Consider a typical magic diamond (ARGV) usage, reducto ad absurdum: 
  perl -e'while(<>){1;}continue{print "$ARGV\n" if eof;}; print $!' fi
+le1 file2 file3
file1
Can't open file2: No such file or directory at -e line 1, <> line 222.
file3
Bad file descriptor

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Note that file 2 doesn't exist, and Perl generates an error message. So the user knows, probably.

However, after the loop, there doesn't seem to be a way for the program to detect that a file wasn't processed. In real life, that could be awkward. Am I missing something?

I suppose that in a continue block, I could push $ARGV onto an array using eof and compare the result to @ARGV after the loop. But that seems awkward and ugly.

Saner alternatives (other than forgoing magic)?

This communication may not represent my employer's views, if any, on the matters discussed.

In reply to Diamond errors by tlhackque

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