Cannot search for certain words (e.g. "using") #10277
Description
Describe the bug
Certain words fail to produce any search results. One such word is "using", but there are likely more.
How to Reproduce
Include this simple document:
util
====
Synopsis
--------
**util** [*options*]
Description
-----------
**util** is great! See :ref:`index`.
Run this command using sudo
---------------------------
Will this be found by the search?Generate some html, then search for "using".
Expected behavior
The page should be included in the search results.
Your project
N/A
Screenshots
No response
OS
Linux
Python version
3.6.12
Sphinx version
4.2.0
Sphinx extensions
No response
Extra tools
No response
Additional context
This is fallout from #2621. Which surprises me a bit since it is ages since that was committed. Perhaps something else hid the bug for so long?
The problem is that the JavaScript code assumes (in Search.query()) a word was left unstemmed if it is shorter than 3 characters. But that is not what SearchLanguage.word_filter() does as it has a much more complex logic. I also assume it can be overloaded for other languages than English.
Things work fine on Sphinx' own home page though for some reason. But it looks like it delegates the search to readthedocs rather than using the default search code.