I think you were trying to say that it makes no sense to decode something that's already been decoded, but that's got nothing to do with whether it's a "perl-internal utf8" buffer or not.

Based on having seen the result of this snippet: 

perl -MEncode -e '$x="\x{0432}"; $y=decode("utf8",$x)'

[download]
my intention was to say that when you pass that sort of string to Encode::decode(), you get a run-time error. I had assumed that "that sort of string" was most easily understood as one whose utf8 flag was already on.

You've shown that things are actually deeper and more complicated -- I added "is_utf8()" to your script, and confirmed that Encode::decode was working without croaking, with the input string's utf8 flag on as well as off.

This is a surprising effect of the utf8::upgrade/downgrade functions, and I'm glad to know about it, though it goes a bit beyond the scope of the OP (and most applications that involve encoding issues).

In reply to Re^3: question about Encode::decode('iso-8859-1', ...) by graff
in thread question about Encode::decode('iso-8859-1', ...) by perl5ever

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