Bug#912780: Line numbers not printed on error despite XML_LIBXML_LINENUMBERS => 1

[Niko Tyni]

On Mon, Jan 14, 2019 at 11:13:14PM +0800, 積丹尼 Dan Jacobson wrote:
> >>>>> "NT" == Niko Tyni <ntyni at debian.org> writes:
> NT> On Sun, Nov 04, 2018 at 04:48:43AM +0800, 積丹尼 Dan Jacobson wrote:
> >> Package: libxml-libxml-perl
> >> Version: 2.0132+dfsg-2+b1
> >> Severity: minor
> >> 
> >> Line numbers not printed on error despite XML_LIBXML_LINENUMBERS => 1:
> >> $ cat e.pl
> >> use XML::LibXML;
> >> my $doc = XML::LibXML::Document->new( XML_LIBXML_LINENUMBERS => 1 );
> >> my $x = $doc->createElement('x');
> >> $x->appendChild($x);
> >> $ perl -w e.pl
> >> appendChild: HIERARCHY_REQUEST_ERR
> 
> NT> Not sure what you expected to get, the offending line in the code
> NT> perhaps?
> 
> NT> It looks to me like this feature is about reporting line numbers
> NT> in parsed XML documents, and you're not parsing anything.
> 
> Well all I know is I want it to say something like
> >> e.pl: 3: appendChild: HIERARCHY_REQUEST_ERR

So you're indeed looking for code line numbers, not document line numbers.
Again, the XML_LIBXML_LINENUMBERS feature is about the latter.

Maybe try Carp::Always or something.

  % cat e.pl
  #!/usr/bin/perl -w
  use strict;
  use Carp::Always;
  
  use XML::LibXML;
  my $doc = XML::LibXML::Document->new( XML_LIBXML_LINENUMBERS => 1 );
  my $x = $doc->createElement('x');
  $x->appendChild($x);
  exit 0;

  % perl e.pl
  appendChild: HIERARCHY_REQUEST_ERR
   at e.pl line 8.
 
Leaving this open as I don't see where XML_LIBXML_LINENUMBERS is
documented. XML::LibXML::Parser is quite clear about the equivalent
line_numbers() method though.

        If this option is activated, libxml2 will store the line
        number of each element node in the parsed document. The line
        number can be obtained using the "line_number()" method of the
        "XML::LibXML::Node" class (for non-element nodes this may report
        the line number of the containing element). The line numbers
        are also used for reporting positions of validation errors.

-- 
Niko Tyni   ntyni at debian.org