diff --git a/runtime/Go/src/antlr4/IntervalSet.go b/runtime/Go/src/antlr4/IntervalSet.go
index 5177f8c45..d2353eaa5 100644
--- a/runtime/Go/src/antlr4/IntervalSet.go
+++ b/runtime/Go/src/antlr4/IntervalSet.go
@@ -23,7 +23,7 @@ func (i *Interval) contains(item int) {
 	return item >= i.start && item < i.stop
 }
 
-func (i *Interval) toString() {
+func (i *Interval) toString() string {
 	if(i.start==i.stop-1) {
 		return strconv.Itoa(i.start)
 	} else {
diff --git a/runtime/Go/src/antlr4/PredictionContext.go b/runtime/Go/src/antlr4/PredictionContext.go
index 0c0e9e7e6..d945c5ae5 100644
--- a/runtime/Go/src/antlr4/PredictionContext.go
+++ b/runtime/Go/src/antlr4/PredictionContext.go
@@ -156,7 +156,7 @@ func (this *SingletonPredictionContext) hashString() {
 	return this.cachedHashString
 }
 
-func (this *SingletonPredictionContext) toString() {
+func (this *SingletonPredictionContext) toString() string {
 	var up = this.parentCtx == nil ? "" : this.parentCtx.toString()
 	if (up.length == 0) {
 		if (this.returnState == this.EMPTY_RETURN_STATE) {
@@ -193,7 +193,7 @@ func (this *EmptyPredictionContext) equals(other) {
 	return this == other
 }
 
-func (this *EmptyPredictionContext) toString() {
+func (this *EmptyPredictionContext) toString() string {
 	return "$"
 }
 
@@ -247,7 +247,7 @@ func (this *ArrayPredictionContext) equals(other) {
 	}
 }
 
-func (this *ArrayPredictionContext) toString() {
+func (this *ArrayPredictionContext) toString() string {
 	if (this.isEmpty()) {
 		return "[]"
 	} else {
diff --git a/runtime/Go/src/antlr4/Token.go b/runtime/Go/src/antlr4/Token.go
index 94dd24a61..604e15e4a 100644
--- a/runtime/Go/src/antlr4/Token.go
+++ b/runtime/Go/src/antlr4/Token.go
@@ -141,7 +141,7 @@ Object.defineProperty(CommonToken.prototype, "text", {
 	}
 })
 
-func (this *CommonToken) toString() {
+func (this *CommonToken) toString() string {
 	var txt = this.text
 	if (txt != nil) {
 		txt = txt.replace(/\n/g, "\\n").replace(/\r/g, "\\r").replace(/\t/g, "\\t")
diff --git a/runtime/Go/src/antlr4/Utils.go b/runtime/Go/src/antlr4/Utils.go
index 98af3b286..84def2695 100644
--- a/runtime/Go/src/antlr4/Utils.go
+++ b/runtime/Go/src/antlr4/Utils.go
@@ -80,7 +80,7 @@ func (this *Set) values() {
 	return l
 }
 
-func (this *Set) toString() {
+func (this *Set) toString() string {
 	return arrayToString(this.values())
 }
 
@@ -131,7 +131,7 @@ Object.defineProperty(BitSet.prototype, "length", {
 	}
 })
 
-func (this *BitSet) toString() {
+func (this *BitSet) toString() string {
 	return "{" + this.values().join(", ") + "}"
 }
 
diff --git a/runtime/Go/src/antlr4/atn/ATNConfig.go b/runtime/Go/src/antlr4/atn/ATNConfig.go
index 96dd98f58..52edd3b5f 100644
--- a/runtime/Go/src/antlr4/atn/ATNConfig.go
+++ b/runtime/Go/src/antlr4/atn/ATNConfig.go
@@ -95,7 +95,7 @@ func (this *ATNConfig) hashString() {
              "/" + this.semanticContext.hashString()
 }
 
-func (this *ATNConfig) toString() {
+func (this *ATNConfig) toString() string {
     return "(" + this.state + "," + this.alt +
         (this.context!=nil ? ",[" + this.context.toString() + "]" : "") +
         (this.semanticContext != SemanticContext.NONE ?
diff --git a/runtime/Go/src/antlr4/atn/ATNConfigSet.go b/runtime/Go/src/antlr4/atn/ATNConfigSet.go
index 587cb99fb..322abe2a3 100644
--- a/runtime/Go/src/antlr4/atn/ATNConfigSet.go
+++ b/runtime/Go/src/antlr4/atn/ATNConfigSet.go
@@ -232,7 +232,7 @@ func (this *ATNConfigSet) setReadonly(readOnly) {
 	}
 }
 
-func (this *ATNConfigSet) toString() {
+func (this *ATNConfigSet) toString() string {
 	return Utils.arrayToString(this.configs) +
 		(this.hasSemanticContext ? ",hasSemanticContext=" + this.hasSemanticContext : "") +
 		(this.uniqueAlt != ATN.INVALID_ALT_NUMBER ? ",uniqueAlt=" + this.uniqueAlt : "") +
diff --git a/runtime/Go/src/antlr4/atn/ATNState.go b/runtime/Go/src/antlr4/atn/ATNState.go
index 5acd01f88..24bb66029 100644
--- a/runtime/Go/src/antlr4/atn/ATNState.go
+++ b/runtime/Go/src/antlr4/atn/ATNState.go
@@ -127,7 +127,7 @@ var ATNState.serializationNames = [
             "PLUS_LOOP_BACK",
             "LOOP_END" ]
 
-func (this *ATNState) toString() {
+func (this *ATNState) toString() string {
 	return this.stateNumber
 }
 
diff --git a/runtime/Go/src/antlr4/atn/LexerAction.go b/runtime/Go/src/antlr4/atn/LexerAction.go
index 6cf6d6282..c06c78021 100644
--- a/runtime/Go/src/antlr4/atn/LexerAction.go
+++ b/runtime/Go/src/antlr4/atn/LexerAction.go
@@ -50,7 +50,7 @@ func (this *LexerSkipAction) execute(lexer) {
     lexer.skip()
 }
 
-func (this *LexerSkipAction) toString() {
+func (this *LexerSkipAction) toString() string {
 	return "skip"
 }
 
@@ -84,7 +84,7 @@ func (this *LexerTypeAction) equals(other) {
     }
 }
 
-func (this *LexerTypeAction) toString() {
+func (this *LexerTypeAction) toString() string {
     return "type(" + this.type + ")"
 }
 
@@ -119,7 +119,7 @@ func (this *LexerPushModeAction) equals(other) {
     }
 }
 
-func (this *LexerPushModeAction) toString() {
+func (this *LexerPushModeAction) toString() string {
 	return "pushMode(" + this.mode + ")"
 }
 
@@ -143,7 +143,7 @@ func (this *LexerPopModeAction) execute(lexer) {
     lexer.popMode()
 }
 
-func (this *LexerPopModeAction) toString() {
+func (this *LexerPopModeAction) toString() string {
 	return "popMode"
 }
 
@@ -166,7 +166,7 @@ func (this *LexerMoreAction) execute(lexer) {
     lexer.more()
 }
 
-func (this *LexerMoreAction) toString() {
+func (this *LexerMoreAction) toString() string {
     return "more"
 }
 
@@ -202,7 +202,7 @@ func (this *LexerModeAction) equals(other) {
     }
 }
 
-func (this *LexerModeAction) toString() {
+func (this *LexerModeAction) toString() string {
     return "mode(" + this.mode + ")"
 }
 
@@ -288,7 +288,7 @@ func (this *LexerChannelAction) equals(other) {
     }
 }
 
-func (this *LexerChannelAction) toString() {
+func (this *LexerChannelAction) toString() string {
     return "channel(" + this.channel + ")"
 }
 
diff --git a/runtime/Go/src/antlr4/atn/SemanticContext.go b/runtime/Go/src/antlr4/atn/SemanticContext.go
index 970ec9cab..c38cb0819 100644
--- a/runtime/Go/src/antlr4/atn/SemanticContext.go
+++ b/runtime/Go/src/antlr4/atn/SemanticContext.go
@@ -122,7 +122,7 @@ func (this *Predicate) equals(other) {
 	}
 }
 
-func (this *Predicate) toString() {
+func (this *Predicate) toString() string {
 	return "{" + this.ruleIndex + ":" + this.predIndex + "}?"
 }
 
@@ -164,7 +164,7 @@ func (this *PrecedencePredicate) equals(other) {
 	}
 }
 
-func (this *PrecedencePredicate) toString() {
+func (this *PrecedencePredicate) toString() string {
 	return "{"+this.precedence+">=prec}?"
 }
 
@@ -277,7 +277,7 @@ func (this *AND) evalPrecedence(parser, outerContext) {
 	return result
 }
 
-func (this *AND) toString() {
+func (this *AND) toString() string {
 	var s = ""
 	this.opnds.map(function(o) {
 		s += "&& " + o.toString()
@@ -379,7 +379,7 @@ func (this *OR) evalPrecedence(parser, outerContext) {
 	return result
 }
 
-func (this *AND) toString() {
+func (this *AND) toString() string {
 	var s = ""
 	this.opnds.map(function(o) {
 		s += "|| " + o.toString()
diff --git a/runtime/Go/src/antlr4/atn/Transition.go b/runtime/Go/src/antlr4/atn/Transition.go
index c67fd8d91..f0b7bd69c 100644
--- a/runtime/Go/src/antlr4/atn/Transition.go
+++ b/runtime/Go/src/antlr4/atn/Transition.go
@@ -91,7 +91,7 @@ func (this *AtomTransition) matches( symbol, minVocabSymbol,  maxVocabSymbol) {
     return this.label_ == symbol
 }
 
-func (this *AtomTransition) toString() {
+func (this *AtomTransition) toString() string {
 	return this.label_
 }
 
@@ -128,7 +128,7 @@ func (this *EpsilonTransition) matches( symbol, minVocabSymbol,  maxVocabSymbol)
 	return false
 }
 
-func (this *EpsilonTransition) toString() {
+func (this *EpsilonTransition) toString() string {
 	return "epsilon"
 }
 
@@ -154,7 +154,7 @@ func (this *RangeTransition) matches(symbol, minVocabSymbol,  maxVocabSymbol) {
 	return symbol >= this.start && symbol <= this.stop
 }
 
-func (this *RangeTransition) toString() {
+func (this *RangeTransition) toString() string {
 	return "'" + String.fromCharCode(this.start) + "'..'" + String.fromCharCode(this.stop) + "'"
 }
 
@@ -187,7 +187,7 @@ func (this *PredicateTransition) getPredicate() {
 	return NewPredicate(this.ruleIndex, this.predIndex, this.isCtxDependent)
 }
 
-func (this *PredicateTransition) toString() {
+func (this *PredicateTransition) toString() string {
 	return "pred_" + this.ruleIndex + ":" + this.predIndex
 }
 
@@ -209,7 +209,7 @@ func (this *ActionTransition) matches(symbol, minVocabSymbol,  maxVocabSymbol) {
 	return false
 }
 
-func (this *ActionTransition) toString() {
+func (this *ActionTransition) toString() string {
 	return "action_" + this.ruleIndex + ":" + this.actionIndex
 }
         
@@ -235,7 +235,7 @@ func (this *SetTransition) matches(symbol, minVocabSymbol,  maxVocabSymbol) {
 }
         
 
-func (this *SetTransition) toString() {
+func (this *SetTransition) toString() string {
 	return this.label.toString()
 }
 
@@ -253,7 +253,7 @@ func (this *NotSetTransition) matches(symbol, minVocabSymbol,  maxVocabSymbol) {
 			!SetTransition.prototype.matches.call(this, symbol, minVocabSymbol, maxVocabSymbol)
 }
 
-func (this *NotSetTransition) toString() {
+func (this *NotSetTransition) toString() string {
 	return '~' + SetTransition.prototype.toString.call(this)
 }
 
@@ -271,7 +271,7 @@ func (this *WildcardTransition) matches(symbol, minVocabSymbol,  maxVocabSymbol)
 	return symbol >= minVocabSymbol && symbol <= maxVocabSymbol
 }
 
-func (this *WildcardTransition) toString() {
+func (this *WildcardTransition) toString() string {
 	return "."
 }
 
@@ -294,7 +294,7 @@ func (this *PrecedencePredicateTransition) getPredicate() {
 	return NewPrecedencePredicate(this.precedence)
 }
 
-func (this *PrecedencePredicateTransition) toString() {
+func (this *PrecedencePredicateTransition) toString() string {
 	return this.precedence + " >= _p"
 }
         
diff --git a/runtime/Go/src/antlr4/dfa/DFASerializer.go b/runtime/Go/src/antlr4/dfa/DFASerializer.go
index b55859ecd..a2761967a 100644
--- a/runtime/Go/src/antlr4/dfa/DFASerializer.go
+++ b/runtime/Go/src/antlr4/dfa/DFASerializer.go
@@ -10,7 +10,7 @@ func DFASerializer(dfa, literalNames, symbolicNames) {
 	return this
 }
 
-func (this *DFASerializer) toString() {
+func (this *DFASerializer) toString() string {
    if(this.dfa.s0 == nil) {
        return nil
    }
diff --git a/runtime/Go/src/antlr4/dfa/DFAState.go b/runtime/Go/src/antlr4/dfa/DFAState.go
index 5cc0de78e..87f97f427 100644
--- a/runtime/Go/src/antlr4/dfa/DFAState.go
+++ b/runtime/Go/src/antlr4/dfa/DFAState.go
@@ -10,7 +10,7 @@ func PredPrediction(pred, alt) {
 	return this
 }
 
-func (this *PredPrediction) toString() {
+func (this *PredPrediction) toString() string {
 	return "(" + this.pred + ", " + this.alt + ")"
 }
 
@@ -120,7 +120,7 @@ func (this *DFAState) equals(other) {
 	}
 }
 
-func (this *DFAState) toString() {
+func (this *DFAState) toString() string {
 	return "" + this.stateNumber + ":" + this.hashString()
 }
 
diff --git a/runtime/Go/src/antlr4/error/Errors.go b/runtime/Go/src/antlr4/error/Errors.go
index 11d5cd920..c76803014 100644
--- a/runtime/Go/src/antlr4/error/Errors.go
+++ b/runtime/Go/src/antlr4/error/Errors.go
@@ -58,7 +58,7 @@ func (this *RecognitionException) getExpectedTokens() {
     }
 }
 
-func (this *RecognitionException) toString() {
+func (this *RecognitionException) toString() string {
     return this.message
 }
 
@@ -72,7 +72,7 @@ func LexerNoViableAltException(lexer, input, startIndex, deadEndConfigs) {
 //LexerNoViableAltException.prototype = Object.create(RecognitionException.prototype)
 //LexerNoViableAltException.prototype.constructor = LexerNoViableAltException
 
-func (this *LexerNoViableAltException) toString() {
+func (this *LexerNoViableAltException) toString() string {
     var symbol = ""
     if (this.startIndex >= 0 && this.startIndex < this.input.size) {
         symbol = this.input.getText((this.startIndex,this.startIndex))
diff --git a/runtime/Go/src/antlr4/tree/Tree.go b/runtime/Go/src/antlr4/tree/Tree.go
index 3decec64f..96a8a08b0 100644
--- a/runtime/Go/src/antlr4/tree/Tree.go
+++ b/runtime/Go/src/antlr4/tree/Tree.go
@@ -165,7 +165,7 @@ func (this *TerminalNodeImpl) getText() {
 	return this.symbol.text
 }
 
-func (this *TerminalNodeImpl) toString() {
+func (this *TerminalNodeImpl) toString() string {
 	if (this.symbol.type == TokenEOF) {
 		return "<EOF>"
 	} else {