Re: Byte-compilation of custom themes

["Basil L. Contovounesios" <contovob@tcd.ie>]

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From 49288975a810d1f2186f656cede92db93ee85c56 Mon Sep 17 00:00:00 2001
From: "Basil L. Contovounesios" <contovob@tcd.ie>
Date: Wed, 31 Jan 2018 23:23:49 +0000
Subject: [PATCH] Clarify byte-compilation of "Custom Themes" in Elisp manual

* doc/lispref/customize.texi (Custom Themes): Clarify status of
byte-compiled custom themes.  Suggested in
https://lists.gnu.org/archive/html/emacs-devel/2018-01/msg00824.html.
---
 doc/lispref/customize.texi | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/lispref/customize.texi b/doc/lispref/customize.texi
index 6c7ca260ab..7fea507fd0 100644
--- a/doc/lispref/customize.texi
+++ b/doc/lispref/customize.texi
@@ -1432,7 +1432,9 @@ Custom Themes
 would be evaluated when loading the theme, but that is bad form.
 To protect against loading themes containing malicious code, Emacs
 displays the source file and asks for confirmation from the user
-before loading any non-built-in theme for the first time.
+before loading any non-built-in theme for the first time.  As
+such, themes are not ordinarily byte-compiled, and source files
+always take precedence when Emacs is looking for a theme to load.
 
   The following functions are useful for programmatically enabling and
 disabling themes:
-- 
2.15.1


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Stefan Monnier <monnier@IRO.UMontreal.CA> writes:

>> diff --git a/doc/lispref/customize.texi b/doc/lispref/customize.texi
>> index 6c7ca260ab..7fea507fd0 100644
>> --- a/doc/lispref/customize.texi
>> +++ b/doc/lispref/customize.texi
>> @@ -1432,7 +1432,9 @@ Custom Themes
>>  would be evaluated when loading the theme, but that is bad form.
>>  To protect against loading themes containing malicious code, Emacs
>>  displays the source file and asks for confirmation from the user
>> -before loading any non-built-in theme for the first time.
>> +before loading any non-built-in theme for the first time.  As
>> +such, themes are not ordinarily byte-compiled, and source files
>> +always take precedence when Emacs is looking for a theme to load.
>>  
>>    The following functions are useful for programmatically enabling and
>>  disabling themes:
>
> Sounds good to me.

I attach a patch with this amendment.  If it is up to scratch, would
someone please push it?

>> Why are built-in themes not exempt to this safety net, though?
>
> They're not?  There is code which tries to exempt them, so if they're
> not, it's a bug in that code.

Sorry, I should have been clearer.  As documented, load-theme indeed
exempts built-in themes from the custom-theme-load-confirm check.  What
I meant to ask is why built-in themes are not byte-compiled in addition
to being considered safe.  Are there any arguments against doing this,
other than any performance gain being negligible?

>> Finally, would you care to post your helpful explanation as an answer to
>> my Stack Exchange question, or would you rather I paraphrased this
>> thread?
>
> Feel free to post my answer there,

Done: https://emacs.stackexchange.com/a/38510/15748.

Thanks,

-- 
Basil