I've come across an issue in some test code which I've reduced down. This initially came about because one test module used Math::FixedPrecision and another test module used bignum. The two were not used together until a new test was written which needed both and then stringifcation of Math::FixedPrecision started failing with Can't use an undefined value as an ARRAY reference.

The reduced version is just to simplify the problem, it serves no useful purpose. I also don't understand why "no bignum" does not fix the issue. This works:

use strict;
use warnings;
use Data::Dumper;

{
    require Math::FixedPrecision;
    my $one = Math::FixedPrecision->new('2', 2);
    print Dumper($one);
    print Dumper("$one");
}
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outputting

$VAR1 = bless( {
                 '_m' => [
                           2
                         ],
                 '_es' => '+',
                 '_p' => -2,
                 '_e' => [
                           0
                         ],
                 'sign' => '+'
               }, 'Math::FixedPrecision' );
$VAR1 = '2.00';
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and this does not work

use strict;
use warnings;
use bignum;
use Data::Dumper;

{
    no bignum;
    require Math::FixedPrecision;
    my $one = Math::FixedPrecision->new('2', 2);
    print Dumper($one);
    print Dumper("$one");
}
[download]

outputting

$VAR1 = bless( {
                 'value' => [
                              2
                            ],
                 '_p' => -2,
                 'sign' => '+'
               }, 'Math::FixedPrecision' );
Can't use an undefined value as an ARRAY reference at /home/perlbrew/p
+erls/perl-5.16.0/lib/5.16.0/Math/BigInt/Calc.pm line 1259.
[download]

Notice the lack of a mantissa in the second case which is actually what causes the final error in Math::BigInt::Calc. Any ideas?