[new-parser] no viable alternative at input from return

[yurloc]

Parent issue

• Experiment: New DRL parser #5678

Failing tests

• org.drools.mvel.integrationtests.ExtendsTest#testExtendsBasic

Notes

Very edge case, but we should keep it working for backward compatibility reasons. The root cause is identical to

• [new-parser] Parsing fails if a Java keyword appears in a qualified name #5818
• [new-parser] Rule named default (without quotes) cannot be parsed #5910
  Due to the usage of JavaLexer, words like package, return, etc. are no longer IDENTIFIER tokens but respective keyword tokens and so they cannot be matched in rules where IDENTIFIER is expected. The obvious solution is to add RETURN as an alternative to the drlIdentifier rule. We should however think twice and make sure this is the right approach. Another solution could be to adapt JavaLexer and drop keywords that are not useful for DRLParser rules.

Rule code snippet

    when
        Cheese( price < 5) from return ([c])

Error output

### parse : ANTLR4_PARSER_ENABLED = true
line 59:32 no viable alternative at input 'from return'
14:42:29.412 [main] ERROR o.d.d.parser.antlr4.DRLParserWrapper.parse:77 - Exception while creating PackageDescr
java.lang.IllegalStateException: ctx.lhsPattern().size() == 0 : 
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitLhsPatternBind(DRLVisitorImpl.java:545)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitLhsPatternBind(DRLVisitorImpl.java:83)
	at org.drools.drl.parser.antlr4.DRLParser$LhsPatternBindContext.accept(DRLParser.java:2661)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitDescrChildren(DRLVisitorImpl.java:1075)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitLhsUnary(DRLVisitorImpl.java:1062)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitLhsUnary(DRLVisitorImpl.java:83)
	at org.drools.drl.parser.antlr4.DRLParser$LhsUnaryContext.accept(DRLParser.java:2477)
	at org.antlr.v4.runtime.tree.AbstractParseTreeVisitor.visitChildren(AbstractParseTreeVisitor.java:46)
	at org.drools.drl.parser.antlr4.DRLParserBaseVisitor.visitLhsUnarySingle(DRLParserBaseVisitor.java:201)
	at org.drools.drl.parser.antlr4.DRLParser$LhsUnarySingleContext.accept(DRLParser.java:2110)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitDescrChildren(DRLVisitorImpl.java:1075)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitLhs(DRLVisitorImpl.java:532)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitRuledef(DRLVisitorImpl.java:340)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitRuledef(DRLVisitorImpl.java:83)
	at org.drools.drl.parser.antlr4.DRLParser$RuledefContext.accept(DRLParser.java:1664)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitDescrChildren(DRLVisitorImpl.java:1075)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitDrlStatementdef(DRLVisitorImpl.java:166)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitDrlStatementdef(DRLVisitorImpl.java:83)
	at org.drools.drl.parser.antlr4.DRLParser$DrlStatementdefContext.accept(DRLParser.java:523)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitDescrChildren(DRLVisitorImpl.java:1075)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitCompilationUnit(DRLVisitorImpl.java:102)
	at org.drools.drl.parser.antlr4.DRLVisitorImpl.visitCompilationUnit(DRLVisitorImpl.java:83)
	at org.drools.drl.parser.antlr4.DRLParser$CompilationUnitContext.accept(DRLParser.java:435)
	at org.antlr.v4.runtime.tree.AbstractParseTreeVisitor.visit(AbstractParseTreeVisitor.java:18)
	at org.drools.drl.parser.antlr4.DRLParserHelper.compilationUnitContext2PackageDescr(DRLParserHelper.java:91)
	at org.drools.drl.parser.antlr4.DRLParserWrapper.parse(DRLParserWrapper.java:75)
	at org.drools.drl.parser.antlr4.DRLParserWrapper.parse(DRLParserWrapper.java:55)
	at org.drools.drl.parser.DrlParser.lambda$parse$2(DrlParser.java:191)
	at org.drools.drl.parser.DrlParser.compileWithAntlr4Parser(DrlParser.java:204)
	at org.drools.drl.parser.DrlParser.parse(DrlParser.java:191)
	at org.drools.drl.parser.DrlParser.parse(DrlParser.java:179)
	at org.drools.drl.parser.DrlParser.parse(DrlParser.java:168)
	at org.drools.compiler.builder.impl.resources.DrlResourceHandler.process(DrlResourceHandler.java:55)
	at org.drools.compiler.builder.impl.PackageDescrBuilder.buildResource(PackageDescrBuilder.java:73)
	at org.drools.compiler.builder.impl.PackageDescrBuilder.build(PackageDescrBuilder.java:51)
	at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.buildPackageDescr(CompositeKnowledgeBuilderImpl.java:173)
	at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:116)
	at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:109)
	at org.drools.compiler.kie.builder.impl.AbstractKieProject.buildKnowledgePackages(AbstractKieProject.java:274)
	at org.drools.compiler.kie.builder.impl.AbstractKieProject.buildKnowledgePackages(AbstractKieProject.java:220)
	at org.drools.compiler.kie.builder.impl.AbstractKieProject.verify(AbstractKieProject.java:84)
	at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildKieProject(KieBuilderImpl.java:285)
	at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:251)
	at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:208)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem(KieUtil.java:149)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem(KieUtil.java:134)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromResources(KieUtil.java:121)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromClasspathResources(KieUtil.java:187)
	at org.drools.testcoverage.common.util.KieBaseUtil.getKieBaseFromClasspathResources(KieBaseUtil.java:57)
	at org.drools.mvel.integrationtests.ExtendsTest.testExtendsBasic(ExtendsTest.java:728)
14:42:29.412 [main] ERROR o.d.c.k.b.impl.AbstractKieProject.buildKnowledgePackages:280 - Unable to build KieBaseModel:KieBaseModelName
[59,32]: no viable alternative at input 'from return'
[0,0]: 
[0,0]: Parser returned a null Package

14:42:29.412 [main] ERROR o.d.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem:165 - KieBuilder errors: [Message [id=1, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=59, column=0
   text=no viable alternative at input 'from return'], Message [id=2, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=0, column=0
   text=], Message [id=3, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=0, column=0
   text=Parser returned a null Package]]

java.lang.AssertionError: [[Message [id=1, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=59, column=0
   text=no viable alternative at input 'from return'], Message [id=2, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=0, column=0
   text=], Message [id=3, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=0, column=0
   text=Parser returned a null Package]]] 
Expecting empty but was: [Message [id=1, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=59, column=0
   text=no viable alternative at input 'from return'],
    Message [id=2, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=0, column=0
   text=],
    Message [id=3, kieBase=KieBaseModelName, level=ERROR, path=extend_rule_test.drl, line=0, column=0
   text=Parser returned a null Package]]

	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem(KieUtil.java:169)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem(KieUtil.java:134)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromResources(KieUtil.java:121)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromClasspathResources(KieUtil.java:187)
	at org.drools.testcoverage.common.util.KieBaseUtil.getKieBaseFromClasspathResources(KieBaseUtil.java:57)
	at org.drools.mvel.integrationtests.ExtendsTest.testExtendsBasic(ExtendsTest.java:728)

[tkobayas]

/take

[yurloc]

Fixed by #5958.