为什么在ANTLR中生成代码时会出现此错误?cannot be cast to org.antlr.tool.GrammarASTorg.antlr.grammar.v3.CodeGenTreeWalker.grammarSpec(CodeGenTreeWalker.java:1441)
org.antlr.grammar.v3(CodeGenerator.
Source=Antlr4.Runtime at Antlr4.Runtime.Lexer.PopMode() at Antlr4.Runtime.Atn.LexerActionExecutor.Execute(Lexer lexer, ICharStream input(ICharStream input, DFASta