pgsql: Allow CURRENT_ROLE where CURRENT_USER is accepted

Allow CURRENT_ROLE where CURRENT_USER is accepted

In the particular case of GRANTED BY, this is specified in the SQL
standard. Since in PostgreSQL, CURRENT_ROLE is equivalent to
CURRENT_USER, and CURRENT_USER is already supported here, adding
CURRENT_ROLE is trivial. The other cases are PostgreSQL extensions,
but for the same reason it also makes sense there.

Reviewed-by: Vik Fearing <vik(at)postgresfriends(dot)org>
Reviewed-by: Asif Rehman <asifr(dot)rehman(at)gmail(dot)com>
Reviewed-by: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/f2feac44-b4c5-f38f-3699-2851d6a76dc9%402ndquadrant.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/45b9805706fdc726906fc9187c9a7b38c559755c

Modified Files
--------------
doc/src/sgml/ref/alter_aggregate.sgml | 2 +-
doc/src/sgml/ref/alter_collation.sgml | 2 +-
doc/src/sgml/ref/alter_conversion.sgml | 2 +-
doc/src/sgml/ref/alter_database.sgml | 2 +-
doc/src/sgml/ref/alter_domain.sgml | 2 +-
doc/src/sgml/ref/alter_event_trigger.sgml | 2 +-
doc/src/sgml/ref/alter_foreign_data_wrapper.sgml | 2 +-
doc/src/sgml/ref/alter_foreign_table.sgml | 2 +-
doc/src/sgml/ref/alter_function.sgml | 2 +-
doc/src/sgml/ref/alter_group.sgml | 1 +
doc/src/sgml/ref/alter_language.sgml | 2 +-
doc/src/sgml/ref/alter_large_object.sgml | 2 +-
doc/src/sgml/ref/alter_materialized_view.sgml | 2 +-
doc/src/sgml/ref/alter_opclass.sgml | 2 +-
doc/src/sgml/ref/alter_operator.sgml | 2 +-
doc/src/sgml/ref/alter_opfamily.sgml | 2 +-
doc/src/sgml/ref/alter_policy.sgml | 2 +-
doc/src/sgml/ref/alter_procedure.sgml | 2 +-
doc/src/sgml/ref/alter_publication.sgml | 2 +-
doc/src/sgml/ref/alter_role.sgml | 2 +
doc/src/sgml/ref/alter_routine.sgml | 2 +-
doc/src/sgml/ref/alter_schema.sgml | 2 +-
doc/src/sgml/ref/alter_sequence.sgml | 2 +-
doc/src/sgml/ref/alter_server.sgml | 2 +-
doc/src/sgml/ref/alter_statistics.sgml | 2 +-
doc/src/sgml/ref/alter_subscription.sgml | 2 +-
doc/src/sgml/ref/alter_table.sgml | 2 +-
doc/src/sgml/ref/alter_tablespace.sgml | 2 +-
doc/src/sgml/ref/alter_tsconfig.sgml | 2 +-
doc/src/sgml/ref/alter_tsdictionary.sgml | 2 +-
doc/src/sgml/ref/alter_type.sgml | 2 +-
doc/src/sgml/ref/alter_user.sgml | 1 +
doc/src/sgml/ref/alter_user_mapping.sgml | 4 +-
doc/src/sgml/ref/alter_view.sgml | 2 +-
doc/src/sgml/ref/create_policy.sgml | 2 +-
doc/src/sgml/ref/create_schema.sgml | 1 +
doc/src/sgml/ref/create_tablespace.sgml | 2 +-
doc/src/sgml/ref/create_user_mapping.sgml | 4 +-
doc/src/sgml/ref/drop_owned.sgml | 2 +-
doc/src/sgml/ref/drop_user_mapping.sgml | 4 +-
doc/src/sgml/ref/grant.sgml | 1 +
doc/src/sgml/ref/reassign_owned.sgml | 4 +-
doc/src/sgml/ref/revoke.sgml | 1 +
src/backend/parser/gram.y | 11 +
src/backend/utils/adt/acl.c | 2 +
src/include/nodes/parsenodes.h | 1 +
.../modules/unsafe_tests/expected/rolenames.out | 622 ++++++++++++---------
src/test/modules/unsafe_tests/sql/rolenames.sql | 225 ++++----
48 files changed, 534 insertions(+), 416 deletions(-)