--- antlr3-3.5.3/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g	2024-09-21 12:35:02.440474037 +0200
+++ antlr3-3.5.3/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g	2024-09-21 12:52:37.133715512 +0200
@@ -53,9 +53,10 @@
 import org.antlr.tool.*;
 import org.antlr.codegen.*;
 
-import java.util.HashSet;
+import java.util.TreeSet;
 import java.util.Set;
 import java.util.Collection;
+import java.util.Collections;
 import org.antlr.runtime.BitSet;
 import org.antlr.runtime.DFA;
 import org.stringtemplate.v4.ST;
@@ -73,7 +74,7 @@
 protected ST currentBlockST = null;
 protected boolean currentAltHasASTRewrite = false;
 protected int rewriteTreeNestingLevel = 0;
-protected HashSet<Object> rewriteRuleRefs = null;
+protected TreeSet<Object> rewriteRuleRefs = null;
 
 public String getCurrentRuleName() {
     return currentRuleName;
@@ -284,6 +285,7 @@
         }
         labels.add( label );
     }
+    Collections.sort(labels); // ensure reproducible order
     return labels;
 }
 
@@ -1202,18 +1204,18 @@
 				$code.add("rewriteBlockLevel", OUTER_REWRITE_NESTING_LEVEL);
 				$code.add("referencedElementsDeep",
 								  getTokenTypesAsTargetLabels($start.rewriteRefsDeep));
-				Set<String> tokenLabels =
-					grammar.getLabels($start.rewriteRefsDeep, Grammar.TOKEN_LABEL);
-				Set<String> tokenListLabels =
-					grammar.getLabels($start.rewriteRefsDeep, Grammar.TOKEN_LIST_LABEL);
-				Set<String> ruleLabels =
-					grammar.getLabels($start.rewriteRefsDeep, Grammar.RULE_LABEL);
-				Set<String> ruleListLabels =
-					grammar.getLabels($start.rewriteRefsDeep, Grammar.RULE_LIST_LABEL);
-				Set<String> wildcardLabels =
-					grammar.getLabels($start.rewriteRefsDeep, Grammar.WILDCARD_TREE_LABEL);
-				Set<String> wildcardListLabels =
-					grammar.getLabels($start.rewriteRefsDeep, Grammar.WILDCARD_TREE_LIST_LABEL);
+				TreeSet<String> tokenLabels =
+					new TreeSet<String>(grammar.getLabels($start.rewriteRefsDeep, Grammar.TOKEN_LABEL));
+				TreeSet<String> tokenListLabels =
+					new TreeSet<String>(grammar.getLabels($start.rewriteRefsDeep, Grammar.TOKEN_LIST_LABEL));
+				TreeSet<String> ruleLabels =
+					new TreeSet<String>(grammar.getLabels($start.rewriteRefsDeep, Grammar.RULE_LABEL));
+				TreeSet<String> ruleListLabels =
+					new TreeSet<String>(grammar.getLabels($start.rewriteRefsDeep, Grammar.RULE_LIST_LABEL));
+				TreeSet<String> wildcardLabels =
+					new TreeSet<String>(grammar.getLabels($start.rewriteRefsDeep, Grammar.WILDCARD_TREE_LABEL));
+				TreeSet<String> wildcardListLabels =
+					new TreeSet<String>(grammar.getLabels($start.rewriteRefsDeep, Grammar.WILDCARD_TREE_LIST_LABEL));
 				// just in case they ref $r for "previous value", make a stream
 				// from retval.tree
 				ST retvalST = templates.getInstanceOf("prevRuleRootRef");
@@ -1236,7 +1238,7 @@
 }
 	:	^(	REWRITES
 			(
-				{rewriteRuleRefs = new HashSet<Object>();}
+				{rewriteRuleRefs = new TreeSet<Object>();}
 				^( r=REWRITE (pred=SEMPRED)? alt=rewrite_alternative)
 				{
 					rewriteBlockNestingLevel = OUTER_REWRITE_NESTING_LEVEL;