CREATE RULE syntax simplification

There are a couple of gripes in the pgsql-sql list this morning about
being unable to enter CREATE RULE commands that specify multiple
actions --- those folk are getting parser: parse error at or near ""
from what appears to be perfectly valid syntax. I suppose they are
getting burnt by a broken vendor-supplied yacc. But while looking at
this, I couldn't help noticing how crufty the syntax is:

RuleActionList: NOTHING { $$ = NIL; }
| SelectStmt { $$ = lcons($1, NIL); }
| RuleActionStmt { $$ = lcons($1, NIL); }
| '[' RuleActionBlock ']' { $$ = $2; }
| '(' RuleActionBlock ')' { $$ = $2; }
;

RuleActionBlock: RuleActionMulti { $$ = $1; }
| RuleActionStmt { $$ = lcons($1, NIL); }
;

RuleActionMulti: RuleActionMulti RuleActionStmt
{ $$ = lappend($1, $2); }
| RuleActionMulti RuleActionStmt ';'
{ $$ = lappend($1, $2); }
| RuleActionStmt ';'
{ $$ = lcons($1, NIL); }
;

RuleActionStmt: InsertStmt
| UpdateStmt
| DeleteStmt
| NotifyStmt
;

What's wrong with that you say? Well, it allows a RuleActionBlock to
be made up of RuleActionStmts that aren't separated by semicolons.
Specifically
stmt1 ; stmt2 stmt3 stmt4
has a production sequence.

I don't know if that was intentional or not, but it sure looks like
a shift/reduce conflict waiting to happen, as soon as the possible
RuleActionStmts get any more complicated. In any case, it's pretty
bizarre that a semi is only required after the first statement.

I suggest that we require separating semicolons and simplify the
RuleActionBlock production to a more conventional list style,

RuleActionBlock: RuleActionStmt
| RuleActionBlock ';' RuleActionStmt
| RuleActionBlock ';'

(the last alternative isn't normal list style, but it allows a trailing
semicolon which is accepted by the existing grammar).

Aside from forestalling future trouble with syntax extensions, this
might make us work a little better with old versions of yacc. I don't
know exactly why this area is a trouble spot for vendor yaccs, but it
seems to be. Simplifying the syntax may well help.

Comments? Anyone really in love with semicolon-less rule lists?

regards, tom lane