add new rustdoc::hidden_intra_doc_links lint

[lolbinarycat]

fixes #144664

cc @GuillaumeGomez @kpreid

[rustbot]

r? @GuillaumeGomez

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

Use r? to explicitly pick a reviewer

[rustbot]

Unknown labels: T-rustdoc-frontend

[lolbinarycat]

current issue: reexports. an item is only truly "hidden" if there are no non-hidden paths to it. there doesn't seem to be any easy queries to find all the reexports of an item, so the only way to do this would be traversing the entire crate, like how strip_hidden works.

one potential workaround that would get rid of false positives at the cost of way more false negatives would be to only emit the lint if we only emit the lint when linking from something that is not hidden anywhere in the path to something that is directly marked as hidden.

i think the correct solution however is to rework how the strip_hidden pass works to always run, and in --document-hidden-items mode, collect a DefIdSet of all the hidden items.

the lint could also just be based on if an item is actually going to be documented, but then it doesn't work consistently in --document-hidden-items mode...

EDIT: we apparently collect the paths of things before stripping, so that doesn't work, but strip_hidden only runs on non-local crates, so that doesn't work either.

[rustbot]

Unknown labels: S-waiting-on-author

[rust-log-analyzer]

The job aarch64-gnu-llvm-19-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

    Checking gimli v0.32.0
[RUSTC-TIMING] panic_unwind test:false 0.062
[RUSTC-TIMING] std_detect test:false 0.258
    Checking hashbrown v0.15.4
error: non-hidden documentation for `std_detect` links to hidden item `is_x86_feature_detected`
 --> library/std_detect/src/lib.rs:6:29
  |
6 | //! * `x86` and `x86_64`: [`is_x86_feature_detected`]
  |                             ^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
  |
  = note: this link will resolve properly if you pass `--document-hidden-items`
  = note: `-D rustdoc::hidden-intra-doc-links` implied by `-D warnings`
  = help: to override `-D warnings` add `#[allow(rustdoc::hidden_intra_doc_links)]`

error: non-hidden documentation for `std_detect` links to hidden item `is_arm_feature_detected`
 --> library/std_detect/src/lib.rs:7:16
  |
7 | //! * `arm`: [`is_arm_feature_detected`]
  |                ^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
  |
  = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_aarch64_feature_detected`
 --> library/std_detect/src/lib.rs:8:20
  |
8 | //! * `aarch64`: [`is_aarch64_feature_detected`]
  |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
  |
  = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_riscv_feature_detected`
 --> library/std_detect/src/lib.rs:9:18
  |
9 | //! * `riscv`: [`is_riscv_feature_detected`]
  |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
  |
  = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_mips_feature_detected`
  --> library/std_detect/src/lib.rs:10:17
   |
10 | //! * `mips`: [`is_mips_feature_detected`]
   |                 ^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
   |
   = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_mips64_feature_detected`
  --> library/std_detect/src/lib.rs:11:19
   |
11 | //! * `mips64`: [`is_mips64_feature_detected`]
   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
   |
   = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_powerpc_feature_detected`
  --> library/std_detect/src/lib.rs:12:20
   |
12 | //! * `powerpc`: [`is_powerpc_feature_detected`]
   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
   |
   = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_powerpc64_feature_detected`
  --> library/std_detect/src/lib.rs:13:22
   |
13 | //! * `powerpc64`: [`is_powerpc64_feature_detected`]
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
   |
   = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_loongarch_feature_detected`
  --> library/std_detect/src/lib.rs:14:22
   |
14 | //! * `loongarch`: [`is_loongarch_feature_detected`]
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
   |
   = note: this link will resolve properly if you pass `--document-hidden-items`

error: non-hidden documentation for `std_detect` links to hidden item `is_s390x_feature_detected`
  --> library/std_detect/src/lib.rs:15:18
   |
15 | //! * `s390x`: [`is_s390x_feature_detected`]
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ this item is hidden
   |
   = note: this link will resolve properly if you pass `--document-hidden-items`

error: could not document `std_detect`
warning: build failed, waiting for other jobs to finish...
[RUSTC-TIMING] hashbrown test:false 1.150
[RUSTC-TIMING] gimli test:false 4.180
[RUSTC-TIMING] object test:false 6.962
Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:29:52
  local time: Fri Aug  1 20:06:02 UTC 2025
  network time: Fri, 01 Aug 2025 20:06:02 GMT
##[error]Process completed with exit code 1.
Post job cleanup.