`cargo publish --workspace --dry-run`: `ignoring invalid dependency b which is missing a lib target`

[t-moe]

Problem

cargo publish --workspace --dry-run fails to run on dependent crates.

Here is a minimal example with 2 crates.

tree
.
├── a
│   ├── Cargo.toml
│   └── src
│       └── lib.rs
├── b
│   ├── Cargo.toml
│   └── src
│       └── lib.rs
├── Cargo.lock
└── Cargo.toml

a/Cargo.toml:

[package]
name = "a"
version = "0.1.0"
edition = "2024"

[dependencies]
b = { version = "0.1.0", path = "../b" }

a/src/lib.rs:

pub fn hello() {
    b::hello()
}

b/Cargo.toml:

[package]
name = "b"
version = "0.1.0"
edition = "2024"

[dependencies]

b/src/lib.rs:

pub fn hello() {
    println!("Hello, world!");
}

Steps

1. cargo build in the workspace, works as expeced.
2. cargo publish --workspace --dry-run --allow-dirty fails with the following output

 cargo publish --workspace --dry-run --allow-dirty 
    Updating crates.io index
warning: crate a@0.1.0 already exists on crates.io index
warning: crate b@0.1.0 already exists on crates.io index
warning: manifest has no description, license, license-file, documentation, homepage or repository.
See https://doc.rust-lang.org/cargo/reference/manifest.html#package-metadata for more info.
   Packaging b v0.1.0 (/home/t-moe/test_workspace/b)
    Packaged 5 files, 1.1KiB (814B compressed)
warning: manifest has no description, license, license-file, documentation, homepage or repository.
See https://doc.rust-lang.org/cargo/reference/manifest.html#package-metadata for more info.
   Packaging a v0.1.0 (/home/t-moe/test_workspace/a)
    Updating crates.io index
    Packaged 5 files, 1.3KiB (932B compressed)
   Verifying b v0.1.0 (/home/t-moe/test_workspace/b)
   Compiling b v0.1.0 (/home/t-moe/test_workspace/target/package/b-0.1.0)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.30s
   Verifying a v0.1.0 (/home/t-moe/test_workspace/a)
warning: a v0.1.0 (/home/t-moe/test_workspace/target/package/a-0.1.0) ignoring invalid dependency `b` which is missing a lib target
   Compiling a v0.1.0 (/home/t-moe/test_workspace/target/package/a-0.1.0)
error[E0433]: failed to resolve: use of unresolved module or unlinked crate `b`
 --> src/lib.rs:2:5
  |
2 |     b::hello()
  |     ^ use of unresolved module or unlinked crate `b`
  |
  = help: if you wanted to use a crate named `b`, use `cargo add b` to add it to your `Cargo.toml`

For more information about this error, try `rustc --explain E0433`.
error: could not compile `a` (lib) due to 1 previous error
error: failed to verify package tarball

What am I missing? Must be a stupid error...

Possible Solution(s)

No response

Notes

No response

Version

cargo 1.90.0 (840b83a10 2025-07-30)
release: 1.90.0
commit-hash: 840b83a10fb0e039a83f4d70ad032892c287570a
commit-date: 2025-07-30
host: x86_64-unknown-linux-gnu
libgit2: 1.9.1 (sys:0.20.2 vendored)
libcurl: 8.14.1-DEV (sys:0.4.82+curl-8.14.1 vendored ssl:OpenSSL/3.5.0)
ssl: OpenSSL 3.5.0 8 Apr 2025
os: Ubuntu 24.4.0 (noble) [64-bit]