Improperctypes refactor2.2 by niacdoial · Pull Request #155359 · rust-lang/rust

niacdoial · 2026-04-15T21:09:50Z

This is "part 2/3 of 2/3 of 1/2" of the original pull request #134697 (refactor plus overhaul of the ImproperCTypes family of lints)
(all pulls of this series of pulls are supersets of the previous pulls.)
previous pull: #155358
next pull: #146273

This commit splits the lint's visit_type function into multiple functions that focus on specific things:

visit_indirection (references, boxes, raw pointers)
visit_variant_fields (the list of fields of a struct, enum variant, or union)
visit_enum
visit_struct_or_union
visit_type (most "easy" decisions such as labeling char unsafe are here)

since, during these visits, we often move from an "outer type" to an "inner type" (structs, arrays, pointers, etc...),
two structs have been added to track the current state of a visit:

VisitorState tracks the state related to the "original type" being checked (function argument/return, static variable)
OuterTyData tracks the data related to the type "immediately outer to the current visited type"

r? petrochenkov (because you asked me to)

petrochenkov · 2026-04-16T11:16:50Z

Blocked on #155358.
@rustbot blocked

petrochenkov · 2026-04-17T11:15:17Z

#155358 has landed, unblocking.
@rustbot author (to rebase)

rustbot · 2026-04-17T11:15:22Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2026-04-17T11:38:09Z

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.

niacdoial · 2026-04-17T21:34:06Z

can't believe I let this amount of time pass between tests being OK and this...
@rustbot review

petrochenkov · 2026-04-20T15:03:19Z

This PR moves code around and changes that code in the same commit, this makes it hard to see what's going on.
I'd rather split this to at least 2 commits

one mechanically extracting code from fn visit_type to the new functions (code moving)
and another for everything else (code changing)
- this could potentially be split further into smaller single-purpose portions, like introduction of visit_indirection, but I'll leave this to you to decide.

@rustbot author

Another interal change that shouldn't impact rustc users. The goal (of this commit and a few afterwards) is to break apart the gigantic visit_type function into more managable and easily-editable bits that focus on specific parts of FFI safety. For now, we break the code specific to enums one side, and structs/unions on the other, into separate visit_? methods

Another interal change that shouldn't impact rustc users. the list of simpler type-based decisions made by `visit_type` are reordered and are given better documentation.

Another interal change that shouldn't impact rustc users. This time, regroup into `visit_indirections` the code dealing with the FFI safety of Boxes, Refs and RawPtrs.

niacdoial · 2026-04-21T06:58:55Z

@rustbot ready

petrochenkov · 2026-04-21T10:33:22Z

Thanks!
r=me with the if simplified #155359 (comment).
@rustbot author

Another interal change that shouldn't impact rustc users. Code called outside of `visit_type` (and callees) is moved inside, by adding new types to properly track the state of a type visitation. - OuterTyKind tracks the knowledge of the type "directly outside of" the one being visited (if we are visiting a struct's field, an array's element, etc) - RootUseFlags tracks the knowledge of how the "original type being visited" is used: static variable, function argument/return, etc.

petrochenkov · 2026-04-21T13:11:53Z

@bors r+

rust-bors · 2026-04-21T13:11:56Z

📌 Commit 7bb9851 has been approved by petrochenkov

It is now in the queue for this repository.

…uwer Rollup of 4 pull requests Successful merges: - #152611 (Modify error message of importing inherent associated items when `#[feature(import_trait_associated_functions)]` is enabled) - #155359 (Improperctypes refactor2.2) - #155036 (Store a PathBuf rather than SerializedModule for cached modules) - #155554 (add warning message when using x fix)

Rollup merge of #155359 - niacdoial:improperctypes-refactor2.2, r=petrochenkov Improperctypes refactor2.2 This is "part 2/3 of 2/3 of 1/2" of the original pull request #134697 (refactor plus overhaul of the ImproperCTypes family of lints) (all pulls of this series of pulls are supersets of the previous pulls.) previous pull: #155358 next pull: #146273 This commit splits the lint's `visit_type` function into multiple functions that focus on specific things: - visit_indirection (references, boxes, raw pointers) - visit_variant_fields (the list of fields of a struct, enum variant, or union) - visit_enum - visit_struct_or_union - visit_type (most "easy" decisions such as labeling `char` unsafe are here) since, during these visits, we often move from an "outer type" to an "inner type" (structs, arrays, pointers, etc...), two structs have been added to track the current state of a visit: - VisitorState tracks the state related to the "original type" being checked (function argument/return, static variable) - OuterTyData tracks the data related to the type "immediately outer to the current visited type" r? petrochenkov (because you asked me to)

rustbot assigned petrochenkov Apr 15, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 15, 2026

niacdoial mentioned this pull request Apr 15, 2026
lint ImproperCTypes: refactor linting architecture (part 2) #146273
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niacdoial force-pushed the improperctypes-refactor2.2 branch from a439f4d to fa0fcc6Compare April 15, 2026 21:18

rustbot added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 16, 2026

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niacdoial force-pushed the improperctypes-refactor2.2 branch from fa0fcc6 to b2f3002Compare April 17, 2026 11:38

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 17, 2026

petrochenkov reviewed Apr 20, 2026
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Comment threadcompiler/rustc_lint/src/types/improper_ctypes.rs Outdated
Comment threadcompiler/rustc_lint/src/types/improper_ctypes.rs

rustbot 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 Apr 20, 2026

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Comment threadcompiler/rustc_lint/src/types/improper_ctypes.rs Outdated

niacdoial added 3 commits April 21, 2026 00:50

ImproperCTypes: reorder simple type checks
d75c93d
Another interal change that shouldn't impact rustc users. the list of simpler type-based decisions made by `visit_type` are reordered and are given better documentation.

ImproperCTypes: regroup Box/Ptr/Ref logic
6dfa52c
Another interal change that shouldn't impact rustc users. This time, regroup into `visit_indirections` the code dealing with the FFI safety of Boxes, Refs and RawPtrs.

niacdoial force-pushed the improperctypes-refactor2.2 branch 2 times, most recently from 103a8d0 to 1180e38Compare April 20, 2026 23:03

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Apr 21, 2026

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Comment threadcompiler/rustc_lint/src/types/improper_ctypes.rs Outdated

rustbot 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 Apr 21, 2026

niacdoial force-pushed the improperctypes-refactor2.2 branch from 1180e38 to 7bb9851Compare April 21, 2026 13:08

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JonathanBrouwer mentioned this pull request Apr 21, 2026
Rollup of 4 pull requests #155599
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rust-borsBot merged commit f21c57d into rust-lang:mainApr 21, 2026
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rustbot added this to the 1.97.0 milestone Apr 21, 2026

niacdoial mentioned this pull request Aug 2, 2026
lint ImproperCTypes: overhaul (decluttered PR) #160405
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