If I pass a LIMIT > point-max to next-single-char-property-change, Emacs hangs. Of course, I shouldn’t pass such a bad argument, but next-single-char-property-change should probably error out instead of hanging in a infinite loop IMHO.
Here is the relevant C code:
position = Fnext_char_property_change (position, limit);
if (XFIXNAT (position) >= XFIXNAT (limit))
position = limit;
value = Fget_char_property (position, prop, object);
if (!EQ (value, initial_value))
If it gets a LIMIT larger than point-max, position can never == limit, so it will loop in the while loop infinitely. I would add a check in the beginning of the function, to signal an out-of-range error. Or maybe set limit to poin-max quietly. Other similar functions could have the same problem, previous-single-char-property-change comes to my mind.
In GNU Emacs 27.0.60 (build 1, x86_64-apple-darwin19.3.0, NS appkit-1894.30 Version 10.15.3 (Build 19D76))