`cargo doc --example` doesn't provide dev-dependencies

[rillian]

Problem

When building an example, cargo provides crates listed under both dependencies and dev-dependencies to the build. However cargo doc --example foo only passes the regular dependencies, resulting in unresolved import etc. errors for any symbols which aren't necessary for downstream use.

Steps

1. git clone https://github.com/rillian/cargo-doc-example
2. cd cargo-doc-example
3. cargo run --example main
4. cargo doc --example main

error[E0432]: unresolved import `env_logger`
 --> examples/main.rs:2:5
  |
2 | use env_logger::Env;
  |     ^^^^^^^^^^ use of undeclared crate or module `env_logger`

error: Compilation failed, aborting rustdoc

Possible Solution(s)

Probably the cargo doc command should receive the same dependency list as other subcommands under the --example or --examples switches.

Notes

cargo doc --example was added in #9808.

Version

cargo 1.58.0 (f01b232bc 2022-01-19)
release: 1.58.0
commit-hash: f01b232bc7f4d94f0c4603930a5a96277715eb8c
commit-date: 2022-01-19
host: x86_64-unknown-linux-gnu
libgit2: 1.3.0 (sys:0.13.23 vendored)
libcurl: 7.80.0-DEV (sys:0.4.51+curl-7.80.0 vendored ssl:OpenSSL/1.1.1l)
os: OracleLinux 35.0.0 [64-bit]

[ehuss]

Thanks for the detailed report! This has been fixed in #10341 which should be in the 1.60 release. It isn't in nightly, yet, but it should be in a few days.
Closing as a duplicate of #9198.

[rillian]

Ha! thanks for the quick response!