Re: add-hook and defvar

[Philipp Stephani <p.stephani2@gmail.com>]

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Stefan Monnier <monnier@iro.umontreal.ca> schrieb am Mi., 25. Feb. 2015 um
03:56 Uhr:

> > Is this something the byte compiler could warn about? At least normal
> hooks
> > by convention end in "-hook", so a warning could be emitted every time
> such
> > a variable is defined that doesn't have nil as default.
>
> Yes, we could do that.  Patch welcome,
>
>
>
Added a patch.

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From 8aad74d2cb12a7afd6067b8737894c3a4b905a20 Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Thu, 5 Mar 2015 21:06:07 +0100
Subject: [PATCH] Warn if a hook variable is given a non-nil init form

---
 lisp/emacs-lisp/bytecomp.el | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index e929c02..b9db322 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -2311,6 +2311,9 @@ list that represents a doc string reference.
 (defun byte-compile-file-form-defvar (form)
   (let ((sym (nth 1 form)))
     (byte-compile--declare-var sym)
+    (and (string-suffix-p "-hook" (symbol-name sym))
+         (nth 2 form)
+         (byte-compile-warn "hook variable `%s' has non-nil init value" sym))
     (if (eq (car form) 'defconst)
         (push sym byte-compile-const-variables)))
   (if (and (null (cddr form))		;No `value' provided.
-- 
2.2.0.rc0.207.ga3a616c