Remove mutable_borrow_reservation_conflict lint and allow the code pattern #96268

jackh726 · 2022-04-21T02:13:20Z

This was the only breaking issue with the NLL stabilization PR. Lang team decided to go ahead and allow this.

r? @nikomatsakis
Closes #59159
Closes #56254

jackh726 · 2022-04-21T02:14:09Z

Not sure if this needs FCP or not. There's technically no new behavior.

pnkfelix · 2022-04-21T03:54:55Z

I really want to go through the exercise of verifying that the current version of stacked-borrows does indeed allow the coding pattern.

Its not that I don't believe @RalfJung when they told me that it's fine and stacked-borrows has to handle this, but ... its still better to double check that key assumption first...

pnkfelix · 2022-04-21T04:12:19Z

Okay well I at least started digging into it and got far enough in the playground to convince myself that there's nothing in today's miri that is going to "obviously" explode. :)

More simply put, miri successfully executed this:

    #![allow(mutable_borrow_reservation_conflict)]
    let mut v = vec![0, 1, 2];
    let shared = &v;
    v.push(shared.len());
    dbg!(v);

so I'm a little less worried than I was 17 minutes ago.

joshtriplett · 2022-04-21T05:55:42Z

Let's go ahead and confirm consensus on this (momentarily switching labels to T-lang for rfcbot):

@rfcbot merge

rfcbot · 2022-04-21T05:55:43Z

Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

joshtriplett · 2022-04-21T05:56:33Z

@rfcbot f? @RalfJung

joshtriplett · 2022-04-21T05:59:55Z

@rfcbot concern confirmation-from-ralf

@RalfJung, can we get explicit confirmation in this issue that Stacked Borrows won't have an issue with this anymore?

RalfJung · 2022-04-21T14:07:44Z

@pnkfelix we even have that (and more) as a testcase in Miri. ;)

can we get explicit confirmation in this issue that Stacked Borrows won't have an issue with this anymore?

Basically any aliasing model has no issue with 2-phase-borrows if it just entirely gives up on doing anything interesting with them, and treats them like (tagged) raw pointers. So as long as we are okay with (in the worst case) not doing any alias-based optimizations on 2phase-borrows, we are fine. This is exactly what I ended up doing with Stacked Borrows, after failing to do anything smarter.

jackh726 · 2022-04-21T14:08:01Z

Concern didn't go through...maybe because it's now tagged T-compiler again?

cramertj · 2022-04-21T15:35:50Z

@RalfJung

So as long as we are okay with (in the worst case) not doing any alias-based optimizations on 2phase-borrows, we are fine.

Does this mean that we would potentially plan to actually detect places where two-phase is not necessary and optimize only those places, or is this a de-facto "we're not going to do alias-based optimizations"?

If the former, that sounds scary. If the latter, it seems odd to me that one might have to revert to using non-two-phase-borrows-style code in order to unlock optimizations, but that seems like probably a niche enough occurrence that it wouldn't be a huge deal in practice? I have a very hard time judging the impact of these kinds of decisions. Are you able to shed any light on the kinds of optimizations that could be missed in common two-phase-borrows usecases?

bjorn3 · 2022-04-21T16:33:53Z

How easy would it be to support this pattern if we were to move borrowck to THIR after we switch to polonius? (If moving it to THIR is possible in the first place that is.)

RalfJung · 2022-04-21T16:42:31Z

Does this mean that we would potentially plan to actually detect places where two-phase is not necessary and optimize only those places, or is this a de-facto "we're not going to do alias-based optimizations"?

Many (most?) borrows are not two-phase borrows (including all the noalias we currently emit, since they are at function boundaries); those are unaffected.

But I admit I am not entirely familiar with the details of when two-phase borrows vs regular mutable borrows are used inside a function. (Shared references are fine anyway.)

The optimizations are the usual ones for aliasing guarantees -- reordering reads and writes around other code. The Stacked Borrows paper contains some examples.

How easy would it be to support this pattern if we were to move borrowck to THIR after we switch to polonius? (If moving it to THIR is possible in the first place that is.)

Is this directed at me? The questions are about the run-time aliasing model, so borrowck has no bearing on this.

rfcbot · 2022-04-21T17:07:36Z

🔔 This is now entering its final comment period, as per the review above. 🔔

bjorn3 · 2022-04-21T17:08:28Z

Is this directed at me?

Not necessarily. Just throwing it out.

saethlin · 2022-04-22T01:23:03Z

How do we teach this? The only thing that I can imagine is that we now need to teach that "&mut requires uniqueness, except if you write code in waves hands this sort of pattern, in that case &mut isn't unique".

That does not sound good.

rdrpenguin04 · 2022-04-22T02:36:10Z

That's basically where I'm at.

Hello, I'm writing the borrow checker for LCCC, and this behavior seems underspecified. If someone could define why this pattern works, then I'd be all for allowing it; as it stands, this is a nightmare to be compatible with.

I strongly recommend holding off on removing this lint until we have a document specifying exactly why this is valid.

Edit: Okay, we do have a document, RFC 2025 (activating borrows). This should be put into documentation though; this is the first I had heard of two-phase borrows.

asquared31415 · 2022-04-22T02:51:22Z

I would like to point out that it is always sufficient as far as I am aware to transform the code that requires this:

    let mut v = vec![0, 1, 2];
    let shared = &v;
    v.push(shared.len());
    dbg!(v);

into code that instead uses a temporary binding for the inner expression:

    let mut v = vec![0, 1, 2];
    let shared = &v;
    let inner = shared.len();
    v.push(inner);
    dbg!(v);

and there is precedent for requiring users to rearrange code to satisfy the borrow checker or other things, such as reordering unique borrows to not overlap or creating a binding to hold a temporary.

rdrpenguin04 · 2022-04-22T03:18:35Z

To be fair, there is precedent for requiring reordering, but that's not something we should aspire to do. Once I learned the rules for activating borrows, it made sense; the only question now is teaching it, which should be doable.

rfcbot · 2022-05-01T17:12:34Z

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.

saethlin · 2022-05-01T19:23:38Z

So as long as we are okay with (in the worst case) not doing any alias-based optimizations on 2phase-borrows, we are fine.

@RalfJung does this mean it is incorrect to emit noalias for a &mut which is actually a 2-phase-borrow?

nikomatsakis · 2022-05-04T18:39:58Z

@rfcbot fcp reviewed

RalfJung · 2022-05-04T20:30:38Z

does this mean it is incorrect to emit noalias for a &mut which is actually a 2-phase-borrow?

Yes, but we don't currently do that. Function arguments are always proper mutable borrows, on the callee side.

nikomatsakis

r=me if the lint is deprecated "properly"

compiler/rustc_borrowck/src/lib.rs

nikomatsakis · 2022-05-04T18:43:56Z

compiler/rustc_lint_defs/src/builtin.rs

@@ -3179,7 +3145,6 @@ declare_lint_pass! {
        META_VARIABLE_MISUSE,
        DEPRECATED_IN_FUTURE,
        AMBIGUOUS_ASSOCIATED_ITEMS,
-        MUTABLE_BORROW_RESERVATION_CONFLICT,


I think we don't normally remove these altogether but rather move them to some list of deprecated lints ...

It gets registered as removed here: https://github.com/rust-lang/rust/pull/96268/files#diff-cfb1d20a5949dd50b9769edb62eaf10a0de66734637fe71d35bdcf8fb06d767bR494

jackh726 · 2022-05-05T18:31:57Z

@bors r=nikomatsakis rollup=iffy

Note to those that might try to add this to a rollup: tests might have changed that require a re-bless, but I'm not sure.

bors · 2022-05-05T18:31:59Z

📌 Commit 2300401 has been approved by nikomatsakis

bors · 2022-05-06T12:32:48Z

⌛ Testing commit 2300401 with merge 9a25164...

bors · 2022-05-06T14:53:16Z

☀️ Test successful - checks-actions
Approved by: nikomatsakis
Pushing 9a25164 to master...

rust-highfive · 2022-05-06T14:53:41Z

📣 Toolstate changed by #96268!

Tested on commit 9a25164.
Direct link to PR: #96268

💔 miri on windows: test-pass → test-fail (cc @oli-obk @RalfJung @eddyb).
💔 miri on linux: test-pass → test-fail (cc @oli-obk @RalfJung @eddyb).

@oli-obk

Tested on commit rust-lang/rust@9a25164. Direct link to PR: <rust-lang/rust#96268> 💔 miri on windows: test-pass → test-fail (cc @oli-obk @RalfJung @eddyb). 💔 miri on linux: test-pass → test-fail (cc @oli-obk @RalfJung @eddyb).

rust-timer · 2022-05-06T16:10:49Z

Finished benchmarking commit (9a25164): comparison url.

Summary:

Primary benchmarks: no relevant changes found
Secondary benchmarks: 🎉 relevant improvement found

	Regressions 😿 (primary)	Regressions 😿 (secondary)	Improvements 🎉 (primary)	Improvements 🎉 (secondary)	All 😿 🎉 (primary)
count¹	0	0	0	1	0
mean²	N/A	N/A	N/A	-1.7%	N/A
max	N/A	N/A	N/A	-1.7%	N/A

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

number of relevant changes ↩
the arithmetic mean of the percent change ↩

Pkgsrc changes: * adapt patches (libc crate version bump) * no longer pass -I/usr/pkg/include through via gcc-wrap script. Attempt at fixing version skew with curl package vs. internal version of curl. * new checksums Upstream changes: Version 1.62.0 (2022-06-30) ========================== Language -------- - [Stabilize `#[derive(Default)]` on enums with a `#[default]` variant][94457] - [Stop validating some checks in dead code after functions with uninhabited return types][93313] - [Fix constants not getting dropped if part of a diverging expression][94775] - [Support unit struct/enum variant in destructuring assignment][95380] - [Remove mutable_borrow_reservation_conflict lint and allow the code pattern][96268] Compiler -------- - [linker: Stop using whole-archive on dependencies of dylibs][96436] - [Make `unaligned_references` lint deny-by-default][95372] This lint is also a future compatibility lint, and is expected to eventually become a hard error. - [Only add codegen backend to dep info if -Zbinary-dep-depinfo is used][93969] - [Reject `#[thread_local]` attribute on non-static items][95006] - [Add tier 3 `aarch64-pc-windows-gnullvm` and `x86_64-pc-windows-gnullvm` targets\*][94872] - [Implement a lint to warn about unused macro rules][96150] - [Promote `x86_64-unknown-none` target to Tier 2\*][95705] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Move `CStr` to libcore, and `CString` to liballoc][94079] - [Windows: Use a pipe relay for chaining pipes][95841] - [Replace Linux Mutex and Condvar with futex based ones.][95035] - [Replace RwLock by a futex based one on Linux][95801] - [std: directly use pthread in UNIX parker implementation][96393] Stabilized APIs --------------- - [`bool::then_some`] - [`f32::total_cmp`] - [`f64::total_cmp`] - [`Stdin::lines`] - [`windows::CommandExt::raw_arg`] - [`impl<T: Default> Default for AssertUnwindSafe<T>`] - [`From<Rc<str>> for Rc<[u8]>`][rc-u8-from-str] - [`From<Arc<str>> for Arc<[u8]>`][arc-u8-from-str] - [`FusedIterator for EncodeWide`] - [RDM intrinsics on aarch64][stdarch/1285] Clippy ------ - [Create clippy lint against unexpectedly late drop for temporaries in match scrutinee expressions][94206] Cargo ----- - Added the `cargo add` command for adding dependencies to `Cargo.toml` from the command-line. [docs](https://doc.rust-lang.org/nightly/cargo/commands/cargo-add.html) - Package ID specs now support `name@version` syntax in addition to the previous `name:version` to align with the behavior in `cargo add` and other tools. `cargo install` and `cargo yank` also now support this syntax so the version does not need to passed as a separate flag. - The `git` and `registry` directories in Cargo's home directory (usually `~/.cargo`) are now marked as cache directories so that they are not included in backups or content indexing (on Windows). - Added automatic `@` argfile support, which will use "response files" if the command-line to `rustc` exceeds the operating system's limit. Compatibility Notes ------------------- - `cargo test` now passes `--target` to `rustdoc` if the specified target is the same as the host target. [#10594](rust-lang/cargo#10594) - [rustdoc: Remove .woff font files][96279] - [Enforce Copy bounds for repeat elements while considering lifetimes][95819] Internal Changes ---------------- - [Unify ReentrantMutex implementations across all platforms][96042] These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. [93313]: rust-lang/rust#93313 [93969]: rust-lang/rust#93969 [94079]: rust-lang/rust#94079 [94206]: rust-lang/rust#94206 [94457]: rust-lang/rust#94457 [94775]: rust-lang/rust#94775 [94872]: rust-lang/rust#94872 [95006]: rust-lang/rust#95006 [95035]: rust-lang/rust#95035 [95372]: rust-lang/rust#95372 [95380]: rust-lang/rust#95380 [95431]: rust-lang/rust#95431 [95705]: rust-lang/rust#95705 [95801]: rust-lang/rust#95801 [95819]: rust-lang/rust#95819 [95841]: rust-lang/rust#95841 [96042]: rust-lang/rust#96042 [96150]: rust-lang/rust#96150 [96268]: rust-lang/rust#96268 [96279]: rust-lang/rust#96279 [96393]: rust-lang/rust#96393 [96436]: rust-lang/rust#96436 [96557]: rust-lang/rust#96557 [`bool::then_some`]: https://doc.rust-lang.org/stable/std/primitive.bool.html#method.then_some [`f32::total_cmp`]: https://doc.rust-lang.org/stable/std/primitive.f32.html#method.total_cmp [`f64::total_cmp`]: https://doc.rust-lang.org/stable/std/primitive.f64.html#method.total_cmp [`Stdin::lines`]: https://doc.rust-lang.org/stable/std/io/struct.Stdin.html#method.lines [`impl<T: Default> Default for AssertUnwindSafe<T>`]: https://doc.rust-lang.org/stable/std/panic/struct.AssertUnwindSafe.html#impl-Default [rc-u8-from-str]: https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#impl-From%3CRc%3Cstr%3E%3E [arc-u8-from-str]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html#impl-From%3CArc%3Cstr%3E%3E [stdarch/1285]: rust-lang/stdarch#1285 [`windows::CommandExt::raw_arg`]: https://doc.rust-lang.org/stable/std/os/windows/process/trait.CommandExt.html#tymethod.raw_arg [`FusedIterator for EncodeWide`]: https://doc.rust-lang.org/stable/std/os/windows/ffi/struct.EncodeWide.html#impl-FusedIterator

Pkgsrc changes: * Bump required GCC to 7 (same as LLVM) to avoid ABI issues Fixes native i386 and powerpc 8.x build w/pkgsrc LLVM 14 * Bump available bootstraps to 1.61.0. * Also unlimit stacksize * Sync patches over from wip/rust * Adjust line number in patches which had non-zero offsets. * no longer pass -I/usr/pkg/include through via gcc-wrap script when building natively. Attempt at fixing version skew with curl package vs. internal version of curl (may not work...) * The NetBSD bootstraps now use .xz compression. * Use mk/atomic64.mk. Still have conditional for libatomic-links. * Default to using the internal LLVM when cross-building. Upstream changes: Version 1.62.1 (2022-07-19) ========================== Rust 1.62.1 addresses a few recent regressions in the compiler and standard library, and also mitigates a CPU vulnerability on Intel SGX. * [The compiler fixed unsound function coercions involving `impl Trait` return types.][98608] * [The compiler fixed an incremental compilation bug with `async fn` lifetimes.][98890] * [Windows added a fallback for overlapped I/O in synchronous reads and writes.][98950] * [The `x86_64-fortanix-unknown-sgx` target added a mitigation for the MMIO stale data vulnerability][98126], advisory [INTEL-SA-00615]. [98608]: rust-lang/rust#98608 [98890]: rust-lang/rust#98890 [98950]: rust-lang/rust#98950 [98126]: rust-lang/rust#98126 [INTEL-SA-00615]: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00615.html Version 1.62.0 (2022-06-30) ========================== Language -------- - [Stabilize `#[derive(Default)]` on enums with a `#[default]` variant][94457] - [Stop validating some checks in dead code after functions with uninhabited return types][93313] - [Fix constants not getting dropped if part of a diverging expression][94775] - [Support unit struct/enum variant in destructuring assignment][95380] - [Remove mutable_borrow_reservation_conflict lint and allow the code pattern][96268] Compiler -------- - [linker: Stop using whole-archive on dependencies of dylibs][96436] - [Make `unaligned_references` lint deny-by-default][95372] This lint is also a future compatibility lint, and is expected to eventually become a hard error. - [Only add codegen backend to dep info if -Zbinary-dep-depinfo is used][93969] - [Reject `#[thread_local]` attribute on non-static items][95006] - [Add tier 3 `aarch64-pc-windows-gnullvm` and `x86_64-pc-windows-gnullvm` targets\*][94872] - [Implement a lint to warn about unused macro rules][96150] - [Promote `x86_64-unknown-none` target to Tier 2\*][95705] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Move `CStr` to libcore, and `CString` to liballoc][94079] - [Windows: Use a pipe relay for chaining pipes][95841] - [Replace Linux Mutex and Condvar with futex based ones.][95035] - [Replace RwLock by a futex based one on Linux][95801] - [std: directly use pthread in UNIX parker implementation][96393] Stabilized APIs --------------- - [`bool::then_some`] - [`f32::total_cmp`] - [`f64::total_cmp`] - [`Stdin::lines`] - [`windows::CommandExt::raw_arg`] - [`impl<T: Default> Default for AssertUnwindSafe<T>`] - [`From<Rc<str>> for Rc<[u8]>`][rc-u8-from-str] - [`From<Arc<str>> for Arc<[u8]>`][arc-u8-from-str] - [`FusedIterator for EncodeWide`] - [RDM intrinsics on aarch64][stdarch/1285] Clippy ------ - [Create clippy lint against unexpectedly late drop for temporaries in match scrutinee expressions][94206] Cargo ----- - Added the `cargo add` command for adding dependencies to `Cargo.toml` from the command-line. [docs](https://doc.rust-lang.org/nightly/cargo/commands/cargo-add.html) - Package ID specs now support `name@version` syntax in addition to the previous `name:version` to align with the behavior in `cargo add` and other tools. `cargo install` and `cargo yank` also now support this syntax so the version does not need to passed as a separate flag. - The `git` and `registry` directories in Cargo's home directory (usually `~/.cargo`) are now marked as cache directories so that they are not included in backups or content indexing (on Windows). - Added automatic `@` argfile support, which will use "response files" if the command-line to `rustc` exceeds the operating system's limit. Compatibility Notes ------------------- - `cargo test` now passes `--target` to `rustdoc` if the specified target is the same as the host target. [#10594](rust-lang/cargo#10594) - [rustdoc: Remove .woff font files][96279] - [Enforce Copy bounds for repeat elements while considering lifetimes][95819] Internal Changes ---------------- - [Unify ReentrantMutex implementations across all platforms][96042] These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. [93313]: rust-lang/rust#93313 [93969]: rust-lang/rust#93969 [94079]: rust-lang/rust#94079 [94206]: rust-lang/rust#94206 [94457]: rust-lang/rust#94457 [94775]: rust-lang/rust#94775 [94872]: rust-lang/rust#94872 [95006]: rust-lang/rust#95006 [95035]: rust-lang/rust#95035 [95372]: rust-lang/rust#95372 [95380]: rust-lang/rust#95380 [95431]: rust-lang/rust#95431 [95705]: rust-lang/rust#95705 [95801]: rust-lang/rust#95801 [95819]: rust-lang/rust#95819 [95841]: rust-lang/rust#95841 [96042]: rust-lang/rust#96042 [96150]: rust-lang/rust#96150 [96268]: rust-lang/rust#96268 [96279]: rust-lang/rust#96279 [96393]: rust-lang/rust#96393 [96436]: rust-lang/rust#96436 [96557]: rust-lang/rust#96557 [`bool::then_some`]: https://doc.rust-lang.org/stable/std/primitive.bool.html#method.then_some [`f32::total_cmp`]: https://doc.rust-lang.org/stable/std/primitive.f32.html#method.total_cmp [`f64::total_cmp`]: https://doc.rust-lang.org/stable/std/primitive.f64.html#method.total_cmp [`Stdin::lines`]: https://doc.rust-lang.org/stable/std/io/struct.Stdin.html#method.lines [`impl<T: Default> Default for AssertUnwindSafe<T>`]: https://doc.rust-lang.org/stable/std/panic/struct.AssertUnwindSafe.html#impl-Default [rc-u8-from-str]: https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#impl-From%3CRc%3Cstr%3E%3E [arc-u8-from-str]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html#impl-From%3CArc%3Cstr%3E%3E [stdarch/1285]: rust-lang/stdarch#1285 [`windows::CommandExt::raw_arg`]: https://doc.rust-lang.org/stable/std/os/windows/process/trait.CommandExt.html#tymethod.raw_arg [`FusedIterator for EncodeWide`]: https://doc.rust-lang.org/stable/std/os/windows/ffi/struct.EncodeWide.html#impl-FusedIterator Version 1.61.0 (2022-05-19) ========================== Language -------- - [`const fn` signatures can now include generic trait bounds][93827] - [`const fn` signatures can now use `impl Trait` in argument and return position][93827] - [Function pointers can now be created, cast, and passed around in a `const fn`][93827] - [Recursive calls can now set the value of a function's opaque `impl Trait` return type][94081] Compiler -------- - [Linking modifier syntax in `#[link]` attributes and on the command line, as well as the `whole-archive` modifier specifically, are now supported][93901] - [The `char` type is now described as UTF-32 in debuginfo][89887] - The [`#[target_feature]`][target_feature] attribute [can now be used with aarch64 features][90621] - X86 [`#[target_feature = "adx"]` is now stable][93745] Libraries --------- - [`ManuallyDrop<T>` is now documented to have the same layout as `T`][88375] - [`#[ignore = "#"]` messages are printed when running tests][92714] - [Consistently show absent stdio handles on Windows as NULL handles][93263] - [Make `std::io::stdio::lock()` return `'static` handles.][93965] Previously, the creation of locked handles to stdin/stdout/stderr would borrow the handles being locked, which prevented writing `let out = std::io::stdout().lock();` because `out` would outlive the return value of `stdout()`. Such code now works, eliminating a common pitfall that affected many Rust users. - [`Vec::from_raw_parts` is now less restrictive about its inputs][95016] - [`std::thread::available_parallelism` now takes cgroup quotas into account.][92697] Since `available_parallelism` is often used to create a thread pool for parallel computation, which may be CPU-bound for performance, `available_parallelism` will return a value consistent with the ability to use that many threads continuously, if possible. For instance, in a container with 8 virtual CPUs but quotas only allowing for 50% usage, `available_parallelism` will return 4. Stabilized APIs --------------- - [`Pin::static_mut`] - [`Pin::static_ref`] - [`Vec::retain_mut`] - [`VecDeque::retain_mut`] - [`Write` for `Cursor<[u8; N]>`][cursor-write-array] - [`std::os::unix::net::SocketAddr::from_pathname`] - [`std::process::ExitCode`] and [`std::process::Termination`]. The stabilization of these two API s now makes it possible for programs to return errors from `main` with custom exit codes. - [`std::thread::JoinHandle::is_finished`] These APIs are now usable in const contexts: - [`<*const T>::offset` and `<*mut T>::offset`][ptr-offset] - [`<*const T>::wrapping_offset` and `<*mut T>::wrapping_offset`] [ptr-wrapping_offset] - [`<*const T>::add` and `<*mut T>::add`][ptr-add] - [`<*const T>::sub` and `<*mut T>::sub`][ptr-sub] - [`<*const T>::wrapping_add` and `<*mut T>::wrapping_add`][ptr-wrapping_add] - [`<*const T>::wrapping_sub` and `<*mut T>::wrapping_sub`][ptr-wrapping_sub] - [`<[T]>::as_mut_ptr`][slice-as_mut_ptr] - [`<[T]>::as_ptr_range`][slice-as_ptr_range] - [`<[T]>::as_mut_ptr_range`][slice-as_mut_ptr_range] Cargo ----- No feature changes, but see compatibility notes. Compatibility Notes ------------------- - Previously native static libraries were linked as `whole-archive` in some cases, but now rustc tries not to use `whole-archive` unless explicitly requested. This [change][93901] may result in linking errors in some cases. To fix such errors, native libraries linked from the command line, build scripts, or [`#[link]` attributes][link-attr] need to - (more common) either be reordered to respect dependencies between them (if `a` depends on `b` then `a` should go first and `b` second) - (less common) or be updated to use the [`+whole-archive`] modifier. - [Catching a second unwind from FFI code while cleaning up from a Rust panic now causes the process to abort][92911] - [Proc macros no longer see `ident` matchers wrapped in groups][92472] - [The number of `#` in `r#` raw string literals is now required to be less than 256][95251] - [When checking that a dyn type satisfies a trait bound, supertrait bounds are now enforced][92285] - [`cargo vendor` now only accepts one value for each `--sync` flag] [cargo/10448] - [`cfg` predicates in `all()` and `any()` are always evaluated to detect errors, instead of short-circuiting.][94295] The compatibility considerations here arise in nightly-only code that used the short-circuiting behavior of `all` to write something like `cfg(all(feature = "nightly", syntax-requiring-nightly))`, which will now fail to compile. Instead, use either `cfg_attr(feature = "nightly", ...)` or nested uses of `cfg`. - [bootstrap: static-libstdcpp is now enabled by default, and can now be disabled when llvm-tools is enabled][94832] Internal Changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [debuginfo: Refactor debuginfo generation for types][94261] - [Remove the everybody loops pass][93913] [88375]: rust-lang/rust#88375 [89887]: rust-lang/rust#89887 [90621]: rust-lang/rust#90621 [92285]: rust-lang/rust#92285 [92472]: rust-lang/rust#92472 [92697]: rust-lang/rust#92697 [92714]: rust-lang/rust#92714 [92911]: rust-lang/rust#92911 [93263]: rust-lang/rust#93263 [93745]: rust-lang/rust#93745 [93827]: rust-lang/rust#93827 [93901]: rust-lang/rust#93901 [93913]: rust-lang/rust#93913 [93965]: rust-lang/rust#93965 [94081]: rust-lang/rust#94081 [94261]: rust-lang/rust#94261 [94295]: rust-lang/rust#94295 [94832]: rust-lang/rust#94832 [95016]: rust-lang/rust#95016 [95251]: rust-lang/rust#95251 [`+whole-archive`]: https://doc.rust-lang.org/stable/rustc/command-line-arguments.html#linking-modifiers-whole-archive [`Pin::static_mut`]: https://doc.rust-lang.org/stable/std/pin/struct.Pin.html#method.static_mut [`Pin::static_ref`]: https://doc.rust-lang.org/stable/std/pin/struct.Pin.html#method.static_ref [`Vec::retain_mut`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.retain_mut [`VecDeque::retain_mut`]: https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.retain_mut [`std::os::unix::net::SocketAddr::from_pathname`]: https://doc.rust-lang.org/stable/std/os/unix/net/struct.SocketAddr.html#method.from_pathname [`std::process::ExitCode`]: https://doc.rust-lang.org/stable/std/process/struct.ExitCode.html [`std::process::Termination`]: https://doc.rust-lang.org/stable/std/process/trait.Termination.html [`std::thread::JoinHandle::is_finished`]: https://doc.rust-lang.org/stable/std/thread/struct.JoinHandle.html#method.is_finished [cargo/10448]: rust-lang/cargo#10448 [cursor-write-array]: https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#impl-Write-4 [link-attr]: https://doc.rust-lang.org/stable/reference/items/external-blocks.html#the-link-attribute [ptr-add]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.add [ptr-offset]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset [ptr-sub]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.sub [ptr-wrapping_add]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.wrapping_add [ptr-wrapping_offset]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.wrapping_offset [ptr-wrapping_sub]: https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.wrapping_sub [slice-as_mut_ptr]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.as_mut_ptr [slice-as_mut_ptr_range]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.as_mut_ptr_range [slice-as_ptr_range]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.as_ptr_range [target_feature]: https://doc.rust-lang.org/reference/attributes/codegen.html#the-target_feature-attribute

Remove mutable_borrow_reservation_conflict lint

2300401

rust-highfive assigned nikomatsakis Apr 21, 2022

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Apr 21, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 21, 2022

joshtriplett added T-lang Relevant to the language team, which will review and decide on the PR/issue. and removed T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 21, 2022

rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Apr 21, 2022

joshtriplett added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. and removed T-lang Relevant to the language team, which will review and decide on the PR/issue. labels Apr 21, 2022

rfcbot added the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label Apr 21, 2022

rfcbot removed the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Apr 21, 2022

pnkfelix mentioned this pull request Apr 26, 2022

Remove migrate borrowck mode #95565

Merged

RalfJung mentioned this pull request Apr 30, 2022

Stacked borrows: Mutable reference pops stack when created in some cases rust-lang/miri#2082

Closed

rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. to-announce Announce this issue on triage meeting and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels May 1, 2022

nikomatsakis requested changes May 5, 2022

View reviewed changes

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 May 5, 2022

apiraino removed the to-announce Announce this issue on triage meeting label May 6, 2022

bors added the merged-by-bors This PR was explicitly merged by bors. label May 6, 2022

bors merged commit 9a25164 into rust-lang:master May 6, 2022

rustbot added this to the 1.62.0 milestone May 6, 2022

rust-highfive mentioned this pull request May 6, 2022

miri no longer builds after rust-lang/rust#96268 #96773

Closed

jackh726 deleted the remove-mutable_borrow_reservation_conflict-lint branch May 6, 2022 15:02

TonalidadeHidrica mentioned this pull request May 23, 2022

Tracking issue for mutable_borrow_reservation_conflict compatibility lint #59159

Closed

3 tasks

saethlin mentioned this pull request Dec 12, 2022

Assigning Some instead of calling replace triggers Miri under some unsafe conditions rust-lang/miri#2722

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Remove mutable_borrow_reservation_conflict lint and allow the code pattern #96268

Remove mutable_borrow_reservation_conflict lint and allow the code pattern #96268

jackh726 commented Apr 21, 2022 •

edited

Loading

jackh726 commented Apr 21, 2022

pnkfelix commented Apr 21, 2022

pnkfelix commented Apr 21, 2022

joshtriplett commented Apr 21, 2022

rfcbot commented Apr 21, 2022 •

edited by cramertj

Loading

joshtriplett commented Apr 21, 2022

joshtriplett commented Apr 21, 2022

RalfJung commented Apr 21, 2022

jackh726 commented Apr 21, 2022

cramertj commented Apr 21, 2022

bjorn3 commented Apr 21, 2022

RalfJung commented Apr 21, 2022 •

edited

Loading

rfcbot commented Apr 21, 2022

bjorn3 commented Apr 21, 2022

saethlin commented Apr 22, 2022

rdrpenguin04 commented Apr 22, 2022 •

edited

Loading

asquared31415 commented Apr 22, 2022

rdrpenguin04 commented Apr 22, 2022

rfcbot commented May 1, 2022

saethlin commented May 1, 2022

nikomatsakis commented May 4, 2022

RalfJung commented May 4, 2022

nikomatsakis left a comment

nikomatsakis May 4, 2022

jackh726 May 5, 2022

jackh726 commented May 5, 2022

bors commented May 5, 2022

bors commented May 6, 2022

bors commented May 6, 2022

rust-highfive commented May 6, 2022

rust-timer commented May 6, 2022

Remove mutable_borrow_reservation_conflict lint and allow the code pattern #96268

Remove mutable_borrow_reservation_conflict lint and allow the code pattern #96268

Conversation

jackh726 commented Apr 21, 2022 • edited Loading

jackh726 commented Apr 21, 2022

pnkfelix commented Apr 21, 2022

pnkfelix commented Apr 21, 2022

joshtriplett commented Apr 21, 2022

rfcbot commented Apr 21, 2022 • edited by cramertj Loading

joshtriplett commented Apr 21, 2022

joshtriplett commented Apr 21, 2022

RalfJung commented Apr 21, 2022

jackh726 commented Apr 21, 2022

cramertj commented Apr 21, 2022

bjorn3 commented Apr 21, 2022

RalfJung commented Apr 21, 2022 • edited Loading

rfcbot commented Apr 21, 2022

bjorn3 commented Apr 21, 2022

saethlin commented Apr 22, 2022

rdrpenguin04 commented Apr 22, 2022 • edited Loading

asquared31415 commented Apr 22, 2022

rdrpenguin04 commented Apr 22, 2022

rfcbot commented May 1, 2022

saethlin commented May 1, 2022

nikomatsakis commented May 4, 2022

RalfJung commented May 4, 2022

nikomatsakis left a comment

Choose a reason for hiding this comment

nikomatsakis May 4, 2022

Choose a reason for hiding this comment

jackh726 May 5, 2022

Choose a reason for hiding this comment

jackh726 commented May 5, 2022

bors commented May 5, 2022

bors commented May 6, 2022

bors commented May 6, 2022

rust-highfive commented May 6, 2022

rust-timer commented May 6, 2022

Footnotes

jackh726 commented Apr 21, 2022 •

edited

Loading

rfcbot commented Apr 21, 2022 •

edited by cramertj

Loading

RalfJung commented Apr 21, 2022 •

edited

Loading

rdrpenguin04 commented Apr 22, 2022 •

edited

Loading