what version of perl are you using? For me it is:
> perl --version

This is perl 5, version 18, subversion 2 (v5.18.2) built for x86_64-linux-gnu-thread-multi
(with 41 registered patches, see perl -V for more detail)

and please double-check that you actually run that git version:

https://git.gnome.org/browse/gtk-doc/tree/gtkdoc-mkdb.in?id=e7b705c7aebc9534a1a9707e815a66a763bc7c3f#n516

The line 516 of gtkdoc-mkdb at this revision is a blank line.

The line broke at 516 on my screen and I didn't edit it. The line number is actually 5165:

5158     $markup .= substr ($text, 0, $closest_marker_position);
5159     $text = substr ($text, $closest_marker_position);
5160     @markers_rest = map { $markers{$_} ? ($_ eq $closest_marker ? () : $
: () } keys %markers;
5161
5162     if ($closest_marker eq "![" || $closest_marker eq "[") {
5163       my %element;
5164
5165       if (index ($text, "]") && $text =~ /\[((?:[^][]|(?R))*)\]/) {
5166         my $remaining_text;
5167
5168         %element = ( "!" => (substr ($text, 0, 1) eq "!"),
5169                      "a" => $1 );
5170
5171         $offset = length ($&);
5172         if ($element{"!"}) {
5173           $offset++;
5174         }
5175
5176         $remaining_text = substr ($text, $offset);

(In reply to Stefan Sauer (gstreamer, gtkdoc dev) from comment #2)
> and please double-check that you actually run that git version:
> 

$ perl --version

This is perl, v5.8.8 built for msys-64int

Can someone show me how to display the value of $text at line 5165? I tried
 printing to STDOUT and STDERR. I tried to write to a file, but the file was not created. I searched the entire build tree (which is now the source tree because I am now seeing that an out-of-tree build cannot work). I don't know perl at all so maybe I made a mistake.

If you do:
print "text: $text\n"
that will print the value to stdout.


Regarding the '?R', here are the docs for it:
http://perldoc.perl.org/perlre.html (search for ?R). An alternative would be to use (?0) if that makes it work for you.

(In reply to Stefan Sauer (gstreamer, gtkdoc dev) from comment #6)
> If you do:
> print "text: $text\n"
> that will print the value to stdout.
>

I'm sure that I tried that, but it did not work. No text appeared. I ran:
$make check > check.txt 2>&1 &
$tail -F check.txt

and also inspected check.txt at the end.
 
> 
> Regarding the '?R', here are the docs for it:
> http://perldoc.perl.org/perlre.html (search for ?R). An alternative would be
> to use (?0) if that makes it work for you.

?0 does not work either. However, I tried a newer perl (ActiveState):
$ /c/perl/perl/bin/perl --version

This is perl 5, version 20, subversion 2 (v5.20.2) built for MSWin32-x86-multi-t
hread-64int.

All 12 tests now pass, but no PDFs are built. I will open a new bug for that. For this incident, perhaps the configure script's perl version check could be updated. Currently it is:
checking if Perl version >= 5.6.0... yes
but my perl v5.8.8 does not recognise the ?R regular expression in gtkdoc-mkdb.

You can close this bug with whatever status you consider appropriate.

Regarding the logging, in the tests the the logs are already redirected, check the gtkdoc-*.log. When running this normally stdout and stderr work as usual.

Thanks a lot for testing with a newer version of perl. I bumped the required version in commit ea7536e70f783cdd04809d68e04ba07bb754693e.