Function linked_runtime_bytes_in 

pub fn linked_runtime_bytes_in(
    runtime: &BTreeSet<&'static str>,
    mode: Mode,
) -> usize

The same, for whichever build is asked about.

What a development build costs is worth measuring rather than estimating: #140’s whole argument is that the assertions are free to a reader because they are stripped, and the number that makes that checkable is the difference between the two.