[BUG] exist:output-size-limit is not observed when using load-xquery-module

[nverwer]

When a function is loaded using load-xquery-module, any declared exist:output-size-limit is not used.
The only way to set exist:output-size-limit is in the function itself.
This differs from function in modules that are loaded using import.

Expected behavior
A function should always use exist:output-size-limit, regardless of how it is loaded.

To Reproduce
Make the following two files in the same eXist collection.

test-output-size-limit.xql

import module namespace osl="http://output-size.limit/" at "test-output-size-limit.xqm";

declare option exist:output-size-limit "10";

declare variable $osl-uri := "http://output-size.limit/";

let $dynload1 := load-xquery-module($osl-uri, map{"location-hints": "test-output-size-limit.xqm"})
let $dynload1-too-many-nodes as item() := $dynload1?functions?(QName($osl-uri, "osl:too-many-nodes"))?0
let $dynload1-not-many-nodes as item() := $dynload1?functions?(QName($osl-uri, "osl:not-many-nodes"))?1
let $dynload2 := load-xquery-module($osl-uri, map{"location-hints": "test-output-size-limit.xqm", "vendor-options": map{"exist:output-size-limit":"9"}})
let $dynload2-too-many-nodes as item() := $dynload2?functions?(QName($osl-uri, "osl:too-many-nodes"))?0
return
  ( try {
      osl:too-many-nodes()
    } catch * { $err:description }
  , try {
      osl:not-many-nodes(100)
    } catch * { $err:description }
  , try {
      $dynload1-too-many-nodes()
    } catch * { $err:description }
  , try {
      $dynload1-not-many-nodes(8)
    } catch * { $err:description }
  , try {
      $dynload2-too-many-nodes()
    } catch * { $err:description }
  )

test-output-size-limit.xqm

module namespace osl="http://output-size.limit/";

declare option exist:output-size-limit "5";

declare function osl:too-many-nodes() as node()
{
  <a id="too-many" output-size-limit="{util:get-option('exist:output-size-limit')}">
    <b><c/><d/><e><f/></e><g/></b>
    <b><c/><d/><e><f/></e><g/></b>
    <b><c/><d/><e><f/></e><g/></b>
  </a>
};


declare function osl:not-many-nodes($limit) as node()
{
  let $increased-output-size-limit := util:declare-option('exist:output-size-limit', $limit)
  return
  <a id="not-many" output-size-limit="{util:get-option('exist:output-size-limit')}">
    <b><c/><d/><e><f/></e><g/></b>
    <b><c/><d/><e><f/></e><g/></b>
    <b><c/><d/><e><f/></e><g/></b>
  </a>
};

Then execute test-output-size-limit.xql. The output is something like:

exerr:ERROR The constructed document fragment exceeded the predefined output-size-limit (current: 11; allowed: 10). The query has been killed. [at line 9, column 17]
In function:
	osl:too-many-nodes() [14:7:/db/apps/_test/test-output-size-limit.xqm]. The constructed document fragment exceeded the predefined output-size-limit (current: 11; allowed: 10). The query has been killed.
<a id="not-many" output-size-limit="5"><b><c/><d/><e><f/></e><g/></b><b><c/><d/><e><f/></e><g/></b><b><c/><d/><e><f/></e><g/></b></a>
<a id="too-many" output-size-limit="5"><b><c/><d/><e><f/></e><g/></b><b><c/><d/><e><f/></e><g/></b><b><c/><d/><e><f/></e><g/></b></a>
exerr:ERROR The constructed document fragment exceeded the predefined output-size-limit (current: 9; allowed: 8). The query has been killed. [at line 21, column 9]
In function:
	osl:not-many-nodes(item()*) [7:18:/db/apps/_test/test-output-size-limit.xqm]. The constructed document fragment exceeded the predefined output-size-limit (current: 9; allowed: 8). The query has been killed.
<a id="too-many" output-size-limit="5"><b><c/><d/><e><f/></e><g/></b><b><c/><d/><e><f/></e><g/></b><b><c/><d/><e><f/></e><g/></b></a>

The first result is expected, as there are too many nodes. The second result is expected, because exist:output-size-limit has been set to 100.
The third result is wrong, because all possibly relevant exist:output-size-limit declarations would make the output too large.
The fourth result is expected, because the exist:output-size-limit has been changed inside the function.
The fifth result is maybe wrong. I attempted to use the vendor-options to set exist:output-size-limit, just to see if that would work.

The output-size-limit attributes give the value of util:get-option('exist:output-size-limit'), but they are clearly not the output size limit that is used.

Context
eXist Version: 6.4.0-SNAPSHOT
eXist Build: 2024-10-29T10:04:56Z
Operating System: Windows 10 10.0 amd64
Java Version: 11.0.14.1

eXist is started via launcher.bat.

[line-o]

@nverwer thanks for your exhaustive bug report. Have you, by any chance, checked if basex does observe this option regardless of module loading mechanism?

[joewiz]

@line-o BaseX hasn't implemented fn:load-xquery-module yet. https://docs.basex.org/main/XQuery_3.1#functions: Also, BaseX uses pragmas rather than option declarations for setting certain options. Most options, though, are not accessible by the query but are set at the BaseX instance level: https://docs.basex.org/main/Options.

[nverwer]

Thank you @joewiz for clarifying why this cannot be tested in BaseX. I never needed load-xquery-module in my BaseX projects, and I was unaware that it is not implemented in BaseX.

Of course, util:declare-option is also unavailable in BaseX, It is possible to do declare option output:limit "100";, which limits the number of serialized bytes, but not in library modules.

I have not been able to find a specification of how options should behave w.r.t. dynamically loaded modules, but I would think that it should not be different from imported modules.