Re: bison/flex: Best practice to report an libc error to caller of yyparse

[Hans Aberg]

On 13 Jun 2009, at 13:40, Nicolai Stange wrote:

> i wonder how to report an libc error
> (maybe ENOMEM, EIO) that has occured in either yylex or yyparse to the
> caller of yyparse.

As for the first error, memory allocation error, your program is  
likely unrecoverable, so just write an error message and exit.

For other errors, I had to write in .l:
  #define YYERRCODE     256
and then
  { std::cerr << "Error: ...\n"; return YYERRCODE; }

Unfortunately, this relies on Bison innards. It C++ .hh header contains
  yyerrcode_ = 256
so this header might be included and used instead.

It would be better if this header contained an official error token.  
(So I cc some developers.)

  Hans