Doc-tests no longer receive dev-dependencies

[nagisa]

Problem

Similar to #1474, I'm seeing a situation where doc-tests do not observe a specified dev-dependency.

Steps

#[cfg(feature = "libc")]
pub struct Exists;

/// ```
/// use banana::Exists;
/// ```
pub struct Another;

[package]
name = "banana"
version = "0.1.0"
edition = "2018"

[dependencies]
libc = { version = "0.2", optional = true }

[dev-dependencies]
libc = "0.2"

and then cargo test.

Possible Solution(s)

🤷 This works correctly for regular tests. No, that doesn't work either :( Not sure why I thought this is a regression, or a difference in behaviour.

Notes

Output of cargo version: 1.52.0