[Coding Rule]: Do not read from uninitialized union fields by rcseacord · Pull Request #302 · rustfoundation/safety-critical-rust-coding-guidelines

rcseacord · 2025-12-16T14:14:32Z

…alized bytes

gui_UnionPartialInit
Do not read from union fields that may contain uninitialized bytes

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felix91gr · 2025-12-17T15:48:42Z

What's the difference in intent between this one and #300? This one has the title I would like #300 to have, but this one in particular I haven't read yet.

rcseacord · 2025-12-17T16:29:53Z

What's the difference in intent between this one and #300? This one has the title I would like #300 to have, but this one in particular I haven't read yet.

@felix91gr the other one is for validity checks. this one is for reading uninitialized.

workingjubilee

Noticed some sharp edges in the text.

src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

src/coding-guidelines/types-and-traits/gui_UnionPartialInit

…alized bytes gui_UnionPartialInit Do not read from union fields that may contain uninitialized bytes

add new guideline

Clarify rules for accessing struct fields and typed reads.

Standardize IDs and bibliography entries, update example miri/warning handling, and add missing tag definitions for unions/initialization.

github-actions · 2026-01-19T06:05:28Z

👋 Hey @Dillonmcewan! You've been assigned to review this coding guideline PR.

Your Role as Reviewer

As outlined in our contribution guide, please:

Begin your review within 14 days
Provide constructive feedback on the guideline content, examples, and formatting
Iterate with @rcseacord - they may update the PR based on your feedback
When the guideline is ready, approve and add to the merge queue

Review Checklist

Guideline title is clear and follows conventions
Amplification section expands on the title appropriately
Rationale explains the "why" effectively
Non-compliant example(s) clearly show the problem
Compliant example(s) clearly show the solution
Code examples compile (check the CI results)
FLS paragraph ID is correct

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If you need to pass this review:

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@guidelines-bot /away YYYY-MM-DD [reason] - Step away from the queue until a date
@guidelines-bot /release [@username] [reason] - Release assignment (yours or someone else's with triage+ permission)

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src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

Dillonmcewan

Generally looks great! Noticed one minor formatting issue and had one question about some non-compliant examples

src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

Dillonmcewan

LGTM!

github-actions · 2026-02-02T09:24:48Z

⚠️ Review Reminder

Hey @Dillonmcewan, it's been more than 14 days since you were assigned to review this.

Please take one of the following actions:

Begin your review - Post a comment with your feedback
Pass the review - Use @guidelines-bot /pass [reason] to assign the next reviewer
Step away temporarily - Use @guidelines-bot /away YYYY-MM-DD [reason] if you need time off

If no action is taken within 14 days, you may be transitioned from Producer to Observer status per our contribution guidelines.

Life happens! If you're dealing with something, just let us know.

Dillonmcewan

Didn't seem to register my last approval. Trying again

Dillonmcewan · 2026-02-03T04:17:01Z

@PLeVasseur Is there something else I need to do to appease the bot? I approved the PR, but it still flagged me as having not reviewed

PLeVasseur · 2026-02-03T16:58:22Z

@PLeVasseur Is there something else I need to do to appease the bot? I approved the PR, but it still flagged me as having not reviewed

Apologies @Dillonmcewan -- there's a bug / not well defined workflow here. Still working to resolve this. Will respond here once fixed. 🙃

felix91gr · 2026-02-04T12:31:29Z

@Dillonmcewan to keep you in the loop: an issue to fix this has been opened #388 :)

PLeVasseur · 2026-02-04T19:55:39Z

@Dillonmcewan -- I hope I was able to get this fixed, see PR here: #391

Could you try to approve again to see if it'll take?

Dillonmcewan

LGTM again!

felix91gr · 2026-02-05T19:22:54Z

@PLeVasseur I think we have PR merging blocked unless approval is given by members with write access.

But I have 2 reasons to think that perhaps this isn't getting merged because the bot isn't picking up on the approving review:

The bot hasn't given its characteristic 👀 and 👍 reactions to Dillon's approving comment.
I just looked at 📊 Reviewer Bot State (DO NOT CLOSE) #314 and I saw this:

active_reviews:
  (... other stuff...)
  '302':
    skipped: []
    current_reviewer: Dillonmcewan
    assigned_at: '2026-01-19T06:05:28.171437+00:00'
    last_reviewer_activity: '2026-02-03T04:17:12.540512+00:00'
    transition_warning_sent: null
    assignment_method: round-robin

And the last_reviewer_activity strikes me as odd. If the bot had done something, it would've been updated to something along the lines of '2026-02-05', right?

PLeVasseur · 2026-02-09T14:50:07Z

Sorry folks :(

Let me try again @Dillonmcewan

Testing in production 🫠

Dillonmcewan · 2026-02-09T17:19:12Z

No worries. These github integrations are always tricky to get right without fiddling around in prod. Let me know if there's anything I can do to help

PLeVasseur · 2026-02-09T18:39:21Z

@guidelines-bot /rectify

github-actions · 2026-02-09T18:39:39Z

✅ Rectified PR #302: latest review by @Dillonmcewan is APPROVED; marked review complete.

PLeVasseur

Approving so we can merge. Thank you for the patience @Dillonmcewan :)

'302':                                                                                     
  skipped: []                                                                              
  current_reviewer: Dillonmcewan                                                           
  assigned_at: '2026-01-19T06:05:28.171437+00:00'                                          
  last_reviewer_activity: '2026-02-09T18:39:37.786801+00:00'                               
  transition_warning_sent: null                                                            
  assignment_method: round-robin                                                           
  review_completed_at: '2026-02-09T18:39:37.786801+00:00'                                  
  review_completed_by: Dillonmcewan                                                        
  review_completion_source: rectify:reconcile-pr-review

Source: #314

PLeVasseur · 2026-02-09T18:47:43Z

🎉

felix91gr · 2026-02-09T18:54:33Z

🎉

PLeVasseur · 2026-02-10T01:43:50Z

Was a little rough this time, but seems like it should work next time! ☺️
#402 (comment)

rcseacord mentioned this pull request Dec 16, 2025

[Coding Guideline]: Do not read from union fields that may contain uninitialized bytes #297

Open

rcseacord self-assigned this Dec 16, 2025

rcseacord marked this pull request as draft December 16, 2025 14:19

workingjubilee reviewed Dec 31, 2025

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src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc Outdated Show resolved Hide resolved

src/coding-guidelines/types-and-traits/gui_UnionPartialInit Outdated Show resolved Hide resolved

rcseacord and others added 4 commits January 19, 2026 14:01

[Coding Rule]: Do not read from union fields that may contain uniniti…

216103c

…alized bytes gui_UnionPartialInit Do not read from union fields that may contain uninitialized bytes

Update index.rst

cf89c46

add new guideline

Update guidelines on struct field initialization

1f979fd

Clarify rules for accessing struct fields and typed reads.

fix(guidelines): normalize union partial init

1e988e7

Standardize IDs and bibliography entries, update example miri/warning handling, and add missing tag definitions for unions/initialization.

PLeVasseur force-pushed the patch-3 branch from 47d7d3d to 1e988e7 Compare January 19, 2026 06:03

PLeVasseur added coding guideline An issue related to a suggestion for a coding guideline chapter: types-and-traits labels Jan 19, 2026

github-project-automation bot added this to [Safety Critical Rust Consortium Coding Guidelines] Work Items Jan 19, 2026

Refactor union field initialization guidelines

ece1f79

rcseacord commented Jan 19, 2026

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src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc Outdated Show resolved Hide resolved

Refactor main function examples in gui_6JSM7YE7a1KR.rst.inc

72cd96e

rcseacord marked this pull request as ready for review January 20, 2026 15:49

Update src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

e5b8a70

Dillonmcewan reviewed Jan 20, 2026

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src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc Outdated Show resolved Hide resolved

Update src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

6c52823

rcseacord commented Jan 21, 2026

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rcseacord commented Jan 21, 2026

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rcseacord added 2 commits January 21, 2026 11:55

Update src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

830fdfb

Update src/coding-guidelines/types-and-traits/gui_6JSM7YE7a1KR.rst.inc

37f0ada

Dillonmcewan approved these changes Jan 21, 2026

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rcseacord requested a review from PLeVasseur January 21, 2026 20:26

Dillonmcewan approved these changes Feb 3, 2026

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Merge branch 'main' into patch-3

a113eb6

Dillonmcewan approved these changes Feb 5, 2026

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PLeVasseur approved these changes Feb 9, 2026

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PLeVasseur added this pull request to the merge queue Feb 9, 2026

Merged via the queue into rustfoundation:main with commit f1352df Feb 9, 2026
16 checks passed

github-project-automation bot moved this to Done in [Safety Critical Rust Consortium Coding Guidelines] Work Items Feb 9, 2026

PLeVasseur deleted the patch-3 branch February 10, 2026 01:43

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