[Groff] .IP quoting incompatibility

[Colin Watson]

Here's an example, stripped down from pod2man's output for perlvar(1)
with recent versions of Perl, which behaves differently with UNIX [1]
and GNU [2] 'nroff -man'.

  .de Ip \" List item
  .br
  .ie \\n(.$>=3 .ne \\$3
  .el .ne 3
  .IP "\\$1" \\$2
  ..
  .TH FOO 1 ""
  .SH NAME
  .if n .Ip "$""""" 8
  .el .Ip "$""""" 8

UNIX outputs $" while GNU outputs $"" (in compatibility mode too).

Something similar to this (pod2man has been rewritten since in the form
of Pod::Man) is Debian bug #20277 (http://bugs.debian.org/20277).
Fabrizio said back then that latin1 and ascii output were broken, but ps
was fine; $" now seems to go missing in the PostScript output for
perlvar(1), although I don't have a test case for that yet.

I can imagine that pod2man could be improved - it doesn't need to
enclose arguments in double quotes half as much as it does. In any case,
I don't know enough to say where the bug is: is it in pod2man or groff?

For what it's worth, here's the relevant bit of current Pod::Man:

  # Given a command and a single argument that may or may not contain double
  # quotes, handle double-quote formatting for it.  If there are no double
  # quotes, just return the command followed by the argument in double quotes.
  # If there are double quotes, use an if statement to test for nroff, and for
  # nroff output the command followed by the argument in double quotes with
  # embedded double quotes doubled.  For other formatters, remap paired double
  # quotes to LQUOTE and RQUOTE.
  sub switchquotes {
      my $self = shift;
      my $command = shift;
      local $_ = shift;
      my $extra = shift;
      s/\\\*\([LR]\"/\"/g;

      # We also have to deal with \*C` and \*C', which are used to add the
      # quotes around C<> text, since they may expand to " and if they do this
      # confuses the .SH macros and the like no end.  Expand them ourselves.
      # If $extra is set, we're dealing with =item, which in most nroff macro
      # sets requires an extra level of quoting of double quotes.
      my $c_is_quote = ($$self{LQUOTE} =~ /\"/) || ($$self{RQUOTE} =~ /\"/);
      if (/\"/ || ($c_is_quote && /\\\*\(C[\'\`]/)) {
          s/\"/\"\"/g;
          my $troff = $_;
          $troff =~ s/\"\"([^\"]*)\"\"/\`\`$1\'\'/g;
          s/\\\*\(C\`/$$self{LQUOTE}/g;
          s/\\\*\(C\'/$$self{RQUOTE}/g;
          $troff =~ s/\\\*\(C[\'\`]//g;
          s/\"/\"\"/g if $extra;
          $troff =~ s/\"/\"\"/g if $extra;
          $_ = qq("$_") . ($extra ? " $extra" : '');
          $troff = qq("$troff") . ($extra ? " $extra" : '');
          return ".if n $command $_\n.el $command $troff\n";
      } else {
          $_ = qq("$_") . ($extra ? " $extra" : '');
          return "$command $_\n";
      }
  }

[1] Tested on Solaris 2.6 to 2.8, AIX 4.3 and 5.1, HP-UX 10.20 and
    11.00, UnixWare 7.1.1, and OSF/1 4.0.

[2] At least from 1.15 onwards.

Thanks,

-- 
Colin Watson                                     address@hidden