Improve `DispatchFromDyn` and `CoerceUnsized` impl validation#135228

compiler-errors · 2025-01-08T00:52:22Z

Disallow arbitrary 1-ZST fields in DispatchFromDyn -- only PhantomData, and 1-ZSTs that mention no params (which is needed to support, e.g., the Global alloctor in Box<T, U = Global>).
Don't allow coercing between non-ZSTs to ZSTs (since the previous check wasn't actually checking the field tys were the same before checking the layout...)
Normalize the field before checking it's PhantomData.

Fixes #135215
Fixes #135214
Fixes #135220

r? @BoxyUwU or reassign

Darksonn

Thank you!

compiler/rustc_hir_analysis/src/coherence/builtin.rs

Darksonn · 2025-01-10T13:28:23Z

tests/ui/self/phantomdata-in-coerce-and-dispatch-impls.rs

This test is from #135214 that this PR is listed as fixing, but that issue also has another broken example that involves feature(lazy_type_alias). Is that part of #135214 also fixed by this?

Yes, I don't think it's important to include both tests.

BoxyUwU · 2025-01-14T03:02:56Z

@bors r+

bors · 2025-01-14T03:02:59Z

📌 Commit f47c58f has been approved by BoxyUwU

It is now in the queue for this repository.

BoxyUwU · 2025-01-14T03:03:22Z

(feel free to r- and fix the typo before this lands if you care to 🤷‍♀️)

compiler-errors · 2025-01-14T05:53:00Z

hm yeah i'll update it

@bors r-

…alidation

compiler-errors · 2025-01-14T18:47:39Z

@bors r=BoxyUwU

bors · 2025-01-14T18:47:42Z

📌 Commit 3cd7581 has been approved by BoxyUwU

It is now in the queue for this repository.

…atch, r=BoxyUwU Improve `DispatchFromDyn` and `CoerceUnsized` impl validation * Disallow arbitrary 1-ZST fields in `DispatchFromDyn` -- only `PhantomData`, and 1-ZSTs that mention no params (which is needed to support, e.g., the `Global` alloctor in `Box<T, U = Global>`). * Don't allow coercing between non-ZSTs to ZSTs (since the previous check wasn't actually checking the field tys were the same before checking the layout...) * Normalize the field before checking it's `PhantomData`. Fixes rust-lang#135215 Fixes rust-lang#135214 Fixes rust-lang#135220 r? `@BoxyUwU` or reassign

…atch, r=BoxyUwU Improve `DispatchFromDyn` and `CoerceUnsized` impl validation * Disallow arbitrary 1-ZST fields in `DispatchFromDyn` -- only `PhantomData`, and 1-ZSTs that mention no params (which is needed to support, e.g., the `Global` alloctor in `Box<T, U = Global>`). * Don't allow coercing between non-ZSTs to ZSTs (since the previous check wasn't actually checking the field tys were the same before checking the layout...) * Normalize the field before checking it's `PhantomData`. Fixes rust-lang#135215 Fixes rust-lang#135214 Fixes rust-lang#135220 r? ``@BoxyUwU`` or reassign

…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#134940 (Make sure to scrape region constraints from deeply normalizing type outlives assumptions in borrowck) - rust-lang#135047 (Add gpu-kernel calling convention) - rust-lang#135228 (Improve `DispatchFromDyn` and `CoerceUnsized` impl validation) - rust-lang#135264 (Consider more erroneous layouts as `LayoutError::ReferencesError` to suppress spurious errors) - rust-lang#135302 (for purely return-type based searches, deprioritize clone-like functions) - rust-lang#135380 (Make sure we can produce `ConstArgHasWrongType` errors for valtree consts) - rust-lang#135425 (Do not consider traits that have unsatisfied const conditions to be conditionally const) r? `@ghost` `@rustbot` modify labels: rollup

…kingjubilee Rollup of 11 pull requests Successful merges: - rust-lang#134913 (bootstrap: do not rely on LIBRARY_PATH env variable) - rust-lang#134940 (Make sure to scrape region constraints from deeply normalizing type outlives assumptions in borrowck) - rust-lang#135228 (Improve `DispatchFromDyn` and `CoerceUnsized` impl validation) - rust-lang#135264 (Consider more erroneous layouts as `LayoutError::ReferencesError` to suppress spurious errors) - rust-lang#135302 (for purely return-type based searches, deprioritize clone-like functions) - rust-lang#135353 (re-add --disable-minification to rustdoc) - rust-lang#135380 (Make sure we can produce `ConstArgHasWrongType` errors for valtree consts) - rust-lang#135423 (Enforce syntactical stability of const traits in HIR) - rust-lang#135425 (Do not consider traits that have unsatisfied const conditions to be conditionally const) - rust-lang#135499 (fix underlining of hovered intra-doc links.) - rust-lang#135505 (Fix clippy lints in rustdoc) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#135228 - compiler-errors:normalizes-ur-dispatch, r=BoxyUwU Improve `DispatchFromDyn` and `CoerceUnsized` impl validation * Disallow arbitrary 1-ZST fields in `DispatchFromDyn` -- only `PhantomData`, and 1-ZSTs that mention no params (which is needed to support, e.g., the `Global` alloctor in `Box<T, U = Global>`). * Don't allow coercing between non-ZSTs to ZSTs (since the previous check wasn't actually checking the field tys were the same before checking the layout...) * Normalize the field before checking it's `PhantomData`. Fixes rust-lang#135215 Fixes rust-lang#135214 Fixes rust-lang#135220 r? ```@BoxyUwU``` or reassign

compiler-errors added 2 commits January 8, 2025 00:28

Don't allow transmuting ZSTs in dispatch_from_dyn impl

3c31861

Don't allow DispatchFromDyn impls that transmute ZST to non-ZST

11bc805

rustbot assigned BoxyUwU Jan 8, 2025

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 Jan 8, 2025

Darksonn reviewed Jan 10, 2025

View reviewed changes

ojeda mentioned this pull request Jan 13, 2025

Rust unstable features needed for the kernel Rust-for-Linux/linux#2

Open

46 tasks

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 Jan 14, 2025

bors 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 14, 2025

Normalize field before checking PhantomData in coerce/dispatch impl v…

3cd7581

…alidation

compiler-errors force-pushed the normalizes-ur-dispatch branch from f47c58f to 3cd7581 Compare January 14, 2025 18:47

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 14, 2025

matthiaskrgr mentioned this pull request Jan 14, 2025

Rollup of 8 pull requests #135506

Closed

matthiaskrgr mentioned this pull request Jan 14, 2025

Rollup of 7 pull requests #135509

Closed

workingjubilee mentioned this pull request Jan 15, 2025

Rollup of 11 pull requests #135519

Merged

bors merged commit f256f9e into rust-lang:master Jan 15, 2025
6 checks passed

rustbot added this to the 1.86.0 milestone Jan 15, 2025

steffahn mentioned this pull request Jan 16, 2025

CoercePointee doesn't tightly enforce the restriction to #[repr(transparent)]-only wrappers, if other proc-macros are involved #135206

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Comments

Improve `DispatchFromDyn` and `CoerceUnsized` impl validation#135228