How to get more parse error information from lex / yacc?

问题

How to get more parse error information from lex / yacc?

Currently in the lex file I am using:

int yyerror(const char *msg)
{
    fprintf(stderr, "Parse error: %s\n", msg);
    return 0;
}

But when I run my program yyerror outputs a blank message. I tried adding yylineno and yytext to yyerror but these cause compilation errors. I tried adding "%error-verbose" to the yacc file and "%option debug" to the lex file but these made no difference to the message.

I did notice however that yyparse outputs a bracket: '{' from the file I am trying to parse, I don't know the significance of this.

I am using win_flex and win_bison.

回答1:

Much of this is described in the official bison manual when it shows how to use yyerror to get improved error messages.

In particular, it suggests you use %define parse.error verbose in the Bison declarations section to get enhanced error messages.

来源：https://stackoverflow.com/questions/27943284/how-to-get-more-parse-error-information-from-lex-yacc