bug#11913: Unusual Emacs 24.1 arithmetic error (abs) on i386 machine

[Rob Browning]

Glenn Morris <rgm@gnu.org> writes:

> But why does (abs 8.0) return an arithmetic error at all...?

OK, at the moment, I believe the short answer is because fabs() is
changing errno which triggers the default clause in IN_FLOAT() here:

    default: arith_error (float_error_fn_name, float_error_arg);

I've been told that this should be considered an Emacs bug because the
effect of fabs() on errno is strictly undefined, and so fabs() is within
its rights to do whatever it wants to the value.

Hope this helps.
-- 
Rob Browning
rlb @defaultvalue.org and @debian.org
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