Re: Missing docs on AT TIME ZONE precedence?

On 2023-Nov-27, Tom Lane wrote:

> I don't like the existing coding for more reasons than just
> underdocumentation.  Global assignment of precedence is a really,
> really dangerous tool for solving ambiguous-grammar problems, because
> it can mask problems unrelated to the one you think you are solving:
> basically, it eliminates bison's complaints about grammar ambiguities
> related to the token you mark.  (Commits 12b716457 and 28a61fc6c are
> relevant here.)  Attaching precedence to individual productions is
> far safer, because it won't have any effect that extends beyond that
> production.  You still need a precedence attached to the lookahead
> token; but I think we should try very hard to not assign a precedence
> different from IDENT's to any unreserved keywords.

Ooh, this is very useful, thank you.

> After a bit of fooling around I found a patch that seems to meet
> that criterion; attached.

It looks good and passes tests, including the ecpg ones.

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