Slightly better debugging output (issue-26636)

pkg/analyzer/lib/src/task/dart.dart

 // Copyright (c) 2015, 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 analyzer.src.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 3239 matching lines @@
   InferStaticVariableTask(
       InternalAnalysisContext context, VariableElement variable)
       : super(context, variable);
 
   /**
    * Return the declaration of the target within the given compilation [unit].
    * Throw an exception if the declaration cannot be found.
    */
   VariableDeclaration getDeclaration(CompilationUnit unit) {
     VariableElement variable = target;
-    AstNode node = new NodeLocator2(variable.nameOffset).searchWithin(unit);
+    int offset = variable.nameOffset;
+    AstNode node = new NodeLocator2(offset).searchWithin(unit);
     if (node == null) {
       Source variableSource = variable.source;
       Source unitSource = unit.element.source;
       if (variableSource != unitSource) {
         throw new AnalysisException(
             "Failed to find the AST node for the variable "
-            "${variable.displayName} in $variableSource "
+            "${variable.displayName} at $offset in $variableSource "
             "because we were looking in $unitSource");
       }
       throw new AnalysisException(
           "Failed to find the AST node for the variable "
-          "${variable.displayName} in $variableSource");
+          "${variable.displayName} at $offset in $variableSource");
     }
     VariableDeclaration declaration =
         node.getAncestor((AstNode ancestor) => ancestor is VariableDeclaration);
     if (declaration == null || declaration.name != node) {
       Source variableSource = variable.source;
       Source unitSource = unit.element.source;
       if (variableSource != unitSource) {
+        if (declaration == null) {
+          throw new AnalysisException(
+              "Failed to find the declaration of the variable "
+              "${variable.displayName} at $offset in $variableSource "
+              "because the node was not in a variable declaration "
+              "possibly because we were looking in $unitSource");
+        }
         throw new AnalysisException(
             "Failed to find the declaration of the variable "
-            "${variable.displayName} in $variableSource"
+            "${variable.displayName} at $offset in $variableSource "
             "because we were looking in $unitSource");
       }
+      if (declaration == null) {
+        throw new AnalysisException(
+            "Failed to find the declaration of the variable "
+            "${variable.displayName} at $offset in $variableSource "
+            "because the node was not in a variable declaration");
+      }
       throw new AnalysisException(
           "Failed to find the declaration of the variable "
-          "${variable.displayName} in $variableSource");
+          "${variable.displayName} at $offset in $variableSource "
+          "because the node was not the name in a variable declaration");
     }
     return declaration;
   }
 }
 
 /**
  * A task that ensures that all of the inferable static variables in a
  * compilation unit have had their type inferred.
  */
 class InferStaticVariableTypesInUnitTask extends SourceBasedAnalysisTask {
@@ skipping 2652 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }