Zenoh with default-features=false in the workspace

[yellowhatter]

Describe the bug

Currently, I see that zenoh is added into our root workspace like this:
(root Cargo.toml)
zenoh = { version = "0.11.0-dev", path = "zenoh", default-features = false }

By disabling any default features, we exclude literally ANY link implementations. That affects the default zenoh build and makes the example set not working without customizing it's build.

In order to offer a proper solution, I think we need to discuss why we disabled the default features by default (sounds really weird, right?)

To reproduce

run any examples with default build
cargo run --release --package zenoh-examples --example z_pub_shm_thr --features shared-memory -- 8 -e tcp/127.0.0.1:7447 --no-multicast-scouting

System info

dosn't really matter

[Mallets]

I compile and run examples quite often and I've never experienced this behaviour.
Could you please report the various steps to reproduce it?

[yellowhatter]

@Mallets I recently reproduced it with the following command:
cargo run --release --package zenoh-examples --example z_pub_shm_thr --features shared-memory -- 8 -e tcp/127.0.0.1:7447 --no-multicast-scouting
used clean recent main branch

the output was:
thread 'main' panicked at 'called Result::unwrap()on anErrvalue: Unsupported protocol: tcp. at io/zenoh-link/src/lib.rs:140.', examples/examples/z_pub_shm_thr.rs:32:45 note: run withRUST_BACKTRACE=1 environment variable to display a backtrace Aborted
that means that there is no "tcp" link implementation

[Mallets]

Can you retry without passing --package zenoh-examples? It should still be able to compile the examples.

[yellowhatter]

@Mallets hmm, that worked :) unbelievable...

[Mallets]

Great that it worked.
In any case, the way cargo features are propagated in a workspace and included packages is still a bit unclear...

[yellowhatter]

Yes, it is really unclear, because workspace=true must take the workspace's zenoh package without any default features.....

Anyway that is quite strange to disable default features by default, isn't it?

[Mallets]

It is strange but it's the good way to go to avoid having all features enabled by default in any dependency. Otherwise it would be impossible to disable certain features in transitive dependencies in Zenoh.

[yellowhatter]

Ah, ok, I've got the point! Thank you for the explanation