Bug#762135: libyaml-tiny-perl: YAML::Tiny >=1.60 generates certain(?) strings without quotes

[Michael Prokop]

Package: libyaml-tiny-perl
Version: 1.63-1
Severity: important


NOTE: I've already reported this to upstream in
https://rt.cpan.org/Public/Bug/Display.html?id=97870 but as I would
like to prevent this bug to appear in Debian/jessie I'm reporting it
here as well.

I noticed a parsing problem with a YAML file which is caused by the way
YAML::Tiny generates the YAML file since recent versions.

Minimized demo code:

% cat demo.pl
#!/usr/bin/perl

use strict;
use warnings;
use YAML::Tiny;

my $yaml = YAML::Tiny->new;
my $outputfile = shift;

$yaml->[0]->{foo} = '^00|\+([1-9][0-9]+)$';
open(my $fh, '>', "$outputfile");
print $fh $yaml->write_string();


Now that's what's working as expected with older versions:

% dpkg --list libyaml-tiny-perl | grep '^ii'
ii  libyaml-tiny-perl                              1.56-1                       all                          Perl module for reading and writing YAML files
% perl ./demo.pl demo.yml
% cat demo.yml
---
foo: '^00|\+([1-9][0-9]+)$'


But at least since YAML::Tiny v1.60 (verified with 1.60 + 1.63) it's
generating unexpected output WRT the quoting:

% dpkg --list libyaml-tiny-perl | grep '^ii'
ii  libyaml-tiny-perl                           1.63-1                         all          Perl module for reading and writing YAML files
% perl ./demo.pl demo.yml
% cat demo.yml
---
foo: ^00|\+([1-9][0-9]+)$

Notice the missing quotes around the '^00...' string in its output.

This is the (minimised) code that's in use and broke with the
change:

% cat foo.pl
#!/usr/bin/perl
use strict;
use warnings;
use Hash::Merge qw(merge);
use YAML qw/LoadFile/;

my $file = "demo.yml";
my $config = {};
$config = merge($config, LoadFile($file) || die $!);


When using the input from above:

% cat demo.yml
---
foo: ^00|\+([1-9][0-9]+)$

... this fails with:

% perl ./foo.pl
YAML Error: Unrecognized implicit value '^00|\+([1-9][0-9]+)$'
   Code: YAML_PARSE_ERR_BAD_IMPLICIT
   Line: 2
   Document: 1
 at /usr/share/perl5/YAML/Loader.pm line 567.

It works fine with the strings around the ^00....' as generated from
previous versions of YAML::Tiny though. (FTR:
/usr/share/perl5/YAML/Loader.pm is from libyaml-perl, reproduced
with versions 0.98 and 1.09-1.)

regards,
-mika-