Re: master 544db1e: Faster grep pattern for identifiers

[Dmitry Gutov <dgutov@yandex.ru>]

On 15.09.2021 18:56, Eli Zaretskii wrote:
>> branch: master
>> commit 544db1ee8679eec9edd5cee81a340ee1c4d70158
>> Author: Mattias Engdegård<mattiase@acm.org>
>>
>>      Faster grep pattern for identifiers
>>      
>>      * lisp/cedet/semantic/symref/grep.el (semantic-symref-perform-search):
>>      Use the `-w` flag instead of wrapping the pattern in regexps that make
>>      matching much slower.  This speeds up `xref-find-references` by about
>>      3× on macOS.
> Doesn't this change the semantics of the "word"?  The Grep notion of
> the word is not necessarily identical to that of Emacs, since the
> latter depends on the major mode.  The comment in the deleted code
> says that much, AFAICT.  Or what am I missing?

Luckily, -w actually corresponds to the regexp which the previous 
version of the code was using. Rather than to \<...\> which one might 
surmise from reading the docs for some versions of Grep (or Ripgrep).

And the comment was about \< and \>.

The latest Grep manual describes it correctly:

        -w, --word-regexp
               Select  only  those  lines  containing  matches  that 
form whole words.  The test is that the matching substring must either 
be at the beginning of the line, or preceded by a non-word
               constituent character.  Similarly, it must be either at 
the end of the line or followed by a non-word constituent character. 
Word-constituent characters are letters, digits, and  the
               underscore.