[royale-compiler] 02/03: report error if we can figure out a local var was used before its declaration. Use of an instance var of the same name as a local var before the local var is declared seems to work ok in SWF but not in JS so we'll report an error

[ah...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

aharui pushed a commit to branch develop
in repository https://gitbox.apache.org/repos/asf/royale-compiler.git

commit c7d26b06d8fb24dac6b8461aee69334bae5cb7e9
Author: Alex Harui <ah...@apache.org>
AuthorDate: Tue Nov 6 12:26:07 2018 -0800

    report error if we can figure out a local var was used before its declaration.  Use of an instance var of the same name as a local var before the local var is declared seems to work ok in SWF but not in JS so we'll report an error
---
 .../internal/codegen/js/goog/JSGoogEmitter.java    | 20 +++++++
 .../VariableUsedBeforeDeclarationProblem.java      | 62 ++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/compiler-jx/src/main/java/org/apache/royale/compiler/internal/codegen/js/goog/JSGoogEmitter.java b/compiler-jx/src/main/java/org/apache/royale/compiler/internal/codegen/js/goog/JSGoogEmitter.java
index d0d55e9..88628d5 100644
--- a/compiler-jx/src/main/java/org/apache/royale/compiler/internal/codegen/js/goog/JSGoogEmitter.java
+++ b/compiler-jx/src/main/java/org/apache/royale/compiler/internal/codegen/js/goog/JSGoogEmitter.java
@@ -37,6 +37,7 @@ import org.apache.royale.compiler.definitions.IFunctionDefinition;
 import org.apache.royale.compiler.definitions.IPackageDefinition;
 import org.apache.royale.compiler.definitions.ITypeDefinition;
 import org.apache.royale.compiler.definitions.IVariableDefinition;
+import org.apache.royale.compiler.filespecs.IFileSpecification;
 import org.apache.royale.compiler.internal.codegen.as.ASEmitterTokens;
 import org.apache.royale.compiler.internal.codegen.js.royale.JSRoyaleEmitterTokens;
 import org.apache.royale.compiler.internal.codegen.js.JSEmitter;
@@ -44,14 +45,18 @@ import org.apache.royale.compiler.internal.codegen.js.JSEmitterTokens;
 import org.apache.royale.compiler.internal.codegen.js.JSSessionModel;
 import org.apache.royale.compiler.internal.codegen.js.utils.EmitterUtils;
 import org.apache.royale.compiler.internal.definitions.AccessorDefinition;
+import org.apache.royale.compiler.internal.definitions.ClassDefinition;
 import org.apache.royale.compiler.internal.definitions.FunctionDefinition;
 import org.apache.royale.compiler.internal.definitions.NamespaceDefinition.INamepaceDeclarationDirective;
+import org.apache.royale.compiler.internal.definitions.VariableDefinition;
 import org.apache.royale.compiler.internal.scopes.PackageScope;
 import org.apache.royale.compiler.internal.tree.as.ChainedVariableNode;
 import org.apache.royale.compiler.internal.tree.as.FunctionCallNode;
 import org.apache.royale.compiler.internal.tree.as.FunctionNode;
 import org.apache.royale.compiler.internal.tree.as.MemberAccessExpressionNode;
+import org.apache.royale.compiler.internal.tree.as.VariableNode;
 import org.apache.royale.compiler.problems.ICompilerProblem;
+import org.apache.royale.compiler.problems.VariableUsedBeforeDeclarationProblem;
 import org.apache.royale.compiler.projects.ICompilerProject;
 import org.apache.royale.compiler.scopes.IASScope;
 import org.apache.royale.compiler.tree.ASTNodeID;
@@ -928,6 +933,21 @@ public class JSGoogEmitter extends JSEmitter implements IJSGoogEmitter
             return;
         }
         IDefinition definition = node.resolve(getWalker().getProject());
+        if (node.getNodeID() == ASTNodeID.IdentifierID && node.getParent().getNodeID() == ASTNodeID.VariableID)
+        {
+        	if (definition instanceof VariableDefinition && (!(definition.getParent() instanceof ClassDefinition)))
+        	{
+        		IFileSpecification defFile = ((VariableDefinition)definition).getFileSpecification();
+        		IFileSpecification varFile = node.getFileSpecification();
+        		if (defFile != null && varFile != null && varFile.equals(defFile))
+        		{
+        			if (node.getAbsoluteStart() < definition.getAbsoluteStart())
+        			{
+        				getProblems().add(new VariableUsedBeforeDeclarationProblem(node, definition.getBaseName()));
+        			}
+        		}
+        	}
+        }
         if (node.getNodeID() == ASTNodeID.ClassReferenceID)
         {
             write(definition.getQualifiedName());
diff --git a/compiler/src/main/java/org/apache/royale/compiler/problems/VariableUsedBeforeDeclarationProblem.java b/compiler/src/main/java/org/apache/royale/compiler/problems/VariableUsedBeforeDeclarationProblem.java
new file mode 100644
index 0000000..56a4102
--- /dev/null
+++ b/compiler/src/main/java/org/apache/royale/compiler/problems/VariableUsedBeforeDeclarationProblem.java
@@ -0,0 +1,62 @@
+/*
+ *
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+
+package org.apache.royale.compiler.problems;
+
+import org.apache.royale.compiler.tree.as.IASNode;
+
+/**
+ *  Error if we can detect a variable is used before its declaration.
+ *  var foo = bar;
+ *  var bar = 0;
+ *  
+ *  This check is needed when there is also a bar property on the class
+ *  containing the method with the error.
+ *  
+ *  private var bar:int = 0;
+ *  public function baz()
+ *  {
+ *      var foo:int = bar;
+ *      var bar:int = 1;
+ *  }
+ *  
+ *  In the code above, it appears that SWF code will set foo to this.bar.
+ *  I think if a findProp is generated it might know the local variable
+ *  is not in scope?
+ *  But in JS code, foo is set to undefined because at least Safari
+ *  will reference the local variable before it has been initialized.
+ *  
+ *  So, we will generate an error since this code will not work in
+ *  the browser.
+ */
+public final class VariableUsedBeforeDeclarationProblem extends SemanticProblem
+{
+    public static final String DESCRIPTION =
+        "Variable ${declName} used before declaration.";
+
+    public static final int errorCode = 1555;
+
+    public VariableUsedBeforeDeclarationProblem(IASNode site, String declName)
+    {
+        super(site);
+        this.declName = declName;
+    }
+    
+    public final String declName;
+}