cperl-mode 5.23 corrupts compilation-error-regexp-alist under GNU Emacs

[Denis Howe]

In GNU Emacs 21.4.1 (i486-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
of 2006-09-15 on rothera, modified by Debian
configured using `configure '--build=i486-linux-gnu'
'--host=i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib'
'--libexecdir=/usr/lib' '--localstatedir=/var/lib'
'--infodir=/usr/share/info' '--mandir=/usr/share/man'
'--with-pop=yes' '--with-x=yes' '--with-x-toolkit=athena'
'CFLAGS=-DDEBIAN -g -fno-stack-protector -O2'
'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu''

SYMPTOMS

compilation-mode throws an error when it tries to parse Perl
compilation errors or, if global-font-lock-mode is on, Emacs hangs
trying to fontify the compilation output unless you hit Control-G
repeatedly.

ANALYSIS

cperl-mode.el v5.23, cperl-mode defun, near line 3326 says:

         (set 'compilation-error-regexp-alist
               (cons cperl-compilation-error-regexp-alist
                     (symbol-value 'compilation-error-regexp-alist)))

This code for GNU Emacs looks like a copy and paste job from the
XEmacs case.  It breaks GNU Emacs as described above.

FIX

Replace cons with append in the above code.

--
Denis Howe
http://foldoc.org/
T: 020 8450 9448  M: 07950 686 615