Ok. I'll do some installs of other versions on Linux and Windows and try to get to the version where it's borked while I finish my work day. On my Windows system I sometimes develop on, with 5.28.1, I get the aa as well:

c:\repos\berrybrew>perl -le "@_ = qw( a b c ); print( ( shift @_ )[ 0,
+ 0 ] );"
aa

c:\repos\berrybrew>perl -le "@_ = qw( a b c ); @A = ( shift @_ )[ 0, 0
+ ]; print @A"
aa

c:\repos\berrybrew>perl -v

This is perl 5, version 28, subversion 1 (v5.28.1) built for MSWin32-x
+64-multi-thread
[download]

This behavior appears somewhere between versions 5.12.3 and 5.14.4, but a quick scan of the deltas (update: between these versions) shows no justification for it. (Update: All code run under Windows 7.)

c:\@Work\Perl\monks>perl -wMstrict -le
"print 'perl version: ', $];
 ;;
 use Data::Dumper;
 ;;
 @_ = qw( a b c );
 print( ( shift @_ )[ 0, 0, 0 ] );
 ;;
 @_ = qw( a b c );
 my @A = ( shift @_ )[ 0, 0, 0 ];
 print Dumper \@A;
 ;;
 @A = ( 'x', 'y', 'z' )[ 0, 0, 0 ];
 print Dumper \@A;
"

perl version: 5.012003
aaa
$VAR1 = [
          'a',
          'a',
          'a'
        ];

$VAR1 = [
          'x',
          'x',
          'x'
        ];

perl version: 5.014004
aaa
$VAR1 = [
          'a',
          undef,
          undef
        ];

$VAR1 = [
          'x',
          'x',
          'x'
        ];
[download]

Version 5.14 is the latest I can access ATM.

---

Give a man a fish:  <%-{-{-{-<

Nice catch AnomalousMonk, but it still breaks for me on 5.18 per OP's statement above:

c:\repos\berrybrew>perl -le "@_ = qw( a b c ); @A = ( shift @_ )[ 0, 0
+ ]; print @A"
a

c:\repos\berrybrew>perl -v

This is perl 5, version 18, subversion 4 (v5.18.4) built for MSWin32-x
+64-multi-thread
[download]

I'm having some issues (per CB mention) with fetching versions on my Unix machines with perlbrew available, so all I can test on is Windows currently.

I got the same thing with perl 5, version 18, subversion 1 (v5.18.1) built for x86_64-linux-thread-multi