Re: bootstrap problem with union Lisp_Object

[Stefan Monnier]

>     Fixed...  With these options enabled, EQ evaluates its arguments
>     twice.  A while back, Stefan changed NILP to use EQ instead of
>     XFASTINT, which is cleaner, but it turns out some invocations of NILP
>     had non-idempotent arguments.
> Why doesn't EQ use XFASTINT?  We want it to be as fast as possible.

XFASTINT is "slow" (identical to XINT, in the now default case of
USE_LSB_TAG) and incorrect (it fails to check that the tag bits are equal).

If Lisp_Object=int (or long), we want to use "=" directly, which is exactly
what happens with `EQ'.


        Stefan