[bug #55136] [ms] recover from .DS within .DS

[G. Branden Robinson]

Update of bug #55136 (project groff):

                Severity:              3 - Normal => 1 - Wish               
                  Status:                    None => In Progress            
             Assigned to:                    None => gbranden               
                 Summary: [PATCH] s.tmac: Check the closure of the .DS macro
(display) => [ms] recover from .DS within .DS

    _______________________________________________________

Follow-up Comment #2:

Bad news first:

1. I'm rejecting the patch.
2. The ms @fatal macro has been retired since this bug was filed, so it
wouldn't work anyway.

The good news:

3. Checking for nested diversions is a good idea, and user-friendly.
4. The situation is recoverable, with no loss of text, and therefore we don't
need a fatal diagnostic anyway as Bjarni suggested for such a scenario.
5. The recovery mechanism is already implemented and has been in place for
years.
6. A one-line patch not only addresses the simple reproducing case reported in
bug #55099, but it preserves groff ms's existing ability to have a display
within a footnote within a display.
7. We fare much better than Heirloom Doctools ms in this regard; it discards
the contents of all diversions in the stack, producing no diagnostic and
exiting with a successful status.

I'm attaching some reproducers.  Here's the patch.


diff --git a/tmac/s.tmac b/tmac/s.tmac
index 01f92e62..9d617d4b 100644
--- a/tmac/s.tmac
+++ b/tmac/s.tmac
@@ -1013,6 +1013,7 @@ along with this program.  If not, see
<http://www.gnu.org/licenses/>.
 .el .@error-recover mismatched .DE
 ..
 .de DS
+.if '\\n(.z'ds*div' .@error-recover cannot use .DS within a .DS
 .br
 .di ds*div
 .ie '\\$1'B' \{\


I'll do some more tests.

(file #51344, file #51345)
    _______________________________________________________

Additional Item Attachment:

File name: ds-ds-de.ms                    Size:0 KB
    <https://file.savannah.gnu.org/file/ds-ds-de.ms?file_id=51344>

File name: ds-ds-fn-de.ms                 Size:0 KB
    <https://file.savannah.gnu.org/file/ds-ds-fn-de.ms?file_id=51345>



    _______________________________________________________

Reply to this item at:

  <https://savannah.gnu.org/bugs/?55136>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/