Handle pattern as editor placeholder

CodeGeneration/Sources/SyntaxSupport/PatternNodes.swift

@@ -182,4 +182,22 @@ public let PATTERN_NODES: [Node] = [
     ]
   ),
 
+  Node(
+    kind: .editorPlaceholderPattern,
+    base: .pattern,
+    nameForDiagnostics: "editor placeholder",
+    documentation: """
+      An editor placeholder, e.g. `<#pattern#>` that is used in a position that expects a pattern.
+      """,
+    children: [
+      Child(
+        name: "placeholder",
+        kind: .token(choices: [.token(.identifier)]),
+        documentation: """
+          The actual editor placeholder that starts with `<#` and ends with `#>`.
+          """
+      )
+    ]
+  ),
+
 ]

CodeGeneration/Sources/SyntaxSupport/SyntaxNodeKind.swift

@@ -111,6 +111,8 @@ public enum SyntaxNodeKind: String, CaseIterable {
   case dynamicReplacementAttributeArguments
   case editorPlaceholderDecl
   case editorPlaceholderExpr
+  case editorPlaceholderPattern
+  case editorPlaceholderType
   case effectsAttributeArgumentList
   case enumCaseDecl
   case enumCaseElement

CodeGeneration/Sources/SyntaxSupport/TypeNodes.swift

@@ -530,4 +530,28 @@ public let TYPE_NODES: [Node] = [
     ]
   ),
 
+  Node(
+    kind: .editorPlaceholderType,
+    base: .type,
+    nameForDiagnostics: "editor placeholder",
+    documentation: """
+      An editor placeholder, e.g. `<#Type#>` that is used in a position that expects a type.
+      """,
+    children: [
+      Child(
+        name: "placeholder",
+        kind: .token(choices: [.token(.identifier)]),
+        documentation: """
+          The actual editor placeholder that starts with `<#` and ends with `#>`.
+          """
+      ),
+      Child(
+        name: "genericArgumentClause",
+        kind: .node(kind: .genericArgumentClause),
+        documentation: "Generic arguments that is attatched to the type.",
+        isOptional: true
+      ),
+    ]
+  ),
+
 ]

Release Notes/510.md

@@ -21,6 +21,16 @@
   - Description: Remarks are used by the Swift compiler and other tools to describe some aspect of translation that doesn't reflect correctness, but may be useful for the user. Remarks have been added to the diagnostic severity enums to align with the Swift compiler.
   - Pull Request: https://github.com/apple/swift-syntax/pull/2143
 
+- New pattern node `EditorPlaceholderPatternSyntax`
+  - Description: This node type will be placeholder that is used in a position that expects a pattern.
+  - Issue: https://github.com/apple/swift-syntax/issues/2147
+  - Pull Request: https://github.com/apple/swift-syntax/pull/2150
+
+- New type node `EditorPlaceholderTypeSyntax`
+  - Description: This node type will be placeholder that is used in a position that expects a type.
+  - Issue: https://github.com/apple/swift-syntax/issues/2156
+  - Pull Request: https://github.com/apple/swift-syntax/pull/2150
+
 ## API Behavior Changes
 
 ## Deprecations

Sources/SwiftParser/Patterns.swift

@@ -70,12 +70,21 @@ extension Parser {
       )
     case (.lhs(.identifier), let handle)?:
       let identifier = self.eat(handle)
-      return RawPatternSyntax(
-        RawIdentifierPatternSyntax(
-          identifier: identifier,
-          arena: self.arena
+      if identifier.tokenText.isEditorPlaceholder {
+        return RawPatternSyntax(
+          RawEditorPlaceholderPatternSyntax(
+            placeholder: identifier,
+            arena: self.arena
+          )
         )
-      )
+      } else {
+        return RawPatternSyntax(
+          RawIdentifierPatternSyntax(
+            identifier: identifier,
+            arena: self.arena
+          )
+        )
+      }
     case (.lhs(.dollarIdentifier), let handle)?:
       let dollarIdent = self.eat(handle)
       let unexpectedBeforeIdentifier = RawUnexpectedNodesSyntax(elements: [RawSyntax(dollarIdent)], arena: self.arena)

Sources/SwiftParser/Types.swift

@@ -349,14 +349,25 @@ extension Parser {
       generics = nil
     }
 
-    return RawTypeSyntax(
-      RawIdentifierTypeSyntax(
-        unexpectedBeforeName,
-        name: name,
-        genericArgumentClause: generics,
-        arena: self.arena
+    if name.tokenText.isEditorPlaceholder {
+      return RawTypeSyntax(
+        RawEditorPlaceholderTypeSyntax(
+          placeholder: name,
+          genericArgumentClause: generics,
+          arena: self.arena
+        )
       )
-    )
+    } else {
+      return RawTypeSyntax(
+        RawIdentifierTypeSyntax(
+          unexpectedBeforeName,
+          name: name,
+          genericArgumentClause: generics,
+          arena: self.arena
+        )
+      )
+    }
+
   }
 
   /// Parse the existential `Any` type.
@@ -938,7 +949,9 @@ extension Parser {
 
 extension Parser {
   mutating func parseResultType() -> RawTypeSyntax {
-    if self.at(prefix: "<") {
+    if self.at(prefix: "<#") {
+      return self.parseTypeIdentifier()
+    } else if self.at(prefix: "<") {
       let generics = self.parseGenericParameters()
       let baseType = self.parseType()
       return RawTypeSyntax(

Sources/SwiftParserDiagnostics/generated/SyntaxKindNameForDiagnostics.swift

@@ -143,6 +143,10 @@ extension SyntaxKind {
       return "editor placeholder"
     case .editorPlaceholderExpr:
       return "editor placeholder"
+    case .editorPlaceholderPattern:
+      return "editor placeholder"
+    case .editorPlaceholderType:
+      return "editor placeholder"
     case .effectsAttributeArgumentList:
       return "@_effects arguments"
     case .enumCaseDecl:

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

@@ -151,6 +151,7 @@ These articles are intended for developers wishing to contribute to SwiftSyntax
 - <doc:SwiftSyntax/PatternSyntax>
 - <doc:SwiftSyntax/PatternSyntaxProtocol>
 - <doc:SwiftSyntax/MissingPatternSyntax>
+- <doc:SwiftSyntax/EditorPlaceholderPatternSyntax>
 - <doc:SwiftSyntax/ExpressionPatternSyntax>
 - <doc:SwiftSyntax/IdentifierPatternSyntax>
 - <doc:SwiftSyntax/IsTypePatternSyntax>
@@ -190,6 +191,7 @@ These articles are intended for developers wishing to contribute to SwiftSyntax
 - <doc:SwiftSyntax/ClassRestrictionTypeSyntax>
 - <doc:SwiftSyntax/CompositionTypeSyntax>
 - <doc:SwiftSyntax/DictionaryTypeSyntax>
+- <doc:SwiftSyntax/EditorPlaceholderTypeSyntax>
 - <doc:SwiftSyntax/FunctionTypeSyntax>
 - <doc:SwiftSyntax/IdentifierTypeSyntax>
 - <doc:SwiftSyntax/ImplicitlyUnwrappedOptionalTypeSyntax>

Sources/SwiftSyntax/generated/ChildNameForKeyPath.swift

@@ -1077,6 +1077,22 @@ public func childName(_ keyPath: AnyKeyPath) -> String? {
     return "placeholder"
   case \EditorPlaceholderExprSyntax.unexpectedAfterPlaceholder:
     return "unexpectedAfterPlaceholder"
+  case \EditorPlaceholderPatternSyntax.unexpectedBeforePlaceholder:
+    return "unexpectedBeforePlaceholder"
+  case \EditorPlaceholderPatternSyntax.placeholder:
+    return "placeholder"
+  case \EditorPlaceholderPatternSyntax.unexpectedAfterPlaceholder:
+    return "unexpectedAfterPlaceholder"
+  case \EditorPlaceholderTypeSyntax.unexpectedBeforePlaceholder:
+    return "unexpectedBeforePlaceholder"
+  case \EditorPlaceholderTypeSyntax.placeholder:
+    return "placeholder"
+  case \EditorPlaceholderTypeSyntax.unexpectedBetweenPlaceholderAndGenericArgumentClause:
+    return "unexpectedBetweenPlaceholderAndGenericArgumentClause"
+  case \EditorPlaceholderTypeSyntax.genericArgumentClause:
+    return "genericArgumentClause"
+  case \EditorPlaceholderTypeSyntax.unexpectedAfterGenericArgumentClause:
+    return "unexpectedAfterGenericArgumentClause"
   case \EnumCaseDeclSyntax.unexpectedBeforeAttributes:
     return "unexpectedBeforeAttributes"
   case \EnumCaseDeclSyntax.attributes:

Sources/SwiftSyntax/generated/SyntaxAnyVisitor.swift

@@ -776,6 +776,22 @@ open class SyntaxAnyVisitor: SyntaxVisitor {
     visitAnyPost(node._syntaxNode)
   }
 
+  override open func visit(_ node: EditorPlaceholderPatternSyntax) -> SyntaxVisitorContinueKind {
+    return visitAny(node._syntaxNode)
+  }
+
+  override open func visitPost(_ node: EditorPlaceholderPatternSyntax) {
+    visitAnyPost(node._syntaxNode)
+  }
+
+  override open func visit(_ node: EditorPlaceholderTypeSyntax) -> SyntaxVisitorContinueKind {
+    return visitAny(node._syntaxNode)
+  }
+
+  override open func visitPost(_ node: EditorPlaceholderTypeSyntax) {
+    visitAnyPost(node._syntaxNode)
+  }
+
   override open func visit(_ node: EffectsAttributeArgumentListSyntax) -> SyntaxVisitorContinueKind {
     return visitAny(node._syntaxNode)
   }

Sources/SwiftSyntax/generated/SyntaxBaseNodes.swift

@@ -770,7 +770,7 @@ public struct PatternSyntax: PatternSyntaxProtocol, SyntaxHashable {
 
   public init?(_ node: some SyntaxProtocol) {
     switch node.raw.kind {
-    case .expressionPattern, .identifierPattern, .isTypePattern, .missingPattern, .tuplePattern, .valueBindingPattern, .wildcardPattern:
+    case .editorPlaceholderPattern, .expressionPattern, .identifierPattern, .isTypePattern, .missingPattern, .tuplePattern, .valueBindingPattern, .wildcardPattern:
       self._syntaxNode = node._syntaxNode
     default:
       return nil
@@ -795,6 +795,7 @@ public struct PatternSyntax: PatternSyntaxProtocol, SyntaxHashable {
 
   public static var structure: SyntaxNodeStructure {
     return .choices([
+          .node(EditorPlaceholderPatternSyntax.self),
           .node(ExpressionPatternSyntax.self),
           .node(IdentifierPatternSyntax.self),
           .node(IsTypePatternSyntax.self),
@@ -1298,7 +1299,7 @@ public struct TypeSyntax: TypeSyntaxProtocol, SyntaxHashable {
 
   public init?(_ node: some SyntaxProtocol) {
     switch node.raw.kind {
-    case .arrayType, .attributedType, .classRestrictionType, .compositionType, .dictionaryType, .functionType, .identifierType, .implicitlyUnwrappedOptionalType, .memberType, .metatypeType, .missingType, .namedOpaqueReturnType, .optionalType, .packElementType, .packExpansionType, .someOrAnyType, .suppressedType, .tupleType:
+    case .arrayType, .attributedType, .classRestrictionType, .compositionType, .dictionaryType, .editorPlaceholderType, .functionType, .identifierType, .implicitlyUnwrappedOptionalType, .memberType, .metatypeType, .missingType, .namedOpaqueReturnType, .optionalType, .packElementType, .packExpansionType, .someOrAnyType, .suppressedType, .tupleType:
       self._syntaxNode = node._syntaxNode
     default:
       return nil
@@ -1328,6 +1329,7 @@ public struct TypeSyntax: TypeSyntaxProtocol, SyntaxHashable {
           .node(ClassRestrictionTypeSyntax.self),
           .node(CompositionTypeSyntax.self),
           .node(DictionaryTypeSyntax.self),
+          .node(EditorPlaceholderTypeSyntax.self),
           .node(FunctionTypeSyntax.self),
           .node(IdentifierTypeSyntax.self),
           .node(ImplicitlyUnwrappedOptionalTypeSyntax.self),
@@ -1486,6 +1488,8 @@ extension Syntax {
           .node(DynamicReplacementAttributeArgumentsSyntax.self),
           .node(EditorPlaceholderDeclSyntax.self),
           .node(EditorPlaceholderExprSyntax.self),
+          .node(EditorPlaceholderPatternSyntax.self),
+          .node(EditorPlaceholderTypeSyntax.self),
           .node(EffectsAttributeArgumentListSyntax.self),
           .node(EnumCaseDeclSyntax.self),
           .node(EnumCaseElementListSyntax.self),

Sources/SwiftSyntax/generated/SyntaxEnum.swift

@@ -105,6 +105,8 @@ public enum SyntaxEnum {
   case dynamicReplacementAttributeArguments(DynamicReplacementAttributeArgumentsSyntax)
   case editorPlaceholderDecl(EditorPlaceholderDeclSyntax)
   case editorPlaceholderExpr(EditorPlaceholderExprSyntax)
+  case editorPlaceholderPattern(EditorPlaceholderPatternSyntax)
+  case editorPlaceholderType(EditorPlaceholderTypeSyntax)
   case effectsAttributeArgumentList(EffectsAttributeArgumentListSyntax)
   case enumCaseDecl(EnumCaseDeclSyntax)
   case enumCaseElementList(EnumCaseElementListSyntax)
@@ -479,6 +481,10 @@ public extension Syntax {
       return .editorPlaceholderDecl(EditorPlaceholderDeclSyntax(self)!)
     case .editorPlaceholderExpr:
       return .editorPlaceholderExpr(EditorPlaceholderExprSyntax(self)!)
+    case .editorPlaceholderPattern:
+      return .editorPlaceholderPattern(EditorPlaceholderPatternSyntax(self)!)
+    case .editorPlaceholderType:
+      return .editorPlaceholderType(EditorPlaceholderTypeSyntax(self)!)
     case .effectsAttributeArgumentList:
       return .effectsAttributeArgumentList(EffectsAttributeArgumentListSyntax(self)!)
     case .enumCaseDecl:

Sources/SwiftSyntax/generated/SyntaxKind.swift

@@ -105,6 +105,8 @@ public enum SyntaxKind: CaseIterable {
   case dynamicReplacementAttributeArguments
   case editorPlaceholderDecl
   case editorPlaceholderExpr
+  case editorPlaceholderPattern
+  case editorPlaceholderType
   case effectsAttributeArgumentList
   case enumCaseDecl
   case enumCaseElementList
@@ -600,6 +602,10 @@ public enum SyntaxKind: CaseIterable {
       return EditorPlaceholderDeclSyntax.self
     case .editorPlaceholderExpr:
       return EditorPlaceholderExprSyntax.self
+    case .editorPlaceholderPattern:
+      return EditorPlaceholderPatternSyntax.self
+    case .editorPlaceholderType:
+      return EditorPlaceholderTypeSyntax.self
     case .effectsAttributeArgumentList:
       return EffectsAttributeArgumentListSyntax.self
     case .enumCaseDecl:

Sources/SwiftSyntax/generated/SyntaxRewriter.swift

@@ -710,6 +710,20 @@ open class SyntaxRewriter {
     return ExprSyntax(visitChildren(node))
   }
 
+  /// Visit a ``EditorPlaceholderPatternSyntax``.
+  ///   - Parameter node: the node that is being visited
+  ///   - Returns: the rewritten node
+  open func visit(_ node: EditorPlaceholderPatternSyntax) -> PatternSyntax {
+    return PatternSyntax(visitChildren(node))
+  }
+
+  /// Visit a ``EditorPlaceholderTypeSyntax``.
+  ///   - Parameter node: the node that is being visited
+  ///   - Returns: the rewritten node
+  open func visit(_ node: EditorPlaceholderTypeSyntax) -> TypeSyntax {
+    return TypeSyntax(visitChildren(node))
+  }
+
   /// Visit a ``EffectsAttributeArgumentListSyntax``.
   ///   - Parameter node: the node that is being visited
   ///   - Returns: the rewritten node
@@ -2456,6 +2470,14 @@ open class SyntaxRewriter {
       return {
         self.visitImpl($0, EditorPlaceholderExprSyntax.self, self.visit)
       }
+    case .editorPlaceholderPattern:
+      return {
+        self.visitImpl($0, EditorPlaceholderPatternSyntax.self, self.visit)
+      }
+    case .editorPlaceholderType:
+      return {
+        self.visitImpl($0, EditorPlaceholderTypeSyntax.self, self.visit)
+      }
     case .effectsAttributeArgumentList:
       return {
         self.visitImpl($0, EffectsAttributeArgumentListSyntax.self, self.visit)
@@ -3390,6 +3412,10 @@ open class SyntaxRewriter {
       return visitImpl(node, EditorPlaceholderDeclSyntax.self, visit)
     case .editorPlaceholderExpr:
       return visitImpl(node, EditorPlaceholderExprSyntax.self, visit)
+    case .editorPlaceholderPattern:
+      return visitImpl(node, EditorPlaceholderPatternSyntax.self, visit)
+    case .editorPlaceholderType:
+      return visitImpl(node, EditorPlaceholderTypeSyntax.self, visit)
     case .effectsAttributeArgumentList:
       return visitImpl(node, EffectsAttributeArgumentListSyntax.self, visit)
     case .enumCaseDecl: