Refactor syntax node manipulation to use variable setters

Examples/Sources/AddOneToIntegerLiterals/AddOneToIntegerLiterals.swift

@@ -31,7 +31,8 @@ private class AddOneToIntegerLiterals: SyntaxRewriter {
     let int = Int(integerText)!
 
     // Create a new integer literal token with `int + 1` as its text.
-    let newIntegerLiteralToken = token.with(\.tokenKind, .integerLiteral("\(int + 1)"))
+    var newIntegerLiteralToken = token
+    newIntegerLiteralToken.tokenKind = .integerLiteral("\(int + 1)")
 
     // Return the new integer literal.
     return newIntegerLiteralToken

Examples/Sources/MacroExamples/Implementation/ComplexMacros/DictionaryIndirectionMacro.swift

@@ -21,10 +21,7 @@ extension DictionaryStorageMacro: MemberMacro {
     providingMembersOf declaration: some DeclGroupSyntax,
     in context: some MacroExpansionContext
   ) throws -> [DeclSyntax] {
-    let storage: DeclSyntax = "var _storage: [String: Any] = [:]"
-    return [
-      storage.with(\.leadingTrivia, [.newlines(1), .spaces(2)])
-    ]
+    return ["\n  var _storage: [String: Any] = [:]"]
   }
 }
 
@@ -43,11 +40,11 @@ extension DictionaryStorageMacro: MemberAttributeMacro {
 
     return [
       AttributeSyntax(
+        leadingTrivia: [.newlines(1), .spaces(2)],
         attributeName: IdentifierTypeSyntax(
           name: .identifier("DictionaryStorageProperty")
         )
       )
-      .with(\.leadingTrivia, [.newlines(1), .spaces(2)])
     ]
   }
 }

Examples/Sources/MacroExamples/Implementation/Expression/AddBlocker.swift

@@ -27,7 +27,7 @@ public struct AddBlocker: ExpressionMacro {
       _ node: InfixOperatorExprSyntax
     ) -> ExprSyntax {
       // Identify any infix operator + in the tree.
-      if let binOp = node.operator.as(BinaryOperatorExprSyntax.self) {
+      if var binOp = node.operator.as(BinaryOperatorExprSyntax.self) {
         if binOp.operator.text == "+" {
           // Form the warning
           let messageID = MessageID(domain: "silly", id: "addblock")
@@ -72,17 +72,9 @@ public struct AddBlocker: ExpressionMacro {
             )
           )
 
-          return ExprSyntax(
-            node.with(
-              \.operator,
-              ExprSyntax(
-                binOp.with(
-                  \.operator,
-                  binOp.operator.with(\.tokenKind, .binaryOperator("-"))
-                )
-              )
-            )
-          )
+          binOp.operator.tokenKind = .binaryOperator("-")
+
+          return ExprSyntax(node.with(\.operator, ExprSyntax(binOp)))
         }
       }
 

Examples/Sources/MacroExamples/Implementation/Expression/FontLiteralMacro.swift

@@ -35,14 +35,12 @@ private func replaceFirstLabel(
   of tuple: LabeledExprListSyntax,
   with newLabel: String
 ) -> LabeledExprListSyntax {
-  guard let firstElement = tuple.first else {
+  if tuple.isEmpty {
     return tuple
   }
 
   var tuple = tuple
-  tuple[tuple.startIndex] =
-    firstElement
-    .with(\.label, .identifier(newLabel))
-    .with(\.colon, .colonToken())
+  tuple[tuple.startIndex].label = .identifier(newLabel)
+  tuple[tuple.startIndex].colon = .colonToken()
   return tuple
 }

Examples/Sources/MacroExamples/Implementation/MemberAttribute/WrapStoredPropertiesMacro.swift

@@ -48,11 +48,11 @@ public struct WrapStoredPropertiesMacro: MemberAttributeMacro {
 
     return [
       AttributeSyntax(
+        leadingTrivia: [.newlines(1), .spaces(2)],
         attributeName: IdentifierTypeSyntax(
           name: .identifier(wrapperName.content.text)
         )
       )
-      .with(\.leadingTrivia, [.newlines(1), .spaces(2)])
     ]
   }
 }

Examples/Sources/MacroExamples/Implementation/Peer/AddAsyncMacro.swift

@@ -30,7 +30,7 @@ public struct AddAsyncMacro: PeerMacro {
   ) throws -> [DeclSyntax] {
 
     // Only on functions at the moment.
-    guard let funcDecl = declaration.as(FunctionDeclSyntax.self) else {
+    guard var funcDecl = declaration.as(FunctionDeclSyntax.self) else {
       throw CustomError.message("@addAsync only works on functions")
     }
 
@@ -42,7 +42,7 @@ public struct AddAsyncMacro: PeerMacro {
     }
 
     // This only makes sense void functions
-    if funcDecl.signature.returnClause?.type.with(\.leadingTrivia, []).with(\.trailingTrivia, []).description != "Void" {
+    if funcDecl.signature.returnClause?.type.as(IdentifierTypeSyntax.self)?.name.text != "Void" {
       throw CustomError.message(
         "@addAsync requires an function that returns void"
       )
@@ -58,7 +58,7 @@ public struct AddAsyncMacro: PeerMacro {
     }
 
     // Completion handler needs to return Void
-    if completionHandlerParameter.returnClause.type.with(\.leadingTrivia, []).with(\.trailingTrivia, []).description != "Void" {
+    if completionHandlerParameter.returnClause.type.as(IdentifierTypeSyntax.self)?.name.text != "Void" {
       throw CustomError.message(
         "@addAsync requires an function that has a completion handler that returns Void"
       )
@@ -72,9 +72,11 @@ public struct AddAsyncMacro: PeerMacro {
     // Remove completionHandler and comma from the previous parameter
     var newParameterList = funcDecl.signature.parameterClause.parameters
     newParameterList.removeLast()
-    let newParameterListLastParameter = newParameterList.last!
+    var newParameterListLastParameter = newParameterList.last!
     newParameterList.removeLast()
-    newParameterList.append(newParameterListLastParameter.with(\.trailingTrivia, []).with(\.trailingComma, nil))
+    newParameterListLastParameter.trailingTrivia = []
+    newParameterListLastParameter.trailingComma = nil
+    newParameterList.append(newParameterListLastParameter)
 
     // Drop the @addAsync attribute from the new declaration.
     let newAttributeList = funcDecl.attributes.filter {
@@ -121,42 +123,36 @@ public struct AddAsyncMacro: PeerMacro {
 
       """
 
-    let newFunc =
-      funcDecl
-      .with(
-        \.signature,
-        funcDecl.signature
-          .with(
-            \.effectSpecifiers,
-            FunctionEffectSpecifiersSyntax(
-              leadingTrivia: .space,
-              asyncSpecifier: .keyword(.async),
-              throwsSpecifier: isResultReturn ? .keyword(.throws) : nil
-            )  // add async
-          )
-          .with(
-            \.returnClause,
-            successReturnType != nil ? ReturnClauseSyntax(leadingTrivia: .space, type: successReturnType!.with(\.leadingTrivia, .space)) : nil
-          )  // add result type
-          .with(
-            \.parameterClause,
-            funcDecl.signature.parameterClause.with(\.parameters, newParameterList)  // drop completion handler
-              .with(\.trailingTrivia, [])
-          )
-      )
-      .with(
-        \.body,
-        CodeBlockSyntax(
-          leftBrace: .leftBraceToken(leadingTrivia: .space),
-          statements: CodeBlockItemListSyntax(
-            [CodeBlockItemSyntax(item: .expr(newBody))]
-          ),
-          rightBrace: .rightBraceToken(leadingTrivia: .newline)
-        )
-      )
-      .with(\.attributes, newAttributeList)
-      .with(\.leadingTrivia, .newlines(2))
+    // add async
+    funcDecl.signature.effectSpecifiers = FunctionEffectSpecifiersSyntax(
+      leadingTrivia: .space,
+      asyncSpecifier: .keyword(.async),
+      throwsSpecifier: isResultReturn ? .keyword(.throws) : nil
+    )
+
+    // add result type
+    if let successReturnType {
+      funcDecl.signature.returnClause = ReturnClauseSyntax(leadingTrivia: .space, type: successReturnType.with(\.leadingTrivia, .space))
+    } else {
+      funcDecl.signature.returnClause = nil
+    }
+
+    // drop completion handler
+    funcDecl.signature.parameterClause.parameters = newParameterList
+    funcDecl.signature.parameterClause.trailingTrivia = []
+
+    funcDecl.body = CodeBlockSyntax(
+      leftBrace: .leftBraceToken(leadingTrivia: .space),
+      statements: CodeBlockItemListSyntax(
+        [CodeBlockItemSyntax(item: .expr(newBody))]
+      ),
+      rightBrace: .rightBraceToken(leadingTrivia: .newline)
+    )
+
+    funcDecl.attributes = newAttributeList
+
+    funcDecl.leadingTrivia = .newlines(2)
 
-    return [DeclSyntax(newFunc)]
+    return [DeclSyntax(funcDecl)]
   }
 }

Examples/Sources/MacroExamples/Implementation/Peer/AddCompletionHandlerMacro.swift

@@ -25,20 +25,22 @@ public struct AddCompletionHandlerMacro: PeerMacro {
   ) throws -> [DeclSyntax] {
     // Only on functions at the moment. We could handle initializers as well
     // with a bit of work.
-    guard let funcDecl = declaration.as(FunctionDeclSyntax.self) else {
+    guard var funcDecl = declaration.as(FunctionDeclSyntax.self) else {
       throw CustomError.message("@addCompletionHandler only works on functions")
     }
 
     // This only makes sense for async functions.
     if funcDecl.signature.effectSpecifiers?.asyncSpecifier == nil {
-      let newEffects: FunctionEffectSpecifiersSyntax
+      var newEffects: FunctionEffectSpecifiersSyntax
       if let existingEffects = funcDecl.signature.effectSpecifiers {
-        newEffects = existingEffects.with(\.asyncSpecifier, .keyword(.async))
+        newEffects = existingEffects
+        newEffects.asyncSpecifier = .keyword(.async)
       } else {
         newEffects = FunctionEffectSpecifiersSyntax(asyncSpecifier: .keyword(.async))
       }
 
-      let newSignature = funcDecl.signature.with(\.effectSpecifiers, newEffects)
+      var newSignature = funcDecl.signature
+      newSignature.effectSpecifiers = newEffects
       let messageID = MessageID(domain: "MacroExamples", id: "MissingAsync")
 
       let diag = Diagnostic(
@@ -73,7 +75,9 @@ public struct AddCompletionHandlerMacro: PeerMacro {
     }
 
     // Form the completion handler parameter.
-    let resultType: TypeSyntax? = funcDecl.signature.returnClause?.type.with(\.leadingTrivia, []).with(\.trailingTrivia, [])
+    var resultType = funcDecl.signature.returnClause?.type
+    resultType?.leadingTrivia = []
+    resultType?.trailingTrivia = []
 
     let completionHandlerParam =
       FunctionParameterSyntax(
@@ -85,14 +89,12 @@ public struct AddCompletionHandlerMacro: PeerMacro {
     // Add the completion handler parameter to the parameter list.
     let parameterList = funcDecl.signature.parameterClause.parameters
     var newParameterList = parameterList
-    if let lastParam = parameterList.last {
+    if var lastParam = parameterList.last {
       // We need to add a trailing comma to the preceding list.
       newParameterList.removeLast()
+      lastParam.trailingComma = .commaToken(trailingTrivia: .space)
       newParameterList += [
-        lastParam.with(
-          \.trailingComma,
-          .commaToken(trailingTrivia: .space)
-        ),
+        lastParam,
         completionHandlerParam,
       ]
     } else {
@@ -136,35 +138,28 @@ public struct AddCompletionHandlerMacro: PeerMacro {
       return attributeType.name.text != nodeType.name.text
     }
 
-    let newFunc =
-      funcDecl
-      .with(
-        \.signature,
-        funcDecl.signature
-          .with(
-            \.effectSpecifiers,
-            funcDecl.signature.effectSpecifiers?.with(\.asyncSpecifier, nil)  // drop async
-          )
-          .with(\.returnClause, nil)  // drop result type
-          .with(
-            \.parameterClause,  // add completion handler parameter
-            funcDecl.signature.parameterClause.with(\.parameters, newParameterList)
-              .with(\.trailingTrivia, [])
-          )
-      )
-      .with(
-        \.body,
-        CodeBlockSyntax(
-          leftBrace: .leftBraceToken(leadingTrivia: .space),
-          statements: CodeBlockItemListSyntax(
-            [CodeBlockItemSyntax(item: .expr(newBody))]
-          ),
-          rightBrace: .rightBraceToken(leadingTrivia: .newline)
-        )
-      )
-      .with(\.attributes, newAttributeList)
-      .with(\.leadingTrivia, .newlines(2))
+    // drop async
+    funcDecl.signature.effectSpecifiers?.asyncSpecifier = nil
+
+    // drop result type
+    funcDecl.signature.returnClause = nil
+
+    // add completion handler parameter
+    funcDecl.signature.parameterClause.parameters = newParameterList
+    funcDecl.signature.parameterClause.trailingTrivia = []
+
+    funcDecl.body = CodeBlockSyntax(
+      leftBrace: .leftBraceToken(leadingTrivia: .space),
+      statements: CodeBlockItemListSyntax(
+        [CodeBlockItemSyntax(item: .expr(newBody))]
+      ),
+      rightBrace: .rightBraceToken(leadingTrivia: .newline)
+    )
+
+    funcDecl.attributes = newAttributeList
+
+    funcDecl.leadingTrivia = .newlines(2)
 
-    return [DeclSyntax(newFunc)]
+    return [DeclSyntax(funcDecl)]
   }
 }

Examples/Sources/MacroExamples/Playground/PeerMacrosPlayground.swift

@@ -54,7 +54,7 @@ func runPeerMacrosPlayground() {
     var value = 0
   }
 
-  let counter = Counter()
+  _ = Counter()
 
   //  print("Peer value with suffix name for \(Counter.self): \(String(describing: Counter_peer))")
 }