refactor: use fmt.Fprintf instad of fmt.Sprintf (#4581)

Author: Kazuyoshi Kato

.golangci.yml

@@ -41,7 +41,6 @@ linters:
         - -QF1002 # could use tagged switch
         - -QF1003 # could use tagged switch on app
         - -QF1008 # could remove embedded field ... from selector
-        - -QF1012 # Use fmt.Fprintf(...) instead of WriteString(fmt.Sprintf(...))
   exclusions:
     generated: lax
     presets:

doc/main.go

@@ -93,9 +93,9 @@ func GenMarkdownCustom(cmd *cobra.Command, w io.Writer, linkHandler func(string)
 
 		// If it's runnable, show the useline otherwise show a version with [command]
 		if cmd.Runnable() {
-			buf.WriteString(fmt.Sprintf("```\n%s\n```\n\n", cmd.UseLine()))
+			fmt.Fprintf(buf, "```\n%s\n```\n\n", cmd.UseLine())
 		} else {
-			buf.WriteString(fmt.Sprintf("```\n%s [command] [flags]\n```", cmd.CommandPath()) + "\n\n")
+			fmt.Fprintf(buf, "```\n%s [command] [flags]\n```\n\n", cmd.CommandPath())
 		}
 	}
 
@@ -111,14 +111,14 @@ func GenMarkdownCustom(cmd *cobra.Command, w io.Writer, linkHandler func(string)
 			cname := name + " " + child.Name()
 			link := cname + ".md"
 			link = strings.ReplaceAll(link, " ", "_")
-			buf.WriteString(fmt.Sprintf("* [%s](%s)\t - %s\n", child.Name(), linkHandler(link), child.Short))
+			fmt.Fprintf(buf, "* [%s](%s)\t - %s\n", child.Name(), linkHandler(link), child.Short)
 		}
 		buf.WriteString("\n")
 	}
 
 	if len(cmd.Example) > 0 {
 		buf.WriteString(titlePrefix + "Examples\n\n")
-		buf.WriteString(fmt.Sprintf("```\n%s\n```\n\n", cmd.Example))
+		fmt.Fprintf(buf, "```\n%s\n```\n\n", cmd.Example)
 	}
 
 	if err := printOptions(buf, cmd, name); err != nil {
@@ -131,7 +131,7 @@ func GenMarkdownCustom(cmd *cobra.Command, w io.Writer, linkHandler func(string)
 			pname := parent.CommandPath()
 			link := pname + ".md"
 			link = strings.ReplaceAll(link, " ", "_")
-			buf.WriteString(fmt.Sprintf("* [%s](%s)\t - %s\n", pname, linkHandler(link), parent.Short))
+			fmt.Fprintf(buf, "* [%s](%s)\t - %s\n", pname, linkHandler(link), parent.Short)
 			cmd.VisitParents(func(c *cobra.Command) {
 				if c.DisableAutoGenTag {
 					cmd.DisableAutoGenTag = c.DisableAutoGenTag

internal/command/launch/dockerfiles.go

@@ -103,7 +103,7 @@ func createDockerignoreFromGitignores(root string, gitIgnores []string) (string,
 				} else {
 					f.Write(linebreak)
 				}
-				_, err := f.WriteString(fmt.Sprintf("# flyctl launch added from %s\n", relFile))
+				_, err := fmt.Fprintf(f, "# flyctl launch added from %s\n", relFile)
 				if err != nil {
 					return "", err
 				}

tools/distribute/flypkgs/errors.go

@@ -14,9 +14,10 @@ type ErrorResponse struct {
 
 func (e ErrorResponse) Error() string {
 	var sb strings.Builder
-	sb.WriteString(fmt.Sprintf("API error: %d\n", e.Code))
+
+	fmt.Fprintf(&sb, "API error: %d\n", e.Code)
 	for _, msg := range e.Messages {
-		sb.WriteString(fmt.Sprintf("  - %s\n", msg))
+		fmt.Fprintf(&sb, "  - %s\n", msg)
 	}
 
 	return sb.String()