Error handling in the new C++ parser

Error handling in the new C++ parser

[Andi Kleen]

Hi,

I looked at the new C++ parser in mainline and noticed there are lots 
of unchecked cp_parser_require() in parser.c. Sometimes it checks 
later using cp_parser_error_occurred(), but in many other cases
it doesn't.

There seems to be no effort to skip to a sychronizing token
(like ';' or ')') after a normal syntax error, like the old bison
parser did.  I expect it will just become hopelessly confused in this 
case then.

Can someone please expand a bit on how the syntax error recovery 
is supposed to work ? 

Thanks,

-Andi

Re: Error handling in the new C++ parser

[Mark Mitchell]

> There seems to be no effort to skip to a sychronizing token
> (like ';' or ')') after a normal syntax error, like the old bison
> parser did.

It does that when it wants to do that.

There's no need to attempt immediately recovery after missing one
required token; we can wait util it's convenient.

Look for functions with names like cp_parser_skip* to find places where
we skip ahead until something sensible shows up.

I'm sure the error recovery can be improved, but it does OK most of
the time.

-- 
Mark Mitchell                mark@codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com