Issue 35241. Fix for NPE when the referenced constant variable does not have initializer.

[email protected]

Bug: #35241
Change-Id: I406a44467bf3ed2463e8a24c52c45e228c9b6dfa
Reviewed-on: https://dart-review.googlesource.com/c/86100
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/constant/evaluation.dart

@@ -1608,8 +1608,9 @@ class ConstantVisitor extends UnifyingAstVisitor<DartObjectImpl> {
       // Driver, we compute values of all dependencies first (or detect  cycle).
       // So, the value has already been computed. Just return it.
       if (evaluationEngine.forAnalysisDriver) {
-        if (variableElement.isConst) {
-          return variableElement.evaluationResult.value;
+        EvaluationResultImpl value = variableElement.evaluationResult;
+        if (variableElement.isConst && value != null) {
+          return value.value;
         }
       } else {
         // TODO(scheglov) Once we remove task model, we can remove this code.

pkg/analyzer/test/src/dart/resolution/constant_test.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -130,6 +131,25 @@ main() {}
     var value = node.elementAnnotation.constantValue;
     expect(value.getField('(super)').getField('f').toIntValue(), 42);
   }
+
+  test_constNotInitialized() async {
+    addTestFile(r'''
+class B {
+  const B(_);
+}
+
+class C extends B {
+  static const a;
+  const C() : super(a);
+}
+''');
+    await resolveTestFile();
+    assertTestErrors([
+      CompileTimeErrorCode.NON_CONSTANT_VALUE_IN_INITIALIZER,
+      CompileTimeErrorCode.CONST_NOT_INITIALIZED,
+      CompileTimeErrorCode.CONST_NOT_INITIALIZED,
+    ]);
+  }
 }
 
 @reflectiveTest