tbs

Author: rintaro

CodeGeneration/Sources/SyntaxSupport/CommonNodes.swift

@@ -177,7 +177,7 @@ public let COMMON_NODES: [Node] = [
     kind: .decl,
     base: .syntax,
     nameForDiagnostics: "declaration",
-    parserFunction: "parseDeclaration"
+    parserFunction: "parseDeclarationOrIfConfig"
   ),
 
   Node(

CodeGeneration/Sources/generate-swift-syntax/templates/swiftparser/LayoutNodesParsableFile.swift

@@ -68,7 +68,7 @@ let layoutNodesParsableFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
     DeclSyntax(
       """
       mutating func parseNonOptionalCodeBlockItem() -> RawCodeBlockItemSyntax {
-        guard let node = self.parseCodeBlockItem(isAtTopLevel: false, allowInitDecl: true) else {
+        guard let node = self.self.parseCodeBlockItem(allowInitDecl: true, until: { _ in false }) else {
           // The missing item is not necessary to be a declaration,
           // which is just a placeholder here
           return RawCodeBlockItemSyntax(

Sources/SwiftParser/Declarations.swift

@@ -2368,3 +2368,17 @@ extension Parser {
     )
   }
 }
+
+extension Parser {
+  mutating func parseDeclarationOrIfConfig() -> RawDeclSyntax {
+    if self.at(.poundIf) {
+      return RawDeclSyntax(
+        self.parsePoundIfDirective({
+          .decls($0.parseMemberDeclList(until: { $0.atEndOfIfConfigClauseBody() }))
+        })
+      )
+    } else {
+      return parseDeclaration(in: .memberDeclList)
+    }
+  }
+}

Sources/SwiftParser/Statements.swift

@@ -1030,11 +1030,6 @@ extension Parser.Lookahead {
   /// - Note: This function must be kept in sync with `parseStatement()`.
   /// - Seealso: ``Parser/parseStatement()``
   mutating func atStartOfStatement(preferExpr: Bool) -> Bool {
-//    if self.atStartOfSwitchCase() {
-//      // We consider 'case' statements so we don't parse the start of a new case item as trailing parts of an expression.
-//      return true
-//    }
-
     _ = self.consume(if: .identifier, followedBy: .colon)
     switch self.at(anyIn: CanBeStatementStart.self)?.0 {
     case .return?,

Sources/SwiftParser/generated/LayoutNodes+Parsable.swift

@@ -37,6 +37,39 @@ class EntryTests: ParserTestCase {
     )
   }
 
+  func testDeclSyntaxParseIfConfig() throws {
+    assertParse(
+      """
+      #if FLAG
+      func test() {}
+      #endif
+      """,
+      { DeclSyntax.parse(from: &$0) },
+      substructure: IfConfigDeclSyntax(
+        clauses: IfConfigClauseListSyntax([
+          IfConfigClauseSyntax(
+            poundKeyword: .poundIfToken(),
+            condition: ExprSyntax(DeclReferenceExprSyntax(baseName: .identifier("FLAG"))),
+            elements: .init([
+              MemberBlockItemSyntax(
+                decl: DeclSyntax(
+                  FunctionDeclSyntax(
+                    funcKeyword: .keyword(.func),
+                    name: .identifier("test"),
+                    signature: FunctionSignatureSyntax(
+                      parameterClause: FunctionParameterClauseSyntax(parameters: [])
+                    ),
+                    body: CodeBlockSyntax(statements: [])
+                  )
+                )
+              )
+            ])
+          )
+        ])
+      )
+    )
+  }
+
   func testRemainderUnexpected() throws {
     assertParse(
       "func test() {} 1️⃣other tokens",