Remove HasTrailingComma protocol

Turns out we don’t actually need it.

Author: ahoppen

CodeGeneration/Sources/generate-swiftsyntax/templates/swiftsyntaxbuilder/BuildableNodesFile.swift

@@ -23,38 +23,14 @@ let buildableNodesFile = SourceFileSyntax {
 
   for node in SYNTAX_NODES where node.isBuildable {
     let type = node.type
-    let hasTrailingComma = node.traits.contains("WithTrailingComma")
 
-    let convenienceInit = createConvenienceInitializer(node: node)
-    if convenienceInit != nil || hasTrailingComma {
+    if let convenienceInit = createConvenienceInitializer(node: node) {
       let docComment: SwiftSyntax.Trivia = node.documentation.isEmpty ? [] : .docLineComment("/// \(node.documentation)") + .newline
       ExtensionDeclSyntax(
         leadingTrivia: docComment,
-        extendedType: SimpleTypeIdentifierSyntax(name: .identifier(type.syntaxBaseName)),
-        inheritanceClause: hasTrailingComma ? TypeInheritanceClauseSyntax { InheritedTypeSyntax(typeName: TypeSyntax("HasTrailingComma")) } : nil
+        extendedType: SimpleTypeIdentifierSyntax(name: .identifier(type.syntaxBaseName))
       ) {
-        if let convenienceInit = convenienceInit {
-          convenienceInit
-        }
-
-        if hasTrailingComma {
-          VariableDeclSyntax(
-          """
-          var hasTrailingComma: Bool {
-            return trailingComma != nil
-          }
-          """
-          )
-
-          FunctionDeclSyntax(
-          """
-          /// Conformance to `HasTrailingComma`.
-          public func withTrailingComma(_ withComma: Bool) -> Self {
-            return withTrailingComma(withComma ? .commaToken() : nil)
-          }
-          """
-          )
-        }
+        convenienceInit
       }
     }
   }

Sources/SwiftSyntaxBuilder/CMakeLists.txt

@@ -8,11 +8,11 @@
 
 add_swift_host_library(SwiftSyntaxBuilder
   ConvenienceInitializers.swift
-  HasTrailingComma.swift
   Indenter.swift
   ResultBuilderExtensions.swift
   Syntax+StringInterpolation.swift
   SyntaxNodeWithBody.swift
+  WithTrailingCommaSyntax+EnsuringTrailingComma.swift
 
 
   generated/BuildableCollectionNodes.swift

Sources/SwiftSyntaxBuilder/HasTrailingComma.swift renamed to Sources/SwiftSyntaxBuilder/WithTrailingCommaSyntax+EnsuringTrailingComma.swift

@@ -12,15 +12,12 @@
 
 import SwiftSyntax
 
-protocol HasTrailingComma {
-  var hasTrailingComma: Bool { get }
-
-  /// Returns this node overriding presence of the trailing comma
-  func withTrailingComma(_ withComma: Bool) -> Self
-}
-
-extension HasTrailingComma {
+extension WithTrailingCommaSyntax {
   func ensuringTrailingComma() -> Self {
-    hasTrailingComma ? self : withTrailingComma(true)
+    if trailingComma == nil {
+      return self.withTrailingComma(.commaToken())
+    } else {
+      return self
+    }
   }
 }