fad44c424f
const: make ptr.is_null() stop execution on ambiguity This seems better than saying `false` -- saying `false` is in fact actively unsound if `NonNull` then uses this to permit putting this pointer inside of it, but at runtime it turns out to be null. Part of https://github.com/rust-lang/rust/issues/74939 Cc ```@rust-lang/wg-const-eval```