Info-search-whitespace (Was: Improvements to `(emacs)File Variables')

[Juri Linkov <juri@jurta.org>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
> Go to the Emacs manual and do a M-s search for "unibyte: *t".

Out of curiosity I looked at what the Emacs manual does say about
unibyte mode and noticed such a problem: Emacs hangs with "unibyte: *t"
Info search string.  This is because Info-search expands it with
Info-search-whitespace to "unibyte:\\(?:\\s-+\\)*t" and on the line

* --unibyte:                             Initial Options.     (line 101)

Emacs goes into a long loop because it tries to match whitespace
\\(?:\\s-+\\)* in extremely many ways.

Perhaps Info-search should search for a string only, not a regexp:
i.e. preprocess a search string with `regexp-quote' before replacing
whitespace with Info-search-whitespace and re-searching for it.

Anyway, the standalone Info reader already doesn't search for a regexp
with the `s' key, and the Emacs Info reader should not differ from it.
Of course, this doesn't prohibit from adding a new command
`Info-search-regexp' (without keybinding) to the Emacs Info reader,
which won't expand whitespace to Info-search-whitespace and will
use a search regexp exactly as specified by the user.

-- 
Juri Linkov
http://www.jurta.org/emacs/