pgsql: Allow referring to functions without arguments when unique

Allow referring to functions without arguments when unique

In DDL commands referring to an existing function, allow omitting the
argument list if the function name is unique in its schema, per SQL
standard.

This uses the same logic that the regproc type uses for finding
functions by name only.

Reviewed-by: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/aefeb68741fb9456f14b4d690b0c646e532fea6b

Modified Files
--------------
doc/src/sgml/ref/alter_extension.sgml | 2 +-
doc/src/sgml/ref/alter_function.sgml | 13 +++++----
doc/src/sgml/ref/alter_opfamily.sgml | 7 +++--
doc/src/sgml/ref/comment.sgml | 2 +-
doc/src/sgml/ref/create_cast.sgml | 6 ++--
doc/src/sgml/ref/create_transform.sgml | 12 +++++---
doc/src/sgml/ref/drop_function.sgml | 35 ++++++++++++++++++++---
doc/src/sgml/ref/grant.sgml | 2 +-
doc/src/sgml/ref/revoke.sgml | 2 +-
doc/src/sgml/ref/security_label.sgml | 2 +-
src/backend/nodes/copyfuncs.c | 1 +
src/backend/nodes/equalfuncs.c | 1 +
src/backend/parser/gram.y | 27 ++++++++++++++++++
src/backend/parser/parse_func.c | 37 +++++++++++++++++++++++--
src/include/nodes/parsenodes.h | 3 ++
src/test/regress/expected/create_function_3.out | 11 +++++++-
src/test/regress/sql/create_function_3.sql | 8 ++++++
17 files changed, 143 insertions(+), 28 deletions(-)