The units::parse module has a bunch of public stuff in it. Do we really want to commit to everything in there?

eg

/// Not strictly necessary but serves as a lint - avoids weird behavior if someone accidentally
/// passes non-integer to the `parse()` function.
pub trait Integer: FromStr<Err = core::num::ParseIntError> + TryFrom<i8> + Sized {}

• Possibly related: units: Remove internals::InputString from the public API  #3708 (also may violate C-STRUCT-BOUNDS)
• The macros in general but specifically (units: Make macros evocative #3707).
• The hex prefix stuff (possibly related to Sort out "should hex strings have 0x prefixes" #2498) On further thought I don't think this is relevant
• trait parse::Integer should be sealed (C-SEALED) if its to be kept