What does this warning mean?

Warning: A value of class "matlab.internal.editor.eval.TempFolder" was indexed with no

subscripts specified. Currently the result of this operation is the indexed value

itself, but in a future release, it will be an error.

[Rik]

Where does this warning occur? What are you doing at the time you see it?

[John D'Errico]

Please don't add new answers just to make a comment. Moved:

"This started today; it happens every time I run a script."

[Nicholas Davey]

I also see this warning sometimes. R2018b on Linux. Has anyone found an explanation?

Thanks

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/437050-error-message-when-compiling-app-warning-a-value-of-class-char-was-indexed-with-no-subscripts-s#answer_353705

https://www.mathworks.com/matlabcentral/answers/457222-warning-about-a-value-indexed-with-no-subscripts-and-error-in-future-release