--text follows this line--
The current behavior of indent-region function is that it will first indent the buffer and then throw an error at the end that it couldn't apply the indentation. Instead the below patch checks if the buffer if read-only first before trying to indent.
diff --git a/lisp/indent.el b/lisp/indent.el
index 0bbb520..d525511 100644
--- a/lisp/indent.el
+++ b/lisp/indent.el
@@ -509,6 +509,7 @@ indent-region
If the third argument COLUMN is an integer, it specifies the
column to indent to; if it is nil, use one of the three methods above."
(interactive "r\nP")
+ (barf-if-buffer-read-only)
(cond
;; If a numeric prefix is given, indent to that column.
(column
In GNU Emacs 25.0.91.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.23)
of 2016-02-25 built on ...
Repository revision: d2dd614716e34edb5891e58c029741cd6b32217d
Windowing system distributor 'The X.Org Foundation', version 11.0.60900000
System Description: Red Hat Enterprise Linux Workstation release 6.6 (Santiago)
Configured using:
'configure --prefix=/home/kmodi/usr_local/apps/6/emacs/emacs-25
'CPPFLAGS=-fgnu89-inline -I/home/kmodi/usr_local/6/include
-I/usr/include/freetype2 -I/usr/include' 'CFLAGS=-ggdb3 -O0'
'CXXFLAGS=-ggdb3 -O0' 'LDFLAGS=-L/home/kmodi/usr_local/6/lib
-L/home/kmodi/usr_local/6/lib64 -ggdb3'
PKG_CONFIG_PATH=/home/kmodi/usr_local/6/lib/pkgconfig:/home/kmodi/usr_local/6/lib64/pkgconfig:/cad/adi/apps/gnu/linux/x86_64/6/lib/pkgconfig:/cad/adi/apps/gnu/linux/x86_64/6/lib64/pkgconfig:/usr/lib/pkgconfig:/usr/lib64/pkgconfig:/usr/share/pkgconfig:/lib/pkgconfig:/lib64/pkgconfig'
Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK2 X11