[parser] Empty record

dart-lang/language#2535

Change-Id: I8241119ee858ce39673472056b88c9393799e1a0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/262600
Commit-Queue: Jens Johansen <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: jensjoha

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -9961,17 +9961,6 @@ const MessageCode messagePrivateNamedParameter = const MessageCode(
     analyzerCodes: <String>["PRIVATE_OPTIONAL_PARAMETER"],
     problemMessage: r"""An optional named parameter can't start with '_'.""");
 
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Null> codeRecordLiteralEmpty = messageRecordLiteralEmpty;
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const MessageCode messageRecordLiteralEmpty = const MessageCode(
-    "RecordLiteralEmpty",
-    index: 128,
-    problemMessage: r"""Record literal can't be empty.""",
-    correctionMessage:
-        r"""Try adding elements or use 'Record.empty()' instead.""");
-
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeRecordLiteralOnePositionalFieldNoTrailingComma =
     messageRecordLiteralOnePositionalFieldNoTrailingComma;
@@ -9984,18 +9973,42 @@ const MessageCode messageRecordLiteralOnePositionalFieldNoTrailingComma =
             r"""Record literal with one field requires a trailing comma.""",
         correctionMessage: r"""Try adding a trailing comma.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeRecordLiteralZeroFieldsWithTrailingComma =
+    messageRecordLiteralZeroFieldsWithTrailingComma;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageRecordLiteralZeroFieldsWithTrailingComma =
+    const MessageCode("RecordLiteralZeroFieldsWithTrailingComma",
+        index: 128,
+        problemMessage:
+            r"""Record literal without fields can't have a trailing comma.""",
+        correctionMessage: r"""Try removing the trailing comma.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeRecordTypeOnePositionalFieldNoTrailingComma =
     messageRecordTypeOnePositionalFieldNoTrailingComma;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageRecordTypeOnePositionalFieldNoTrailingComma =
     const MessageCode("RecordTypeOnePositionalFieldNoTrailingComma",
-        index: 130,
+        index: 131,
         problemMessage:
             r"""Record type with one entry requires a trailing comma.""",
         correctionMessage: r"""Try adding a trailing comma.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeRecordTypeZeroFieldsButTrailingComma =
+    messageRecordTypeZeroFieldsButTrailingComma;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageRecordTypeZeroFieldsButTrailingComma =
+    const MessageCode("RecordTypeZeroFieldsButTrailingComma",
+        index: 130,
+        problemMessage:
+            r"""Record type without fields can't have a trailing comma.""",
+        correctionMessage: r"""Try removing the trailing comma.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeRedirectingConstructorWithAnotherInitializer =
     messageRedirectingConstructorWithAnotherInitializer;

pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart

@@ -1403,20 +1403,16 @@ class Parser {
 
   /// Parse a record type similarly as a formal parameter list of a function.
   ///
-  /// TODO(jensj): Update this to fit any new updates to the spec.
-  /// E.g. having two recordTypeNamedField entries doesn't make sense.
-  ///
   /// recordType          ::= '(' recordTypeFields ',' recordTypeNamedFields ')'
   ///                       | '(' recordTypeFields ','? ')'
-  ///                       | '(' recordTypeNamedFields ')'
+  ///                       | '(' recordTypeNamedFields? ')'
   ///
   /// recordTypeFields      ::= recordTypeField ( ',' recordTypeField )*
   /// recordTypeField       ::= metadata type identifier?
   ///
   /// recordTypeNamedFields ::= '{' recordTypeNamedField
   ///                           ( ',' recordTypeNamedField )* ','? '}'
-  /// recordTypeNamedField  ::= type identifier
-  /// recordTypeNamedField  ::= metadata typedIdentifier
+  /// recordTypeNamedField  ::= metadata type identifier
   Token parseRecordType(final Token start, Token token) {
     token = token.next!;
     assert(optional('(', token));
@@ -1429,11 +1425,18 @@ class Parser {
     int parameterCount = 0;
     bool hasNamedFields = false;
     bool sawComma = false;
+    Token? illegalTrailingComma;
     while (true) {
       Token next = token.next!;
       if (optional(')', next)) {
         token = next;
         break;
+      } else if (parameterCount == 0 &&
+          optional(',', next) &&
+          optional(')', next.next!)) {
+        illegalTrailingComma = next;
+        token = next.next!;
+        break;
       }
       ++parameterCount;
       String? value = next.stringValue;
@@ -1478,7 +1481,11 @@ class Parser {
     }
     assert(optional(')', token));
 
-    if (parameterCount == 1 && !hasNamedFields && !sawComma) {
+    if (parameterCount == 0 && illegalTrailingComma != null) {
+      // Empty record type with a comma `(,)`.
+      reportRecoverableError(illegalTrailingComma,
+          codes.messageRecordTypeZeroFieldsButTrailingComma);
+    } else if (parameterCount == 1 && !hasNamedFields && !sawComma) {
       // Single non-named element without trailing comma.
       reportRecoverableError(
           token, codes.messageRecordTypeOnePositionalFieldNoTrailingComma);
@@ -6143,9 +6150,20 @@ class Parser {
     int count = 0;
     bool wasRecord = constKeywordForRecord != null;
     bool wasValidRecord = false;
+    Token? illegalTrailingComma;
     while (true) {
       Token next = token.next!;
-      if ((count > 0 || wasRecord) && optional(')', next)) {
+      if (optional(')', next)) {
+        if (count == 0) {
+          wasRecord = true;
+        }
+        break;
+      } else if (count == 0 &&
+          optional(',', next) &&
+          optional(')', next.next!)) {
+        illegalTrailingComma = next;
+        wasRecord = true;
+        token = next;
         break;
       }
       Token? colon = null;
@@ -6179,8 +6197,10 @@ class Parser {
     assert(wasRecord || count <= 1);
 
     if (wasRecord) {
-      if (count == 0) {
-        reportRecoverableError(token, codes.messageRecordLiteralEmpty);
+      if (count == 0 && illegalTrailingComma != null) {
+        // Empty record literal with a comma `(,)`.
+        reportRecoverableError(illegalTrailingComma,
+            codes.messageRecordLiteralZeroFieldsWithTrailingComma);
       } else if (count == 1 && !wasValidRecord) {
         reportRecoverableError(
             token, codes.messageRecordLiteralOnePositionalFieldNoTrailingComma);
@@ -9484,9 +9504,7 @@ class Parser {
     assert(wasRecord || count <= 1);
 
     if (wasRecord) {
-      if (count == 0) {
-        reportRecoverableError(token, codes.messageRecordLiteralEmpty);
-      } else if (count == 1 && !wasValidRecord) {
+      if (count == 1 && !wasValidRecord) {
         reportRecoverableError(
             token, codes.messageRecordLiteralOnePositionalFieldNoTrailingComma);
       }

pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml

@@ -2180,8 +2180,12 @@ ParserErrorCode.EMPTY_ENUM_BODY:
   notes: |-
     We can't guess at the names or number of the enum constants that should be
     added.
+ParserErrorCode.EMPTY_RECORD_LITERAL_WITH_COMMA:
+  status: needsEvaluation
 ParserErrorCode.EMPTY_RECORD_TYPE_NAMED_FIELDS_LIST:
   status: needsEvaluation
+ParserErrorCode.EMPTY_RECORD_TYPE_WITH_COMMA:
+  status: needsEvaluation
 ParserErrorCode.ENUM_IN_CLASS:
   status: needsEvaluation
 ParserErrorCode.EQUALITY_CANNOT_BE_EQUALITY_OPERAND:
@@ -2464,8 +2468,6 @@ ParserErrorCode.POSITIONAL_PARAMETER_OUTSIDE_GROUP:
   status: needsEvaluation
 ParserErrorCode.PREFIX_AFTER_COMBINATOR:
   status: needsEvaluation
-ParserErrorCode.RECORD_LITERAL_EMPTY:
-  status: needsEvaluation
 ParserErrorCode.RECORD_LITERAL_ONE_POSITIONAL_NO_TRAILING_COMMA:
   status: needsEvaluation
 ParserErrorCode.RECORD_TYPE_ONE_POSITIONAL_NO_TRAILING_COMMA:

pkg/analysis_server/test/services/completion/statement/statement_completion_test.dart

@@ -1451,13 +1451,14 @@ void f() {
 ''',
         atEnd: true);
     _assertHasChange(
-        'Insert a newline at the end of the current line',
+        'Add a semicolon and newline',
         '''
 void f() {
-  int g()
+  int g();
+  
 }
 ''',
-        (s) => _afterLast(s, '()'));
+        (s) => _afterLast(s, '();\n  '));
   }
 
   @failingTest

pkg/analyzer/lib/error/error.dart

@@ -749,7 +749,9 @@ const List<ErrorCode> errorCodeValues = [
   ParserErrorCode.DUPLICATE_PREFIX,
   ParserErrorCode.DUPLICATED_MODIFIER,
   ParserErrorCode.EMPTY_ENUM_BODY,
+  ParserErrorCode.EMPTY_RECORD_LITERAL_WITH_COMMA,
   ParserErrorCode.EMPTY_RECORD_TYPE_NAMED_FIELDS_LIST,
+  ParserErrorCode.EMPTY_RECORD_TYPE_WITH_COMMA,
   ParserErrorCode.ENUM_IN_CLASS,
   ParserErrorCode.EQUALITY_CANNOT_BE_EQUALITY_OPERAND,
   ParserErrorCode.EXPECTED_BODY,
@@ -891,7 +893,6 @@ const List<ErrorCode> errorCodeValues = [
   ParserErrorCode.POSITIONAL_AFTER_NAMED_ARGUMENT,
   ParserErrorCode.POSITIONAL_PARAMETER_OUTSIDE_GROUP,
   ParserErrorCode.PREFIX_AFTER_COMBINATOR,
-  ParserErrorCode.RECORD_LITERAL_EMPTY,
   ParserErrorCode.RECORD_LITERAL_ONE_POSITIONAL_NO_TRAILING_COMMA,
   ParserErrorCode.RECORD_TYPE_ONE_POSITIONAL_NO_TRAILING_COMMA,
   ParserErrorCode.REDIRECTING_CONSTRUCTOR_WITH_BODY,

pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart

@@ -142,8 +142,9 @@ final fastaAnalyzerErrorCodes = <ErrorCode?>[
   ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET,
   ParserErrorCode.INVALID_UNICODE_ESCAPE_STARTED,
   ParserErrorCode.RECORD_LITERAL_ONE_POSITIONAL_NO_TRAILING_COMMA,
-  ParserErrorCode.RECORD_LITERAL_EMPTY,
+  ParserErrorCode.EMPTY_RECORD_LITERAL_WITH_COMMA,
   ParserErrorCode.EMPTY_RECORD_TYPE_NAMED_FIELDS_LIST,
+  ParserErrorCode.EMPTY_RECORD_TYPE_WITH_COMMA,
   ParserErrorCode.RECORD_TYPE_ONE_POSITIONAL_NO_TRAILING_COMMA,
 ];
 
@@ -435,13 +436,26 @@ class ParserErrorCode extends ErrorCode {
     correctionMessage: "Try declaring a constant.",
   );
 
+  static const ParserErrorCode EMPTY_RECORD_LITERAL_WITH_COMMA =
+      ParserErrorCode(
+    'EMPTY_RECORD_LITERAL_WITH_COMMA',
+    "Record literal without fields can't have a trailing comma.",
+    correctionMessage: "Try removing the trailing comma.",
+  );
+
   static const ParserErrorCode EMPTY_RECORD_TYPE_NAMED_FIELDS_LIST =
       ParserErrorCode(
     'EMPTY_RECORD_TYPE_NAMED_FIELDS_LIST',
     "Record type named fields list can't be empty.",
     correctionMessage: "Try adding a record type named field to the list.",
   );
 
+  static const ParserErrorCode EMPTY_RECORD_TYPE_WITH_COMMA = ParserErrorCode(
+    'EMPTY_RECORD_TYPE_WITH_COMMA',
+    "Record type without fields can't have a trailing comma.",
+    correctionMessage: "Try removing the trailing comma.",
+  );
+
   static const ParserErrorCode ENUM_IN_CLASS = ParserErrorCode(
     'ENUM_IN_CLASS',
     "Enums can't be declared inside classes.",
@@ -1422,12 +1436,6 @@ class ParserErrorCode extends ErrorCode {
     correctionMessage: "Try moving the prefix before the combinators.",
   );
 
-  static const ParserErrorCode RECORD_LITERAL_EMPTY = ParserErrorCode(
-    'RECORD_LITERAL_EMPTY',
-    "Record literal can't be empty.",
-    correctionMessage: "Try adding elements or use 'Record.empty()' instead.",
-  );
-
   static const ParserErrorCode RECORD_LITERAL_ONE_POSITIONAL_NO_TRAILING_COMMA =
       ParserErrorCode(
     'RECORD_LITERAL_ONE_POSITIONAL_NO_TRAILING_COMMA',

pkg/analyzer/test/generated/class_member_parser_test.dart

@@ -1540,7 +1540,7 @@ void Function<A>(core.List<core.int> x) m() => null;
     // https://github.com/dart-lang/sdk/issues/37693
     parseCompilationUnit('class C{ C() : super() * (); }', errors: [
       expectedError(ParserErrorCode.INVALID_INITIALIZER, 15, 12),
-      expectedError(ParserErrorCode.MISSING_IDENTIFIER, 26, 1),
+      expectedError(ParserErrorCode.EXPERIMENT_NOT_ENABLED, 25, 1),
     ]);
   }
 

pkg/analyzer/test/generated/error_parser_test.dart

@@ -1445,7 +1445,7 @@ class Wrong<T> {
     expectNotNullIfNoErrors(statement);
     listener.assertErrors([
       expectedError(ParserErrorCode.EXPECTED_TOKEN, 7, 1),
-      expectedError(ParserErrorCode.MISSING_IDENTIFIER, 9, 1),
+      expectedError(ParserErrorCode.EXPERIMENT_NOT_ENABLED, 8, 1),
       expectedError(ParserErrorCode.EXPECTED_TOKEN, 9, 1),
     ]);
   }

pkg/analyzer/test/generated/recovery_parser_test.dart

@@ -490,7 +490,7 @@ class B = Object with A {}''', codes:
     CompilationUnit unit =
         parseCompilationUnit("class A { A() : a = (){}; var v; }", codes: [
       ParserErrorCode.EXPECTED_CLASS_MEMBER,
-      ParserErrorCode.MISSING_IDENTIFIER,
+      ParserErrorCode.EXPERIMENT_NOT_ENABLED,
     ]);
 // Make sure we recovered and parsed "var v" correctly
     ClassDeclaration declaration = unit.declarations[0] as ClassDeclaration;

pkg/analyzer/test/generated/simple_parser_test.dart

@@ -127,7 +127,6 @@ class C {
       expectedError(ParserErrorCode.EXPECTED_IDENTIFIER_BUT_GOT_KEYWORD, 24, 5),
       expectedError(ParserErrorCode.MISSING_IDENTIFIER, 24, 5),
       expectedError(ParserErrorCode.EXPERIMENT_NOT_ENABLED, 29, 1),
-      expectedError(ParserErrorCode.RECORD_LITERAL_EMPTY, 30, 1),
     ]);
   }