cat doesn't print files with "invalid unicode"

[TheGoddessInari]

At least on Windows, it prints

1  cat: text was not valid unicode

when attempting to cat -n or cat -b a file with presumably invalid unicode. Without any other arguments, it prints a blank line. This is an important distinction because GNU cat, and redirecting input (like cat < file) both work. Only when passing the file via arguments does it fail in this way.

Notably, this fails with most executables.

[Arcterus]

This main part of this issue seems to be caused by rust-lang/rust#23344. I'm not really sure if there's an easy fix unfortunately. That said, I'm still not totally sure why the issue only shows up when opening a file directly. I'm guessing it has to do with stdin only reading in UTF-16 pairs or something so there is no need to worry about half pairs.

The other part should be split into a separate issue (I'd appreciate it if you would do so). We should not be separating the line number prefix write from the data write to avoid weird output like this.

[stale]

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