Unable to use the docsrs configuration under Windows

Version 1.38.0

Platform Windows 11 Pro / 64 bit

Description On Windows, the documentation for a project using Tokio cannot be build with docsrs enabled. This makes it difficult-to-impossible to include the automatically generated feature flag details. More details are available from this post on the Rust Users forum.

A test project was created with cargo new tokio-issue-112683.

Cargo.toml was updated to this...

[package]
name = "tokio-issue-112683"
version = "0.1.0"
edition = "2021"

[dependencies]
tokio = { version = "1.38.0", features = ["full"] }

[package.metadata.docs.rs]
all-features = true
rustdoc-args = ["--cfg", "docsrs"]

Set the RUSTFLAGS environment variable... set RUSTFLAGS=--cfg docsrs

Then try to build the documentation... cargo +nightly doc --all-features

The error list is long...

    Checking tokio v1.38.0
error[E0433]: failed to resolve: could not find `unix` in `os`
  --> C:\Users\bcook\.cargo\registry\src\index.crates.io-6f17d22bba15001f\tokio-1.38.0\src\io\bsd\poll_aio.rs:12:14
   |
12 | use std::os::unix::io::AsRawFd;
   |              ^^^^ could not find `unix` in `os`
   |
note: found an item that was configured out
  --> C:\Users\bcook\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\std\src\os\mod.rs:26:9
   |
26 | pub mod unix {}
   |         ^^^^
note: found an item that was configured out
  --> C:\Users\bcook\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\std\src\os\mod.rs:64:9
   |
64 | pub mod unix;
   |         ^^^^

error[E0433]: failed to resolve: could not find `unix` in `os`
  --> C:\Users\bcook\.cargo\registry\src\index.crates.io-6f17d22bba15001f\tokio-1.38.0\src\io\bsd\poll_aio.rs:13:14
   |
13 | use std::os::unix::prelude::RawFd;
   |              ^^^^ could not find `unix` in `os`
   |
note: found an item that was configured out
  --> C:\Users\bcook\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\std\src\os\mod.rs:26:9
   |
26 | pub mod unix {}
   |         ^^^^
note: found an item that was configured out
  --> C:\Users\bcook\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\std\src\os\mod.rs:64:9
   |
64 | pub mod unix;
   |         ^^^^

...

tokio-rs / tokio

Unable to use the docsrs configuration under Windows #6625