Re: [PATCH] Make byte-compile-error-on-warn a safe variable for file compilation

[Robert Cochran <robert+Emacs@cochranmail.com>]

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Stefan Monnier <monnier@iro.umontreal.ca> writes:

> That's because the var and its safety predicate are only known once the
> bytecompiler is loaded, so if you iopen the file in a session where the
> bytecompiler has not yet been loaded Emacs won't know about the
> safety predicate.

Huh. I would have guessed that the byte compiler would have been loaded
automatically myself, but I suppose I can see why it wouldn't be.

> For this reason the `:safe` arg of defcustom is often not useful.
> Instead, you want to use the `(put ...)` form with a `;;;###autoload`
> cookie in front of it, so that the safety predicate is preloaded.
>

Yeah, I noticed I forgot the autoload cookie, so I knew I had to do it
over again anyways.

Thus, new (and hopefully) final version of the patch.

Please let me know if I need to do anything else.

Thanks,
-- 
~Robert Cochran

GPG Fingerprint - BD0C 5F8B 381C 64F0 F3CE  E7B9 EC9A 872C 41B2 77C2


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From f7e5bc29caafba09766ec17853f6c6561d96434f Mon Sep 17 00:00:00 2001
From: Robert Cochran <robert-git@cochranmail.com>
Date: Sat, 6 Jan 2018 13:19:55 -0800
Subject: [PATCH] Make byte-compile-error-on-warn a safe variable for file
 compilation

This allows individual files to easily specify whether or not byte
compilation should error on encountering warnings, ala -Werror from
GCC.

* lisp/emacs-lisp/bytecomp.el (byte-compile-error-on-warn): Mark as a
  safe local variable.
---
 lisp/emacs-lisp/bytecomp.el | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 2f5f9f8c05..a481b41aa5 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -295,6 +295,7 @@ byte-compile-error-on-warn
   "If true, the byte-compiler reports warnings with `error'."
   :group 'bytecomp
   :type 'boolean)
+;;;###autoload(put 'byte-compile-error-on-warn 'safe-local-variable 'booleanp)
 
 (defconst byte-compile-warning-types
   '(redefine callargs free-vars unresolved
-- 
2.14.3