Deprecate placeholder nodes

Author: kimdv

CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift

@@ -554,6 +554,8 @@ public let DECL_NODES: [Node] = [
     nameForDiagnostics: "editor placeholder",
     documentation: """
       An editor placeholder, e.g. `<#declaration#>` that is used in a position that expects a declaration.
+
+      - Warning: This ``EditorPlaceholderDeclSyntax`` node is not generated by the parser anymore. Placeholders are represented by a ``MissingDeclSyntax``.
       """,
     traits: [
       "WithAttributes",

CodeGeneration/Sources/SyntaxSupport/ExprNodes.swift

@@ -792,6 +792,9 @@ public let EXPR_NODES: [Node] = [
     kind: .editorPlaceholderExpr,
     base: .expr,
     nameForDiagnostics: "editor placeholder",
+    documentation: """
+      - Warning: This ``EditorPlaceholderExprSyntax`` node is not generated by the parser anymore. Placeholders are represented by a ``DeclReferenceExprSyntax``.
+      """,
     children: [
       Child(
         name: "placeholder",

Release Notes/511.md

@@ -30,6 +30,10 @@
   - Issue: https://github.com/apple/swift-syntax/issues/2267
   - Pull request: https://github.com/apple/swift-syntax/pull/2272
 
+- `EditorPlaceholderDeclSyntax` & `EditorPlaceholderExprSyntax`:
+  - Description: `EditorPlaceholderDeclSyntax` & `EditorPlaceholderExprSyntax` are now deprecated and not parsed anymore. They will now be parsed as identifiers.
+  - Pull request: https://github.com/apple/swift-syntax/pull/2237
+
 ## API-Incompatible Changes
 
 - Effect specifiers:

Sources/SwiftParser/Declarations.swift

@@ -275,9 +275,9 @@ extension Parser {
       }
 
       if self.currentToken.isEditorPlaceholder {
-        let placeholder = self.consumeAnyToken()
+        let placeholder = self.parseAnyIdentifier()
         return RawDeclSyntax(
-          RawEditorPlaceholderDeclSyntax(
+          RawMissingDeclSyntax(
             attributes: attrs.attributes,
             modifiers: attrs.modifiers,
             placeholder: placeholder,

Sources/SwiftParser/Expressions.swift

@@ -1241,14 +1241,6 @@ extension Parser {
   mutating func parseIdentifierExpression() -> RawExprSyntax {
     let declName = self.parseDeclReferenceExpr(.compoundNames)
     guard self.withLookahead({ $0.canParseAsGenericArgumentList() }) else {
-      if declName.baseName.tokenText.isEditorPlaceholder && declName.argumentNames == nil {
-        return RawExprSyntax(
-          RawEditorPlaceholderExprSyntax(
-            placeholder: declName.baseName,
-            arena: self.arena
-          )
-        )
-      }
       return RawExprSyntax(declName)
     }
 

Sources/SwiftParserDiagnostics/MissingNodesError.swift

@@ -381,7 +381,18 @@ extension ParseDiagnosticsGenerator {
 
     // Walk all upcoming sibling to see if they are also missing to handle them in this diagnostic.
     // If this is the case, handle all of them in this diagnostic.
-    var missingNodes = [Syntax(node)]
+    var missingNodes: [Syntax] = [Syntax(node)]
+
+    // If the node is an `MissingDeclSyntax` and the placeholder is an editor placeholder
+    // we should not add a diagnostic that it's missing.
+    // Instead, we should emit a diagnostic about the fact that there is an editor placeholder in the source file.
+    if let missing = missingNodes.first?.as(MissingDeclSyntax.self),
+      missing.placeholder.isEditorPlaceholder,
+      !missing.placeholder.isMissing
+    {
+      return .visitChildren
+    }
+
     if let parentWithTokens = ancestorWithMoreTokens, let index {
       let siblings = parentWithTokens.children(viewMode: .all)
       let siblingsAfter = siblings[siblings.index(after: index)...]

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -678,7 +678,7 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
     if shouldSkip(node) {
       return .skipChildren
     }
-    if node.statements.only?.item.is(EditorPlaceholderExprSyntax.self) == true {
+    if let item = node.statements.only?.item.as(DeclReferenceExprSyntax.self), item.baseName.isEditorPlaceholder {
       // Only emit a single diagnostic about the editor placeholder and none for the missing '{' and '}'.
       addDiagnostic(node, .editorPlaceholderInSourceFile, handledNodes: [node.id])
       return .skipChildren

Sources/SwiftRefactor/ExpandEditorPlaceholder.swift

@@ -135,7 +135,8 @@ public struct ExpandEditorPlaceholder: EditRefactoringProvider {
 /// Expansion on `closure1` and `normalArg` is the same as `ExpandEditorPlaceholder`.
 public struct ExpandEditorPlaceholders: EditRefactoringProvider {
   public static func textRefactor(syntax token: TokenSyntax, in context: Void) -> [SourceEdit] {
-    guard let placeholder = token.parent?.as(EditorPlaceholderExprSyntax.self),
+    guard let placeholder = token.parent?.as(DeclReferenceExprSyntax.self),
+      placeholder.baseName.isEditorPlaceholder,
       let arg = placeholder.parent?.as(LabeledExprSyntax.self),
       let argList = arg.parent?.as(LabeledExprListSyntax.self),
       let call = argList.parent?.as(FunctionCallExprSyntax.self)
@@ -190,8 +191,8 @@ extension FunctionTypeSyntax {
       placeholder = ExpandEditorPlaceholder.wrapInTypePlaceholder(ret, type: ret)
     }
 
-    let statementPlaceholder = EditorPlaceholderExprSyntax(
-      placeholder: .identifier(placeholder)
+    let statementPlaceholder = DeclReferenceExprSyntax(
+      baseName: .identifier(placeholder)
     )
     let closureStatement = CodeBlockItemSyntax(
       item: .expr(ExprSyntax(statementPlaceholder))
@@ -234,8 +235,9 @@ extension FunctionCallExprSyntax {
     var includedArg = false
     var argsToExpand = 0
     for arg in arguments.reversed() {
-      guard let expr = arg.expression.as(EditorPlaceholderExprSyntax.self),
-        let data = EditorPlaceholderData(token: expr.placeholder),
+      guard let expr = arg.expression.as(DeclReferenceExprSyntax.self),
+        expr.baseName.isEditorPlaceholder,
+        let data = EditorPlaceholderData(token: expr.baseName),
         case let .typed(_, type) = data,
         type.is(FunctionTypeSyntax.self)
       else {
@@ -253,7 +255,7 @@ extension FunctionCallExprSyntax {
 
     var expandedArgs = [LabeledExprSyntax]()
     for arg in arguments.suffix(argsToExpand) {
-      let edits = ExpandEditorPlaceholder.textRefactor(syntax: arg.expression.cast(EditorPlaceholderExprSyntax.self).placeholder)
+      let edits = ExpandEditorPlaceholder.textRefactor(syntax: arg.expression.cast(DeclReferenceExprSyntax.self).baseName)
       guard edits.count == 1, let edit = edits.first, !edit.replacement.isEmpty else {
         return nil
       }

Sources/SwiftSyntax/generated/syntaxNodes/SyntaxNodesEF.swift

@@ -15,6 +15,8 @@
 // MARK: - EditorPlaceholderDeclSyntax
 
 /// An editor placeholder, e.g. `<#declaration#>` that is used in a position that expects a declaration.
+/// 
+/// - Warning: This ``EditorPlaceholderDeclSyntax`` node is not generated by the parser anymore. Placeholders are represented by a ``MissingDeclSyntax``.
 ///
 /// ### Children
 /// 
@@ -220,6 +222,8 @@ public struct EditorPlaceholderDeclSyntax: DeclSyntaxProtocol, SyntaxHashable, _
 
 // MARK: - EditorPlaceholderExprSyntax
 
+/// - Warning: This ``EditorPlaceholderExprSyntax`` node is not generated by the parser anymore. Placeholders are represented by a ``DeclReferenceExprSyntax``.
+///
 /// ### Children
 /// 
 ///  - `placeholder`: `<identifier>`

Tests/SwiftParserTest/DeclarationTests.swift

@@ -2313,7 +2313,7 @@ final class DeclarationTests: ParserTestCase {
         1️⃣<#code#>
       }
       """,
-      substructure: MemberBlockItemSyntax(decl: EditorPlaceholderDeclSyntax(placeholder: .identifier("<#code#>"))),
+      substructure: MemberBlockItemSyntax(decl: MissingDeclSyntax(placeholder: .identifier("<#code#>"))),
       diagnostics: [
         DiagnosticSpec(message: "editor placeholder in source file")
       ]
@@ -2847,8 +2847,8 @@ final class DeclarationTests: ParserTestCase {
             CodeBlockItemSyntax(
               item: .expr(
                 ExprSyntax(
-                  EditorPlaceholderExprSyntax(
-                    placeholder: .identifier("<#function body#>")
+                  DeclReferenceExprSyntax(
+                    baseName: .identifier("<#function body#>")
                   )
                 )
               )
@@ -2892,8 +2892,8 @@ final class DeclarationTests: ParserTestCase {
             CodeBlockItemSyntax(
               item: .expr(
                 ExprSyntax(
-                  EditorPlaceholderExprSyntax(
-                    placeholder: .identifier("<#function body#>")
+                  DeclReferenceExprSyntax(
+                    baseName: .identifier("<#function body#>")
                   )
                 )
               )

Tests/SwiftParserTest/PatternTests.swift

@@ -180,8 +180,8 @@ final class PatternTests: ParserTestCase {
               identifier: .identifier("<#name#>")
             ),
             initializer: InitializerClauseSyntax(
-              value: EditorPlaceholderExprSyntax(
-                placeholder: .identifier("<#value#>")
+              value: DeclReferenceExprSyntax(
+                baseName: .identifier("<#value#>")
               )
             )
           )

Tests/SwiftParserTest/translated/TrailingClosuresTests.swift

@@ -185,7 +185,7 @@ final class TrailingClosuresTests: ParserTestCase {
           leftBrace: .leftBraceToken(presence: .missing),
           statements: CodeBlockItemListSyntax([
             CodeBlockItemSyntax(
-              item: .init(EditorPlaceholderExprSyntax(placeholder: .identifier("<#T##() -> Void#>")))
+              item: .init(DeclReferenceExprSyntax(baseName: .identifier("<#T##() -> Void#>")))
             )
           ]),
           rightBrace: .rightBraceToken(presence: .missing)

Tests/SwiftRefactorTest/ExpandEditorPlaceholderTests.swift

@@ -103,7 +103,7 @@ fileprivate func assertRefactorPlaceholder(
   } else {
     var parser = Parser(placeholder)
     let expr = ExprSyntax.parse(from: &parser)
-    token = try XCTUnwrap(expr.as(EditorPlaceholderExprSyntax.self)?.placeholder, file: file, line: line)
+    token = try XCTUnwrap(expr.as(DeclReferenceExprSyntax.self)?.baseName, file: file, line: line)
   }
 
   try assertRefactor(token, context: (), provider: ExpandEditorPlaceholder.self, expected: [SourceEdit.replace(token, with: expected)], file: file, line: line)

Tests/SwiftRefactorTest/ExpandEditorPlaceholdersTests.swift

@@ -112,7 +112,7 @@ fileprivate func assertRefactorPlaceholderCall(
   var parser = Parser(expr)
   let call = try XCTUnwrap(ExprSyntax.parse(from: &parser).as(FunctionCallExprSyntax.self), file: file, line: line)
   let arg = call.arguments[call.arguments.index(at: placeholder)]
-  let token: TokenSyntax = try XCTUnwrap(arg.expression.as(EditorPlaceholderExprSyntax.self), file: file, line: line).placeholder
+  let token: TokenSyntax = try XCTUnwrap(arg.expression.as(DeclReferenceExprSyntax.self), file: file, line: line).baseName
 
   try assertRefactor(token, context: (), provider: ExpandEditorPlaceholders.self, expected: [SourceEdit.replace(call, with: expected)], file: file, line: line)
 }
@@ -127,7 +127,7 @@ fileprivate func assertRefactorPlaceholderToken(
   var parser = Parser(expr)
   let call = try XCTUnwrap(ExprSyntax.parse(from: &parser).as(FunctionCallExprSyntax.self), file: file, line: line)
   let arg = call.arguments[call.arguments.index(at: placeholder)]
-  let token: TokenSyntax = try XCTUnwrap(arg.expression.as(EditorPlaceholderExprSyntax.self), file: file, line: line).placeholder
+  let token: TokenSyntax = try XCTUnwrap(arg.expression.as(DeclReferenceExprSyntax.self), file: file, line: line).baseName
 
   try assertRefactor(token, context: (), provider: ExpandEditorPlaceholders.self, expected: [SourceEdit.replace(token, with: expected)], file: file, line: line)
 }