I suppose there are cases where it's not immediately apparent to the parser if a given occurrence is an lvalue or rvalue?

Perl is very much aware of which expressions should return something "M"odifiable. 

$ perl -MO=Concise,-exec -e'  $x=$#a        ' 2>&1 | grep av2arylen
5  <1> av2arylen sK/1

$ perl -MO=Concise,-exec -e'  $#a=$x        ' 2>&1 | grep av2arylen
6  <1> av2arylen sKRM*/1

$ perl -MO=Concise,-exec -e'  foo($#a)      ' 2>&1 | grep av2arylen
6  <1> av2arylen sKM/1

$ perl -MO=Concise,-exec -e'  \$#a          ' 2>&1 | grep av2arylen
5  <1> av2arylen sKRM/1

$ perl -MO=Concise,-exec -e'  1 for $#a     ' 2>&1 | grep av2arylen
7  <1> av2arylen sKM/1

$ perl -MO=Concise,-exec -e'  1 for 0..$#a  ' 2>&1 | grep av2arylen
8  <1> av2arylen sK/1

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In reply to Re^7: Does @{ } copy arrays? by ikegami
in thread Does @{ } copy arrays? by tford

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