From e392dea804a48bd74990ab23f79b7fbdba0c3c14 Mon Sep 17 00:00:00 2001
From: Artem Novichkov <artem.novichkov@rosberry.com>
Date: Wed, 10 Jun 2020 09:34:26 +0600
Subject: [PATCH 1/3] Update label for default subcommand

---
 Sources/ArgumentParser/Usage/HelpGenerator.swift | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Sources/ArgumentParser/Usage/HelpGenerator.swift b/Sources/ArgumentParser/Usage/HelpGenerator.swift
index 26ac4301c..44d9b03fc 100644
--- a/Sources/ArgumentParser/Usage/HelpGenerator.swift
+++ b/Sources/ArgumentParser/Usage/HelpGenerator.swift
@@ -213,11 +213,16 @@ internal struct HelpGenerator {
       optionElements.append(.init(label: helpLabels, abstract: "Show help information."))
     }
 
+    let configuration = commandStack.last!.configuration
     let subcommandElements: [Section.Element] =
-      commandStack.last!.configuration.subcommands.compactMap { command in
+      configuration.subcommands.compactMap { command in
         guard command.configuration.shouldDisplay else { return nil }
+        var label = command._commandName
+        if command == configuration.defaultSubcommand {
+            label += " (default)"
+        }
         return Section.Element(
-          label: command._commandName,
+          label: label,
           abstract: command.configuration.abstract)
     }
     

From 337d81f40490e74e5b9ac0a91e25ab8059460df6 Mon Sep 17 00:00:00 2001
From: Artem Novichkov <artem.novichkov@rosberry.com>
Date: Wed, 10 Jun 2020 09:46:13 +0600
Subject: [PATCH 2/3] Add test for default subcommand

---
 .../HelpGenerationTests.swift                 | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift b/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift
index 338ad8baa..48539f452 100644
--- a/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift
+++ b/Tests/ArgumentParserUnitTests/HelpGenerationTests.swift
@@ -377,4 +377,24 @@ extension HelpGenerationTests {
 
     """)
   }
+
+  struct M: ParsableCommand {
+  }
+  struct N: ParsableCommand {
+    static var configuration = CommandConfiguration(subcommands: [M.self], defaultSubcommand: M.self)
+  }
+
+  func testHelpWithDefaultCommand() {
+    AssertHelp(for: N.self, equals: """
+    USAGE: n <subcommand>
+
+    OPTIONS:
+      -h, --help              Show help information.
+
+    SUBCOMMANDS:
+      m (default)
+
+      See 'n help <subcommand>' for detailed help.
+    """)
+  }
 }

From 1cb6cf6e44cd1643a1bfc8fbd434bb26e071632e Mon Sep 17 00:00:00 2001
From: Artem Novichkov <artem.novichkov@rosberry.com>
Date: Thu, 11 Jun 2020 08:36:05 +0600
Subject: [PATCH 3/3] Fix test fixtures with default subcommand help message

---
 Tests/ArgumentParserExampleTests/MathExampleTests.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Tests/ArgumentParserExampleTests/MathExampleTests.swift b/Tests/ArgumentParserExampleTests/MathExampleTests.swift
index cd0761462..7515f9b0a 100644
--- a/Tests/ArgumentParserExampleTests/MathExampleTests.swift
+++ b/Tests/ArgumentParserExampleTests/MathExampleTests.swift
@@ -30,7 +30,7 @@ final class MathExampleTests: XCTestCase {
           -h, --help              Show help information.
 
         SUBCOMMANDS:
-          add                     Print the sum of the values.
+          add (default)           Print the sum of the values.
           multiply                Print the product of the values.
           stats                   Calculate descriptive statistics.