capture more info to debug 37528

Dan Rubel · commit-bot@chromium.org · commit d7cb52b863b0 · 2019-07-22T20:18:17.000Z
This updates the exception message to capture more information about where the exception is occurring. Hopefully that information can be used to fix #37528 Change-Id: Iaf10395091f8bd8b540dddc59001f23b6dc6a073 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/109920 Reviewed-by: Brian Wilkerson <brianwilkerson@google.com> Commit-Queue: Dan Rubel <danrubel@google.com>
diff --git a/pkg/analyzer/test/generated/parser_fasta_test.dart b/pkg/analyzer/test/generated/parser_fasta_test.dart
@@ -1095,6 +1095,22 @@ main() { // missing async
         ]);
   }
 
+  void test_missing_closing_bracket_issue37528() {
+    final code = '\${foo';
+    createParser(code);
+    final result = fasta.scanString(code);
+    expect(result.hasErrors, isTrue);
+    var token = _parserProxy.fastaParser.syntheticPreviousToken(result.tokens);
+    try {
+      _parserProxy.fastaParser.parseExpression(token);
+      // TODO(danrubel): Replace this test once root cause is found
+      fail('exception expected');
+    } catch (e) {
+      var msg = e.toString();
+      expect(msg.contains('test_missing_closing_bracket_issue37528'), isTrue);
+    }
+  }
+
   void test_partialNamedConstructor() {
     parseCompilationUnit('class C { C. }', errors: [
       expectedError(ParserErrorCode.MISSING_IDENTIFIER, 13, 1),
diff --git a/pkg/front_end/lib/src/fasta/scanner/error_token.dart b/pkg/front_end/lib/src/fasta/scanner/error_token.dart
@@ -72,7 +72,23 @@ abstract class ErrorToken extends SimpleToken {
   @override
   int get length => 1;
 
-  String get lexeme => throw assertionMessage.message;
+  String get lexeme {
+    var errorMsg = assertionMessage.message;
+
+    // Attempt to include the location which is calling the parser
+    // in an effort to debug https://github.com/dart-lang/sdk/issues/37528
+    var pattern = RegExp('^#[0-9]* *Parser');
+    var traceLines = StackTrace.current.toString().split('\n');
+    for (int index = traceLines.length - 2; index >= 0; --index) {
+      var line = traceLines[index];
+      if (line.startsWith(pattern)) {
+        errorMsg = '$errorMsg - ${traceLines[index + 1]}';
+        break;
+      }
+    }
+
+    throw errorMsg;
+  }
 
   Message get assertionMessage;
 
