Hide option group with new OptionGroup constructor

Sources/ArgumentParser/Parsable Properties/Argument.swift

@@ -27,7 +27,8 @@ public struct Argument<Value>:
   Decodable, ParsedWrapper
 {
   internal var _parsedValue: Parsed<Value>
-
+  internal var _hiddenFromHelp: Bool = false
+
   internal init(_parsedValue: Parsed<Value>) {
     self._parsedValue = _parsedValue
   }

Sources/ArgumentParser/Parsable Properties/Flag.swift

@@ -39,7 +39,8 @@
 @propertyWrapper
 public struct Flag<Value>: Decodable, ParsedWrapper {
   internal var _parsedValue: Parsed<Value>
-
+  internal var _hiddenFromHelp: Bool = false
+
   internal init(_parsedValue: Parsed<Value>) {
     self._parsedValue = _parsedValue
   }

Sources/ArgumentParser/Parsable Properties/Option.swift

@@ -29,7 +29,8 @@
 @propertyWrapper
 public struct Option<Value>: Decodable, ParsedWrapper {
   internal var _parsedValue: Parsed<Value>
-
+  internal var _hiddenFromHelp: Bool = false
+
   internal init(_parsedValue: Parsed<Value>) {
     self._parsedValue = _parsedValue
   }

Sources/ArgumentParser/Parsable Properties/OptionGroup.swift

@@ -31,6 +31,7 @@
 @propertyWrapper
 public struct OptionGroup<Value: ParsableArguments>: Decodable, ParsedWrapper {
   internal var _parsedValue: Parsed<Value>
+  internal var _hiddenFromHelp: Bool = false
 
   internal init(_parsedValue: Parsed<Value>) {
     self._parsedValue = _parsedValue
@@ -88,3 +89,11 @@ extension OptionGroup: CustomStringConvertible {
     }
   }
 }
+
+// Experimental use with caution
+extension OptionGroup {
+    public init(_hiddenFromHelp: Bool) {
+        self.init()
+        self._hiddenFromHelp = _hiddenFromHelp
+    }
+}

Sources/ArgumentParser/Parsable Types/ParsableArguments.swift

@@ -229,10 +229,12 @@ func nilOrValue(_ value: Any) -> Any? {
 /// the argument set that they define.
 protocol ArgumentSetProvider {
   func argumentSet(for key: InputKey) -> ArgumentSet
+
+  var _hiddenFromHelp: Bool { get }
 }
 
 extension ArgumentSet {
-  init(_ type: ParsableArguments.Type) {
+  init(_ type: ParsableArguments.Type, creatingHelp: Bool = false) {
 
     #if DEBUG
     do {
@@ -248,6 +250,10 @@ extension ArgumentSet {
         guard var codingKey = child.label else { return nil }
 
         if let parsed = child.value as? ArgumentSetProvider {
+          if creatingHelp {
+            guard !parsed._hiddenFromHelp else { return nil }
+          }
+
           // Property wrappers have underscore-prefixed names
           codingKey = String(codingKey.first == "_"
                               ? codingKey.dropFirst(1)

Sources/ArgumentParser/Usage/HelpGenerator.swift

@@ -149,7 +149,7 @@ internal struct HelpGenerator {
       return []
     }
 
-    let args = Array(ArgumentSet(commandType))
+    let args = Array(ArgumentSet(commandType, creatingHelp: true))
 
     var i = 0
     while i < args.count {

Tests/ArgumentParserUnitTests/HelpGenerationTests.swift

@@ -473,4 +473,36 @@ extension HelpGenerationTests {
 
     """)
   }
+
+  struct optionsToHide: ParsableArguments {
+    @Flag(help: "Verbose")
+    var verbose: Bool = false
+
+    @Option(help: "Custom Name")
+    var customName: String?
+  }
+
+  struct HideDriver: ParsableCommand {
+    static let configuration = CommandConfiguration(commandName: "driver", abstract: "Demo hiding option groups")
+
+    @OptionGroup(_hiddenFromHelp: true)
+    var hideMe: optionsToHide
+
+    @Option(help: "Time to wait before timeout (in seconds)")
+    var timeout: Int?
+  }
+
+  func testHidingOptionGroup() throws {
+    AssertHelp(for: HideDriver.self, equals: """
+        OVERVIEW: Demo hiding option groups
+
+        USAGE: driver [--verbose] [--custom-name <custom-name>] [--timeout <timeout>]
+
+        OPTIONS:
+          --timeout <timeout>     Time to wait before timeout (in seconds)
+          -h, --help              Show help information.
+
+        """
+    )
+  }
 }