
@@ -22,7 +22,7 @@ import (
 
 // TODO: configure the architecture
 
-var testOut *bytes.Buffer // Gathers output when testing.
+var testOut *strings.Builder // Gathers output when testing.
 
 // append adds the Prog to the end of the program-thus-far.
 // If doLabel is set, it also defines the labels collect for this Prog.

src/cmd/asm/internal/asm/endtoend_test.go

@@ -34,7 +34,7 @@ func testEndToEnd(t *testing.T, goarch, file string) {
 	parser := NewParser(ctxt, architecture, lexer, false)
 	pList := new(obj.Plist)
 	var ok bool
-	testOut = new(bytes.Buffer) // The assembler writes test output to this buffer.
+	testOut = new(strings.Builder) // The assembler writes test output to this buffer.
 	ctxt.Bso = bufio.NewWriter(os.Stdout)
 	ctxt.IsAsm = true
 	defer ctxt.Bso.Flush()
@@ -277,7 +277,7 @@ func testErrors(t *testing.T, goarch, file string, flags ...string) {
 	parser := NewParser(ctxt, architecture, lexer, false)
 	pList := new(obj.Plist)
 	var ok bool
-	testOut = new(bytes.Buffer) // The assembler writes test output to this buffer.
+	testOut = new(strings.Builder) // The assembler writes test output to this buffer.
 	ctxt.Bso = bufio.NewWriter(os.Stdout)
 	ctxt.IsAsm = true
 	defer ctxt.Bso.Flush()

src/cmd/asm/internal/asm/pseudo_test.go

@@ -5,7 +5,6 @@
 package asm
 
 import (
-	"bytes"
 	"strings"
 	"testing"
 
@@ -81,7 +80,7 @@ func TestErroneous(t *testing.T) {
 	// Note these errors should be independent of the architecture.
 	// Just run the test with amd64.
 	parser := newParser("amd64")
-	var buf bytes.Buffer
+	var buf strings.Builder
 	parser.errorWriter = &buf
 
 	for _, cat := range testcats {

src/cmd/asm/internal/lex/lex_test.go

@@ -5,7 +5,6 @@
 package lex
 
 import (
-	"bytes"
 	"strings"
 	"testing"
 	"text/scanner"
@@ -275,7 +274,7 @@ func lines(a ...string) string {
 
 // drain returns a single string representing the processed input tokens.
 func drain(input *Input) string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for {
 		tok := input.Next()
 		if tok == scanner.EOF {