The `unreachable_pub` lint makes us aware of uses of `pub` that are not actually reachable from the crate root. This is considered good because it means reading a `pub` somewhere means it is actually public API. Some of our crates are quite large and keeping their entire API surface in your head is difficult.
We should strive for most items being `pub(crate)`. This lint helps us enforce that.
Pull-Request: #3735.
Due to cargo's feature unification, a full build of our workspace doesn't actually check whether the examples compile as standalone projects.
We add a new CI check that iterates through all crates in the `examples/` directory and runs a plain `cargo check` on them. Any failure is bubbled up via `set -e`, thus failing CI in case one of the `cargo check` commands fails.
To fix the current failures, we construct a simple TCP transport everywhere where we were previously using `development_transport`. That is because `development_transport` requires `mplex` which is now deprecated.
Related #3657.
Related #3809.
Pull-Request: #3811.
