Move SyntaxTraits from gyb to codegen

CodeGeneration/Sources/generate-swiftsyntax/GenerateSwiftSyntax.swift

@@ -59,6 +59,7 @@ struct GenerateSwiftSyntax: ParsableCommand {
       TemplateSpec(sourceFile: syntaxBaseNodesFile, module: swiftSyntaxDir, filename: "SyntaxBaseNodes.swift"),
       TemplateSpec(sourceFile: syntaxEnumFile, module: swiftSyntaxDir, filename: "SyntaxEnum.swift"),
       TemplateSpec(sourceFile: syntaxKindFile, module: swiftSyntaxDir, filename: "SyntaxKind.swift"),
+      TemplateSpec(sourceFile: syntaxTraitsFile, module: swiftSyntaxDir, filename: "SyntaxTraits.swift"),
       TemplateSpec(sourceFile: buildableCollectionNodesFile, module: swiftSyntaxBuilderDir, filename: "BuildableCollectionNodes.swift"),
       TemplateSpec(sourceFile: buildableNodesFile, module: swiftSyntaxBuilderDir, filename: "BuildableNodes.swift"),
       TemplateSpec(sourceFile: resultBuildersFile, module: swiftSyntaxBuilderDir, filename: "ResultBuilders.swift"),

CodeGeneration/Sources/generate-swiftsyntax/templates/swiftsyntax/SyntaxTraitsFile.swift

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 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 SwiftSyntax
+import SwiftSyntaxBuilder
+import SyntaxSupport
+import Utils
+
+let syntaxTraitsFile = SourceFileSyntax {
+  for trait in TRAITS {
+    ProtocolDeclSyntax("""
+      // MARK: - \(trait.traitName)Syntax
+
+      public protocol \(trait.traitName)Syntax: SyntaxProtocol
+      """) {
+
+      for child in trait.children {
+        VariableDeclSyntax("var \(raw: child.swiftName): \(raw: child.typeName)\(raw: child.isOptional ? "?" : "") { get }")
+        FunctionDeclSyntax("func with\(raw: child.name)(_ newChild: \(raw: child.typeName)?) -> Self")
+      }
+    }
+
+    ExtensionDeclSyntax("public extension SyntaxProtocol") {
+      FunctionDeclSyntax("""
+        /// Check whether the non-type erased version of this syntax node conforms to
+        /// `\(raw: trait.traitName)Syntax`.
+        /// Note that this will incur an existential conversion.
+        func isProtocol(_: \(raw: trait.traitName)Syntax.Protocol) -> Bool {
+          return self.asProtocol(\(raw: trait.traitName)Syntax.self) != nil
+        }
+        """)
+
+      FunctionDeclSyntax("""
+        /// Return the non-type erased version of this syntax node if it conforms to
+        /// `\(raw: trait.traitName)Syntax`. Otherwise return `nil`.
+        /// Note that this will incur an existential conversion.
+        func asProtocol(_: \(raw: trait.traitName)Syntax.Protocol) -> \(raw: trait.traitName)Syntax? {
+          return Syntax(self).asProtocol(SyntaxProtocol.self) as? \(raw: trait.traitName)Syntax
+        }
+        """)
+    }
+  }
+
+  for node in SYNTAX_NODES where !node.isBase && !node.traits.isEmpty {
+    ExtensionDeclSyntax("extension \(raw: node.name): \(raw: node.traits.map { $0 + "Syntax" }.joined(separator: ", ")) {}")
+  }
+}

Package.swift

@@ -70,7 +70,6 @@ let package = Package(
         "SyntaxNodes.swift.gyb.template",
         "SyntaxRewriter.swift.gyb",
         "SyntaxTransform.swift.gyb",
-        "SyntaxTraits.swift.gyb",
         "SyntaxVisitor.swift.gyb",
         "TokenKind.swift.gyb",
         "Tokens.swift.gyb",

Sources/SwiftSyntax/CMakeLists.txt

@@ -39,7 +39,7 @@ add_swift_host_library(SwiftSyntax
   gyb_generated/SyntaxFactory.swift
   generated/SyntaxKind.swift
   gyb_generated/SyntaxRewriter.swift
-  gyb_generated/SyntaxTraits.swift
+  generated/SyntaxTraits.swift
   gyb_generated/SyntaxTransform.swift
   gyb_generated/SyntaxVisitor.swift
   gyb_generated/TokenKind.swift