Convert implicitly unwrapped optionals to proper optionals #1320

- created ConvertIUOToProperOptional that will suggest a conversion when the token in concern is
    - an IUO;
    - a direct child of an IUO; or
    - a direct child of the wrappedType of an IUO.
- registered in SyntaxCodeActions.allSyntaxCodeActions
- added a test in CodeActionTests
- added ConvertIUOToProperOptional.swift to CMakeLists of SourceKitLSP

Author: AppAppWorks

Sources/SourceKitLSP/CMakeLists.txt

@@ -30,6 +30,7 @@ target_sources(SourceKitLSP PRIVATE
   Swift/AdjustPositionToStartOfIdentifier.swift
   Swift/CodeActions/AddDocumentation.swift
   Swift/CodeActions/ConvertIntegerLiteral.swift
+  Swift/CodeActions/ConvertIUOToProperOptional.swift
   Swift/CodeActions/ConvertJSONToCodableStruct.swift
   Swift/CodeActions/PackageManifestEdits.swift
   Swift/CodeActions/SyntaxCodeActionProvider.swift

Sources/SourceKitLSP/Swift/CodeActions/ConvertIUOToProperOptional.swift

@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import LanguageServerProtocol
+import SwiftRefactor
+import SwiftSyntax
+
+/// Convert implicitly unwrapped optionals (IUOs) to proper optionals
+@_spi(Testing)
+public struct ConvertIUOToProperOptional: SyntaxRefactoringProvider {
+  public typealias Input = ImplicitlyUnwrappedOptionalTypeSyntax
+  public typealias Context = Void
+  public typealias Output = OptionalTypeSyntax
+
+  @_spi(Testing)
+  public static func refactor(syntax: Input, in context: Context) -> Output? {
+    OptionalTypeSyntax(
+      leadingTrivia: syntax.leadingTrivia,
+      syntax.unexpectedBeforeWrappedType,
+      wrappedType: syntax.wrappedType,
+      syntax.unexpectedBetweenWrappedTypeAndExclamationMark,
+      questionMark: .postfixQuestionMarkToken(
+        leadingTrivia: syntax.exclamationMark.leadingTrivia,
+        trailingTrivia: syntax.exclamationMark.trailingTrivia
+      )
+    )
+  }
+}
+
+extension ConvertIUOToProperOptional: SyntaxRefactoringCodeActionProvider {
+  static let title: String = "Convert Implicitly Unwrapped Optional to Proper Optional"
+
+  static func nodeToRefactor(in scope: SyntaxCodeActionScope) -> Input? {
+    guard let token = scope.innermostNodeContainingRange else {
+      return nil
+    }
+
+    return if let iuoType = token.as(Input.self) ?? token.parent?.as(Input.self) {
+      iuoType
+    } else if token.is(TokenSyntax.self),
+      let wrappedType = token.parent?.as(TypeSyntax.self),
+      let iuoType = wrappedType.parent?.as(Input.self),
+      iuoType.wrappedType == wrappedType
+    {
+      iuoType
+    } else {
+      nil
+    }
+  }
+}

Sources/SourceKitLSP/Swift/CodeActions/SyntaxCodeActions.swift

@@ -18,6 +18,7 @@ let allSyntaxCodeActions: [SyntaxCodeActionProvider.Type] = [
   AddDocumentation.self,
   AddSeparatorsToIntegerLiteral.self,
   ConvertIntegerLiteral.self,
+  ConvertIUOToProperOptional.self,
   ConvertJSONToCodableStruct.self,
   FormatRawStringLiteral.self,
   MigrateToNewIfLetSyntax.self,

Tests/SourceKitLSPTests/CodeActionTests.swift

@@ -1006,6 +1006,34 @@ final class CodeActionTests: XCTestCase {
     }
   }
 
+  func testConvertIUOToProperOptional() async throws {
+    try await assertCodeActions(
+      """
+      func (a: 1️⃣(String, /* tuple */ Int)!2️⃣/*tra3️⃣iling*/4️⃣)
+      """,
+      markers: ["1️⃣", "2️⃣", "3️⃣"],
+      ranges: [("1️⃣", "2️⃣"), ("1️⃣", "3️⃣")],
+      exhaustive: false
+    ) { uri, positions in
+      [
+        CodeAction(
+          title: "Convert Implicitly Unwrapped Optional to Proper Optional",
+          kind: .refactorInline,
+          edit: WorkspaceEdit(
+            changes: [
+              uri: [
+                TextEdit(
+                  range: positions["1️⃣"]..<positions["4️⃣"],
+                  newText: "(String, /* tuple */ Int)?/*trailing*/"
+                )
+              ]
+            ]
+          )
+        )
+      ]
+    }
+  }
+
   /// Retrieves the code action at a set of markers and asserts that it matches a list of expected code actions.
   ///
   /// - Parameters: