Re: [Emacs-diffs] scratch/widen-less a4ba846: Replace prog-widen with consolidating widen calls

["Wedler, Christoph" <christoph.wedler@sap.com>]

Sorry for not having followed this discussion earlier - as the one who
has somehow introduced `prog-indentation-context', I probably should have...

If it works and you tell me how to do it, I have no issues with an
alternative way to make the indentation function of a "sub mode" work
for code chunks inside an "outer language" (like ANTLR grammar files).

I you want to try some ANTLR grammar examples yourself, I would
recommend:

 - antlr-mode 3.1.4
   from https://sourceforge.net/projects/antlr-mode/files/

 - example grammar files, especially lines 46 to 51 in
   https://github.com/antlr/examples-v3/blob/master/Python/C/C.g

 - and others in that repo (mentioned in line 100 of antlr-mode.el)

Now to the elements in `prog-indentation-context':

 - FIRST-COLUMN: I understood that you want to keep (s/th like) that...

 - (START . END) = the region of the code chunk: well, some indentation
   engines got confused to see unknown code before code written in the
   "sub-modes" - for some I could do `narrow-to-region' myself, other
   engines did widen, like python.  IMHO, modes with widening provide a
   better indentation experience than those without, see below.

 - PREVIOUS-CHUNKS: well, I was told to introduce this to be more
   general... - some modes (like cc-mode) could be told that the code is
   not some usual "top-level" code, but just some "normal statement".
   (antlr-mode includes some ugly hack for cc-mode).

If all this is covered by a better way - fine with me!  Even if does not cover
PREVIOUS-CHUNKS…

Now to a mode with non-widening indentation function: emacs-lisp mode:

Consider the following code
    (defun foo ()
      (+ 1 3))

I would assume that the indentation of line 2 does not change
when I narrow to line 2 - but Emacs-25.1.1 now deletes the first 2
spaces of line 2...  (yes; I also need to update to a newer Emacs)

- Christoph

P.S. antlr-mode 3.1.5 will have docstrings for all function and
variables - just the last 100 lines are missing.  After that, I need to
adapt it to "the new way" and it could replace the very old antlr-mode
in Emacs (or move it to ELPA or whatever you like).