Fix constant evaluation logic for String.length.

pkg/analyzer/test/generated/compile_time_error_code_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library engine.compile_time_error_code_test;
 
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/parser.dart' show ParserErrorCode;
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:unittest/unittest.dart' as _ut;
@@ skipping 3233 matching lines @@
 f() {
   x: while (true) {
     continue y;
   }
 }''');
     resolve(source);
     assertErrors(source, [CompileTimeErrorCode.LABEL_UNDEFINED]);
     // We cannot verify resolution with undefined labels
   }
 
+  void test_length_of_erroneous_constant() {
+    // Attempting to compute the length of constant that couldn't be evaluated
+    // (due to an error) should not crash the analyzer (see dartbug.com/23383)
+    Source source = addSource("const int i = (1 ? 'alpha' : 'beta').length;");
+    resolve(source);
+    assertErrors(source, [
+      CompileTimeErrorCode.CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE,
+      CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL,
+      StaticTypeWarningCode.NON_BOOL_CONDITION
+    ]);
+    verify([source]);
+  }
+
   void test_memberWithClassName_field() {
     Source source = addSource(r'''
 class A {
   int A = 0;
 }''');
     resolve(source);
     assertErrors(source, [CompileTimeErrorCode.MEMBER_WITH_CLASS_NAME]);
     verify([source]);
   }
 
@@ skipping 2426 matching lines @@
         source, [CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR]);
     verify([source]);
     reset();
   }
 
   void _check_wrongNumberOfParametersForOperator1(String name) {
     _check_wrongNumberOfParametersForOperator(name, "");
     _check_wrongNumberOfParametersForOperator(name, "a, b");
   }
 }