pgsql/src/backend/parser gram.y

CVSROOT:    /home/projects/pgsql/cvsroot
Module name:    pgsql
Changes by:    tgl@hub.org    01/01/15 15:36:36

Modified files:
    src/backend/parser: gram.y

Log message:
    Fix problems with parentheses around sub-SELECT --- for the last time,
    I hope.  I finally realized that we were going at it backwards: when
    there are excess parentheses, they need to be treated as part of the
    sub-SELECT, not as part of the surrounding expression.  Although either
    choice yields an unambiguous grammar, only this way produces a grammar
    that is LALR(1).  With the old approach we were guaranteed to fail on
    either 'SELECT (((SELECT 2)) + 3)' or
    'SELECT (((SELECT 2)) UNION SELECT 2)' depending on which way we
    resolve the initial shift/reduce conflict.  With the new way, the same
    reduction track can be followed in both cases until we have advanced
    far enough to know whether we are done with the sub-SELECT or not.