wrapped in scalar,

Not only is there nothing odd with using scalar, substr imposes a scalar context on its fourth arg.

Invokes a non-existant command,

Pointless unless you're arguing we should get rid of the warning entirely. It's an example of a function that returns an error.

As for Can't exec, I didn't know about that warning when I came up with the example earlier.

The point that using PV_sv_undef isn't sufficient to detect an explicit undef stands. I didn't say it wasn't possible to detect an explicit undef, I just said checking PV_sv_undef doesn't cut it.

In reply to Re^5: Use of uninitialized value in substr by ikegami
in thread Use of uninitialized value in substr by BrowserUk

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