rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones by jakubadamw · Pull Request #154444 · rust-lang/rust

jakubadamw · 2026-03-26T23:36:35Z

rustdoc assumed every Deref impl has an associated Target type, but negative impls (e.g. impl !Deref for T {}) have none.

Skip them in both the trait-impl collection pass and the HTML render pass to avoid panicking on the missing Target.

Closes #128801.

rustbot · 2026-03-26T23:36:40Z

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fmease

Thanks! I've got an optional request. If you don't want to impl it, I'm fine with accepting this PR as is.

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fmease · 2026-03-27T12:46:46Z

src/librustdoc/html/render/mod.rs

The two build_impl fns (one in clean/mod.rs, the other in clean/mod.rs) also invoke extra code when encountering Deref trait impls by calling build_deref_target_impls. Likewise, in render/sidebar.rs we have two places that perform extra work for deref impls.

I'm relatively sure that all four of these places still process negative deref trait impls, likely unnecessarily so. If it's not too much work for you, could you filter out negative impls in these places (unless it's impossible for negative deref impls to show up there). It probably doesn't save that much or any processing time but it might be more robust.

If you do that it might also be worth adding a HTML test in tests/rustdoc-html to ensure that we still actually render impl !Deref for … impls (in the sidebar and the main container).

@fmease, thank you for reviewing the PR. 🙂

The two build_impl fns (one in clean/mod.rs, the other in clean/mod.rs)

I take it you mean clean/mod.rs and clean/inline.rs, as well as clean_impl and build_impl, respectively? I pushed a commit that addresses the suggestion for those four sites, and adds an HTML test. 🙂

Thanks again! Let me know if there’s anything else I’m missing here.

@rustbot ready

@fmease, would you be able to take a look at this again? I made the requested change. Thanks! 🙂

The two build_impl fns (one in clean/mod.rs, the other in clean/mod.rs)

I take it you mean clean/mod.rs and clean/inline.rs, as well as clean_impl and build_impl, respectively?

Ah yes, haha. Silly typo.

Thanks for addressing my feedback! Sorry, the PR slipped through the cracks because apparently rustbot still doesn't honor @rustbot ready in review comments, so this PR didn't show up using my usual filter.

…t` impls

…egative ones rustdoc assumed every `Deref` impl has an associated `Target` type, but negative impls (e.g. `impl !Deref for T {}`) have none. Skip them in both the trait-impl collection pass and the HTML render pass to avoid panicking on the missing Target.

rustbot · 2026-04-01T22:06:17Z

This PR was rebased onto a different main 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.

fmease

Thanks! @bors r+ rollup

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rust-bors · 2026-04-02T19:31:19Z

📌 Commit 02a73db has been approved by fmease

It is now in the queue for this repository.

rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones rustdoc assumed every `Deref` impl has an associated `Target` type, but negative impls (e.g. `impl !Deref for T {}`) have none. Skip them in both the trait-impl collection pass and the HTML render pass to avoid panicking on the missing `Target`. Closes rust-lang#128801.

…uwer Rollup of 4 pull requests Successful merges: - #154444 (rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones) - #154590 (Make #[cfg] suggest any or all on #[cfg(a, b)]) - #154691 (core: Update the feature gate on `TryFrom<integer> for bool`) - #154697 (rustdoc: fix href of extern crates in search results) Failed merges: - #154722 (fix(lints): Improve `ill_formed_attribute_input` with better help message)

rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones rustdoc assumed every `Deref` impl has an associated `Target` type, but negative impls (e.g. `impl !Deref for T {}`) have none. Skip them in both the trait-impl collection pass and the HTML render pass to avoid panicking on the missing `Target`. Closes rust-lang#128801.

Rollup of 6 pull requests Successful merges: - #154444 (rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones) - #154590 (Make #[cfg] suggest any or all on #[cfg(a, b)]) - #154691 (core: Update the feature gate on `TryFrom<integer> for bool`) - #154697 (rustdoc: fix href of extern crates in search results) - #154728 (rustdoc: Improve internal function name) - #154732 (fix(std): avoid AT_MINSIGSTKSZ on uclibc targets) Failed merges: - #154722 (fix(lints): Improve `ill_formed_attribute_input` with better help message)

rustbot assigned fmease Mar 26, 2026

fmease approved these changes Mar 27, 2026

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fmease added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 27, 2026

jakubadamw force-pushed the issue-128801 branch from 83091df to d3cf791 Compare March 28, 2026 00:32

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rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 1, 2026

jakubadamw added 3 commits April 1, 2026 23:05

Add a regression test for rustdoc ICEing on negative Deref/`DerefMu…

3888a63

…t` impls

Address review feedback.

02a73db

jakubadamw force-pushed the issue-128801 branch from 845e2b7 to 02a73db Compare April 1, 2026 22:06

jakubadamw requested a review from fmease April 2, 2026 16:49

fmease approved these changes Apr 2, 2026

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JonathanBrouwer mentioned this pull request Apr 2, 2026

Rollup of 4 pull requests #154726

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jhpratt mentioned this pull request Apr 3, 2026

Rollup of 6 pull requests #154740

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rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones#154444

rustdoc ICE fix: When collecting `Deref` impls with their targets, skip the negative ones#154444
jakubadamw wants to merge 3 commits intorust-lang:mainfrom
jakubadamw:issue-128801

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