rm'd $foo references from lexer actions and added a good error message.

tool/playground/T.g

@@ -2,5 +2,5 @@ grammar T;
 
 s : INT { System.out.println($start.getText());} ;
 
-INT : [0-9]+ {$type = 3; String x = $text; $channel, $mode} ;
+INT : [0-9]+ {$x.type = 3; String x = $text; $channel, $mode} ;
 WS : [ \t\n]+ -> skip ;

tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg

@@ -522,7 +522,6 @@ TokenRef(t) ::= "<ctx(t)>.<t.name>"
 LabelRef(t) ::= "<ctx(t)>.<t.name>"
 ListLabelRef(t) ::= "<ctx(t)>.<ListLabelName(t.name)>"
 SetAttr(s,rhsChunks) ::= "<ctx(s)>.<s.name> = <rhsChunks>;"
-LexerSetAttr(s,rhsChunks) ::= "_<s.name> = <rhsChunks>;" // _type etc...
 
 TokenLabelType() ::= "<file.TokenLabelType; null={Token}>"
 InputSymbolType() ::= "<file.InputSymbolType; null={Token}>"

tool/src/org/antlr/v4/codegen/ActionTranslator.java

@@ -36,7 +36,6 @@ import org.antlr.v4.codegen.model.chunk.ActionChunk;
 import org.antlr.v4.codegen.model.chunk.ActionText;
 import org.antlr.v4.codegen.model.chunk.ArgRef;
 import org.antlr.v4.codegen.model.chunk.LabelRef;
-import org.antlr.v4.codegen.model.chunk.LexerSetAttr;
 import org.antlr.v4.codegen.model.chunk.ListLabelRef;
 import org.antlr.v4.codegen.model.chunk.LocalRef;
 import org.antlr.v4.codegen.model.chunk.NonLocalAttrRef;
@@ -240,7 +239,6 @@ public class ActionTranslator implements ActionSplitterListener {
 		gen.g.tool.log("action-translator", "setAttr "+x+" "+rhs);
 		List<ActionChunk> rhsChunks = translateActionChunk(factory,rf,rhs.getText(),node);
 		SetAttr s = new SetAttr(nodeContext, x.getText(), rhsChunks);
-		if ( factory.getGrammar().isLexer() ) s = new LexerSetAttr(nodeContext, x.getText(), rhsChunks);
 		chunks.add(s);
 	}
 

tool/src/org/antlr/v4/codegen/model/chunk/LexerSetAttr.java

@@ -1,40 +0,0 @@
-/*
- [The "BSD license"]
- Copyright (c) 2011 Terence Parr
- All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
-
- 1. Redistributions of source code must retain the above copyright
-    notice, this list of conditions and the following disclaimer.
- 2. Redistributions in binary form must reproduce the above copyright
-    notice, this list of conditions and the following disclaimer in the
-    documentation and/or other materials provided with the distribution.
- 3. The name of the author may not be used to endorse or promote products
-    derived from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-package org.antlr.v4.codegen.model.chunk;
-
-import org.antlr.v4.codegen.model.decl.StructDecl;
-
-import java.util.List;
-
-public class LexerSetAttr extends SetAttr {
-	public LexerSetAttr(StructDecl ctx, String name, List<ActionChunk> rhsChunks) {
-		super(ctx, name, rhsChunks);
-	}
-}

tool/src/org/antlr/v4/semantics/AttributeChecks.java

@@ -118,6 +118,11 @@ public class AttributeChecks implements ActionSplitterListener {
 	// $x.y
 	@Override
 	public void qualifiedAttr(String expr, Token x, Token y) {
+		if ( g.isLexer() ) {
+			errMgr.grammarError(ErrorType.ATTRIBUTE_IN_LEXER_ACTION,
+								g.fileName, x, x.getText()+"."+y.getText(), expr);
+			return;
+		}
 		if ( node.resolver.resolveToAttribute(x.getText(), node)!=null ) {
 			// must be a member access to a predefined attribute like $ctx.foo
 			attr(expr, x);
@@ -149,6 +154,11 @@ public class AttributeChecks implements ActionSplitterListener {
 
 	@Override
 	public void setAttr(String expr, Token x, Token rhs) {
+		if ( g.isLexer() ) {
+			errMgr.grammarError(ErrorType.ATTRIBUTE_IN_LEXER_ACTION,
+								g.fileName, x, x.getText(), expr);
+			return;
+		}
 		if ( node.resolver.resolveToAttribute(x.getText(), node)==null ) {
 			errMgr.grammarError(ErrorType.UNKNOWN_SIMPLE_ATTRIBUTE,
 								g.fileName, x, x.getText(), expr);
@@ -158,6 +168,11 @@ public class AttributeChecks implements ActionSplitterListener {
 
 	@Override
     public void attr(String expr, Token x) {
+		if ( g.isLexer() ) {
+			errMgr.grammarError(ErrorType.ATTRIBUTE_IN_LEXER_ACTION,
+								g.fileName, x, x.getText(), expr);
+			return;
+		}
 		if ( node.resolver.resolveToAttribute(x.getText(), node)==null ) {
 			if ( node.resolver.resolvesToToken(x.getText(), node) ) {
 				return; // $ID for token ref or label of token

tool/src/org/antlr/v4/tool/ErrorType.java

@@ -148,6 +148,7 @@ public enum ErrorType {
 	IMPLICIT_TOKEN_DEFINITION(125, "implicit definition of token <arg> in parser", ErrorSeverity.WARNING),
 	IMPLICIT_STRING_DEFINITION(126, "cannot create implicit token for string literal <arg> in non-combined grammar", ErrorSeverity.ERROR),
 //	ALIAS_REASSIGNMENT(127, "token literal <arg> aliased to new token name <arg2>", ErrorSeverity.WARNING),
+	ATTRIBUTE_IN_LEXER_ACTION(128, "attribute references not allowed in lexer actions: $<arg>", ErrorSeverity.ERROR),
 
 	/** Documentation comment is unterminated */
     //UNTERMINATED_DOC_COMMENT(, "", ErrorSeverity.ERROR),

tool/src/org/antlr/v4/tool/Grammar.java

@@ -107,9 +107,6 @@ public class Grammar implements AttributeResolver {
 
     public static Map<String, AttributeDict> grammarAndLabelRefTypeToScope =
         new HashMap<String, AttributeDict>() {{
-            put("lexer:RULE_LABEL", Rule.predefinedLexerRulePropertiesDict);
-//            put("lexer:LEXER_STRING_LABEL", Rule.predefinedLexerRulePropertiesDict);
-//			put("lexer:TOKEN_LABEL", AttributeDict.predefinedTokenDict);
             put("parser:RULE_LABEL", Rule.predefinedRulePropertiesDict);
             put("parser:TOKEN_LABEL", AttributeDict.predefinedTokenDict);
             put("combined:RULE_LABEL", Rule.predefinedRulePropertiesDict);

tool/src/org/antlr/v4/tool/Rule.java

@@ -58,14 +58,6 @@ public class Rule implements AttributeResolver {
             add(new Attribute("ctx"));
         }};
 
-    public static AttributeDict predefinedLexerRulePropertiesDict =
-        new AttributeDict(AttributeDict.DictType.PREDEFINED_LEXER_RULE) {{
-            add(new Attribute("text"));
-            add(new Attribute("type"));
-			add(new Attribute("channel"));
-			add(new Attribute("mode"));
-        }};
-
 	public static Set<String> validLexerCommands = new HashSet<String>() {{
 		// CALLS
 		add("mode");