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Merged
merged 3 commits into from
Aug 5, 2025
Merged

Document Poisoning in LazyCell and LazyLock #144872

merged 3 commits into from
Aug 5, 2025

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@connortsui20 connortsui20 commented Aug 3, 2025 •
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Currently, there is no documentation of poisoning behavior in either LazyCell or LazyLock, even though both of them can be observed as poisoned by users.

LazyCell plagyround example

LazyLock playground example

Open Questions

  • Is it worth making the implementation of LazyLock more complicated to ensure that the the panic message is "LazyLock instance has previously been poisoned" instead of "Once instance has previously been poisoned"? See the LazyLock playground link above for more context.
  • Does it make sense to move LazyLock into the poison module? It is certainly a poison-able type, but at the same time it is slightly different from the 4 other types currently in the poison module in that it is unrecoverable. I think this is more of a libs-api question.

@rustbot label +T-libs-api

Please let me know if these open questions deserve a separate issue / PR!

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rustbot commented Aug 3, 2025

r? @thomcc

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Aug 3, 2025
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Actually r? @Amanieu since you recently reviewed the poisoning documentation PR #144185?

@rustbot rustbot assigned Amanieu and unassigned thomcc Aug 4, 2025
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Amanieu commented Aug 4, 2025 •
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  • Is it worth making the implementation of LazyLock more complicated to ensure that the the panic message is "LazyLock instance has previously been poisoned" instead of "Once instance has previously been poisoned"? See the LazyLock playground link above for more context.

I think this is valid since Once is an internal implementation detail of LazyLock: users seeing this panic message will be confused since they don't use Once directly in their code. However this can be done in a separate PR.

  • Does it make sense to move LazyLock into the poison module? It is certainly a poison-able type, but at the same time it is slightly different from the 4 other types currently in the poison module in that it is unrecoverable. I think this is more of a libs-api question.

This should probably be raised as an open question in #134646, which tracks the poison module.

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Amanieu commented Aug 4, 2025

@bors r+ rollup

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bors commented Aug 4, 2025

📌 Commit 96adb7d has been approved by Amanieu

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 4, 2025
@connortsui20 connortsui20 mentioned this pull request Aug 4, 2025
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samueltardieu added a commit to samueltardieu/rust that referenced this pull request Aug 4, 2025
@samueltardieu
Rollup merge of rust-lang#144872 - connortsui20:once-poison-docs, r=A…
d1c6a82 
…manieu

Document Poisoning in `LazyCell` and `LazyLock`

Currently, there is no documentation of poisoning behavior in either `LazyCell` or `LazyLock`, even though both of them can be observed as poisoned by users.

`LazyCell` [plagyround example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=9cf38b8dc56db100848f54085c2c697d)

`LazyLock` [playground example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=f1cd6f9fe16636e347ebb695a0ce30c0)

# Open Questions

- [x] Is it worth making the implementation of `LazyLock` more complicated to ensure that the the panic message is `"LazyLock instance has previously been poisoned"` instead of `"Once instance has previously been poisoned"`? See the `LazyLock` playground link above for more context.
- [x] Does it make sense to move `LazyLock` into the `poison` module? It is certainly a poison-able type, but at the same time it is slightly different from the 4 other types currently in the `poison` module in that it is unrecoverable. I think this is more of a libs-api question.

`@rustbot` label +T-libs-api

Please let me know if these open questions deserve a separate issue / PR!
@samueltardieu samueltardieu mentioned this pull request Aug 4, 2025
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@tgross35 tgross35 mentioned this pull request Aug 4, 2025
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bors added a commit that referenced this pull request Aug 4, 2025
@bors
Auto merge of #144929 - samueltardieu:rollup-n2c14p7, r=samueltardieu
5bd6cac 
Rollup of 18 pull requests

Successful merges:

 - #144467 (rustdoc template font links only emit `crossorigin` when needed)
 - #144548 (Rehome 21 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`)
 - #144596 (libtest: print the type of test being run)
 - #144741 (fix: Error on illegal `[const]`s inside blocks within legal positions)
 - #144776 (`Printer` cleanups)
 - #144779 (Implement debugging output of the bootstrap Step graph into a DOT file)
 - #144813 (Add a tidy check to prevent adding UI tests directly under `tests/ui/`)
 - #144817 (Properly reject tail calls to `&FnPtr` or `&FnDef`)
 - #144852 (Rename `rust_panic_without_hook` to `resume_unwind` )
 - #144866 (Remove `SHOULD_EMIT_LINTS` in favor of `should_emit`)
 - #144867 (Use `as_array` in PartialEq for arrays)
 - #144872 (Document Poisoning in `LazyCell` and `LazyLock`)
 - #144877 (coverage: Various small cleanups)
 - #144887 (`rust-analyzer` subtree update)
 - #144890 (Add `InterpCx::project_fields`)
 - #144894 (Delete `tests/ui/threads-sendsync/tcp-stress.rs`)
 - #144905 (rustc-dev-guide subtree update)
 - #144920 (Dont print arg span in MIR dump for tail call)

r? `@ghost`
`@rustbot` modify labels: rollup
@samueltardieu samueltardieu mentioned this pull request Aug 5, 2025
Merged
bors added a commit that referenced this pull request Aug 5, 2025
@bors
Auto merge of #144934 - samueltardieu:rollup-25jvb9g, r=samueltardieu
0f35336 
Rollup of 17 pull requests

Successful merges:

 - #144467 (rustdoc template font links only emit `crossorigin` when needed)
 - #144548 (Rehome 21 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`)
 - #144741 (fix: Error on illegal `[const]`s inside blocks within legal positions)
 - #144776 (`Printer` cleanups)
 - #144779 (Implement debugging output of the bootstrap Step graph into a DOT file)
 - #144813 (Add a tidy check to prevent adding UI tests directly under `tests/ui/`)
 - #144817 (Properly reject tail calls to `&FnPtr` or `&FnDef`)
 - #144852 (Rename `rust_panic_without_hook` to `resume_unwind` )
 - #144866 (Remove `SHOULD_EMIT_LINTS` in favor of `should_emit`)
 - #144867 (Use `as_array` in PartialEq for arrays)
 - #144872 (Document Poisoning in `LazyCell` and `LazyLock`)
 - #144877 (coverage: Various small cleanups)
 - #144887 (`rust-analyzer` subtree update)
 - #144890 (Add `InterpCx::project_fields`)
 - #144894 (Delete `tests/ui/threads-sendsync/tcp-stress.rs`)
 - #144905 (rustc-dev-guide subtree update)
 - #144920 (Dont print arg span in MIR dump for tail call)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 1724af9 into rust-lang:master Aug 5, 2025
10 checks passed
@rustbot rustbot added this to the 1.91.0 milestone Aug 5, 2025
rust-timer added a commit that referenced this pull request Aug 5, 2025
@rust-timer
Unrolled build for #144872
69ec5cb 
Rollup merge of #144872 - connortsui20:once-poison-docs, r=Amanieu

Document Poisoning in `LazyCell` and `LazyLock`

Currently, there is no documentation of poisoning behavior in either `LazyCell` or `LazyLock`, even though both of them can be observed as poisoned by users.

`LazyCell` [plagyround example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=9cf38b8dc56db100848f54085c2c697d)

`LazyLock` [playground example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=f1cd6f9fe16636e347ebb695a0ce30c0)

# Open Questions

- [x] Is it worth making the implementation of `LazyLock` more complicated to ensure that the the panic message is `"LazyLock instance has previously been poisoned"` instead of `"Once instance has previously been poisoned"`? See the `LazyLock` playground link above for more context.
- [x] Does it make sense to move `LazyLock` into the `poison` module? It is certainly a poison-able type, but at the same time it is slightly different from the 4 other types currently in the `poison` module in that it is unrecoverable. I think this is more of a libs-api question.

``@rustbot`` label +T-libs-api

Please let me know if these open questions deserve a separate issue / PR!
github-actions bot pushed a commit to model-checking/verify-rust-std that referenced this pull request Aug 6, 2025
@samueltardieu
Rollup merge of rust-lang#144872 - connortsui20:once-poison-docs, r=A…
7112d06 
…manieu

Document Poisoning in `LazyCell` and `LazyLock`

Currently, there is no documentation of poisoning behavior in either `LazyCell` or `LazyLock`, even though both of them can be observed as poisoned by users.

`LazyCell` [plagyround example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=9cf38b8dc56db100848f54085c2c697d)

`LazyLock` [playground example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=f1cd6f9fe16636e347ebb695a0ce30c0)

# Open Questions

- [x] Is it worth making the implementation of `LazyLock` more complicated to ensure that the the panic message is `"LazyLock instance has previously been poisoned"` instead of `"Once instance has previously been poisoned"`? See the `LazyLock` playground link above for more context.
- [x] Does it make sense to move `LazyLock` into the `poison` module? It is certainly a poison-able type, but at the same time it is slightly different from the 4 other types currently in the `poison` module in that it is unrecoverable. I think this is more of a libs-api question.

``@rustbot`` label +T-libs-api

Please let me know if these open questions deserve a separate issue / PR!
github-actions bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Aug 7, 2025
@bors
Auto merge of #144934 - samueltardieu:rollup-25jvb9g, r=samueltardieu
811f376 
Rollup of 17 pull requests

Successful merges:

 - rust-lang/rust#144467 (rustdoc template font links only emit `crossorigin` when needed)
 - rust-lang/rust#144548 (Rehome 21 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`)
 - rust-lang/rust#144741 (fix: Error on illegal `[const]`s inside blocks within legal positions)
 - rust-lang/rust#144776 (`Printer` cleanups)
 - rust-lang/rust#144779 (Implement debugging output of the bootstrap Step graph into a DOT file)
 - rust-lang/rust#144813 (Add a tidy check to prevent adding UI tests directly under `tests/ui/`)
 - rust-lang/rust#144817 (Properly reject tail calls to `&FnPtr` or `&FnDef`)
 - rust-lang/rust#144852 (Rename `rust_panic_without_hook` to `resume_unwind` )
 - rust-lang/rust#144866 (Remove `SHOULD_EMIT_LINTS` in favor of `should_emit`)
 - rust-lang/rust#144867 (Use `as_array` in PartialEq for arrays)
 - rust-lang/rust#144872 (Document Poisoning in `LazyCell` and `LazyLock`)
 - rust-lang/rust#144877 (coverage: Various small cleanups)
 - rust-lang/rust#144887 (`rust-analyzer` subtree update)
 - rust-lang/rust#144890 (Add `InterpCx::project_fields`)
 - rust-lang/rust#144894 (Delete `tests/ui/threads-sendsync/tcp-stress.rs`)
 - rust-lang/rust#144905 (rustc-dev-guide subtree update)
 - rust-lang/rust#144920 (Dont print arg span in MIR dump for tail call)

r? `@ghost`
`@rustbot` modify labels: rollup
@connortsui20 connortsui20 deleted the once-poison-docs branch August 7, 2025 09:57
github-actions bot pushed a commit to rust-lang/rust-analyzer that referenced this pull request Aug 11, 2025
@bors
Auto merge of #144934 - samueltardieu:rollup-25jvb9g, r=samueltardieu
6e3ab74 
Rollup of 17 pull requests

Successful merges:

 - rust-lang/rust#144467 (rustdoc template font links only emit `crossorigin` when needed)
 - rust-lang/rust#144548 (Rehome 21 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`)
 - rust-lang/rust#144741 (fix: Error on illegal `[const]`s inside blocks within legal positions)
 - rust-lang/rust#144776 (`Printer` cleanups)
 - rust-lang/rust#144779 (Implement debugging output of the bootstrap Step graph into a DOT file)
 - rust-lang/rust#144813 (Add a tidy check to prevent adding UI tests directly under `tests/ui/`)
 - rust-lang/rust#144817 (Properly reject tail calls to `&FnPtr` or `&FnDef`)
 - rust-lang/rust#144852 (Rename `rust_panic_without_hook` to `resume_unwind` )
 - rust-lang/rust#144866 (Remove `SHOULD_EMIT_LINTS` in favor of `should_emit`)
 - rust-lang/rust#144867 (Use `as_array` in PartialEq for arrays)
 - rust-lang/rust#144872 (Document Poisoning in `LazyCell` and `LazyLock`)
 - rust-lang/rust#144877 (coverage: Various small cleanups)
 - rust-lang/rust#144887 (`rust-analyzer` subtree update)
 - rust-lang/rust#144890 (Add `InterpCx::project_fields`)
 - rust-lang/rust#144894 (Delete `tests/ui/threads-sendsync/tcp-stress.rs`)
 - rust-lang/rust#144905 (rustc-dev-guide subtree update)
 - rust-lang/rust#144920 (Dont print arg span in MIR dump for tail call)

r? `@ghost`
`@rustbot` modify labels: rollup
@connortsui20 connortsui20 mentioned this pull request Aug 12, 2025
Merged
samueltardieu added a commit to samueltardieu/rust that referenced this pull request Aug 23, 2025
@samueltardieu
Rollup merge of rust-lang#145307 - connortsui20:lazylock-poison-msg, …
813d98f 
…r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang#144872 (comment)

r? `@Amanieu`
jhpratt added a commit to jhpratt/rust that referenced this pull request Aug 23, 2025
@jhpratt
Rollup merge of rust-lang#145307 - connortsui20:lazylock-poison-msg, …
0ece83f 
…r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang#144872 (comment)

r? ``@Amanieu``
Zalathar added a commit to Zalathar/rust that referenced this pull request Aug 24, 2025
@Zalathar
Rollup merge of rust-lang#145307 - connortsui20:lazylock-poison-msg, …
fa990f4 
…r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang#144872 (comment)

r? `@Amanieu`
Zalathar added a commit to Zalathar/rust that referenced this pull request Aug 24, 2025
@Zalathar
Rollup merge of rust-lang#145307 - connortsui20:lazylock-poison-msg, …
9636f98 
…r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang#144872 (comment)

r? ``@Amanieu``
jhpratt added a commit to jhpratt/rust that referenced this pull request Aug 24, 2025
@jhpratt
Rollup merge of rust-lang#145307 - connortsui20:lazylock-poison-msg, …
d5340c2 
…r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang#144872 (comment)

r? ```@Amanieu```
rust-timer added a commit that referenced this pull request Aug 24, 2025
@rust-timer
Unrolled build for #145307
762d21b 
Rollup merge of #145307 - connortsui20:lazylock-poison-msg, r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in #144872 (comment)

r? ```@Amanieu```
github-actions bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Aug 25, 2025
@jhpratt
Rollup merge of #145307 - connortsui20:lazylock-poison-msg, r=Amanieu
a6d6857 
Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang/rust#144872 (comment)

r? ```@Amanieu```
github-actions bot pushed a commit to rust-lang/miri that referenced this pull request Aug 25, 2025
@jhpratt
Rollup merge of #145307 - connortsui20:lazylock-poison-msg, r=Amanieu
23cbe9d 
Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang/rust#144872 (comment)

r? ```@Amanieu```
github-actions bot pushed a commit to model-checking/verify-rust-std that referenced this pull request Aug 26, 2025
@jhpratt
Rollup merge of rust-lang#145307 - connortsui20:lazylock-poison-msg, …
d69503d 
…r=Amanieu

Fix `LazyLock` poison panic message

Fixes the issue raised in rust-lang#144872 (comment)

r? ```@Amanieu```
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