pub fn host_modules(
schemas: &HostSchemas,
) -> impl Iterator<Item = &'static str> + '_Expand description
The host modules a package may name without declaring them.
This is HostSchemas, the one description of the host modules this
compilation can see, rather than a list kept here in step with it: the
compiler cannot ask the runtime, which depends on it, but it can read the
schema both of them do. It used to be a hand-written array with a
cross-crate test to catch the drift, written after http had already
drifted out of it and let a package module shadow the host module in
silence.
It is only consulted to refuse a package module that would shadow a host
module. A use naming a module that is not here is still accepted, since
a host may register any module it likes. Such a use warns instead: a
module no schema describes is checked by nothing until the run reaches the
boundary.