Dear Perl Monks! Please explain why the program doesn't print "Z: passed" but displays "E: failed"? 
#!/usr/bin/perl


my $a = " -1";  

# remove trailing spaces 
warn "A: pos is ", pos $a;   
$a =~ /\G */gc;

warn "B: pos is ", pos $a;    
$a =~ /\G(?=-)/gc or die "C: failed";     

warn "D: pos is ", pos $a;
$a =~ /\G(?=-)/gc or die "E: failed";      

print "Z: passed";

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output is: 
 
A: pos is  at ./l2 line 7.
B: pos is 1 at ./l2 line 10.
D: pos is 1 at ./l2 line 13.
E: failed at ./l2 line 14.

[download]
Strange is that "pos $a" is 1, and look ahead for minus sign fails. B: situation is exactly the same as D:, but C: doesn't fail, but E: does...

In reply to strange behaviour: continue with \G and /gc and look forward by leszekdubiel

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