Hi Ihor, wolf,

Ihor Radchenko writes:
> Confirmed.
> This is caused by `org-src--contents-for-write-back' not adjusting
> blank line indentation in some cases.

I don't think that's the issue. In fact, applying your diff didn't
seem to solve the issue on my end.

Generally, if you edit the given yaml in a =C-c C-'= buffer and go
back to the org buffer with the default configuration, spaces will be
converted to tabs, because =indent-tabs-mode= is =t= in the org buffer.

I don't think there's much that we can do about it. We could try to
read the value of =indent-tabs-mode= in the native buffer and preserve
it in the org buffer, but then the org buffer would have mixed
indentation all over, and that's exactly what the current code tries to
avoid.

To fix the original issue, you can set =indent-tabs-mode= to =nil= in
your org files, or possibly set =org-preserve-indentation= to =t=
(untested).

> I feel that the whole approach we use now with preserve-fl, use-tabs?,
> and preserve-blank-line is overcomplicated. Maybe someone can explain
> why we need all these special cases? The code does not reveal a whole lot.

  - =use-tabs?= seems pretty straightforward, its purpose is to respect
    the value of =indent-tabs-mode= in the org buffer.
  - =preserve-fl= is an isolated issue, and only concerns LaTeX
    fragments. I will attach a test with the issue it solves with
    multiline LaTeX fragments. I think LaTeX fragments are particular
    because in the org buffer they do not need to start at the
    beginning of a line.
  - The =preserve-blank-line= part (committed by me) is quite abstruse.
    Its name does not make any sense !

    Originally, we did not try to reindent blank lines when writing
    back to the org buffer. I changed it so that when using
    =org-return=, the newline would get correctly indented, I think.
    Then I changed it again so that only the current blank line might
    get indented, see
    : https://list.orgmode.org/725763.1632663635@apollo2.minshall.org/T/
    The variable =preserve-blank-line= decides whether we should indent
    the current blank line (if it is empty, we should maybe not).


Here are three patches attached.
  1. Two tests : about editing LaTeX fragments, and preserving empty
     lines.
  2. Renaming of =preserve-blank-line=, for clarity.
  3. Two more tests testing the behaviour of =org-return= and
     indentation, with the default configuration. When writing these, I
     found the behaviour was buggy in one case, and modified
     =org-indent-line= to fix it.

Does that look alright to you ?

Regards,
-- 
Sébastien Miquel