Fix @CasePathable when using Element generic. (#183)

* Fix @CasePathable when using Eement generic.

* wip

Package.resolved

@@ -23,17 +23,17 @@
  "kind" : "remoteSourceControl",
  "location" : "https://github.com/pointfreeco/swift-macro-testing",
  "state" : {
- "revision" : "5c4a1b9d7c23cd5c08ea50677d8e89080365cb00",
- "version" : "0.4.0"
+ "revision" : "a35257b7e9ce44e92636447003a8eeefb77b145c",
+ "version" : "0.5.1"
  }
  },
  {
  "identity" : "swift-snapshot-testing",
  "kind" : "remoteSourceControl",
  "location" : "https://github.com/pointfreeco/swift-snapshot-testing",
  "state" : {
- "revision" : "625ccca8570773dd84a34ee51a81aa2bc5a4f97a",
- "version" : "1.16.0"
+ "revision" : "c097f955b4e724690f0fc8ffb7a6d4b881c9c4e3",
+ "version" : "1.17.2"
  }
  },
  {

Sources/CasePaths/Macros.swift

@@ -26,7 +26,7 @@
 /// \UserAction.Cases.settings // CasePath<UserAction, SettingsAction>
 /// ```
 @attached(extension, conformances: CasePathable, CasePathIterable)
-@attached(member, names: named(AllCasePaths), named(allCasePaths))
+@attached(member, names: named(AllCasePaths), named(allCasePaths), named(_$Element))
 public macro CasePathable() =
  #externalMacro(
  module: "CasePathsMacros", type: "CasePathableMacro"

Sources/CasePathsMacros/CasePathableMacro.swift

@@ -98,7 +98,7 @@ extension CasePathableMacro: MemberMacro {
 
  let subscriptReturn = allCases.isEmpty ? #"\.never"# : #"return \.never"#
 
- return [
+ var decls: [DeclSyntax] = [
  """
  public struct AllCasePaths: CasePaths.CasePathReflectable, Sendable, Sequence {
  public subscript(root: \(enumName)) -> CasePaths.PartialCaseKeyPath<\(enumName)> {
@@ -115,6 +115,15 @@ extension CasePathableMacro: MemberMacro {
  public static var allCasePaths: AllCasePaths { AllCasePaths() }
  """
  ]
+
+ let hasElementGeneric = enumDecl.genericParameterClause?.parameters
+ .contains { $0.name.text == "Element" }
+ ?? false
+ if hasElementGeneric {
+ decls.append("public typealias _$Element = Element")
+ }
+
+ return decls
  }
 
  static func generateCases(
@@ -170,7 +179,9 @@ extension CasePathableMacro: MemberMacro {
  ) -> [DeclSyntax] {
  decl.elements.map {
  let caseName = $0.name.trimmed
- let associatedValueName = $0.trimmedTypeDescription
+ let associatedValueName = $0.trimmedTypeDescription == "Element"
+ ? "_$Element"
+ : $0.trimmedTypeDescription
  let hasPayload = $0.parameterClause.map { !$0.parameters.isEmpty } ?? false
  let embedNames: String
  let bindingNames: String

Tests/CasePathsMacrosTests/CasePathableMacroTests.swift

@@ -6,7 +6,7 @@ import XCTest
 final class CasePathableMacroTests: XCTestCase {
  override func invokeTest() {
  withMacroTesting(
- // isRecording: true,
+ //record: .failed,
  macros: [CasePathableMacro.self]
  ) {
  super.invokeTest()
@@ -1215,4 +1215,53 @@ final class CasePathableMacroTests: XCTestCase {
  """#
  }
  }
+
+ func testElementGeneric() {
+ assertMacro {
+ """
+ @CasePathable enum Action<Element> {
+ case element(Element)
+ }
+ """
+ } expansion: {
+ #"""
+ enum Action<Element> {
+ case element(Element)
+
+ public struct AllCasePaths: CasePaths.CasePathReflectable, Sendable, Sequence {
+ public subscript(root: Action) -> CasePaths.PartialCaseKeyPath<Action> {
+ if root.is(\.element) {
+ return \.element
+ }
+ return \.never
+ }
+ public var element: CasePaths.AnyCasePath<Action, _$Element> {
+ CasePaths.AnyCasePath<Action, _$Element>(
+ embed: {
+ Action.element($0)
+ },
+ extract: {
+ guard case let .element(v0) = $0 else {
+ return nil
+ }
+ return v0
+ }
+ )
+ }
+ public func makeIterator() -> IndexingIterator<[CasePaths.PartialCaseKeyPath<Action>]> {
+ var allCasePaths: [CasePaths.PartialCaseKeyPath<Action>] = []
+ allCasePaths.append(\.element)
+ return allCasePaths.makeIterator()
+ }
+ }
+ public static var allCasePaths: AllCasePaths { AllCasePaths() }
+
+ public typealias _$Element = Element
+ }
+
+ extension Action: CasePaths.CasePathable, CasePaths.CasePathIterable {
+ }
+ """#
+ }
+ }
 }

Tests/CasePathsTests/MacroTests.swift

@@ -14,3 +14,7 @@ private enum Comments {
 enum Action {
  case alert(Never)
 }
+
+@CasePathable enum EnumWithElementGeneric<Element> {
+ case element(Element)
+}