Description

The ref_as_ptr lint currently warns on all reference → pointer casts, including borrows of named locals. There is an internal TODO in the implementation:

// TODO: only block the lint if `cast_expr` is a temporary

I interpret “temporary” to mean values created by expressions without a named local, e.g., literals (&42), function return values (&foo()), struct/tuple literals, etc., whose lifetime ends at statement evaluation — not references to named variables. Under this definition:

let val = 1;
f(&val as *const _);       // should *not* lint
f(&val as *const i32);     // should *not* lint

but

f(&42 as *const _);        // should lint
let _ = &String::new() as *const _;  // should lint

because those expressions borrow temporaries.

The current implementation lints both cases. If the goal of the TODO is to only warn when cast_expr is a true temporary, I want to confirm if this understanding is correct.