bug#28527: unexpected behaviour of char-after if argument is marker that don't point to the current buffer

[Eli Zaretskii]

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> Resent-From: Fritz Stelzer <brotzeitmacher@gmail.com>
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> From: Fritz Stelzer <brotzeitmacher@gmail.com>
> Date: Wed, 20 Sep 2017 15:29:07 +0200
> 
> When the argument for char-after is a marker, the function gets bytepos from 
> the buffer the marker is pointing
> to by calling marker_byte_position. But then pos_byte is compared to 
> BEGV_BYTE and ZV_BYTE that use the
> current buffer. At the end of the function, pos_byte is passed to FETCH_CHAR, 
> which also operates on the
> current buffer.

This is according to the documentation, which explicitly says the
position is looked up in the current buffer.  So this sounds like an
intentional and documented behavior.