Subject: Re: bug#74091: 31.0.50; string-pixel-width in mode line disables region

From: Eli Zaretskii <[email-masked]>
Date: Sun, 10 Nov 2024 12:42:59 +0200

> Cc: [email-masked], [email-masked]
> Date: Sun, 10 Nov 2024 08:50:49 +0200
> From: Eli Zaretskii <[email-masked]>
> 
> > Cc: [email-masked], [email-masked]
> > Date: Sun, 10 Nov 2024 07:50:47 +0200
> > From: Eli Zaretskii <[email-masked]>
> > 
> > > > @@ -1170,7 +1171,7 @@ reset_buffer_local_variables (struct buffer *b, bool permanent_too)
> > > >  	      swap_in_global_binding (XSYMBOL (sym));
> > > >  	    }
> > > >  
> > > > -          if (!NILP (prop))
> > > > +          if (!NILP (prop) && permanent_too)
> > > >              {
> > > >                /* If permanent-local, keep it.  */
> > > >                last = tmp;
> > > 
> > > This should be an || rather than an &&, no?
> > 
> > No, I don't think so.  If the permanent-local property is nil, we
> > should not take this branch, even if permanent_too is non-zero.  Or
> > what am I missing?
> 
> Hmm... but something is still amiss, because Emacs built with my patch
> comes up without fontifications, although font-lock-mode is t.  Any
> ideas?

Sorry, here's the correct patch:

diff --git a/src/buffer.c b/src/buffer.c
index 744b0ef..995984e 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -113,7 +113,7 @@ #define OVERLAY_COUNT_MAX						\
 static void call_overlay_mod_hooks (Lisp_Object list, Lisp_Object overlay,
                                     bool after, Lisp_Object arg1,
                                     Lisp_Object arg2, Lisp_Object arg3);
-static void reset_buffer_local_variables (struct buffer *, bool);
+static void reset_buffer_local_variables (struct buffer *, int);
 
 /* Alist of all buffer names vs the buffers.  This used to be
    a Lisp-visible variable, but is no longer, to prevent lossage
@@ -1112,10 +1112,11 @@ reset_buffer (register struct buffer *b)
    Instead, use Fkill_all_local_variables.
 
    If PERMANENT_TOO, reset permanent buffer-local variables.
-   If not, preserve those.  */
+   If not, preserve those.  PERMANENT_TOO = 2 means ignore
+   the permanent-local property of non-builtin variables.  */
 
 static void
-reset_buffer_local_variables (struct buffer *b, bool permanent_too)
+reset_buffer_local_variables (struct buffer *b, int permanent_too)
 {
   int offset, i;
 
@@ -1141,7 +1142,7 @@ reset_buffer_local_variables (struct buffer *b, bool permanent_too)
   bset_invisibility_spec (b, Qt);
 
   /* Reset all (or most) per-buffer variables to their defaults.  */
-  if (permanent_too)
+  if (permanent_too == 1)
     bset_local_var_alist (b, Qnil);
   else
     {
@@ -1170,7 +1171,7 @@ reset_buffer_local_variables (struct buffer *b, bool permanent_too)
 	      swap_in_global_binding (XSYMBOL (sym));
 	    }
 
-          if (!NILP (prop))
+          if (!NILP (prop) && !permanent_too)
             {
               /* If permanent-local, keep it.  */
               last = tmp;
@@ -3001,7 +3002,7 @@ DEFUN ("kill-all-local-variables", Fkill_all_local_variables,
 
   /* Actually eliminate all local bindings of this buffer.  */
 
-  reset_buffer_local_variables (current_buffer, !NILP (kill_permanent));
+  reset_buffer_local_variables (current_buffer, !NILP (kill_permanent) ? 2 : 0);
 
   /* Force mode-line redisplay.  Useful here because all major mode
      commands call this function.  */