pg_typeof() (was: Mysterious Bus Error with get_fn_expr_argtype())

Hi folks,

As discussed on -hackers [1], here is a patch to add a pg_typeof()
builtin function to core.

The function accepts one argument (type "any") and returns the regtype
of that argument. This can be helpful in various circumstances,
including troubleshooting cast/coercion behaviour in a query, or
constructing dynamic SQL statements.

It's declared in builtins.h and defined in utils/adt/misc.c.

The patch includes a small documentation update; I added pg_typeof()
to Table 9-47. System Catalog Information Functions, and a brief
descriptive paragraph underneath the table.

This didn't seem like it warranted any additional regression tests.

Added to the November commitfest.

Cheers,
BJ

doc/src/sgml/func.sgml | 15 +++++++++++++++
src/backend/utils/adt/misc.c | 9 +++++++++
src/include/catalog/catversion.h | 2 !!
src/include/catalog/pg_proc.h | 2 ++
src/include/utils/builtins.h | 1 +
5 files changed, 27 insertions(+), 2 modifications(!)

[1] http://archives.postgresql.org/message-id/37ed240d0809012135k1a7621d5x2acf18b31c7f9281@mail.gmail.com