GNU bug report logs - #50539
Don't use comment colors in HTML textareas

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: bug-gnu-emacs <at> gnu.org
Subject: Don't use comment colors in HTML textareas
Date: Sun, 12 Sep 2021 14:11:25 +0800

Here emacs misleads the user via comment color,
into thinking that the so-called comment is still
a comment in an HTML textarea:

$ emacs some.html
 <form>
  <p>
  <textarea readonly="1">Ralph is tall.
<!-- He's cute. -->
</textarea>
  </p>
 </form>

When in fact it gets rendered by browsers.

Message #8 received at 50539 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 50539 <at> debbugs.gnu.org
Subject: Re: bug#50539: Don't use comment colors in HTML textareas
Date: Sun, 12 Sep 2021 20:55:28 +0200

積丹尼 Dan Jacobson <jidanni <at> jidanni.org> writes:

> Here emacs misleads the user via comment color,
> into thinking that the so-called comment is still
> a comment in an HTML textarea:
>
> $ emacs some.html
>  <form>
>   <p>
>   <textarea readonly="1">Ralph is tall.
> <!-- He's cute. -->
> </textarea>
>   </p>
>  </form>
>
> When in fact it gets rendered by browsers.

It gets rendered, but I'm not sure what the actual definition here is.

https://www.w3.org/TR/html401/interact/forms.html#h-17.7

says that the contents of <textarea> is PCDATA (parsed character data),
so for that to be rendered that way by browsers, it should be something
like:

<textarea readonly="1">Ralph is tall.
&lt;!-- He's cute. --&gt;
</textarea>

But browsers use pretty sloppy parsers, and does a lot of DWIM.

libxml2 does parse that as a textarea containing a comment.

I spent a couple minutes to say whether there's any standard that says
whether <!-- comments are allowed in PCDATA or not, but I'd assume so.
Does anybody know for sure?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #13 received at 50539 <at> debbugs.gnu.org (full text, mbox):

From: Gregory Heytings <gregory <at> heytings.org>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 50539 <at> debbugs.gnu.org,
 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Subject: Re: bug#50539: Don't use comment colors in HTML textareas
Date: Sun, 12 Sep 2021 22:05:08 +0000

>
> I spent a couple minutes to say whether there's any standard that says 
> whether <!-- comments are allowed in PCDATA or not, but I'd assume so. 
> Does anybody know for sure?
>

I'm not absolutely sure, but AFAIK all HTML tags are rendered as is in a 
text area, not only <!-- comments.

Message #16 received at 50539 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Gregory Heytings <gregory <at> heytings.org>
Cc: 50539 <at> debbugs.gnu.org,
 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Subject: Re: bug#50539: Don't use comment colors in HTML textareas
Date: Mon, 13 Sep 2021 10:10:56 +0200

Gregory Heytings <gregory <at> heytings.org> writes:

>> I spent a couple minutes to say whether there's any standard that
>> says whether <!-- comments are allowed in PCDATA or not, but I'd
>> assume so. Does anybody know for sure?
>
> I'm not absolutely sure, but AFAIK all HTML tags are rendered as is in
> a text area, not only <!-- comments.

Firefox does that:

<textarea>
<p>
</textarea>

But not for

<textarea>
</textarea>
</textarea>

:-)

But, like I said, the contents here are defined to be PCDATA, so this is
just Firefox (and probably Chrome, too) just being generous and trying
to interpret as they guess the writer intended.

HTML-mode also highlights the <p> as if it's a tag...  which it is,
even if Firefox doesn't interpret it as such.

So I think, on the whole, that html-mode does everything correctly here,
and I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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