Re: Re: gram.y PROBLEM with UNDER

Chris Bitmead <chrisb(at)nimrod(dot)itg(dot)telstra(dot)com(dot)au> writes:
>> If you don't get rid of those then your parser will behave in surprising
>> ways. So far you have noticed the fallout from only one of those
>> conflicts, but every one of them is a potential bug. Be advised that
>> gram.y patches that create unresolved conflicts will *not* be accepted.

> I thought shift/reduce conflicts were part and parcel of most language
> syntaxes. reduce/reduce being rather more naughty. The standard syntax
> already produces 95 shift/reduce conflicts. Can you clarify about
> unresolved conflicts not being accepted?

What's to clarify? The existing grammar does produce a long list of
*resolved* conflicts, which are not very interesting (they just indicate
that we are using operator precedence rules instead of creating a
detailed grammar for expressions). Unresolved conflicts are a far
more serious problem, because they tell you that there is an unreachable
part of your language. As indeed was happening to you in this case.

regards, tom lane