Fixed testRecovery157

Sources/SwiftParser/Expressions.swift

@@ -32,6 +32,8 @@ extension TokenConsumer {
       } else {
         return true
       }
+    case (.primaryExpressionStart(.atSign), let handle)?:
+      break
     case (_, _)?:
       return true
     case nil:
@@ -1168,6 +1170,8 @@ extension Parser {
           arena: self.arena
         )
       )
+    case (.atSign, _)?:
+      return RawExprSyntax(self.parseStringLiteral())
     case (.rawStringDelimiter, _)?, (.stringQuote, _)?, (.multilineStringQuote, _)?, (.singleQuote, _)?:
       return RawExprSyntax(self.parseStringLiteral())
     case (.extendedRegexDelimiter, _)?, (.regexSlash, _)?:

Sources/SwiftParser/StringLiterals.swift

@@ -467,8 +467,12 @@ extension Parser {
     /// Parse opening raw string delimiter if exist.
     let openDelimiter = self.consume(if: .rawStringDelimiter)
 
+    /// Try to parse @ in order to recover from Objective-C style literals
+    let unexpectedAtSign = self.consume(if: .atSign)
+
     /// Parse open quote.
     var (unexpectedBeforeOpenQuote, openQuote) = self.expect(.stringQuote, .multilineStringQuote, default: .stringQuote)
+    unexpectedBeforeOpenQuote = RawUnexpectedNodesSyntax(combining: unexpectedAtSign, unexpectedBeforeOpenQuote, arena: self.arena)
     var openQuoteKind: RawTokenKind = openQuote.tokenKind
     if openQuote.isMissing, let singleQuote = self.consume(if: .singleQuote) {
       unexpectedBeforeOpenQuote = RawUnexpectedNodesSyntax(combining: unexpectedBeforeOpenQuote, singleQuote, arena: self.arena)

Sources/SwiftParser/TokenSpecSet.swift

@@ -569,6 +569,7 @@ enum ParameterModifier: TokenSpecSet {
 
 enum PrimaryExpressionStart: TokenSpecSet {
   case anyKeyword
+  case atSign  // For recovery
   case capitalSelfKeyword
   case dollarIdentifier
   case falseKeyword
@@ -598,6 +599,7 @@ enum PrimaryExpressionStart: TokenSpecSet {
   init?(lexeme: Lexer.Lexeme) {
     switch PrepareForKeywordMatch(lexeme) {
     case TokenSpec(.Any): self = .anyKeyword
+    case TokenSpec(.atSign): self = .atSign
     case TokenSpec(.Self): self = .capitalSelfKeyword
     case TokenSpec(.dollarIdentifier): self = .dollarIdentifier
     case TokenSpec(.false): self = .falseKeyword
@@ -630,6 +632,7 @@ enum PrimaryExpressionStart: TokenSpecSet {
   var spec: TokenSpec {
     switch self {
     case .anyKeyword: return .keyword(.Any)
+    case .atSign: return .atSign
     case .capitalSelfKeyword: return .keyword(.Self)
     case .dollarIdentifier: return .dollarIdentifier
     case .falseKeyword: return .keyword(.false)

Sources/SwiftParserDiagnostics/ParseDiagnosticsGenerator.swift

@@ -1003,6 +1003,17 @@ public class ParseDiagnosticsGenerator: SyntaxAnyVisitor {
     if shouldSkip(node) {
       return .skipChildren
     }
+    // recover from Objective-C style literals
+    if let atSign = node.unexpectedBetweenOpenDelimiterAndOpenQuote?.onlyToken(where: { $0.tokenKind == .atSign }) {
+      addDiagnostic(
+        node,
+        .stringLiteralAtSign,
+        fixIts: [
+          FixIt(message: RemoveNodesFixIt(atSign), changes: .makeMissing(atSign))
+        ],
+        handledNodes: [atSign.id]
+      )
+    }
     if let singleQuote = node.unexpectedBetweenOpenDelimiterAndOpenQuote?.onlyToken(where: { $0.tokenKind == .singleQuote }) {
       let fixIt = FixIt(
         message: ReplaceTokensFixIt(replaceTokens: [singleQuote], replacement: node.openQuote),

Sources/SwiftParserDiagnostics/ParserDiagnosticMessages.swift

@@ -194,6 +194,9 @@ extension DiagnosticMessage where Self == StaticParserError {
   public static var standaloneSemicolonStatement: Self {
     .init("standalone ';' statements are not allowed")
   }
+  public static var stringLiteralAtSign: Self {
+    .init("string literals in Swift are not preceded by an '@' sign")
+  }
   public static var subscriptsCannotHaveNames: Self {
     .init("subscripts cannot have a name")
   }

Tests/SwiftParserTest/translated/RecoveryTests.swift

@@ -1881,16 +1881,20 @@ final class RecoveryTests: XCTestCase {
   }
 
   func testRecovery157() {
+    // <rdar://problem/19833424> QoI: Bad error message when using Objective-C literals (@"Hello")
     assertParse(
       #"""
-      // <rdar://problem/19833424> QoI: Bad error message when using Objective-C literals (@"Hello") in Swift files
       let myString = 1️⃣@"foo"
       """#,
       diagnostics: [
-        // TODO: Old parser expected error on line 2: string literals in Swift are not preceded by an '@' sign, Fix-It replacements: 16 - 17 = ''
-        DiagnosticSpec(message: "expected expression in variable"),
-        DiagnosticSpec(message: #"extraneous code '@"foo"' at top level"#),
-      ]
+        DiagnosticSpec(
+          message: "string literals in Swift are not preceded by an '@' sign",
+          fixIts: ["remove '@'"]
+        )
+      ],
+      fixedSource: """
+        let myString = "foo"
+        """
     )
   }