Added logging of config file location

Sources/CommandLine.swift

@@ -675,7 +675,11 @@ func inferOptions(from inputURLs: [URL], options: FileOptions) -> (Int, FormatOp
     var filesParsed = 0
     let baseOptions = Options(fileOptions: options)
     for inputURL in inputURLs {
-        errors += enumerateFiles(withInputURL: inputURL, options: baseOptions) { inputURL, _, _ in
+        errors += enumerateFiles(
+            withInputURL: inputURL,
+            options: baseOptions,
+            logger: { print($0, as: .info) }
+        ) { inputURL, _, _ in
             guard let input = try? String(contentsOf: inputURL) else {
                 throw FormatError.reading("Failed to read file \(inputURL.path)")
             }
@@ -784,12 +788,14 @@ func processInput(_ inputURLs: [URL],
     // Format files
     var errors = [Error]()
     for inputURL in inputURLs {
-        errors += enumerateFiles(withInputURL: inputURL,
-                                 outputURL: outputURL,
-                                 options: options,
-                                 concurrent: !verbose,
-                                 skipped: skippedHandler) { inputURL, outputURL, options in
-
+        errors += enumerateFiles(
+            withInputURL: inputURL,
+            outputURL: outputURL,
+            options: options,
+            concurrent: !verbose,
+            logger: { print($0, as: .info) },
+            skipped: skippedHandler
+        ) { inputURL, outputURL, options in
             guard let input = try? String(contentsOf: inputURL) else {
                 throw FormatError.reading("Failed to read file \(inputURL.path)")
             }

Sources/SwiftFormat.swift

@@ -73,6 +73,9 @@ public typealias FileEnumerationHandler = (
     _ options: Options
 ) throws -> () throws -> Void
 
+/// Callback for info-level logging
+public typealias Logger = (String) -> Void
+
 /// Enumerate all swift files at the specified location and (optionally) calculate an output file URL for each.
 /// Ignores the file if any of the excluded file URLs is a prefix of the input file URL.
 ///
@@ -86,6 +89,7 @@ public func enumerateFiles(withInputURL inputURL: URL,
                            outputURL: URL? = nil,
                            options baseOptions: Options = .default,
                            concurrent: Bool = true,
+                           logger print: Logger? = nil,
                            skipped: FileEnumerationHandler? = nil,
                            handler: @escaping FileEnumerationHandler) -> [Error] {
     let manager = FileManager.default
@@ -234,6 +238,7 @@ public func enumerateFiles(withInputURL inputURL: URL,
             let data = try Data(contentsOf: configFile)
             let args = try parseConfigFile(data)
             try options.addArguments(args, in: inputURL.path)
+            print?("Reading config file at \(configFile.path)")
         }
         let versionFile = inputURL.appendingPathComponent(swiftVersionFile)
         if manager.fileExists(atPath: versionFile.path) {