Fix ALTER TABLE error message

This bogus error message was introduced in 2013 by commit f177cbf,
because of misunderstanding the processCASbits() API; at the time, no
test cases were added that would be affected by this change.  Only in
ca87c41 was one added (along with a couple of typos), with an XXX
note that the error message was bogus.  Fix the whole, add some test
cases.

Backpatch all the way back.

Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/202503041822.aobpqke3igvb@alvherre.pgsql

Author: alvherre

src/backend/parser/gram.y

@@ -2649,7 +2649,7 @@ alter_table_cmd:
 					n->def = (Node *) c;
 					c->contype = CONSTR_FOREIGN; /* others not supported, yet */
 					c->conname = $3;
-					processCASbits($4, @4, "ALTER CONSTRAINT statement",
+					processCASbits($4, @4, "FOREIGN KEY",
 									&c->deferrable,
 									&c->initdeferred,
 									NULL, NULL, yyscanner);

src/test/regress/expected/foreign_key.out

@@ -1278,11 +1278,15 @@ DETAIL:  Key (fk)=(20) is not present in table "pktable".
 COMMIT;
 -- try additional syntax
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
--- illegal option
+-- illegal options
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
 ERROR:  constraint declared INITIALLY DEFERRED must be DEFERRABLE
 LINE 1: ...e ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY ...
                                                              ^
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NO INHERIT;
+ERROR:  FOREIGN KEY constraints cannot be marked NO INHERIT
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT VALID;
+ERROR:  FOREIGN KEY constraints cannot be marked NOT VALID
 -- test order of firing of FK triggers when several RI-induced changes need to
 -- be made to the same row.  This was broken by subtransaction-related
 -- changes in 8.0.

src/test/regress/sql/foreign_key.sql

@@ -970,8 +970,10 @@ COMMIT;
 
 -- try additional syntax
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE;
--- illegal option
+-- illegal options
 ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT DEFERRABLE INITIALLY DEFERRED;
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NO INHERIT;
+ALTER TABLE fktable ALTER CONSTRAINT fktable_fk_fkey NOT VALID;
 
 -- test order of firing of FK triggers when several RI-induced changes need to
 -- be made to the same row.  This was broken by subtransaction-related