怎么知道哪个package Rust 编译失败？

Question

I have dependencies in my Cargo.toml that fail compilation (because of using too new language features).

I am trying to solve the trouble by lowering dependency packages versions.

But trying to do it, I also have a trouble to understand whose package's version I need to lower:

Here is my Cargo.toml :

[package]
name = "..."
version = "0.1.0"
authors = ["..."]
edition = "2018"

[dependencies]
tokio = { version = "<0.3.0", features = ["macros", "sync"] }
warp = ">=0.0.0"

...
   Compiling socket2 v0.4.0
     Running `rustc --crate-name socket2 --edition=2018 /home/user/.cargo/registry/src/github.com-1ecc6299db9ec823/socket2-0.4.0/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type lib --emit=dep-info,metadata,link -C debuginfo=2 -C metadata=d227fc33c8864b39 -C extra-filename=-d227fc33c8864b39 --out-dir /home/user/Projects/GoldFever/exchange-server-rust/target/debug/deps -L dependency=/home/user/Projects/GoldFever/exchange-server-rust/target/debug/deps --extern libc=/home/user/Projects/GoldFever/exchange-server-rust/target/debug/deps/liblibc-f603594c75a963a0.rmeta --cap-lints allow`
error[E0658]: `match` is not allowed in a `const fn`
   --> /home/user/.cargo/registry/src/github.com-1ecc6299db9ec823/socket2-0.4.0/src/lib.rs:156:9
    |
156 | /         match address {
157 | |             SocketAddr::V4(_) => Domain::IPV4,
158 | |             SocketAddr::V6(_) => Domain::IPV6,
159 | |         }
    | |_________^
    |
    = note: for more information, see https://github.com/rust-lang/rust/issues/49146

I do not understand which chain of package dependencies caused this compilation error:

Why was socket2 v0.4.0 compiled? I don't know which package requires it. I want to see the chain of dependencies that led to socket2 to know whose package's version to lower to make it compile.

If I try to write:

socket2 = "<0.4.0"

it does not prevent cargo to build socket2 v0.4.0 . So it build through a chain of dependencies from something in Cargo.toml . I see no easy enough to use in practice way to see the full chain.

Ideally, I would want a program that would automatically try to reduce versions of used packages till it becomes compilable. So?

Answer 1

Why was socket2 v0.4.0 compiled? I don't know which package requires it. I want to see the chain of dependencies that led to socket2 to know whose package's version to lower to make it compile.

This can be seen by running cargo tree -i socket2 (you may have to install the subcommand separately on older toolchains), which for me looks like this:

socket2 v0.4.0
└── hyper v0.14.7
    └── warp v0.3.1
        └── tests v0.1.0 (C:\Users\kmdreko\Projects\rust-tests)

You can try out warp = "0.2" instead of "0.3" .