bug#17207: 24.3; html-mode incorrect indentation inside template syntax

[Stefan Kangas <stefan@marxist.se>]

Jon Dufresne <jon.dufresne@gmail.com> writes:

> Create a test.html file. Use html-mode. Fill with the following
> contents:
>
> ```
> <table>
>   <thead>
>     <tr>
>       {% for header in headers %}
> 	<th>{{ header.attr1 }}</th>
>       <th>{{ header.attr2 }}</th>
>       {% endfor %}
>     </tr>
>   </thead>
> </table>
> ```
>
> This is a mix of HTML and Django template syntax [0]. If you indent line
> 6 (<th>{{ header.attr2 }}</th>) I would expect the line to align itself
> with the previous line (<th>{{ header.attr1 }}</th>). Instead it appears
> to aligns itself with the "for" template tag or perhaps the <tr> plus an
> offset. The final result after indenting line 6 is as it appears above.
>
> The mode pony-tpl-mode [1] uses html-mode to calculate indentation when
> then previous line looks like HTML and not special syntax. See my bug
> report there: https://github.com/davidmiller/pony-mode/issues/81
>
> [0] https://docs.djangoproject.com/en/dev/topics/templates/
> [1] https://github.com/davidmiller/pony-mode

This was reported 5 years ago, but unfortunately never got a reply at
the time.

I can reproduce this on current master, but I wonder if it makes sense
to make html-mode support Django template syntax.  Shouldn't there be
a separate (perhaps derived) mode for that?

Best regards,
Stefan Kangas