it seems to me that for part 2 you are 'say'ing the for loop and thus $_ will be the constant 1 then 2.

Thanks for your thoughts, but the parsing you suggest is not quite right:

$ perl5.10 -MO=Deparse,-p -E 'say for 1..2'
BEGIN {
    $^H{'feature_say'} = q(1);
    $^H{'feature_state'} = q(1);
    $^H{'feature_switch'} = q(1);
}
;
say($_) foreach (1 .. 2);
-e syntax OK
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That is, say for ... is understood as say($_) for .... The problem is, unfortunately, much sillier than that: for aliases $_, so I wasn't incrementing the variable that I thought I was incrementing!