Issue 2382. Using a variable in a scope before its declared that shadows another variable

compiler/java/com/google/dart/compiler/resolver/Resolver.java

Index: compiler/java/com/google/dart/compiler/resolver/Resolver.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/Resolver.java b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
index 34dc319f31b878f4b088404db256c5ee4ae657c1..09fecaee5f63ff456aa176f821c52582a365794f 100644
--- a/compiler/java/com/google/dart/compiler/resolver/Resolver.java
+++ b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
@@ -744,6 +744,8 @@ public class Resolver {
               inFactoryContext(currentMethod),
               TypeErrorCode.NO_SUCH_TYPE);
       for (DartVariable variable : node.getVariables()) {
+        String name = variable.getVariableName();
+        getContext().getScope().removeDeclaredButNotReachedVariable(name);
         Elements.setType(resolveVariable(variable, node.getModifiers()), type);
         checkVariableStatement(node, variable, isImplicitlyInitialized);
       }
@@ -794,6 +796,18 @@ public class Resolver {
     public Element visitBlock(DartBlock x) {
       getContext().pushScope("<block>");
       addLabelToStatement(x);
+      // Remember names of Block variables.
+      for (DartStatement statement : x.getStatements()) {
+        if (statement instanceof DartVariableStatement) {
+          DartVariableStatement node = (DartVariableStatement) statement;
+          List<DartVariable> variables = node.getVariables();
+          for (DartVariable variable : variables) {
+            String name = variable.getVariableName();
+            getContext().getScope().addDeclaredButNotReachedVariable(name);
+          }
+        }
+      }
+      // Visit statements.
       x.visitChildren(this);
       getContext().popScope();
       return null;
@@ -1013,6 +1027,11 @@ public class Resolver {
         }
       }
 
+      // May be local variable declared in lexical scope, but its declaration is not visited yet.
+      if (getContext().getScope().isDeclaredButNotReachedVariable(name)) {
+        onError(x, ResolverErrorCode.USING_LOCAL_VARIABLE_BEFORE_DECLARATION, x);
+      }
+
       // If we we haven't resolved the identifier, it will be normalized to
       // this.<identifier>.