Only write .bazelrc file if it is not empty

tools/rulegen/main.go

@@ -205,6 +205,7 @@ func mustWriteLanguageExampleBazelrcFile(dir string, lang *Language, rule *Rule)
 			out.w("#")
 		}
 		out.w("%s --%s=%s", f.Category, f.Name, f.Value)
+		out.ln()
 	}
 	for _, f := range rule.Flags {
 		if f.Description != "" {
@@ -213,9 +214,18 @@ func mustWriteLanguageExampleBazelrcFile(dir string, lang *Language, rule *Rule)
 			out.w("#")
 		}
 		out.w("%s --%s=%s", f.Category, f.Name, f.Value)
+		out.ln()
+	}
+
+	// Only write a .bazelrc if it's not empty
+	if len(out.lines) > 0 {
+		out.MustWrite(filepath.Join(dir, ".bazelrc"))
+	} else {
+		e := os.Remove(filepath.Join(dir, ".bazelrc"))
+		if e != nil {
+			log.Fatal(e)
+		}
 	}
-	out.ln()
-	out.MustWrite(filepath.Join(dir, ".bazelrc"))
 }
 
 func mustWriteLanguageDefs(dir string, lang *Language) {