Dmitry Gutov wrote:
> On 12/18/17 7:41 PM, Wedler, Christoph wrote:

>>      Head:     widen-less Consolidate 'widen' calls
>>      Merge:    origin/widen-less Consolidate 'widen' calls
>>      Tag:      emacs-26.0.90 (351)

> Not sure which tool's output this is.

It is copied from the magit status buffer for Emacs…

> Could you try with 'make bootstrap' instead of just 'make'?

I did that – no effect.
And if I look at

(defun indent-for-tab-command (&optional arg)
  … 
      (or (not (eq (funcall indent-line-function) 'noindent))
          (indent--default-inside-comment)
          (when (or (<= (current-column) (current-indentation))
                    (not (eq tab-always-indent 'complete)))
            (save-restriction
              (widen)
              (funcall (default-value 'indent-line-function)))))

I do not see why it should now behave correctly
(the “called” funcall is outside “save-restriction – widen”)

> I don't get syntax highlighting there, but indentation works fine. I 
> just needed to know which part of the example file to test.

Hm, with src/emacs –q &  and M-x load-file <path-to-antlr-mode-3.1.5>/antlr-mode.elc
I get the result of the attached screenshot area. 

If 'make bootstrap' doesn't help, could you try a step-by-step 
instruction, or a video, or something?

In bash:
      ./autogen.sh
      ./configure --with-ns --without-makeinfo --with-gnutls=no
      make
      src/emacs –q &

in Emacs_
      C-x C-f new.el RET
      Insert: “(defun foo ()” RET
      Insert: <2 spaces> “3)” RET
      C-x SPC  C-p  C-x n n (enable narrowing with  SPC)
      (region still active) TAB -> works (i.e., no deletion of the spaces)
      (region no longer active) TAB -> deletes the 2 spaces (wrong as before)