cmd/go: change Printer.Output -> Printer.Printf for consistency

Currently, the Printer interface has `Output`, which acts like Print
and `Errorf`, which acts like Printf. It's confusing that the
formatting style is tied to whether it's regular output or an error.

Fix this by replacing Output with Printf, so both use Printf-style
formatting.

Change-Id: I4c76f941e956f2599c5620b455bf41e21636b44e
Reviewed-on: https://go-review.googlesource.com/c/go/+/627795
Reviewed-by: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/go/internal/load/printer.go

@@ -17,15 +17,15 @@ import (
 
 // A Printer reports output about a Package.
 type Printer interface {
-	// Output reports output from building pkg. The arguments are of the form
+	// Printf reports output from building pkg. The arguments are of the form
-	// expected by fmt.Print.
+	// expected by [fmt.Printf].
 	//
 	// pkg may be nil if this output is not associated with the build of a
 	// particular package.
 	//
 	// The caller is responsible for checking if printing output is appropriate,
 	// for example by checking cfg.BuildN or cfg.BuildV.
-	Output(pkg *Package, args ...any)
+	Printf(pkg *Package, format string, args ...any)
 
 	// Errorf prints output in the form of `log.Errorf` and reports that
 	// building pkg failed.
@@ -68,8 +68,8 @@ type TextPrinter struct {
 	Writer io.Writer
 }
 
-func (p *TextPrinter) Output(_ *Package, args ...any) {
+func (p *TextPrinter) Printf(_ *Package, format string, args ...any) {
-	fmt.Fprint(p.Writer, args...)
+	fmt.Fprintf(p.Writer, format, args...)
 }
 
 func (p *TextPrinter) Errorf(_ *Package, format string, args ...any) {
@@ -92,10 +92,10 @@ type jsonBuildEvent struct {
 	Output     string `json:",omitempty"` // Non-empty if Action == “build-output”
 }
 
-func (p *JSONPrinter) Output(pkg *Package, args ...any) {
+func (p *JSONPrinter) Printf(pkg *Package, format string, args ...any) {
 	ev := &jsonBuildEvent{
 		Action: "build-output",
-		Output: fmt.Sprint(args...),
+		Output: fmt.Sprintf(format, args...),
 	}
 	if ev.Output == "" {
 		// There's no point in emitting a completely empty output event.
@@ -112,7 +112,7 @@ func (p *JSONPrinter) Errorf(pkg *Package, format string, args ...any) {
 	// For clarity, emit each line as a separate output event.
 	for len(s) > 0 {
 		i := strings.IndexByte(s, '\n')
-		p.Output(pkg, s[:i+1])
+		p.Printf(pkg, "%s", s[:i+1])
 		s = s[i+1:]
 	}
 	ev := &jsonBuildEvent{

src/cmd/go/internal/work/action.go

@@ -298,7 +298,7 @@ func NewBuilder(workDir string) *Builder {
 	b.backgroundSh = NewShell(b.WorkDir, nil)
 
 	if printWorkDir {
-		b.BackgroundShell().Print("WORK=", b.WorkDir, "\n")
+		b.BackgroundShell().Printf("WORK=%s\n", b.WorkDir)
 	}
 
 	if err := CheckGOOSARCHPair(cfg.Goos, cfg.Goarch); err != nil {

src/cmd/go/internal/work/buildid.go

@@ -618,7 +618,7 @@ func showStdout(b *Builder, c cache.Cache, a *Action, key string) error {
 			sh.ShowCmd("", "%s  # internal", joinUnambiguously(str.StringList("cat", c.OutputFile(stdoutEntry.OutputID))))
 		}
 		if !cfg.BuildN {
-			sh.Print(string(stdout))
+			sh.Printf("%s", stdout)
 		}
 	}
 	return nil
@@ -626,7 +626,7 @@ func showStdout(b *Builder, c cache.Cache, a *Action, key string) error {
 
 // flushOutput flushes the output being queued in a.
 func (b *Builder) flushOutput(a *Action) {
-	b.Shell(a).Print(string(a.output))
+	b.Shell(a).Printf("%s", a.output)
 	a.output = nil
 }
 

src/cmd/go/internal/work/exec.go

@@ -520,11 +520,11 @@ func (b *Builder) build(ctx context.Context, a *Action) (err error) {
 		// different sections of the bootstrap script have to
 		// be merged, the banners give patch something
 		// to use to find its context.
-		sh.Print("\n#\n# " + p.ImportPath + "\n#\n\n")
+		sh.Printf("\n#\n# %s\n#\n\n", p.ImportPath)
 	}
 
 	if cfg.BuildV {
-		sh.Print(p.ImportPath + "\n")
+		sh.Printf("%s\n", p.ImportPath)
 	}
 
 	if p.Error != nil {

src/cmd/go/internal/work/shell.go

@@ -71,16 +71,16 @@ func (sh *Shell) pkg() *load.Package {
 	return sh.action.Package
 }
 
-// Print emits a to this Shell's output stream, formatting it like fmt.Print.
+// Printf emits a to this Shell's output stream, formatting it like fmt.Printf.
 // It is safe to call concurrently.
-func (sh *Shell) Print(a ...any) {
+func (sh *Shell) Printf(format string, a ...any) {
 	sh.printLock.Lock()
 	defer sh.printLock.Unlock()
-	sh.printer.Output(sh.pkg(), a...)
+	sh.printer.Printf(sh.pkg(), format, a...)
 }
 
-func (sh *Shell) printLocked(a ...any) {
+func (sh *Shell) printfLocked(format string, a ...any) {
-	sh.printer.Output(sh.pkg(), a...)
+	sh.printer.Printf(sh.pkg(), format, a...)
 }
 
 // Errorf reports an error on sh's package and sets the process exit status to 1.
@@ -371,7 +371,7 @@ func (sh *Shell) ShowCmd(dir string, format string, args ...any) {
 	if dir != "" && dir != "/" {
 		if dir != sh.scriptDir {
 			// Show changing to dir and update the current directory.
-			sh.printLocked(sh.fmtCmd("", "cd %s\n", dir))
+			sh.printfLocked("%s", sh.fmtCmd("", "cd %s\n", dir))
 			sh.scriptDir = dir
 		}
 		// Replace scriptDir is our working directory. Replace it
@@ -383,7 +383,7 @@ func (sh *Shell) ShowCmd(dir string, format string, args ...any) {
 		cmd = strings.ReplaceAll(" "+cmd, " "+dir, dot)[1:]
 	}
 
-	sh.printLocked(cmd + "\n")
+	sh.printfLocked("%s\n", cmd)
 }
 
 // reportCmd reports the output and exit status of a command. The cmdOut and
@@ -522,7 +522,7 @@ func (sh *Shell) reportCmd(desc, dir string, cmdOut []byte, cmdErr error) error
 		a.output = append(a.output, err.Error()...)
 	} else {
 		// Write directly to the Builder output.
-		sh.Print(err.Error())
+		sh.Printf("%s", err)
 	}
 	return nil
 }