From 6f3ef3a6ac39443a7b0c4f7fec091246c5d344d8 Mon Sep 17 00:00:00 2001
From: TTOzzi <devttozzi@gmail.com>
Date: Sun, 12 Jan 2025 06:27:05 +0900
Subject: [PATCH] Print a usage description when the user enters the
 swift-format command without arguments

---
 Sources/swift-format/Subcommands/Format.swift | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Sources/swift-format/Subcommands/Format.swift b/Sources/swift-format/Subcommands/Format.swift
index 42c2da16..5ac3ff17 100644
--- a/Sources/swift-format/Subcommands/Format.swift
+++ b/Sources/swift-format/Subcommands/Format.swift
@@ -36,6 +36,16 @@ extension SwiftFormatCommand {
     var performanceMeasurementOptions: PerformanceMeasurementsOptions
 
     func validate() throws {
+      if formatOptions.paths.isEmpty && !inPlace {
+        throw ValidationError(
+          """
+          No input files specified. Use one of the following:
+            - Provide the path to a directory along with the '--recursive' option to format all Swift files within it.
+            - Provide the path to a specific Swift source code file.
+          And use '--in-place' to overwrite files in-place.
+          """
+        )
+      }
       if inPlace && formatOptions.paths.isEmpty {
         throw ValidationError("'--in-place' is only valid when formatting files")
       }