According to the manual, apropos-user-option can search not only user options but variables when adding C-u prefix.> With C-u prefix, or if ‘apropos-do-all’ is non-nil, also show variables, not just user options.
From the documentation, I think using C-u should have the same effect as setting apropos-do-all to t. But my experiment got 2 different results.
1. set apropos-do-all to t
(let ((apropos-do-all t))
(call-interactively #'apropos-user-option))
Insert "emacs", and I got the result shown in figure 1. In the Apropos buffer, each variable has a hyperlink to the corresponding *help* buffer.
2. C-u M-x apropos-user-option, and insert "emacs"
The result is shown in figure 2. As you can see, those entries have no hyperlinks to the documentation.
I think the behavior is not consistent compared to other apropos commands. For example, no matter using method 1 or 2 to invoke apropos-commands (C-h a), we would get 2 same buffers both with hyperlinks to click off.
Regards,
Liang-Jie Lee