I am using Emacs 23 and php-mode.el 1.5.0. When I have this in my .emacs:
(require 'php-mode)
I get this error message when Emacs starts:
Warning (initialization): An error occurred while loading `/Users/kdj/.emacs':
error: `c-lang-defconst' must be used in a file
To ensure normal operation, you should investigate and remove the cause of the error in your initialization file. Start Emacs with the `--debug-init' option to view a complete error backtrace.
If I evaluate (require 'php-mode) after Emacs starts, I don't get any error messages.
I found a blog entry which indicates that this problem is specific to Emacs 23 (that is, there is no error with Emacs 22.x), but it doesn't give any solutions.
I don't know if this matters, but I'm using Mac OS X, and I built Emacs from the current CVS sources, using ./configure --with-ns.
What's going on here, and/or how I can fix it?
I ran into the same problem when trying to get the csharp-mode up and running. I finally found the solution when digging into the actual Emacs Lisp file for csharp-mode:
;; This code doesn't seem to work when you compile it, then
;; load/require in the Emacs file. You will get an error (error
;; "`c-lang-defconst' must be used in a file") which happens because
;; cc-mode doesn't think it is in a buffer while loading directly
;; from the init. However, if you call it based on a file extension,
;; it works properly. Interestingly enough, this doesn't happen if
;; you don't byte-compile cc-mode.
So, the quick and dirty fix to put in your .emacs is to auto load on extension and not put (require 'php-mode) or (load "php-mode") in there. Without further ado,
(autoload 'php-mode "php-mode" "Major mode for editing php code." t)
(add-to-list 'auto-mode-alist '("\\.php$" . php-mode))
(add-to-list 'auto-mode-alist '("\\.inc$" . php-mode))
I hope this helps! Now I just need to get the PHP/HTML mode switching stuff working. Wish me luck.