Downgrade const eval dangling ptr in final to future incompat lint #122204

pnkfelix · 2024-03-08T19:16:40Z

Short term band-aid for issue #121610, downgrading the prior hard error to a future-incompat lint (tracked in issue #122153).

Note we should not mark #121610 as resolved until after this (or something analogous) is beta backported.

rustbot · 2024-03-08T19:16:48Z

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rustbot · 2024-03-08T19:16:49Z

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

wesleywiser · 2024-03-08T19:20:55Z

r? wesleywiser

pnkfelix · 2024-03-08T20:14:27Z

ugh I have to do more updating to placate our tidy+diagnostics checking

@rustbot author

pnkfelix · 2024-03-08T20:54:39Z

Okay hopefully the tidy and diagnostic checks are all placated now.

@rustbot reviewer

wesleywiser · 2024-03-08T21:28:53Z

tests/ui/consts/miri_unleashed/mutable_references_err.rs

 const INTERIOR_MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _;
 //~^ ERROR: mutable pointer in final value
+//~| WARNING this was previously accepted by the compiler


It looks like we have some places where we were already generating an error but now we report the future incompatibility warning. That's perhaps a bit confusing but I don't think it needs to block the PR.

Note that this file uses -Zunleash-the-miri-inside-of-you. I am not sure if this can even be triggered on stable.

Could just not emit the future incompat lint if unleash mode is on

We want the error in unleash mode, it's the only way unleash mode can be sound.

Could just not emit the future incompat lint if unleash mode is on

As a variation on the above, I was musing that if any future-incompat lint is set to deny or forbid, then we could stop emitting that boilerplate about the thing being potentially rejected in a future version of the compiler, just to cut down on the diagnostic flooding...

tests/ui/consts/miri_unleashed/mutable_references.stderr

RalfJung · 2024-03-09T15:31:31Z

The compiler part of the diff LGTM.

compiler/rustc_lint_defs/src/builtin.rs

bors · 2024-03-12T13:39:22Z

☔ The latest upstream changes (presumably #121644) made this pull request unmergeable. Please resolve the merge conflicts.

…at lint to address issue 121610.

…tests that were expecting the hard error for it. I attempted to do this in a manner that preserved the line numbers to reduce the review effort on the resulting diff, but we still have to deal with the ramifications of how a future-incompat lint behaves compared to a hard-error (in terms of its impact on the diagnostic output).

… added lint.

wesleywiser

r=me when CI is green 👍

pnkfelix · 2024-03-13T15:40:06Z

Regarding the beta-nomination: This ended up requiring a bit more changes than I had anticipated when we discussed it last week.

Another option, that may be more palatable for backporting, would be to just disable the hard-error with no lint at all on beta, and let the future-incompat code ride the train.

RalfJung · 2024-03-13T15:45:55Z

Almost all the changes are in tests. So in terms of the diffstat I don't think that would be much smaller?

pnkfelix · 2024-03-13T18:19:33Z

oh. of course. need to handle tests that are 32-bit specific (sigh)

(I'll admit its not immediately obvious to me why the CI test above is hitting a 32-bit target from that specific context that it listed with the command /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-codegen/x86_64-unknown-linux-gnu/release/y test --use-system-gcc --use-backend gcc --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools/cg_gcc --release --mini-tests --std-tests, but I'll figure it out.)

wesleywiser · 2024-03-13T19:03:40Z

Almost all the changes are in tests. So in terms of the diffstat I don't think that would be much smaller?

I agree with Ralf, the functional changes are only ~60 lines with the rest being in test output and the added test case. I don't see an issue with backporting that.

wesleywiser · 2024-03-13T20:17:50Z

Thanks for getting this done @pnkfelix!

@bors r+ p=1

Resolves P-high issue we want to backport

bors · 2024-03-13T20:17:53Z

📌 Commit 8f45a9e has been approved by wesleywiser

It is now in the queue for this repository.

bors · 2024-03-14T00:06:28Z

⌛ Testing commit 8f45a9e with merge c7fed9f...

bors · 2024-03-14T02:05:23Z

☀️ Test successful - checks-actions
Approved by: wesleywiser
Pushing c7fed9f to master...

rust-timer · 2024-03-14T03:20:47Z

Finished benchmarking commit (c7fed9f): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.5%	[1.5%, 1.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	3.8%	[3.8%, 3.8%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.8%	[3.8%, 3.8%]	1

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.6%	[2.1%, 3.3%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 675.071s -> 677.02s (0.29%)
Artifact size: 310.73 MiB -> 310.67 MiB (-0.02%)

apiraino · 2024-03-14T14:23:45Z

Beta backport approved as per compiler team on Zulip. A backport PR will be authored by the release team at the end of the current development cycle.

@rustbot label +beta-accepted

[beta] backports - AST validation: Improve handling of inherent impls nested within functions and anon consts rust-lang#122004 - Downgrade const eval dangling ptr in final to future incompat lint rust-lang#122204 r? cuviper

Pkgsrc changes: * Adapt checksums and patches. Upstream chnages: Version 1.77.0 (2024-03-21) ========================== - [Reveal opaque types within the defining body for exhaustiveness checking.] (rust-lang/rust#116821) - [Stabilize C-string literals.] (rust-lang/rust#117472) - [Stabilize THIR unsafeck.] (rust-lang/rust#117673) - [Add lint `static_mut_refs` to warn on references to mutable statics.] (rust-lang/rust#117556) - [Support async recursive calls (as long as they have indirection).] (rust-lang/rust#117703) - [Undeprecate lint `unstable_features` and make use of it in the compiler.] (rust-lang/rust#118639) - [Make inductive cycles in coherence ambiguous always.] (rust-lang/rust#118649) - [Get rid of type-driven traversal in const-eval interning] (rust-lang/rust#119044), only as a [future compatiblity lint] (rust-lang/rust#122204) for now. - [Deny braced macro invocations in let-else.] (rust-lang/rust#119062) Compiler -------- - [Include lint `soft_unstable` in future breakage reports.] (rust-lang/rust#116274) - [Make `i128` and `u128` 16-byte aligned on x86-based targets.] (rust-lang/rust#116672) - [Use `--verbose` in diagnostic output.] (rust-lang/rust#119129) - [Improve spacing between printed tokens.] (rust-lang/rust#120227) - [Merge the `unused_tuple_struct_fields` lint into `dead_code`.] (rust-lang/rust#118297) - [Error on incorrect implied bounds in well-formedness check] (rust-lang/rust#118553), with a temporary exception for Bevy. - [Fix coverage instrumentation/reports for non-ASCII source code.] (rust-lang/rust#119033) - [Fix `fn`/`const` items implied bounds and well-formedness check.] (rust-lang/rust#120019) - [Promote `riscv32{im|imafc}-unknown-none-elf` targets to tier 2.] (rust-lang/rust#118704) - Add several new tier 3 targets: - [`aarch64-unknown-illumos`] (rust-lang/rust#112936) - [`hexagon-unknown-none-elf`] (rust-lang/rust#117601) - [`riscv32imafc-esp-espidf`] (rust-lang/rust#119738) - [`riscv32im-risc0-zkvm-elf`] (rust-lang/rust#117958) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Implement `From<&[T; N]>` for `Cow<[T]>`.] (rust-lang/rust#113489) - [Remove special-case handling of `vec.split_off (0)`.](rust-lang/rust#119917) Stabilized APIs --------------- - [`array::each_ref`] (https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_ref) - [`array::each_mut`] (https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_mut) - [`core::net`] (https://doc.rust-lang.org/stable/core/net/index.html) - [`f32::round_ties_even`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#method.round_ties_even) - [`f64::round_ties_even`] (https://doc.rust-lang.org/stable/std/primitive.f64.html#method.round_ties_even) - [`mem::offset_of!`] (https://doc.rust-lang.org/stable/std/mem/macro.offset_of.html) - [`slice::first_chunk`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first_chunk) - [`slice::first_chunk_mut`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first_chunk_mut) - [`slice::split_first_chunk`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first_chunk) - [`slice::split_first_chunk_mut`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first_chunk_mut) - [`slice::last_chunk`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last_chunk) - [`slice::last_chunk_mut`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last_chunk_mut) - [`slice::split_last_chunk`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last_chunk) - [`slice::split_last_chunk_mut`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last_chunk_mut) - [`slice::chunk_by`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.chunk_by) - [`slice::chunk_by_mut`] (https://doc.rust-lang.org/stable/std/primitive.slice.html#method.chunk_by_mut) - [`Bound::map`] (https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.map) - [`File::create_new`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.create_new) - [`Mutex::clear_poison`] (https://doc.rust-lang.org/stable/std/sync/struct.Mutex.html#method.clear_poison) - [`RwLock::clear_poison`] (https://doc.rust-lang.org/stable/std/sync/struct.RwLock.html#method.clear_poison) Cargo ----- - [Extend the build directive syntax with `cargo::`.] (rust-lang/cargo#12201) - [Stabilize metadata `id` format as `PackageIDSpec`.] (rust-lang/cargo#12914) - [Pull out as `cargo-util-schemas` as a crate.] (rust-lang/cargo#13178) - [Strip all debuginfo when debuginfo is not requested.] (rust-lang/cargo#13257) - [Inherit jobserver from env for all kinds of runners.] (rust-lang/cargo#12776) - [Deprecate rustc plugin support in cargo.] (rust-lang/cargo#13248) Rustdoc ----- - [Allows links in markdown headings.] (rust-lang/rust#117662) - [Search for tuples and unit by type with `()`.] (rust-lang/rust#118194) - [Clean up the source sidebar's hide button.] (rust-lang/rust#119066) - [Prevent JS injection from `localStorage`.] (rust-lang/rust#120250) Misc ---- - [Recommend version-sorting for all sorting in style guide.] (rust-lang/rust#115046) Internal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - [Add more weirdness to `weird-exprs.rs`.] (rust-lang/rust#119028)

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pnkfelix force-pushed the downgrade-const-eval-dnagling-ptr-in-final-to-future-incompat-lint branch from 410d2a2 to 611c62f Compare March 8, 2024 20:46

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pnkfelix added 4 commits March 13, 2024 10:32

downgrade mutable-ptr-in-final-value from hard-error to future-incomp…

a8549b4

…at lint to address issue 121610.

regression test from 121610.

f86b46a

Added an "Explanation" header and expanded that section for the newly…

6ca46da

… added lint.

pnkfelix force-pushed the downgrade-const-eval-dnagling-ptr-in-final-to-future-incompat-lint branch from 2e2fe68 to 9c33cc6 Compare March 13, 2024 14:59

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include 32-bit variant for updated test of miri diagnostics.

8f45a9e

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 Mar 13, 2024

bors added the merged-by-bors This PR was explicitly merged by bors. label Mar 14, 2024

bors merged commit c7fed9f into rust-lang:master Mar 14, 2024
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Validate before interning #122432

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RalfJung mentioned this pull request Mar 14, 2024

Tracking issue for &mut T in const contexts (const_mut_refs) #57349

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[beta] backports #122524

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regression: encountered mutable pointer in final value when "outer scope" rule applies in const/static with interior mutability #121610

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Tracking Issue for CONST_EVAL_MUTABLE_PTR_IN_FINAL_VALUE #122153

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Downgrade const eval dangling ptr in final to future incompat lint #122204

Downgrade const eval dangling ptr in final to future incompat lint #122204

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pnkfelix commented Mar 13, 2024 •

edited

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Downgrade const eval dangling ptr in final to future incompat lint #122204

Downgrade const eval dangling ptr in final to future incompat lint #122204

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pnkfelix commented Mar 13, 2024 • edited

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Overall result: ❌ regressions - no action needed

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edited