As a workaround:
- Get rid of most warnings by clicking the yellow triangle and pressing the return button, which will do some automatic correction.

- For the one with an exclamation mark in the triangle, delete the part of the comment.

Basically, this will change some comments in opencv sources. Since my local copy, not git clone. I assume that mostly the guys from opencv need to fix this. However, it would be nice to know which compiler option in Swift disables these warnings.
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