Stop removing underscores from CodingKey names in InputKey (#548)

When a property wrapper is applied to a property, the property's
storage is given a name with a prefixed underscore. That is,
for a property named `x`, the actual storage is named `_x`.

That prefixed storage is what is visible through reflection, so
when building an ArgumentSet from a command type's Mirror, we
need to remove the leading underscore. This is done when creating
an InputKey for each property.

However, InputKeys are also created from CodingKeys during
decoding of a ParsableCommand. These CodingKeys _do not_ have
the leading underscore that is visible, so any underscores
that appear are actually from the declaration of the property
with an underscored name. Removing leading underscores from
CodingKey names results in a mismatch when trying to find
the decoded value.

This change simplifies the InputKey type to use an array
path instead of an indirect enum and removes the leading
underscore dropping when creating an InputKey from a CodingKey.

rdar://104928743

Author: natecook1000

Sources/ArgumentParser/Completions/BashCompletionsGenerator.swift

@@ -132,7 +132,7 @@ struct BashCompletionsGenerator {
   ///
   /// These consist of completions that are defined as `.list` or `.custom`.
   fileprivate static func generateArgumentCompletions(_ commands: [ParsableCommand.Type]) -> [String] {
-    ArgumentSet(commands.last!, visibility: .default, parent: .root)
+    ArgumentSet(commands.last!, visibility: .default, parent: nil)
       .compactMap { arg -> String? in
         guard arg.isPositional else { return nil }
 
@@ -159,7 +159,7 @@ struct BashCompletionsGenerator {
 
   /// Returns the case-matching statements for supplying completions after an option or flag.
   fileprivate static func generateOptionHandlers(_ commands: [ParsableCommand.Type]) -> String {
-    ArgumentSet(commands.last!, visibility: .default, parent: .root)
+    ArgumentSet(commands.last!, visibility: .default, parent: nil)
       .compactMap { arg -> String? in
         let words = arg.bashCompletionWords()
         if words.isEmpty { return nil }

Sources/ArgumentParser/Parsable Properties/Flag.swift

@@ -396,7 +396,7 @@ extension Flag where Value: EnumerableFlag {
       // flag, the default value to show to the user is the `--value-name`
       // flag that a user would provide on the command line, not a Swift value.
       let defaultValueFlag = initial.flatMap { value -> String? in
-        let defaultKey = InputKey(name: String(describing: value), parent: .key(key))
+        let defaultKey = InputKey(name: String(describing: value), parent: key)
         let defaultNames = Value.name(for: value).makeNames(defaultKey)
         return defaultNames.first?.synopsisString
       }
@@ -405,7 +405,7 @@ extension Flag where Value: EnumerableFlag {
       let hasCustomCaseHelp = caseHelps.contains(where: { $0 != nil })
 
       let args = Value.allCases.enumerated().map { (i, value) -> ArgumentDefinition in
-        let caseKey = InputKey(name: String(describing: value), parent: .key(key))
+        let caseKey = InputKey(name: String(describing: value), parent: key)
         let name = Value.name(for: value)
 
         let helpForCase = caseHelps[i] ?? help
@@ -519,7 +519,7 @@ extension Flag {
       let hasCustomCaseHelp = caseHelps.contains(where: { $0 != nil })
 
       let args = Element.allCases.enumerated().map { (i, value) -> ArgumentDefinition in
-        let caseKey = InputKey(name: String(describing: value), parent: .key(parentKey))
+        let caseKey = InputKey(name: String(describing: value), parent: parentKey)
         let name = Element.name(for: value)
         let helpForCase = hasCustomCaseHelp ? (caseHelps[i] ?? help) : help
 
@@ -552,7 +552,7 @@ extension Flag {
       let hasCustomCaseHelp = caseHelps.contains(where: { $0 != nil })
 
       let args = Element.allCases.enumerated().map { (i, value) -> ArgumentDefinition in
-        let caseKey = InputKey(name: String(describing: value), parent: .key(parentKey))
+        let caseKey = InputKey(name: String(describing: value), parent: parentKey)
         let name = Element.name(for: value)
         let helpForCase = hasCustomCaseHelp ? (caseHelps[i] ?? help) : help
         let help = ArgumentDefinition.Help(

Sources/ArgumentParser/Parsable Properties/NameSpecification.swift

@@ -167,7 +167,7 @@ extension FlagInversion {
         case .short, .customShort:
           return includingShort ? element.name(for: key) : nil
         case .long:
-          let modifiedKey = key.with(newName: key.name.addingIntercappedPrefix(prefix))
+          let modifiedKey = InputKey(name: key.name.addingIntercappedPrefix(prefix), parent: key)
           return element.name(for: modifiedKey)
         case .customLong(let name, let withSingleDash):
           let modifiedName = name.addingPrefixWithAutodetectedStyle(prefix)

Sources/ArgumentParser/Parsable Properties/OptionGroup.swift

@@ -78,7 +78,7 @@ public struct OptionGroup<Value: ParsableArguments>: Decodable, ParsedWrapper {
     visibility: ArgumentVisibility = .default
   ) {
     self.init(_parsedValue: .init { parentKey in
-      var args = ArgumentSet(Value.self, visibility: .private, parent: .key(parentKey))
+      var args = ArgumentSet(Value.self, visibility: .private, parent: parentKey)
       args.content.withEach {
         $0.help.parentTitle = title
       }

Sources/ArgumentParser/Parsable Types/ParsableArguments.swift

@@ -248,7 +248,7 @@ extension ArgumentSetProvider {
 }
 
 extension ArgumentSet {
-  init(_ type: ParsableArguments.Type, visibility: ArgumentVisibility, parent: InputKey.Parent) {
+  init(_ type: ParsableArguments.Type, visibility: ArgumentVisibility, parent: InputKey?) {
     #if DEBUG
     do {
       try type._validate(parent: parent)

Sources/ArgumentParser/Parsable Types/ParsableArgumentsValidation.swift

@@ -10,7 +10,7 @@
 //===----------------------------------------------------------------------===//
 
 fileprivate protocol ParsableArgumentsValidator {
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError?
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError?
 }
 
 enum ValidatorErrorKind {
@@ -37,7 +37,7 @@ struct ParsableArgumentsValidationError: Error, CustomStringConvertible {
 }
 
 extension ParsableArguments {
-  static func _validate(parent: InputKey.Parent) throws {
+  static func _validate(parent: InputKey?) throws {
     let validators: [ParsableArgumentsValidator.Type] = [
       PositionalArgumentsValidator.self,
       ParsableArgumentsCodingKeyValidator.self,
@@ -80,7 +80,7 @@ struct PositionalArgumentsValidator: ParsableArgumentsValidator {
     var kind: ValidatorErrorKind { .failure }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let sets: [ArgumentSet] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in
@@ -190,7 +190,7 @@ struct ParsableArgumentsCodingKeyValidator: ParsableArgumentsValidator {
     }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let argumentKeys: [InputKey] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in
@@ -235,7 +235,7 @@ struct ParsableArgumentsUniqueNamesValidator: ParsableArgumentsValidator {
     var kind: ValidatorErrorKind { .failure }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let argSets: [ArgumentSet] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in
@@ -283,7 +283,7 @@ struct NonsenseFlagsValidator: ParsableArgumentsValidator {
     var kind: ValidatorErrorKind { .warning }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let argSets: [ArgumentSet] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in

Sources/ArgumentParser/Parsable Types/ParsableCommand.swift

@@ -166,7 +166,7 @@ extension ParsableCommand {
   /// `true` if this command contains any array arguments that are declared
   /// with `.unconditionalRemaining`.
   internal static var includesUnconditionalArguments: Bool {
-    ArgumentSet(self, visibility: .private, parent: .root).contains(where: {
+    ArgumentSet(self, visibility: .private, parent: nil).contains(where: {
       $0.isRepeatingPositional && $0.parsingStrategy == .allRemainingInput
     })
   }

Sources/ArgumentParser/Parsing/ArgumentDefinition.swift

@@ -217,7 +217,7 @@ extension ArgumentDefinition {
   ///
   /// This initializer is used for any property defined on a `ParsableArguments`
   /// type that isn't decorated with one of ArgumentParser's property wrappers.
-  init(unparsedKey: String, default defaultValue: Any?, parent: InputKey.Parent) {
+  init(unparsedKey: String, default defaultValue: Any?, parent: InputKey?) {
     self.init(
       container: Bare<Any>.self,
       key: InputKey(name: unparsedKey, parent: parent),

Sources/ArgumentParser/Parsing/ArgumentSet.swift

@@ -438,7 +438,7 @@ extension ArgumentSet {
   func firstPositional(
     named name: String
   ) -> ArgumentDefinition? {
-    let key = InputKey(name: name, parent: .root)
+    let key = InputKey(name: name, parent: nil)
     return first(where: { $0.help.keys.contains(key) })
   }
 

Sources/ArgumentParser/Parsing/CommandParser.swift

@@ -140,7 +140,7 @@ extension CommandParser {
   /// possible.
   fileprivate mutating func parseCurrent(_ split: inout SplitArguments) throws -> ParsableCommand {
     // Build the argument set (i.e. information on how to parse):
-    let commandArguments = ArgumentSet(currentNode.element, visibility: .private, parent: .root)
+    let commandArguments = ArgumentSet(currentNode.element, visibility: .private, parent: nil)
 
     // Parse the arguments, ignoring anything unexpected
     let values = try commandArguments.lenientParse(
@@ -325,7 +325,7 @@ extension CommandParser {
     let completionValues = Array(args)
 
     // Generate the argument set and parse the argument to find in the set
-    let argset = ArgumentSet(current.element, visibility: .private, parent: .root)
+    let argset = ArgumentSet(current.element, visibility: .private, parent: nil)
     let parsedArgument = try! parseIndividualArg(argToMatch, at: 0).first!
 
     // Look up the specified argument and retrieve its custom completion function