Tom Lane 83a5641945 Provide more-specific error details/hints for function lookup failures.
Up to now we've contented ourselves with a one-size-fits-all error
hint when we fail to find any match to a function or procedure call.
That was mostly okay in the beginning, but it was never great, and
since the introduction of named arguments it's really not adequate.
We at least ought to distinguish "function name doesn't exist" from
"function name exists, but not with those argument names".  And the
rules for named-argument matching are arcane enough that some more
detail seems warranted if we match the argument names but the call
still doesn't work.

This patch creates a framework for dealing with these problems:
FuncnameGetCandidates and related code will now pass back a bitmask of
flags showing how far the match succeeded.  This allows a considerable
amount of granularity in the reports.  The set-bits-in-a-bitmask
approach means that when there are multiple candidate functions, the
report will reflect the match(es) that got the furthest, which seems
correct.  Also, we can avoid mentioning "maybe add casts" unless
failure to match argument types is actually the issue.

Extend the same return-a-bitmask approach to OpernameGetCandidates.
The issues around argument names don't apply to operator syntax,
but it still seems worth distinguishing between "there is no
operator of that name" and "we couldn't match the argument types".

While at it, adjust these messages and related ones to more strictly
separate "detail" from "hint", following our message style guidelines'
distinction between those.

Reported-by: Dominique Devienne <ddevienne@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/1756041.1754616558@sss.pgh.pa.us
2025-09-16 12:17:02 -04:00
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The PostgreSQL contrib tree
---------------------------

This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree.  This does not preclude their
usefulness.

User documentation for each module appears in the main SGML
documentation.

When building from the source distribution, these modules are not
built automatically, unless you build the "world" target.  You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.

Some directories supply new user-defined functions, operators, or
types.  To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command.  In a fresh database,
you can simply do

    CREATE EXTENSION module_name;

See the PostgreSQL documentation for more information about this
procedure.