Interesting. Definitely a bug in Perl, but it seems it's been already fixed: 
$ blead perl -wle '$_ = "abcdefgh"; print "2" . ( m/./g )[()]'
Use of uninitialized value in concatenation (.) or string at -e line 1
+.
2

[download]

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In reply to Re: Forcing list context. Brackets (with list within) as an unary right-associative operator by choroba
in thread Forcing list context. Brackets (with list within) as an unary right-associative operator by rsFalse

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