[bug #58447] me macros: valid input with specific parameters causes a fatal error

[Dave]

URL:
  <https://savannah.gnu.org/bugs/?58447>

                 Summary: me macros: valid input with specific parameters
causes a fatal error
                 Project: GNU troff
            Submitted by: barx
            Submitted on: Tue 26 May 2020 12:39:13 PM CDT
                Category: Macro - others
                Severity: 3 - Normal
              Item Group: Incorrect behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:

The attached input file, which uses the -me macro set, results in


stack_limit_bug:41: fatal error: input stack limit exceeded (probable infinite
loop)


Groff 1.22.3 fails immediately with this error.  The latest groff code from
git eventually fails with this error after emitting a few thousand lines of
backtrace messages.

The file itself is linear, with one diversion (in the form of the macro pair
".(f" and ".)f") but no loops, so the error must come from the -me macro set.

groff fails with this error for the default output device (-Tps) and for
-Tpdf, but not for -Tascii or other TTY output formats.

I've been unable to make the example any simpler.  Triggering the bug seems to
require specific combinations of values in the -me registers tp, tm, and $v,
as documented in the comments within the attached file, along with a header
defined by the .he macro (its contents don't seem to matter, but it must be
present to trigger the bug) and a footnote long enough to span a page break.



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File Attachments:


-------------------------------------------------------
Date: Tue 26 May 2020 12:39:13 PM CDT  Name: stack_limit_bug  Size: 2KiB   By:
barx
sample groff input file to demonstrate the stack limit violation
<http://savannah.gnu.org/bugs/download.php?file_id=49178>

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