Make `ptr_cast_add_auto_to_object` lint into hard error #136764

traviscross · 2025-02-09T06:28:45Z

In Rust 1.81, we added a FCW lint (including linting in dependencies) against pointer casts that add an auto trait to dyn bounds. This was part of work making casts of pointers involving trait objects stricter, and was part of the work needed to restabilize trait upcasting.

We considered just making this a hard error, but opted against it at that time due to breakage found by crater. This breakage was mostly due to the anymap crate which has been a persistent problem for us.

It's now a year later, and the fact that this is not yet a hard error is giving us pause about stabilizing arbitrary self types and derive(CoercePointee). So let's see about making a hard error of this.

r? ghost

cc @adetaylor @Darksonn @BoxyUwU @RalfJung @compiler-errors @oli-obk @WaffleLapkin

compiler/rustc_error_codes/src/error_codes/E0802.md

traviscross · 2025-02-09T08:43:45Z

@bors try

...in preparation for a crater run.

…o_to_object-hard-error, r=<try> Make `ptr_cast_add_auto_to_object` lint into hard error In Rust 1.81, we added a FCW lint (including linting in dependencies) against pointer casts that add an auto trait to dyn bounds. This was part of work making casts of pointers involving trait objects stricter, and was part of the work needed to restabilize trait upcasting. We considered just making this a hard error, but opted against it at that time due to breakage found by crater. This breakage was mostly due to the `anymap` crate which has been a persistent problem for us. It's now a year later, and the fact that this is not yet a hard error is giving us pause about stabilizing arbitrary self types and `derive(CoercePointee)`. So let's see about making a hard error of this. r? ghost cc `@adetaylor` `@Darksonn` `@BoxyUwU` `@RalfJung` `@compiler-errors` `@oli-obk` `@WaffleLapkin` Related: - rust-lang#135881 - rust-lang#136702 Tracking: - rust-lang#127323 - rust-lang#44874 - rust-lang#123430

bors · 2025-02-09T08:44:56Z

⌛ Trying commit 866c3cf with merge 8cf44c8...

bors · 2025-02-09T10:32:57Z

☀️ Try build successful - checks-actions
Build commit: 8cf44c8 (8cf44c88fc5805dc578c5c987397615b47d2e2b2)

traviscross · 2025-02-09T11:13:44Z

@craterbot check

craterbot · 2025-02-09T11:13:58Z

👌 Experiment pr-136764 created and queued.
🤖 Automatically detected try build 8cf44c8
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2025-02-09T11:14:48Z

🚧 Experiment pr-136764 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2025-02-10T09:03:18Z

🎉 Experiment pr-136764 is completed!
📊 95 regressed and 2 fixed (580506 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

traviscross · 2025-02-10T09:44:13Z

@rustbot labels +I-lang-nominated

As expected, all the real regressions are due to anymap. Let's discuss what we want to do here.

cc @rust-lang/lang

traviscross · 2025-02-12T16:46:17Z

We talked about this in triage today. The feeling is that the FCW has been out there long enough, so we're within our rights to do this.

@rfcbot fcp merge

bors · 2025-02-19T08:41:51Z

☔ The latest upstream changes (presumably #137248) made this pull request unmergeable. Please resolve the merge conflicts.

rfcbot · 2025-02-22T16:54:08Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

In Rust 1.81, we added a FCW lint (including linting in dependencies) against pointer casts that add an auto trait to dyn bounds. This was part of work making casts of pointers involving trait objects stricter which was needed to restabilize trait upcasting. We considered just making this a hard error at the time, but opted against it due to breakage found by crater. This breakage was mostly due to the `anymap` crate which has been a persistent problem for us. It's now a year later, and the fact that this is not yet a hard error is giving us pause about stabilizing arbitrary self types and `derive(CoercePointee)`. So let's now make a hard error of this.

traviscross · 2025-02-22T23:05:50Z

r? @oli-obk

cc @compiler-errors

tests/ui/lint/removed-lints/README.md

tests/ui/cast/ptr-to-trait-obj-add-auto.rs

oli-obk · 2025-03-04T18:52:28Z

@bors r+

bors · 2025-03-04T18:52:31Z

📌 Commit ef337a6 has been approved by oli-obk

It is now in the queue for this repository.

compiler-errors · 2025-03-04T20:03:01Z

@bors rollup

…uto_to_object-hard-error, r=oli-obk Make `ptr_cast_add_auto_to_object` lint into hard error In Rust 1.81, we added a FCW lint (including linting in dependencies) against pointer casts that add an auto trait to dyn bounds. This was part of work making casts of pointers involving trait objects stricter, and was part of the work needed to restabilize trait upcasting. We considered just making this a hard error, but opted against it at that time due to breakage found by crater. This breakage was mostly due to the `anymap` crate which has been a persistent problem for us. It's now a year later, and the fact that this is not yet a hard error is giving us pause about stabilizing arbitrary self types and `derive(CoercePointee)`. So let's see about making a hard error of this. r? ghost cc `@adetaylor` `@Darksonn` `@BoxyUwU` `@RalfJung` `@compiler-errors` `@oli-obk` `@WaffleLapkin` Related: - rust-lang#135881 - rust-lang#136702 - rust-lang#136776 Tracking: - rust-lang#127323 - rust-lang#44874 - rust-lang#123430

…kingjubilee Rollup of 33 pull requests Successful merges: - rust-lang#136581 (Retire the legacy `Makefile`-based `run-make` test infra) - rust-lang#136764 (Make `ptr_cast_add_auto_to_object` lint into hard error) - rust-lang#136798 (Added documentation for flushing per rust-lang#74348) - rust-lang#136865 (Perform deeper compiletest path normalization for `$TEST_BUILD_DIR` to account for compare-mode/debugger cases, and normalize long type file filename hashes) - rust-lang#136975 (Look for `python3` first on MacOS, not `py`) - rust-lang#137240 (Slightly reformat `std::fs::remove_dir_all` error docs) - rust-lang#137303 (Remove `MaybeForgetReturn` suggestion) - rust-lang#137327 (Undeprecate env::home_dir) - rust-lang#137502 (Don't include global asm in `mir_keys`, fix error body synthesis) - rust-lang#137534 ([rustdoc] hide item that is not marked as doc(inline) and whose src is doc(hidden)) - rust-lang#137565 (Try to point of macro expansion from resolver and method errors if it involves macro var) - rust-lang#137643 (Add DWARF test case for non-C-like `repr128` enums) - rust-lang#137758 (fix usage of ty decl macro fragments in attributes) - rust-lang#137764 (Ensure that negative auto impls are always applicable) - rust-lang#137772 (Fix char count in `Display` for `ByteStr`) - rust-lang#137798 (ci: use ubuntu 24 on arm large runner) - rust-lang#137805 (adjust Layout debug printing to match the internal field name) - rust-lang#137808 (Do not require that unsafe fields lack drop glue) - rust-lang#137820 (Clarify why InhabitedPredicate::instantiate_opt exists) - rust-lang#137825 (Provide more context on resolve error caused from incorrect RTN) - rust-lang#137829 (Stabilize [T]::split_off... methods) - rust-lang#137834 (rustc_fluent_macro: use CARGO_CRATE_NAME instead of CARGO_PKG_NAME) - rust-lang#137850 (Stabilize `box_uninit_write`) - rust-lang#137912 (Do not recover missing lifetime with random in-scope lifetime) - rust-lang#137913 (Allow struct field default values to reference struct's generics) - rust-lang#137923 (Simplify `<Postorder as Iterator>::size_hint`) - rust-lang#137949 (Update MSVC INSTALL.md instructions to recommend VS 2022 + recent Windows 10/11 SDK) - rust-lang#137963 (Add ``dyn`` keyword to `E0373` examples) - rust-lang#137975 (Remove unused `PpMode::needs_hir`) - rust-lang#137986 (Fix some typos) - rust-lang#137991 (Add `avr-none` to SUMMARY.md and platform-support.md) - rust-lang#137993 (Remove obsolete comment from DeduceReadOnly) - rust-lang#137996 (Revert "compiler/rustc_data_structures/src/sync/worker_local.rs: delete "unsafe impl Sync"") r? `@ghost` `@rustbot` modify labels: rollup

…uto_to_object-hard-error, r=oli-obk Make `ptr_cast_add_auto_to_object` lint into hard error In Rust 1.81, we added a FCW lint (including linting in dependencies) against pointer casts that add an auto trait to dyn bounds. This was part of work making casts of pointers involving trait objects stricter, and was part of the work needed to restabilize trait upcasting. We considered just making this a hard error, but opted against it at that time due to breakage found by crater. This breakage was mostly due to the `anymap` crate which has been a persistent problem for us. It's now a year later, and the fact that this is not yet a hard error is giving us pause about stabilizing arbitrary self types and `derive(CoercePointee)`. So let's see about making a hard error of this. r? ghost cc ``@adetaylor`` ``@Darksonn`` ``@BoxyUwU`` ``@RalfJung`` ``@compiler-errors`` ``@oli-obk`` ``@WaffleLapkin`` Related: - rust-lang#135881 - rust-lang#136702 - rust-lang#136776 Tracking: - rust-lang#127323 - rust-lang#44874 - rust-lang#123430

…kingjubilee Rollup of 20 pull requests Successful merges: - rust-lang#136581 (Retire the legacy `Makefile`-based `run-make` test infra) - rust-lang#136764 (Make `ptr_cast_add_auto_to_object` lint into hard error) - rust-lang#136798 (Added documentation for flushing per rust-lang#74348) - rust-lang#136865 (Perform deeper compiletest path normalization for `$TEST_BUILD_DIR` to account for compare-mode/debugger cases, and normalize long type file filename hashes) - rust-lang#136975 (Look for `python3` first on MacOS, not `py`) - rust-lang#137240 (Slightly reformat `std::fs::remove_dir_all` error docs) - rust-lang#137303 (Remove `MaybeForgetReturn` suggestion) - rust-lang#137327 (Undeprecate env::home_dir) - rust-lang#137502 (Don't include global asm in `mir_keys`, fix error body synthesis) - rust-lang#137534 ([rustdoc] hide item that is not marked as doc(inline) and whose src is doc(hidden)) - rust-lang#137565 (Try to point of macro expansion from resolver and method errors if it involves macro var) - rust-lang#137643 (Add DWARF test case for non-C-like `repr128` enums) - rust-lang#137758 (fix usage of ty decl macro fragments in attributes) - rust-lang#137764 (Ensure that negative auto impls are always applicable) - rust-lang#137772 (Fix char count in `Display` for `ByteStr`) - rust-lang#137798 (ci: use ubuntu 24 on arm large runner) - rust-lang#137805 (adjust Layout debug printing to match the internal field name) - rust-lang#137808 (Do not require that unsafe fields lack drop glue) - rust-lang#137820 (Clarify why InhabitedPredicate::instantiate_opt exists) - rust-lang#137825 (Provide more context on resolve error caused from incorrect RTN) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 20 pull requests Successful merges: - rust-lang#134063 (dec2flt: Clean up float parsing modules) - rust-lang#136581 (Retire the legacy `Makefile`-based `run-make` test infra) - rust-lang#136662 (Count char width at most once in `Formatter::pad`) - rust-lang#136764 (Make `ptr_cast_add_auto_to_object` lint into hard error) - rust-lang#136798 (Added documentation for flushing per rust-lang#74348) - rust-lang#136865 (Perform deeper compiletest path normalization for `$TEST_BUILD_DIR` to account for compare-mode/debugger cases, and normalize long type file filename hashes) - rust-lang#136975 (Look for `python3` first on MacOS, not `py`) - rust-lang#136977 (Upload Datadog metrics with citool) - rust-lang#137240 (Slightly reformat `std::fs::remove_dir_all` error docs) - rust-lang#137298 (Check signature WF when lowering MIR body) - rust-lang#137463 ([illumos] attempt to use posix_spawn to spawn processes) - rust-lang#137477 (uefi: Add Service Binding Protocol abstraction) - rust-lang#137569 (Stabilize `string_extend_from_within`) - rust-lang#137633 (Only use implied bounds hack if bevy, and use deeply normalize in implied bounds hack) - rust-lang#137679 (Various coretests improvements) - rust-lang#137723 (Make `rust.description` more general-purpose and pass `CFG_VER_DESCRIPTION`) - rust-lang#137728 (Remove unsizing coercions for tuples) - rust-lang#137731 (Resume one waiter at once in deadlock handler) - rust-lang#137875 (mir_build: Integrate "simplification" steps into match-pair-tree creation) - rust-lang#138028 (compiler: add `ExternAbi::is_rustic_abi`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#136764 - traviscross:TC/make-ptr_cast_add_auto_to_object-hard-error, r=oli-obk Make `ptr_cast_add_auto_to_object` lint into hard error In Rust 1.81, we added a FCW lint (including linting in dependencies) against pointer casts that add an auto trait to dyn bounds. This was part of work making casts of pointers involving trait objects stricter, and was part of the work needed to restabilize trait upcasting. We considered just making this a hard error, but opted against it at that time due to breakage found by crater. This breakage was mostly due to the `anymap` crate which has been a persistent problem for us. It's now a year later, and the fact that this is not yet a hard error is giving us pause about stabilizing arbitrary self types and `derive(CoercePointee)`. So let's see about making a hard error of this. r? ghost cc ```@adetaylor``` ```@Darksonn``` ```@BoxyUwU``` ```@RalfJung``` ```@compiler-errors``` ```@oli-obk``` ```@WaffleLapkin``` Related: - rust-lang#135881 - rust-lang#136702 - rust-lang#136776 Tracking: - rust-lang#127323 - rust-lang#44874 - rust-lang#123430

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nikomatsakis mentioned this pull request Feb 20, 2025

Stabilize tooling needed by Rust for Linux rust-lang/rust-project-goals#116

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Tracking issue for release notes of #136764: Make ptr_cast_add_auto_to_object lint into hard error #137429

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Tracking issue for RFC 3519: arbitrary_self_types #44874

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Rollup of 33 pull requests #138020

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Make `ptr_cast_add_auto_to_object` lint into hard error #136764

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Make ptr_cast_add_auto_to_object lint into hard error #136764

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Make `ptr_cast_add_auto_to_object` lint into hard error #136764

Make `ptr_cast_add_auto_to_object` lint into hard error #136764

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