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07eee5a0dc
Historically we've put type "char" into the S (String) typcategory,
although calling it a string is a stretch considering it can only
store one byte. (In our actual usage, it's more like an enum.)
This choice now seems wrong in view of the special heuristics
that parse_func.c and parse_coerce.c have for TYPCATEGORY_STRING:
it's not a great idea for "char" to have those preferential casting
behaviors.
Worse than that, recent patches inventing special-purpose types
like pg_node_tree have assigned typcategory S to those types,
meaning they also get preferential casting treatment that's designed
on the assumption that they can hold arbitrary text.
To fix, invent a new category TYPCATEGORY_INTERNAL for internal-use
types, and assign that to all these types. I used code 'Z' for
lack of a better idea ('I' was already taken).
This change breaks one query in psql/describe.c, which now needs to
explicitly cast a catalog "char" column to text before concatenating
it with an undecorated literal. Also, a test case in contrib/citext
now needs an explicit cast to convert citext to "char". Since the
point of this change is to not have "char" be a surprisingly-available
cast target, these breakages seem OK.
Per report from Ian Campbell.
Discussion: https://postgr.es/m/2216388.1638480141@sss.pgh.pa.us
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.