How do I run src/main.rs by default with cargo run?

[friendbear]

Sorry for the rudimentary question.
When I run cargo run I get the following output.

❯ cargo run
error: `cargo run` could not determine which binary to run. Use the `--bin` option to specify a binary, or the `default-run` manifest key.
Available binaries: async_await_basic, asynchronous, thread_and_async

I am instructed to specify the bin directory, but I want to run src/main.rs, so I investigated if the module structure is bad, but there is no module conflict.

Directory structure

perfect-rust/practice_collection/thread_and_async on  develop [!?] via 🦀 v1.72.0 
➜ tree
.
├── Cargo.toml
README.md
└── src
    ├── basic.rs
    ├── bin
    │ ├── async_await_basic.rs
    │ └─ asynchronous.rs
    ├─ cross_beam.rs
    ├── exclusive_mutex.rs
    ├── exclusive_rwlock.rs
    ├── exclusive_shradelock.rs
    ├── lib.rs
    ├── main.rs
    ├─ messaging_crossbeam.rs
    ├─ messaging_std.rs
    └─ task
        ├─ client.rs
        ├── customer.rs
        ├── mod.rs
        ├─ task_controller.rs
        └─ writer.rs

If I set the default-run key in the Cargo.toml file to thread_and_sync, the cargo run works as expected.
I just don't understand why I have to set default-run to the above.

I am sorry, but could you please enlighten me on this point?

[quinedot]

@friendbear

If I set the default-run key in the Cargo.toml file to thread_and_sync, the cargo run works as expected.

That's the answer to the question in your subject.^[1]

@friendbear

I just don't understand why I have to set default-run to the above.

I am sorry, but could you please enlighten me on this point?

You mean, why was it designed this way? Seems to be just how things happened. That issue is pretty old; not sure if making main.rs or name-of-package.rs the effectively default default-run has been discussed since then or not.

---

1. I'm assuming you mean thread_and_async, i.e. the name of the package. ↩︎

[friendbear]

@quinedot

ou mean, why was it designed this way? Seems to be just how things happened. That issue is pretty old; not sure if making main.rs or name-of-package.rs the effectively default default-run has been discussed since then or not.

Thank you very much for your help due to my lack of knowledge, I have read the entire ISSUE and understand how this issue was resolved.
Thank you very much for your reply.