Help text: Display argv[0] for root command by default

Sources/ArgumentParser/Parsable Types/CommandConfiguration.swift

@@ -15,6 +15,10 @@ public struct CommandConfiguration: Sendable {
   ///
   /// If `nil`, the command name is derived by converting the name of
   /// the command type to hyphen-separated lowercase words.
+  /// 
+  /// NOTE: In help and usage texts if this is the root command and commandName is
+  /// `nil`, the name shown will be derived from the binary being invoked (argv[0]),
+  /// otherwise `commandName` will be displayed.
   public var commandName: String?
 
   /// The name of this command's "super-command". (experimental)

Sources/ArgumentParser/Usage/HelpGenerator.swift

@@ -89,6 +89,7 @@ internal struct HelpGenerator {
   var commandStack: [ParsableCommand.Type]
   var abstract: String
   var usage: String
+  var commandNames: String
   var sections: [Section]
   var discussionSections: [DiscussionSection]
 
@@ -101,15 +102,22 @@ internal struct HelpGenerator {
     self.commandStack = commandStack
 
     // Build the tool name and subcommand name from the command configuration
-    var toolName = commandStack.map { $0._commandName }.joined(separator: " ")
     if let superName = commandStack.first!.configuration._superCommandName {
-      toolName = "\(superName) \(toolName)"
+        self.commandNames = commandStack.map { $0._commandName }.joined(separator: " ")
+        self.commandNames = "\(superName) \(commandNames)"
+    } else {
+      // If the user explicitly provided a command name, use this. Otherwise default to showing argv[0].
+      let binaryName = CommandLine._staticArguments[0].split(separator: "/").last.map(String.init) ?? "<command>"
+      self.commandNames = commandStack[0].configuration.commandName ?? binaryName
+      if commandStack.count > 1 {
+        self.commandNames += " " + commandStack[1...].map { $0._commandName }.joined(separator: " ")
+      }
     }
 
     if let usage = currentCommand.configuration.usage {
       self.usage = usage
     } else {
-      var usage = UsageGenerator(toolName: toolName, definition: [currentArgSet])
+      var usage = UsageGenerator(toolName: self.commandNames, definition: [currentArgSet])
         .synopsis
       if !currentCommand.configuration.subcommands.isEmpty {
         if usage.last != " " { usage += " " }
@@ -245,7 +253,11 @@ internal struct HelpGenerator {
     guard !usage.isEmpty else { return "" }
     return "Usage: \(usage.hangingIndentingEachLine(by: 7))"
   }
-
+
+  func getCommandNames() -> String {
+    return self.commandNames
+  }
+
   var includesSubcommands: Bool {
     guard let subcommandSection = sections.first(where: { $0.header == .subcommands })
       else { return false }

Sources/ArgumentParser/Usage/MessageInfo.swift

@@ -82,9 +82,10 @@ enum MessageInfo {
       parserError = .userValidationError(error)
     }
 
-    var usage = HelpGenerator(commandStack: commandStack, visibility: .default).usageMessage()
+    let generator = HelpGenerator(commandStack: commandStack, visibility: .default)
+    var usage = generator.usageMessage()
+    let commandNames = generator.getCommandNames()
 
-    let commandNames = commandStack.map { $0._commandName }.joined(separator: " ")
     if let helpName = commandStack.getPrimaryHelpName() {
       if !usage.isEmpty {
         usage += "\n"

Sources/ArgumentParserTestHelpers/TestHelpers.swift

@@ -119,6 +119,10 @@ public func AssertParse<A>(_ type: A.Type, _ arguments: [String], file: StaticSt
   }
 }
 
+public func getFirstArgument() -> String {
+  return CommandLine.arguments[0].split(separator: "/").last.map(String.init) ?? "<command>"
+}
+
 public func AssertParseCommand<A: ParsableCommand>(_ rootCommand: ParsableCommand.Type, _ type: A.Type, _ arguments: [String], file: StaticString = #file, line: UInt = #line, closure: (A) throws -> Void) {
   do {
     let command = try rootCommand.parseAsRoot(arguments)

Tests/ArgumentParserEndToEndTests/FlagsEndToEndTests.swift

@@ -179,7 +179,9 @@ enum Shape: String, EnumerableFlag {
   case oblong
 }
 
-fileprivate struct Baz: ParsableArguments {
+fileprivate struct Baz: ParsableArguments, ParsableCommand {
+  static let configuration = CommandConfiguration(commandName: "baz")
+
   @Flag()
   var color: Color
 

Tests/ArgumentParserEndToEndTests/SubcommandEndToEndTests.swift

@@ -20,7 +20,7 @@ final class SubcommandEndToEndTests: XCTestCase {
 
 fileprivate struct Foo: ParsableCommand {
   static let configuration =
-    CommandConfiguration(subcommands: [CommandA.self, CommandB.self])
+    CommandConfiguration(commandName: "foo", subcommands: [CommandA.self, CommandB.self])
 
   @Option() var name: String
 }

Tests/ArgumentParserEndToEndTests/TransformEndToEndTests.swift

@@ -37,8 +37,8 @@ extension Convert {
 fileprivate struct FooOption: Convert, ParsableArguments {
 
   static var usageString: String = """
-  Usage: foo_option --string <int_str>
-    See 'foo_option --help' for more information.
+  Usage: \(getFirstArgument()) --string <int_str>
+    See '\(getFirstArgument()) --help' for more information.
   """
   static var help: String = "Help:  --string <int_str>  Convert string to integer\n"
 
@@ -48,7 +48,8 @@ fileprivate struct FooOption: Convert, ParsableArguments {
 }
 
 fileprivate struct BarOption: Convert, ParsableCommand {
-
+  static var configuration = CommandConfiguration(commandName: "bar-option")
+
   static var usageString: String = """
   Usage: bar-option [--strings <int_str> ...]
     See 'bar-option --help' for more information.
@@ -100,8 +101,8 @@ extension TransformEndToEndTests {
 fileprivate struct FooArgument: Convert, ParsableArguments {
 
   static var usageString: String = """
-  Usage: foo_argument <int_str>
-    See 'foo_argument --help' for more information.
+  Usage: \(getFirstArgument()) <int_str>
+    See '\(getFirstArgument()) --help' for more information.
   """
   static var help: String = "Help:  <int_str>  Convert string to integer\n"
 
@@ -115,6 +116,7 @@ fileprivate struct FooArgument: Convert, ParsableArguments {
 }
 
 fileprivate struct BarArgument: Convert, ParsableCommand {
+  static var configuration = CommandConfiguration(commandName: "bar-argument")
 
   static var usageString: String = """
   Usage: bar-argument [<int_str> ...]

Tests/ArgumentParserEndToEndTests/ValidationEndToEndTests.swift

@@ -29,12 +29,12 @@ fileprivate enum UserValidationError: LocalizedError {
 
 fileprivate struct Foo: ParsableArguments {
   static var usageString: String = """
-    Usage: foo [--count <count>] [<names> ...] [--version] [--throw]
-      See 'foo --help' for more information.
+    Usage: \(getFirstArgument()) [--count <count>] [<names> ...] [--version] [--throw]
+      See '\(getFirstArgument()) --help' for more information.
     """
 
   static var helpString: String = """
-    USAGE: foo [--count <count>] [<names> ...] [--version] [--throw]
+    USAGE: \(getFirstArgument()) [--count <count>] [<names> ...] [--version] [--throw]
 
     ARGUMENTS:
       <names>

Tests/ArgumentParserPackageManagerTests/HelpTests.swift

@@ -169,7 +169,7 @@ struct Simple: ParsableArguments {
   @Argument() var max: Int
 
   static var helpText = """
-        USAGE: simple [--verbose] [--min <min>] <max>
+        USAGE: \(getFirstArgument()) [--verbose] [--min <min>] <max>
 
         ARGUMENTS:
           <max>
@@ -195,6 +195,7 @@ extension HelpTests {
 
 struct CustomHelp: ParsableCommand {
   static let configuration = CommandConfiguration(
+    commandName: "custom-help",
     helpNames: [.customShort("?"), .customLong("show-help")]
   )
 }
@@ -216,6 +217,7 @@ extension HelpTests {
 
 struct NoHelp: ParsableCommand {
   static let configuration = CommandConfiguration(
+    commandName: "no-help",
     helpNames: []
   )
 

Tests/ArgumentParserPackageManagerTests/PackageManager/Options.swift

@@ -89,6 +89,7 @@ struct Options: ParsableArguments {
 
 struct Package: ParsableCommand {
   static let configuration = CommandConfiguration(
+    commandName: "package",
     subcommands: [Clean.self, Config.self, Describe.self, GenerateXcodeProject.self, Hidden.self])
 }
 

Tests/ArgumentParserUnitTests/HelpGenerationTests+AtArgument.swift

@@ -22,41 +22,57 @@ extension HelpGenerationTests {
     struct A { }
 
     struct BareNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "bare-no-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A
     }
 
     struct BareDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "bare-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A = A()
     }
 
     struct OptionalNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-no-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A?
     }
 
     struct OptionalDefaultNil: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-default-nil")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A? = nil
     }
 
     struct OptionalDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A? = A()
     }
 
     struct ArrayNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-no-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: [A]
     }
 
     struct ArrayDefaultEmpty: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-default-empty")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: [A] = []
     }
 
     struct ArrayDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: [A] = [A()]
     }
@@ -202,42 +218,58 @@ extension HelpGenerationTests {
     }
 
     struct BareNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "bare-no-default")
+
       @Argument(help: "example")
       var arg0: A
     }
 
     struct BareDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "bare-default")
+
       @Argument(help: "example")
       var arg0: A = A()
     }
 
     struct OptionalNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-no-default")
+
       @Argument(help: "example")
       var arg0: A?
     }
 
     struct OptionalDefaultNil: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-default-nil")
+
       @Argument(help: "example")
       var arg0: A? = nil
     }
 
     @available(*, deprecated, message: "Included for test coverage")
     struct OptionalDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-default")
+
       @Argument(help: "example")
       var arg0: A? = A()
     }
 
     struct ArrayNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-no-default")
+
       @Argument(help: "example")
       var arg0: [A]
     }
 
     struct ArrayDefaultEmpty: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-default-empty")
+
       @Argument(help: "example")
       var arg0: [A] = []
     }
 
     struct ArrayDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-default")
+
       @Argument(help: "example")
       var arg0: [A] = [A()]
     }
@@ -367,41 +399,57 @@ extension HelpGenerationTests {
     }
 
     struct BareNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "bare-no-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A
     }
 
     struct BareDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "bare-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A = A()
     }
 
     struct OptionalNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-no-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A?
     }
 
     struct OptionalDefaultNil: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-default-nil")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A? = nil
     }
 
     struct OptionalDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "optional-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: A? = A()
     }
 
     struct ArrayNoDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-no-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: [A]
     }
 
     struct ArrayDefaultEmpty: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-default-empty")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: [A] = []
     }
 
     struct ArrayDefault: ParsableCommand {
+      static let configuration = CommandConfiguration(commandName: "array-default")
+
       @Argument(help: "example", transform: { _ in A() })
       var arg0: [A] = [A()]
     }