Do not implement unsafe auto traits for types with unsafe fields by jswrenn · Pull Request #133934 · rust-lang/rust

jswrenn · 2024-12-05T20:21:02Z

If a type has unsafe fields, its safety invariants are not simply the conjunction of its field types' safety invariants. Consequently, it's invalid to reason about the safety properties of these types in a purely structural manner — i.e., the manner in which auto traits are implemented. Consequently, auto implementations of unsafe auto traits should not be generated for types with unsafe fields.

Tracking: #132922

r? @compiler-errors

compiler-errors

Please adjust this logic in the new trait solver too. Also, there's no test as far as I can tell.

compiler-errors · 2024-12-05T20:28:29Z

Also make sure the test exercises the behavior in both the old and new solvers. You can do something like:

//@ revisions: current next
//@[next] compile-flags: -Znext-solver

jswrenn · 2024-12-05T20:29:22Z

Whoops, somehow failed to push the test I wrote. It's here: https://github.com/rust-lang/rust/compare/e6e322f79713b156d43d77be6135463ec2d4b6e7..baec50ee0b8afc7433c3bd2f2b862a21addd2f57

compiler-errors · 2024-12-05T20:29:49Z

tests/ui/unsafe-fields/auto-traits.rs

+
+#![feature(auto_traits)]
+#![feature(unsafe_fields)]
+#![allow(dead_code, incomplete_features, unconditional_recursion)]


Please remove the unconditional_recursion. No reason not to just split this out into a fn main() {} or something that just calls both of the functions.

No need for dead_code, that's enabled in the UI test suite unconditionally.

jswrenn · 2024-12-05T22:48:22Z

Please adjust this logic in the new trait solver too.

Done

Also make sure the test exercises the behavior in both the old and new solvers. You can do something like:
//@ revisions: current next
//@[next] compile-flags: -Znext-solver

Done

jswrenn · 2024-12-05T23:16:40Z

~~Yuck, look like I accidentally committed some things...~~ Fixed!

compiler-errors · 2024-12-05T23:39:16Z

compiler/rustc_type_ir/src/inherent.rs

        matches!(self.kind(), ty::FnPtr(..))
    }

+    /// Checks whether this type directly contains unsafe fields.


Suggested change

/// Checks whether this type directly contains unsafe fields.

/// Checks whether this type is an ADT that has unsafe fields.

compiler-errors · 2024-12-05T23:40:33Z

@bors r+

bors · 2024-12-05T23:40:35Z

📌 Commit 9ccf285 has been approved by compiler-errors

It is now in the queue for this repository.

If a type has unsafe fields, its safety invariants are not simply the conjunction of its field types' safety invariants. Consequently, it's invalid to reason about the safety properties of these types in a purely structural manner — i.e., the manner in which `auto` traits are implemented. Makes progress towards rust-lang#132922.

compiler-errors · 2024-12-06T19:49:23Z

@bors r+

bors · 2024-12-06T19:49:26Z

📌 Commit a122dde has been approved by compiler-errors

It is now in the queue for this repository.

jswrenn · 2024-12-06T19:50:54Z

@bors r=compiler-errors

bors · 2024-12-06T19:50:56Z

💡 This pull request was already approved, no need to approve it again.

There's another pull request that is currently being tested, blocking this pull request: Stabilize noop_waker #133089

bors · 2024-12-06T19:50:57Z

📌 Commit a122dde has been approved by compiler-errors

It is now in the queue for this repository.

…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#130209 (Stabilize `std::io::ErrorKind::CrossesDevices`) - rust-lang#130254 (Stabilize `std::io::ErrorKind::QuotaExceeded`) - rust-lang#132187 (Add Extend impls for tuples of arity 1 through 12) - rust-lang#133875 (handle `--json-output` properly) - rust-lang#133934 (Do not implement unsafe auto traits for types with unsafe fields) - rust-lang#133954 (Hide errors whose suggestions would contain error constants or types) - rust-lang#133960 (rustdoc: remove eq for clean::Attributes) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#133934 - jswrenn:unsafe-fields-auto-traits, r=compiler-errors Do not implement unsafe auto traits for types with unsafe fields If a type has unsafe fields, its safety invariants are not simply the conjunction of its field types' safety invariants. Consequently, it's invalid to reason about the safety properties of these types in a purely structural manner — i.e., the manner in which `auto` traits are implemented. Consequently, auto implementations of unsafe auto traits should not be generated for types with unsafe fields. Tracking: rust-lang#132922 r? `@compiler-errors`

…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#130209 (Stabilize `std::io::ErrorKind::CrossesDevices`) - rust-lang#130254 (Stabilize `std::io::ErrorKind::QuotaExceeded`) - rust-lang#132187 (Add Extend impls for tuples of arity 1 through 12) - rust-lang#133875 (handle `--json-output` properly) - rust-lang#133934 (Do not implement unsafe auto traits for types with unsafe fields) - rust-lang#133954 (Hide errors whose suggestions would contain error constants or types) - rust-lang#133960 (rustdoc: remove eq for clean::Attributes) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned compiler-errors Dec 5, 2024

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 Dec 5, 2024

compiler-errors suggested changes Dec 5, 2024

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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 Dec 5, 2024

jswrenn force-pushed the unsafe-fields-auto-traits branch from e6e322f to baec50e Compare December 5, 2024 20:28

compiler-errors reviewed Dec 5, 2024

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jswrenn force-pushed the unsafe-fields-auto-traits branch from baec50e to 9d604ce Compare December 5, 2024 22:44

rustbot added the WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) label Dec 5, 2024

jswrenn requested a review from compiler-errors December 5, 2024 22:48

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 Dec 5, 2024

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jswrenn force-pushed the unsafe-fields-auto-traits branch from 9d604ce to 9ccf285 Compare December 5, 2024 23:18

compiler-errors approved these changes Dec 5, 2024

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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 Dec 5, 2024

jswrenn force-pushed the unsafe-fields-auto-traits branch from 9ccf285 to a122dde Compare December 5, 2024 23:52

matthiaskrgr mentioned this pull request Dec 6, 2024

Rollup of 7 pull requests #133978

Merged

bors merged commit 6457761 into rust-lang:master Dec 7, 2024

rustbot added this to the 1.85.0 milestone Dec 7, 2024

jswrenn mentioned this pull request Dec 13, 2024

Tracking issue for RFC 3458: Unsafe fields #132922

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	/// Checks whether this type directly contains unsafe fields.
	/// Checks whether this type is an ADT that has unsafe fields.

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