On 12/13/2017 08:20 AM, Eli Zaretskii wrote:
> using a (fake) pointer is only marginally safer than using an
> integer, isn't it?

The fake pointer catches (at compile-time) common faults like the one 
the attached patch fixes, where an int was passed where a Lisp_Object 
was expected. These are the most important faults that 
--enable-check-lisp-object-type catches.

We could say that the fake pointer is only marginally safer, in the 
sense that --enable-check-lisp-object-type is only marginally safer than 
--disable-check-lisp-object-type. However, this marginal safety is 
useful; and once you have the fake pointer, 
--enable-check-lisp-object-type doesn't buy much extra safety that is 
useful.