Merge pull request #2359 from DougGregor/with-optional-code-block

Add WithOptionalCodeBlock trait and adopt it where there's a body

Author: DougGregor

CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift

@@ -82,7 +82,10 @@ public let DECL_NODES: [Node] = [
     base: .decl,
     nameForDiagnostics: "accessor",
     parserFunction: "parseAccessorDecl",
-    traits: ["WithAttributes"],
+    traits: [
+      "WithOptionalCodeBlock",
+      "WithAttributes",
+    ],
     children: [
       Child(
         name: "attributes",
@@ -493,6 +496,7 @@ public let DECL_NODES: [Node] = [
     traits: [
       "WithAttributes",
       "WithModifiers",
+      "WithOptionalCodeBlock",
     ],
     children: [
       Child(
@@ -879,6 +883,7 @@ public let DECL_NODES: [Node] = [
       "WithAttributes",
       "WithGenericParameters",
       "WithModifiers",
+      "WithOptionalCodeBlock",
     ],
     children: [
       Child(
@@ -1217,6 +1222,7 @@ public let DECL_NODES: [Node] = [
       "WithAttributes",
       "WithGenericParameters",
       "WithModifiers",
+      "WithOptionalCodeBlock",
     ],
     children: [
       Child(

CodeGeneration/Sources/SyntaxSupport/Traits.swift

@@ -151,6 +151,12 @@ public let TRAITS: [Trait] = [
       Child(name: "modifiers", kind: .node(kind: .declModifierList))
     ]
   ),
+  Trait(
+    traitName: "WithOptionalCodeBlock",
+    children: [
+      Child(name: "body", kind: .node(kind: .codeBlock), isOptional: true)
+    ]
+  ),
   Trait(
     traitName: "WithStatements",
     children: [

Release Notes/511.md

@@ -20,6 +20,10 @@
   - Description: Enum to exhaustively switch over all different syntax nodes of each base type.
   - Pull Request: https://github.com/apple/swift-syntax/pull/2351
 
+- `WithOptionalCodeBlock`
+  - Description: A trait for syntax nodes that have an optional code block, such as `FunctionDeclSyntax` and `InitializerDeclSyntax`.
+  - Pull Request: https://github.com/apple/swift-syntax/pull/2359
+
 ## API Behavior Changes
 
 ## Deprecations

Sources/SwiftSyntax/Documentation.docc/generated/SwiftSyntax.md

@@ -401,6 +401,7 @@ These articles are intended for developers wishing to contribute to SwiftSyntax
 - <doc:SwiftSyntax/WithCodeBlockSyntax>
 - <doc:SwiftSyntax/WithGenericParametersSyntax>
 - <doc:SwiftSyntax/WithModifiersSyntax>
+- <doc:SwiftSyntax/WithOptionalCodeBlockSyntax>
 - <doc:SwiftSyntax/WithStatementsSyntax>
 - <doc:SwiftSyntax/WithTrailingCommaSyntax>
 

Sources/SwiftSyntax/generated/SyntaxTraits.swift

@@ -570,6 +570,43 @@ public extension SyntaxProtocol {
   }
 }
 
+// MARK: - WithOptionalCodeBlockSyntax
+
+
+public protocol WithOptionalCodeBlockSyntax: SyntaxProtocol {
+  var body: CodeBlockSyntax? {
+    get
+    set
+  }
+}
+
+public extension WithOptionalCodeBlockSyntax {
+  /// Without this function, the `with` function defined on `SyntaxProtocol`
+  /// does not work on existentials of this protocol type.
+  @_disfavoredOverload
+  func with<T>(_ keyPath: WritableKeyPath<WithOptionalCodeBlockSyntax, T>, _ newChild: T) -> WithOptionalCodeBlockSyntax {
+    var copy: WithOptionalCodeBlockSyntax = self
+    copy[keyPath: keyPath] = newChild
+    return copy
+  }
+}
+
+public extension SyntaxProtocol {
+  /// Check whether the non-type erased version of this syntax node conforms to
+  /// `WithOptionalCodeBlockSyntax`.
+  /// Note that this will incur an existential conversion.
+  func isProtocol(_: WithOptionalCodeBlockSyntax.Protocol) -> Bool {
+    return self.asProtocol(WithOptionalCodeBlockSyntax.self) != nil
+  }
+  
+  /// Return the non-type erased version of this syntax node if it conforms to
+  /// `WithOptionalCodeBlockSyntax`. Otherwise return `nil`.
+  /// Note that this will incur an existential conversion.
+  func asProtocol(_: WithOptionalCodeBlockSyntax.Protocol) -> WithOptionalCodeBlockSyntax? {
+    return Syntax(self).asProtocol(SyntaxProtocol.self) as? WithOptionalCodeBlockSyntax
+  }
+}
+
 // MARK: - WithStatementsSyntax
 
 
@@ -649,7 +686,7 @@ public extension SyntaxProtocol {
 
 extension AccessorBlockSyntax: BracedSyntax {}
 
-extension AccessorDeclSyntax: WithAttributesSyntax {}
+extension AccessorDeclSyntax: WithOptionalCodeBlockSyntax, WithAttributesSyntax {}
 
 extension AccessorEffectSpecifiersSyntax: EffectSpecifiersSyntax {}
 
@@ -693,7 +730,7 @@ extension DeclNameArgumentsSyntax: ParenthesizedSyntax {}
 
 extension DeferStmtSyntax: WithCodeBlockSyntax {}
 
-extension DeinitializerDeclSyntax: WithAttributesSyntax, WithModifiersSyntax {}
+extension DeinitializerDeclSyntax: WithAttributesSyntax, WithModifiersSyntax, WithOptionalCodeBlockSyntax {}
 
 extension DictionaryElementSyntax: WithTrailingCommaSyntax {}
 
@@ -723,7 +760,7 @@ extension ExtensionDeclSyntax: DeclGroupSyntax, WithAttributesSyntax, WithModifi
 
 extension ForStmtSyntax: WithCodeBlockSyntax {}
 
-extension FunctionDeclSyntax: NamedDeclSyntax, WithAttributesSyntax, WithGenericParametersSyntax, WithModifiersSyntax {}
+extension FunctionDeclSyntax: NamedDeclSyntax, WithAttributesSyntax, WithGenericParametersSyntax, WithModifiersSyntax, WithOptionalCodeBlockSyntax {}
 
 extension FunctionEffectSpecifiersSyntax: EffectSpecifiersSyntax {}
 
@@ -747,7 +784,7 @@ extension ImportDeclSyntax: WithAttributesSyntax, WithModifiersSyntax {}
 
 extension InheritedTypeSyntax: WithTrailingCommaSyntax {}
 
-extension InitializerDeclSyntax: WithAttributesSyntax, WithGenericParametersSyntax, WithModifiersSyntax {}
+extension InitializerDeclSyntax: WithAttributesSyntax, WithGenericParametersSyntax, WithModifiersSyntax, WithOptionalCodeBlockSyntax {}
 
 extension LabeledExprSyntax: WithTrailingCommaSyntax {}
 

Sources/SwiftSyntaxBuilder/SyntaxNodeWithBody.swift

@@ -40,11 +40,9 @@ extension SyntaxStringInterpolation {
   }
 }
 
-// MARK: - HasCodeBlock
-
-public protocol HasTrailingCodeBlock {
-  var body: CodeBlockSyntax { get set }
+// MARK: - HasTrailingCodeBlock
 
+public protocol HasTrailingCodeBlock: WithCodeBlockSyntax {
   /// Constructs a syntax node where `header` builds the text of the node before the body in braces and `bodyBuilder` is used to build the node’s body.
   ///
   /// For example, you can construct
@@ -90,11 +88,9 @@ extension ForStmtSyntax: HasTrailingCodeBlock {}
 extension GuardStmtSyntax: HasTrailingCodeBlock {}
 extension WhileStmtSyntax: HasTrailingCodeBlock {}
 
-// MARK: - HasOptionalCodeBlock
-
-public protocol HasTrailingOptionalCodeBlock {
-  var body: CodeBlockSyntax? { get set }
+// MARK: - WithOptionalCodeBlockSyntax
 
+public extension WithOptionalCodeBlockSyntax where Self: DeclSyntaxProtocol {
   /// Constructs a syntax node where `header` builds the text of the node before the body in braces and `bodyBuilder` is used to build the node’s body.
   ///
   /// For example, you can construct
@@ -114,10 +110,6 @@ public protocol HasTrailingOptionalCodeBlock {
   /// ```
   ///
   /// Throws an error if `header` defines a different node type than the type the initializer is called on. E.g. if calling `try FunctionDeclSyntax("init") {}`
-  init(_ header: SyntaxNodeString, @CodeBlockItemListBuilder bodyBuilder: () throws -> CodeBlockItemListSyntax) throws
-}
-
-public extension HasTrailingOptionalCodeBlock where Self: DeclSyntaxProtocol {
   init(_ header: SyntaxNodeString, @CodeBlockItemListBuilder bodyBuilder: () throws -> CodeBlockItemListSyntax) throws {
     let decl = DeclSyntax("\(header) {}")
     guard let castedDecl = decl.as(Self.self) else {
@@ -128,11 +120,6 @@ public extension HasTrailingOptionalCodeBlock where Self: DeclSyntaxProtocol {
   }
 }
 
-extension AccessorDeclSyntax: HasTrailingOptionalCodeBlock {}
-extension DeinitializerDeclSyntax: HasTrailingOptionalCodeBlock {}
-extension FunctionDeclSyntax: HasTrailingOptionalCodeBlock {}
-extension InitializerDeclSyntax: HasTrailingOptionalCodeBlock {}
-
 // MARK: HasTrailingMemberDeclBlock
 
 public protocol HasTrailingMemberDeclBlock {