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Support target.'cfg(..)'.rustdocflags analogously to rustflags#16846

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weihanglo merged 2 commits intorust-lang:masterfrom
ArshLabs:fix/16761-cfg-rustdocflags
Apr 8, 2026
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Support target.'cfg(..)'.rustdocflags analogously to rustflags#16846
weihanglo merged 2 commits intorust-lang:masterfrom
ArshLabs:fix/16761-cfg-rustdocflags

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@ArshLabs ArshLabs commented Apr 7, 2026 •
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What does this PR try to resolve?

Resolves #16761 by supporting target.'cfg(..)'.rustdocflags with behavior analogous to target.'cfg(..)'.rustflags.

Before this change, target.'cfg(..)'.rustdocflags was ignored and warned as an unused key. This PR brings cfg-based rustdocflags support to parity with existing cfg-based rustflags behavior.

This PR is intentionally split into two atomic commits:

  • test: cover ignored target cfg rustdocflags behavior
    • Adds tests that document the prior behavior first (C-TEST).
  • fix: support target cfg rustdocflags
    • Implements cfg-based rustdocflags support.
    • Updates the new tests to the new expected behavior.
    • Updates config reference docs for precedence and target.<cfg>.rustdocflags.

How to test and review this PR?

Suggested review order by commit:

  1. test: cover ignored target cfg rustdocflags behavior
  2. fix: support target cfg rustdocflags

Focused tests:

cargo test -p cargo --test testsuite -- rustdocflags::target_cfg_rustdocflags -- --test-threads=1

Full rustdocflags module:

cargo test -p cargo --test testsuite -- rustdocflags:: -- --test-threads=1

Local validation run for this branch included:

  • cargo build
  • cargo clippy -- -D warnings
  • cargo test -p cargo --test testsuite -- rustdocflags:: -- --test-threads=1

@rustbot rustbot added A-cfg-expr Area: Platform cfg expressions A-documenting-cargo-itself Area: Cargo's documentation labels Apr 7, 2026
@ArshLabs ArshLabs marked this pull request as ready for review April 7, 2026 19:50
@rustbot rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 7, 2026
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rustbot commented Apr 7, 2026

r? @epage

rustbot has assigned @epage.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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Why was this reviewer chosen?

The reviewer was selected based on:

  • Owners of files modified in this PR: @ehuss, @epage, @weihanglo
  • @ehuss, @epage, @weihanglo expanded to ehuss, epage, weihanglo
  • Random selection from ehuss, epage, weihanglo

weihanglo
weihanglo reviewed Apr 8, 2026
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Looks good!

Let me know if you want to work on the other missing part -Zhost-config support: #16761 (comment)

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ArshLabs commented Apr 8, 2026

Looks good!

Let me know if you want to work on the other missing part -Zhost-config support: #16761 (comment)

View changes since this review

Addressed the remaining host config parity point now.

Changes included:

  • Added host rustdocflags support for host artifacts behind -Zhost-config (with -Ztarget-applies-to-host)
  • Added a regression test: host_rustdocflags_for_proc_macro
  • Updated the unstable host-config docs example to include rustdocflags

Local validation passed:

  • cargo fmt --check
  • cargo test -p cargo --test testsuite -- rustdocflags:: -- --test-threads=1
  • cargo test -p cargo --test testsuite -- rustflags::target_applies_to_host_rustdocflags_works -- --test-threads=1
  • cargo test -p cargo --test testsuite -- rustflags::host_config_rustflags_with_target -- --test-threads=1

weihanglo
weihanglo reviewed Apr 8, 2026
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@ArshLabs ArshLabs force-pushed the fix/16761-cfg-rustdocflags branch from d6d2734 to 65ace47 Compare April 8, 2026 19:51
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rustbot commented Apr 8, 2026

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

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ArshLabs commented Apr 8, 2026

Thanks for catching this @weihanglo and no worries!

just dropped the host.rustdocflags change and force-pushed, I also folded the cfg(true) cleanup into the first commit as requested..

also re ran local validation on the rewritten branch:

  • cargo fmt --check
  • cargo test -p cargo --test testsuite -- rustdocflags::target_cfg_rustdocflags -- --test-threads=1
  • cargo test -p cargo --test testsuite -- rustdocflags:: -- --test-threads=1

weihanglo
weihanglo approved these changes Apr 8, 2026
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Thanks!

View changes since this review

@weihanglo weihanglo enabled auto-merge April 8, 2026 20:14
@weihanglo weihanglo added this pull request to the merge queue Apr 8, 2026
Merged via the queue into rust-lang:master with commit 40c3d9c Apr 8, 2026
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@rustbot rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 8, 2026
@weihanglo weihanglo mentioned this pull request Apr 9, 2026
Merged
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Apr 9, 2026
@JonathanBrouwer
Rollup merge of rust-lang#155042 - weihanglo:update-cargo, r=weihanglo
8ad51e9 
Update cargo submodule

5 commits in 101549dddbd2b08e806f50154e3aa4cb3374cc21..eb94155a9a60943bd7b1cb04abec42f5d0de6ddc
2026-04-08 12:51:20 +0000 to 2026-04-09 13:10:20 +0000
- Revert "GitHub fast path uses `http_async`" (rust-lang/cargo#16861)
- Correct spelling in cargo info man page (rust-lang/cargo#16863)
- chore: Update annotate-snippets to 0.12.15 (rust-lang/cargo#16859)
- fix(test): strip RUSTUP_TOOLCHAIN_SOURCE from test environment (rust-lang/cargo#16857)
- Support target.'cfg(..)'.rustdocflags analogously to rustflags (rust-lang/cargo#16846)

r? ghost
@rustbot rustbot modified the milestone: 1.96.0 Apr 9, 2026
rust-timer added a commit to rust-lang/rust that referenced this pull request Apr 9, 2026
@rust-timer
Unrolled build for #155042
8c61ef5 
Rollup merge of #155042 - weihanglo:update-cargo, r=weihanglo

Update cargo submodule

5 commits in 101549dddbd2b08e806f50154e3aa4cb3374cc21..eb94155a9a60943bd7b1cb04abec42f5d0de6ddc
2026-04-08 12:51:20 +0000 to 2026-04-09 13:10:20 +0000
- Revert "GitHub fast path uses `http_async`" (rust-lang/cargo#16861)
- Correct spelling in cargo info man page (rust-lang/cargo#16863)
- chore: Update annotate-snippets to 0.12.15 (rust-lang/cargo#16859)
- fix(test): strip RUSTUP_TOOLCHAIN_SOURCE from test environment (rust-lang/cargo#16857)
- Support target.'cfg(..)'.rustdocflags analogously to rustflags (rust-lang/cargo#16846)

r? ghost
@taiki-e taiki-e mentioned this pull request Apr 10, 2026
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@weihanglo weihanglo weihanglo approved these changes

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@epage epage

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A-cfg-expr Area: Platform cfg expressions A-documenting-cargo-itself Area: Cargo's documentation

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Support target.'cfg(..)'.rustdocflags analogously to rustflags

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