Fix crash when running Lint from LegacyMain

README.md

@@ -91,6 +91,9 @@ as well as the following command line options:
   files in any directories listed on the command line and their descendants.
   Without this flag, it is an error to list a directory on the command line.
 
+* `-s/--strict`: If specified, exits non-zero code if one or more warning are found.
+  This option only works in lint mode.
+
 ### Configuration
 
 For any source file being checked or formatted, `swift-format` looks for a

Sources/swift-format/Subcommands/Lint.swift

@@ -21,18 +21,12 @@ extension SwiftFormatCommand {
 
     @OptionGroup()
     var lintOptions: LintFormatOptions
-
-    @Flag(
-      name: .shortAndLong,
-      help: "Fail on warnings."
-    )
-    var strict: Bool = false
 
     func run() throws {
       let frontend = LintFrontend(lintFormatOptions: lintOptions)
       frontend.run()
       if frontend.errorsWereEmitted { throw ExitCode.failure }
-      if strict,
+      if lintOptions.strict,
          frontend.diagnosticEngine.diagnostics
             .contains(where: { $0.message.severity == .warning }) {
         throw ExitCode.failure

Sources/swift-format/Subcommands/LintFormatOptions.swift

@@ -55,6 +55,11 @@ struct LintFormatOptions: ParsableArguments {
     help: "Process files in parallel, simultaneously across multiple cores.")
   var parallel: Bool = false
 
+  @Flag(
+    name: .shortAndLong,
+    help: "Fail on warnings.")
+  var strict: Bool = false
+
   /// The list of paths to Swift source files that should be formatted or linted.
   @Argument(help: "Zero or more input filenames.")
   var paths: [String] = []