Remove support for postfix (right-unary) operators.

This feature has been a thorn in our sides for a long time, causing
many grammatical ambiguity problems.  It doesn't seem worth the
pain to continue to support it, so remove it.

There are some follow-on improvements we can make in the grammar,
but this commit only removes the bare minimum number of productions,
plus assorted backend support code.

Note that pg_dump and psql continue to have full support, since
they may be used against older servers.  However, pg_dump warns
about postfix operators.  There is also a check in pg_upgrade.

Documentation-wise, I (tgl) largely removed the "left unary"
terminology in favor of saying "prefix operator", which is
a more standard and IMO less confusing term.

I included a catversion bump, although no initial catalog data
changes here, to mark the boundary at which oprkind = 'r'
stopped being valid in pg_operator.

Mark Dilger, based on work by myself and Robert Haas;
review by John Naylor

Discussion: https://postgr.es/m/38ca86db-42ab-9b48-2902-337a0d6b8311@2ndquadrant.com

1 files changed, 0 insertions, 2 deletions

diff --git a/src/include/parser/parse_oper.h b/src/include/parser/parse_oper.h
index bcd861e43ac..09695a2765c 100644
--- a/src/include/parser/parse_oper.h
+++ b/src/include/parser/parse_oper.h
@@ -31,8 +31,6 @@ extern Oid	LookupOperWithArgs(ObjectWithArgs *oper, bool noError);
 /* NB: the selected operator may require coercion of the input types! */
 extern Operator oper(ParseState *pstate, List *op, Oid arg1, Oid arg2,
 					 bool noError, int location);
-extern Operator right_oper(ParseState *pstate, List *op, Oid arg,
-						   bool noError, int location);
 extern Operator left_oper(ParseState *pstate, List *op, Oid arg,
 						  bool noError, int location);