[parser] Avoid an extra error in CFE for dot shorthands.

The parser was still WIP and was emitting an extra error, so this CL removes that error so tests can start passing and so I can properly test the new implementation e2e.

It still needs some fixes after the analyzer implementation is complete. The current extra synthetic tokens added in the parser are temporary to prevent crashes on the analyzer side when the experiment flag is turned off. But it works fine for now, and I'll clean it up in a CL when the feature is complete.

Bug: #59758
Change-Id: I83d8c840f66bedff4aa27a737a3f57e77d3973b8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/412344
Reviewed-by: Paul Berry <[email protected]>
Reviewed-by: Chloe Stefantsova <[email protected]>
Commit-Queue: Kallen Tu <[email protected]>

Author: kallentu

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

@@ -5833,9 +5833,17 @@ class Parser {
 
     bool isDotShorthand = token.next!.isA(TokenType.PERIOD) &&
         (token.next!.next!.isIdentifier || token.next!.next!.isA(Keyword.NEW));
-    // TODO(kallentu): Once the parser handles dot shorthands by default,
-    // we don't need to parse for an error here.
-    token = parseUnaryExpression(token, allowCascades, constantPatternContext);
+    if (isDotShorthand) {
+      // TODO(kallentu): Once the analyzer implementation is done, we can avoid
+      // adding a synthetic identifier completely, but currently, the parser
+      // will crash without one.
+      //
+      // Insert a synthetic identifier to satisfy listeners.
+      token = rewriter.insertSyntheticIdentifier(token);
+    } else {
+      token =
+          parseUnaryExpression(token, allowCascades, constantPatternContext);
+    }
 
     Token bangToken = token;
     if (token.next!.isA(TokenType.BANG)) {

pkg/analyzer/lib/src/fasta/ast_builder.dart

@@ -4063,9 +4063,6 @@ class AstBuilder extends StackListener {
         feature: ExperimentalFeatures.dot_shorthands,
         startToken: token,
       );
-
-      // Recovery.
-      pop();
     }
 
     // TODO(kallentu): Handle dot shorthands.

pkg/analyzer/test/src/diagnostics/experiment_not_enabled_test.dart

@@ -32,6 +32,18 @@ main() {
     ]);
   }
 
+  test_dotShorthands_disabled() async {
+    await assertErrorsInCode(r'''
+void main() {
+  Object c = .hash;
+  print(c);
+}
+''', [
+      error(ParserErrorCode.EXPERIMENT_NOT_ENABLED, 27, 1),
+      error(CompileTimeErrorCode.UNDEFINED_IDENTIFIER, 28, 4),
+    ]);
+  }
+
   test_nonFunctionTypeAliases_disabled() async {
     await assertErrorsInCode(r'''
 // @dart = 2.12

pkg/front_end/lib/src/kernel/body_builder.dart

@@ -10007,15 +10007,13 @@ class BodyBuilder extends StackListenerImpl
 
       // Recovery, avoid crashing with an extra selector.
       pop();
+      push(new ParserErrorGenerator(this, token, cfe.messageSyntheticToken));
       return;
     }
 
-    Object? selector = pop();
-    if (libraryFeatures.dotShorthands.isEnabled && selector is Selector) {
-      // TODO(kallentu): Remove this once we have more of the dot shorthands
-      // implementation complete.
-      pop(); // ParserGeneratorError
-
+    assert(checkState(token, [ValueKinds.Selector]));
+    Selector selector = pop() as Selector;
+    if (libraryFeatures.dotShorthands.isEnabled) {
       // TODO(kallentu): Handle invocations.
 
       push(forest.createDotShorthandPropertyGet(

pkg/front_end/parser_testcases/dot_shorthands/syntax.dart.expect

@@ -1,9 +1,3 @@
-Problems reported:
-
-parser/dot_shorthands/syntax:4:13: Expected an identifier, but got '.'.
-  Color c = .red;
-            ^
-
 beginCompilationUnit(enum)
   beginMetadataStar(enum)
   endMetadataStar(0)
@@ -67,11 +61,6 @@ beginCompilationUnit(enum)
           handleIdentifier(c, localVariableDeclaration)
           beginInitializedIdentifier(c)
             beginVariableInitializer(=)
-              handleRecoverableError(Message[ExpectedIdentifier, Expected an identifier, but got '.'., Try inserting an identifier before '.'., {lexeme: .}], ., .)
-              handleIdentifier(, expression)
-              handleNoTypeArguments(.)
-              handleNoArguments(.)
-              handleSend(, )
               handleIdentifier(red, expressionContinuation)
               handleNoTypeArguments(;)
               handleNoArguments(;)

pkg/front_end/parser_testcases/dot_shorthands/syntax.dart.intertwined.expect

@@ -104,19 +104,7 @@ parseUnit(enum)
                       listener: beginVariableInitializer(=)
                       parseExpression(=)
                         parsePrecedenceExpression(=, 1, true, ConstantPatternContext.none)
-                          parseUnaryExpression(=, true, ConstantPatternContext.none)
-                            parsePrimary(=, expression, ConstantPatternContext.none)
-                              parseSend(=, expression, ConstantPatternContext.none)
-                                isNextIdentifier(=)
-                                ensureIdentifier(=, expression)
-                                  reportRecoverableErrorWithToken(., Template(ExpectedIdentifier))
-                                    listener: handleRecoverableError(Message[ExpectedIdentifier, Expected an identifier, but got '.'., Try inserting an identifier before '.'., {lexeme: .}], ., .)
-                                  rewriter()
-                                  listener: handleIdentifier(, expression)
-                                listener: handleNoTypeArguments(.)
-                                parseArgumentsOpt()
-                                  listener: handleNoArguments(.)
-                                listener: handleSend(, )
+                          rewriter()
                           parsePrimary(., expressionContinuation, ConstantPatternContext.none)
                             parseSendOrFunctionLiteral(., expressionContinuation, ConstantPatternContext.none)
                               parseSend(., expressionContinuation, ConstantPatternContext.none)

pkg/front_end/testcases/dot_shorthands/simple_class.dart.strong.expect

@@ -1,12 +1,4 @@
 library;
-//
-// Problems in library:
-//
-// pkg/front_end/testcases/dot_shorthands/simple_class.dart:12:13: Error: Expected an identifier, but got '.'.
-// Try inserting an identifier before '.'.
-//   Color c = .red;
-//             ^
-//
 import self as self;
 import "dart:core" as core;
 

pkg/front_end/testcases/dot_shorthands/simple_class.dart.strong.modular.expect

@@ -1,12 +1,4 @@
 library;
-//
-// Problems in library:
-//
-// pkg/front_end/testcases/dot_shorthands/simple_class.dart:12:13: Error: Expected an identifier, but got '.'.
-// Try inserting an identifier before '.'.
-//   Color c = .red;
-//             ^
-//
 import self as self;
 import "dart:core" as core;
 

pkg/front_end/testcases/dot_shorthands/simple_class.dart.strong.transformed.expect

@@ -1,12 +1,4 @@
 library;
-//
-// Problems in library:
-//
-// pkg/front_end/testcases/dot_shorthands/simple_class.dart:12:13: Error: Expected an identifier, but got '.'.
-// Try inserting an identifier before '.'.
-//   Color c = .red;
-//             ^
-//
 import self as self;
 import "dart:core" as core;
 

pkg/front_end/testcases/dot_shorthands/simple_enum.dart.strong.expect

@@ -1,12 +1,4 @@
 library;
-//
-// Problems in library:
-//
-// pkg/front_end/testcases/dot_shorthands/simple_enum.dart:8:13: Error: Expected an identifier, but got '.'.
-// Try inserting an identifier before '.'.
-//   Color c = .red;
-//             ^
-//
 import self as self;
 import "dart:core" as core;