$d eq $u is true in the snippet I provided earlier, so open should do the same for both. But it doesn't. That's a bug.

Yes. But you created $d and $u using "internal" Perl functions (AFAICT the programmer is not supposed to invoke upgrade() / downgrade() directly?). Now, can this bug be reproduced using "supported" operations?

You can reproduce it by concatenating the result of readlink() or glob to a codepoint-string, but that in itself means breaking the conventions (because you're not supposed to mix codepoint-strings with byte-strings)

So now I'm starting to lean to the position that one should decode ARGV, decode STDIN, decode readlink() and glob output, and thus always work with codepoint-strings (which can be safely concatenated, trimmed etc and then passed to open(), because open() "calls" transform(), which detects that it needs to encode them).

In reply to Re^5: how are ARGV and filename strings represented? by almr
in thread how are ARGV and filename strings represented? by almr

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