There are 58 instances of 0 as * in the Rust source code.
There are 202 instances of ptr::null in the Rust source code.
Since 0 as *const _ or 0 as *mut _ looks uglier and is used less often, I therefore propose to always use ptr::null() or ptr::null_mut() whenever possible in the Rust source code.
A point was brought up that 0 as * is needed for constants and statics, to which I reply with eddyb’s RFC 911.
Another point was brought up that ptr::null requires ptr to be in scope, to which I reply stop being lazy and use ptr;.
Commence the bikeshedding.