Cargo does not pass `--target` to `rustdoc --test` for the host target

[jyn514]

Problem

cargo test --doc --target x86_64-unknown-linux-gnu does not pass a --target flag to rustdoc if the host target is x86_64-unknown-linux-gnu. This is inconsistent with cargo doc/check/build. It caused trouble for bootstrap in rust-lang/rust#95993.

Steps

1. cargo new --lib example
2. cd example
3. cargo test --doc --target x86_64-unknown-linux-gnu -v

Observe that no --target argument is passed to rustdoc.

Possible Solution(s)

Pass --target to rustdoc.

Notes

No response

Version

cargo 1.61.0-nightly (109bfbd 2022-03-17)
release: 1.61.0-nightly
commit-hash: 109bfbd055325ef87a6e7f63d67da7e838f8300b
commit-date: 2022-03-17
host: x86_64-unknown-linux-gnu
libgit2: 1.4.2 (sys:0.14.2 vendored)
libcurl: 7.80.0-DEV (sys:0.4.51+curl-7.80.0 vendored ssl:OpenSSL/1.1.1m)
os: Pop!_OS 20.04 (focal) [64-bit]

[weihanglo]

Hmm… I believe the feature -Zdoctest-xcompile is still unstable. As far as I know, it waits for rustdoc --enable-per-target-ignores and --runtool|--runtool-arg to be stabilized.

Closing in favor of the tracking issues rust-lang/rust#64245 and #7040. Thanks!

[jyn514]

@weihanglo no, this does not depend on -Zdoctest-xcompile, it works on stable.

[weihanglo]

Sorry. Did you mean Cargo should pass --target to rustdoc if the --target is the host target?

[jyn514]

Yes, exactly. That matches the behavior of cargo build and cargo doc.