If you want to do it in this PR (otherwise in a follow-up), we could add an rustc attribute to those as_ptr/as_mut_ptr methods.

You can follow afcb09b and 2a930d3 (from a PR of mine) with check_applied_to_fn_or_method instead, and something similar to this to check the attribute

rust/compiler/rustc_lint/src/ptr_nulls.rs

Lines 49 to 50 in e454c45

	&& let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
	&& cx.tcx.has_attr(def_id, sym::rustc_never_returns_null_ptr)

Originally posted by @Urgau in #128985 (comment)