bug#47534: Subject: 28.0.50; Regexp lower case pattern matches upper case

[dalanicolai <dalanicolai@gmail.com>]

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Here is a small patch for the re-builder docstring. I hope I did things
correctly...

On Thu, 1 Apr 2021 at 10:12, dalanicolai <dalanicolai@gmail.com> wrote:

> Ah thanks. I thought I used case sensitive replace-regexp before, but
> probably I am mistaking then. Section "34.3 Regular Expressions"  of the
> Emacs manual states that "[a-z]" or "[:lower:]" should match only lower
> case, while it is not mentioned at all that it will not work by default
> (case-fold-search as well as reb-toggle-case and reb-change-syntax are not
> mentioned at all in that section as far as I can find). Indeed I was
> referring to the docstring of re-builder. Anyway, I am happy to provide a
> patch.
>
>
>
> On Thu, 1 Apr 2021 at 00:25, Basil L. Contovounesios <contovob@tcd.ie>
> wrote:
>
>> dalanicolai <dalanicolai@gmail.com> writes:
>>
>> > When using the regexp builder and trying to match only lower case
>> > letters (and spaces), Emacs also includes upper case matches.
>>
>> I think this is the effect of the user option case-fold-search, which
>> defaults to non-nil (this is the case across most search-related parts
>> of Emacs, including Isearch).  You can toggle it in re-builder
>> specifically with C-c C-c (reb-toggle-case), or across all buffers by
>> customising case-fold-search to be nil.
>>
>> > Also, I am unable to find in the manual any information about the
>> > option of setting different syntaxes in the regexp builder
>>
>> I think most of the documentation for re-builder.el is in its commentary
>> at the start of the file; see M-x find-library RET re-builder RET.
>>
>> I haven't used re-builder much, but from M-x customize-group RET
>> re-builder RET I see there is a user option reb-re-syntax for
>> controlling the default syntax.  C-h m in the re-builder buffer further
>> reveals that the command C-c C-i (reb-change-syntax) can modify
>> reb-re-syntax on the fly.
>>
>> > (also the option is not mentioned in the regexp-builder docstring). So
>> > I would additionally like to report this as a documentation bug.
>>
>> Are you referring to the docstring of the re-builder command, or
>> something else?  And is it a listing of key bindings you would like to
>> see, or something else?  Would you like to provide a patch with
>> suggestions for improvements?
>>
>> Thanks,
>>
>> --
>> Basil
>>
>

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diff --git a/lisp/emacs-lisp/re-builder.el b/lisp/emacs-lisp/re-builder.el
index 455fcac701..2bbee18afd 100644
--- a/lisp/emacs-lisp/re-builder.el
+++ b/lisp/emacs-lisp/re-builder.el
@@ -341,7 +341,12 @@ the regexp builder.  It displays a buffer named \"*RE-Builder*\"
 in another window, initially containing an empty regexp.
 
 As you edit the regexp in the \"*RE-Builder*\" buffer, the
-matching parts of the target buffer will be highlighted."
+matching parts of the target buffer will be highlighted.
+
+Case-sensitivity can be toggled with \\[reb-toggle-case].  The
+regexp builder supports three different forms of input which can
+be set with \\[reb-change-syntax]. More options and details
+are provided in the initial comment of`re-builder.el'."
   (interactive)
   (if (and (string= (buffer-name) reb-buffer)
 	   (reb-mode-buffer-p))