From 1c9e52b5d639a9394ef3227d94fb6ea4073db50e Mon Sep 17 00:00:00 2001
From: Sam Harwell <sam@tunnelvisionlabs.com>
Date: Wed, 4 Apr 2012 09:50:51 -0500
Subject: [PATCH 1/2] Use CopyOnWriteArrayList instead of
 Collections.synchronizedList

---
 tool/src/org/antlr/v4/Tool.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tool/src/org/antlr/v4/Tool.java b/tool/src/org/antlr/v4/Tool.java
index dad9c8bab..741107254 100644
--- a/tool/src/org/antlr/v4/Tool.java
+++ b/tool/src/org/antlr/v4/Tool.java
@@ -74,6 +74,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 public class Tool {
 	public String VERSION = "4.0-"+new Date();
@@ -166,8 +167,7 @@ public class Tool {
 	public ErrorManager errMgr = new ErrorManager(this);
     public LogManager logMgr = new LogManager();
 
-	List<ANTLRToolListener> listeners =
-	Collections.synchronizedList(new ArrayList<ANTLRToolListener>());
+	List<ANTLRToolListener> listeners = new CopyOnWriteArrayList<ANTLRToolListener>();
 
 	/** Track separately so if someone adds a listener, it's the only one
 	 *  instead of it and the default stderr listener.

From 2c1f673f621dba72df40ceb161301768dfdbb12a Mon Sep 17 00:00:00 2001
From: Sam Harwell <sam@tunnelvisionlabs.com>
Date: Wed, 4 Apr 2012 09:51:23 -0500
Subject: [PATCH 2/2] Mark ErrorType fields final

---
 tool/src/org/antlr/v4/tool/ErrorType.java | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/tool/src/org/antlr/v4/tool/ErrorType.java b/tool/src/org/antlr/v4/tool/ErrorType.java
index 3d406d9dd..0d49e560c 100644
--- a/tool/src/org/antlr/v4/tool/ErrorType.java
+++ b/tool/src/org/antlr/v4/tool/ErrorType.java
@@ -185,16 +185,18 @@ public enum ErrorType {
 
     ;
 
-	public String msg;
-    public int code; // unique, deterministic unchanging error code once we release
-    public ErrorSeverity severity;
-    public Boolean abortsAnalysis;
-    public Boolean abortsCodegen;
+	public final String msg;
+    public final int code; // unique, deterministic unchanging error code once we release
+    public final ErrorSeverity severity;
+    public final Boolean abortsAnalysis;
+    public final Boolean abortsCodegen;
 
 	ErrorType(int code, String msg, ErrorSeverity severity) {
         this.code = code;
 		this.msg = msg;
         this.severity = severity;
+		this.abortsAnalysis = false;
+		this.abortsCodegen = false;
 	}
 
 //	ErrorType(String msg, ErrorSeverity severity, boolean abortsAnalysis) {