Fix renaming enum case parameters with unnamed associated arguments

We treated enum case parameters the same way as function parameters and weren’t considering that they can be unlabeled. That caused us to insert eg. `_ ` in front of the case’s type, producing `case myCase(_ String)`, which is invalid. Report `enumCaseParameters` as a special parameter kind so that sourcekitd can work with it.

swiftlang/sourcekit-lsp#1228

Author: ahoppen

Sources/SwiftIDEUtils/DeclNameLocation.swift

@@ -102,6 +102,12 @@ public struct DeclNameLocation: Equatable {
     /// The parameter of a function declaration, like `func foo(a b: Int)`
     case parameters([Argument])
 
+    /// An enum case declaration like `case myCase(label: String)`.
+    ///
+    /// For enum case parameters the argument label is removed when set to empty instead of being changed to eg.
+    /// `myCase(_ label: String)`
+    case enumCaseParameters([Argument])
+
     /// Same as `param` but the parameters can't be collapsed if they are the same. This is the case for subscript
     /// declarations.
     ///
@@ -123,6 +129,8 @@ public struct DeclNameLocation: Equatable {
         )
       case .parameters(let parameters):
         return .parameters(parameters.map { $0.advanced(by: utf8Offset) })
+      case .enumCaseParameters(let parameters):
+        return .enumCaseParameters(parameters.map { $0.advanced(by: utf8Offset) })
       case .noncollapsibleParameters(let parameters):
         return .noncollapsibleParameters(parameters.map { $0.advanced(by: utf8Offset) })
       case .selector(let arguments):

Sources/SwiftIDEUtils/NameMatcher.swift

@@ -298,7 +298,7 @@ public class NameMatcher: SyntaxAnyVisitor {
           return .unlabeled(argument: Syntax(argument.secondName) ?? Syntax(argument.colon) ?? Syntax(argument.type))
         }
       }
-      addResolvedLocIfRequested(baseName: node.name, argumentLabels: .parameters(argumentLabels))
+      addResolvedLocIfRequested(baseName: node.name, argumentLabels: .enumCaseParameters(argumentLabels))
     }
     return .visitChildren
   }

Tests/SwiftIDEUtilsTest/NameMatcherTests.swift

@@ -51,6 +51,7 @@ private func assertNameMatcherResult(
     case .noArguments: argumentLabels = []
     case .call(let labels, _): argumentLabels = labels
     case .parameters(let labels): argumentLabels = labels
+    case .enumCaseParameters(let labels): argumentLabels = labels
     case .noncollapsibleParameters(let labels): argumentLabels = labels
     case .selector(let labels): argumentLabels = labels
     }
@@ -75,6 +76,7 @@ private struct DeclNameLocationSpec {
     case noArguments
     case call
     case parameters
+    case enumCaseParameters
     case noncollapsibleParameters
     case selector
 
@@ -83,6 +85,7 @@ private struct DeclNameLocationSpec {
       case .noArguments: self = .noArguments
       case .call: self = .call
       case .parameters: self = .parameters
+      case .enumCaseParameters: self = .enumCaseParameters
       case .noncollapsibleParameters: self = .noncollapsibleParameters
       case .selector: self = .selector
       }
@@ -326,4 +329,56 @@ class NameMatcherTests: XCTestCase {
       ]
     )
   }
+
+  func testEnumCaseParameterWithLabels() {
+    assertNameMatcherResult(
+      """
+      enum MyEnum {
+        case 1️⃣myCase(label: String)
+      }
+      """,
+      expected: [
+        DeclNameLocationSpec(baseName: "myCase", argumentLabels: ["label"], type: .enumCaseParameters)
+      ]
+    )
+  }
+
+  func testEnumCaseParameterWithoutLabels() {
+    assertNameMatcherResult(
+      """
+      enum MyEnum {
+        case 1️⃣myCase(String)
+      }
+      """,
+      expected: [
+        DeclNameLocationSpec(baseName: "myCase", argumentLabels: [""], type: .enumCaseParameters)
+      ]
+    )
+  }
+
+  func testEnumCaseParameterWithoutAssociatedValues() {
+    assertNameMatcherResult(
+      """
+      enum MyEnum {
+        case 1️⃣myCase
+      }
+      """,
+      expected: [
+        DeclNameLocationSpec(baseName: "myCase", argumentLabels: [], type: .noArguments)
+      ]
+    )
+  }
+
+  func testEnumCaseParameterWithoutWildcardAsExternalLabel() {
+    assertNameMatcherResult(
+      """
+      enum MyEnum {
+        case 1️⃣myCase(_ label: String)
+      }
+      """,
+      expected: [
+        DeclNameLocationSpec(baseName: "myCase", argumentLabels: ["_ label"], type: .enumCaseParameters)
+      ]
+    )
+  }
 }