all: use fmt.Appendf

Change-Id: I45f941ba3db26a12b3f56d93bdcd7f9e1d490346
GitHub-Last-Rev: 22b51167b0
GitHub-Pull-Request: golang/go#56030
Reviewed-on: https://go-review.googlesource.com/c/go/+/438539
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

src/cmd/go/internal/modfetch/coderepo.go

@@ -962,7 +962,7 @@ func (r *codeRepo) GoMod(version string) (data []byte, err error) {
 // for dependencies in the middle of a build, impossible to
 // correct. So we stopped.
 func LegacyGoMod(modPath string) []byte {
-	return []byte(fmt.Sprintf("module %s\n", modfile.AutoQuote(modPath)))
+	return fmt.Appendf(nil, "module %s\n", modfile.AutoQuote(modPath))
 }
 
 func (r *codeRepo) modPrefix(rev string) string {

src/cmd/go/internal/modload/build.go

@@ -431,12 +431,12 @@ func ModInfoProg(info string, isgccgo bool) []byte {
 	// look at the module info in their init functions (see issue 29628),
 	// which won't work. See also issue 30344.
 	if isgccgo {
-		return []byte(fmt.Sprintf(`package main
+		return fmt.Appendf(nil, `package main
 import _ "unsafe"
 //go:linkname __set_debug_modinfo__ runtime.setmodinfo
 func __set_debug_modinfo__(string)
 func init() { __set_debug_modinfo__(%q) }
-`, ModInfoData(info)))
+`, ModInfoData(info))
 	}
 	return nil
 }

src/cmd/trace/annotations.go

@@ -1095,7 +1095,7 @@ Search log text: <form onsubmit="window.location.search+='&logtext='+window.logt
 `))
 
 func elapsed(d time.Duration) string {
-	b := []byte(fmt.Sprintf("%.9f", d.Seconds()))
+	b := fmt.Appendf(nil, "%.9f", d.Seconds())
 
 	// For subsecond durations, blank all zeros before decimal point,
 	// and all zeros between the decimal point and the first non-zero digit.

src/net/smtp/auth.go

@@ -103,7 +103,7 @@ func (a *cramMD5Auth) Next(fromServer []byte, more bool) ([]byte, error) {
 		d := hmac.New(md5.New, []byte(a.secret))
 		d.Write(fromServer)
 		s := make([]byte, 0, d.Size())
-		return []byte(fmt.Sprintf("%s %x", a.username, d.Sum(s))), nil
+		return fmt.Appendf(nil, "%s %x", a.username, d.Sum(s)), nil
 	}
 	return nil, nil
 }