bug#48294: Use 'with-current-buffer' byte-compiler warning seems wrong

[Robert Weiner]

Hi:

I get a lot of these byte-compile warnings in my Elisp code:

hbut.el:683:26:Warning: Use ‘with-current-buffer’ rather than
    save-excursion+set-buffer

but since with-current-buffer does not save the value of point, it is
not a valid substitute for save-excursion and should not be suggested.
Evaluate the two samples below and you will see that they are not
equivalent.  If I am correct, I'd like this suggestion disabled.  Thanks.  -- rsw

(save-excursion
  (set-buffer (current-buffer))
  (forward-char 20))

(with-current-buffer (current-buffer)
  (forward-char 20))

------


In GNU Emacs 27.1.90 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 Version 10.14.6 (Build 18G95))
 of 2020-12-18 built on builder10-14.porkrind.org
Windowing system distributor 'Apple', version 10.3.1894
System Description:  Mac OS X 10.15.7

Configured using:
 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules'

Configured features:
NOTIFY KQUEUE ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES
THREADS JSON PDUMPER

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction