Strengthen invalid_value lint to forbid uninit primitives, adjust docs to say that's UB #98919

5225225 · 2022-07-05T09:02:22Z

This does not make it a FCW, but it does explicitly state in the docs that uninit integers are UB.

This also doesn't affect any runtime behavior, uninit u32's will still successfully be created through mem::uninitialized.

rust-highfive · 2022-07-05T09:02:27Z

r? @scottmcm

(rust-highfive has picked a reviewer for you, use r? to override)

rustbot · 2022-07-05T09:02:27Z

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library/core/src/mem/mod.rs

RalfJung · 2022-07-05T17:50:31Z

Gonna ?r

The syntax is "r?" not "?r" :)

RalfJung · 2022-07-05T18:09:27Z

Dear @rust-lang/lang, I would like to nominate this PR for discussion. I am asking that the following code is officially declared to have UB:

fn main() {
    let _val: i32 = mem::uninitialized();
}

That's just an example, of course -- this PR says that uninit memory at int, float, and raw pointer type is immediate UB, including inside tuples/arrays/structs/... (but not inside MaybeUninit, of course). This is the UCG discussion rust-lang/unsafe-code-guidelines#71.

We think this should be UB because

We already have a type, MaybeUninit, to handle uninitialized data. Integer types should be for integers, not arbitrary untyped data.
It will let us use the noundef attribute in LLVM, which can help with optimizations. Many optimizations, including ones that LLVM performs, are incorrect when inputs can be undef. LLVM is adding the noundef attribute to incrementally fix those optimizations by only performing them when inputs are know to not be undef. Clang is adding noundef to integer function arguments and return types, including char, which I do think is not justified by the C standard but anyway it makes the C/C++ equivalent of the above code have UB when compiled with clang.
It greatly simplifies the model of integers in an eventual Rust specification. If we allow uninit data in integers, we have to answer all sorts of new questions:
- When we load an int where some but not all bytes are uninit, and store it back, is that preserved exactly or is now the entire thing uninit?
- Do we allow any kind of operation on (partially) uninit integers, like arithmetic or comparison? When exactly is full initialization required?
In contrast, the model where integers must always be fully initialized, and MaybeUninit needs to be used for arbitrary untyped data, is a lot easier to teach.

The Reference has described this code as UB for a long time. Miri considers this code UB by default for about a month now, and my plan is to soon remove the flag that can opt-out of this UB (because it will enable some significant cleanup in the interpreter engine).

This PR removes the notes from the stdlib docs which call out uninitialized integers as not being finally decided yet. It also cranks up the (warn-by-default) invalid_value lint to trigger when mem::uninitialized() or MaybeUninit::uninit().assume_init() is used to create an uninitialized integer.

joshtriplett · 2022-07-12T18:15:14Z

Speaking only for myself, not for the lang team:

While I don't necessarily know that this pattern is the right way to specify it, I think we should have some (unsafe) mechanism to construct uninitialized or zeroed objects and freeze them. And one day when we have some of the safe-transmute infrastructure, we may have the traits or similar to be able to know when every bit pattern of a type is valid, and then we could have a safe mechanism to construct uninitialized or zeroed objects.

Would it help if MaybeUninit::assume_init() included an LLVM IR freeze instruction?

RalfJung · 2022-07-12T19:07:19Z

Would it help if MaybeUninit::assume_init() included an LLVM IR freeze instruction?

Help to achieve what? It would make the LLVM IR we generate for MaybeUninit::<i32>::uninit().assume_init() not UB any more even with noundef, if that's what you mean. Note however that LLVM freeeze acts on an SSA value, so we could not even easily use it for e.g. MaybeUninit<[i32; 128]>.

However, adding freeze to the language is a pretty fundamental change, that I think needs an RFC. Right now, it is impossible to observe the contents of uninitialized memory in well-defined Rust -- any attempt to do so would be UB. Once we have freeze, it will be possible for well-defined (probably even safe) Rust to observe the contents of freshly allocated memory. And as someone once said, that memory will either contain random garbage or your secret key, whichever of the two is worse for the current situation. So, I myself am fairly undecided about whether or not we should have freeze -- though I do currently expect that we will have it one day.

But I also think (a) that needs to be a deliberate decision on its own, not tied to whether any particular other operation is UB (i.e., I don't think we should entangle the freeze discussion with the discussion whether uninit integers are UB), and (b) I don't think assume_init should freeze; I think that should be done more explicitly (e.g. via a new MaybeUninit::uninit_frozen constructor, or so).

saethlin · 2022-07-12T23:46:24Z

I am not sure freezing the return value of MaybeUnint::assume_init adds much on top of other possibilities. It is possible to synthesize a valid bit pattern for all types (I think) except references, which we can't satisfy because they get dereferenceable and freeze doesn't help there.

RalfJung · 2022-07-13T00:02:52Z

It is possible to synthesize a valid bit pattern for all types (I think) except references,

And uninhabited types.
But that's slow, the idea with freeze is that it doesn't translate to any actual code.

joshtriplett · 2022-07-13T00:06:17Z

While I appreciate not wanting to entangle things unnecessarily, I think this is relevant for the question of whether an uninitialized integer should in fact be UB.

I personally would like zeroed memory to be safe, and uninitialized memory to be unsafe but sound.

RalfJung · 2022-07-13T00:24:18Z

uninitialized memory to be unsafe but sound.

That means never using noundef attributes for integer types. Also this violates our principle that unsafe is for UB concerns only. If it's not UB to do MaybeUninit::<i32>::uninit().assume_init() then it should be fine to expose this as a safe operation.

Btw, I am not sure how exactly you use the word "uninitialized". Memory that has been frozen is initialized, as far as I am concerned. Just to a non-deterministic value. That's how it would look like in a Rust spec, anyway. After all, MaybeUninit::<i32>::uninit() is not the only way to get uninit memory, so even if we make that function freeze, we still have to be able to talk about truly uninitiailized (unfrozen) memory.

Almost all code that uses integers is safe and has them fully initiailized. IMO it would be a bad idea to pessimize optimizations in that code (i.e., not have noundef) just because some tiny amount of code wants to deal with uninit memory. The cost for that should be borne by that niche code (via using MaybeUninit explicitly), not by everyone else.

RalfJung · 2022-07-13T00:31:25Z

Btw, I am not sure how exactly you use the word "uninitialized".

IOW, there is a difference between saying "uninit integers should be sound" and "MaybeUninit::<i32>::uninit() should be sound".

The first statement would also make code like this sound:

use std::alloc::{alloc, dealloc, Layout};

unsafe {
    let layout = Layout::new::<u16>();
    let ptr = alloc(layout);
    assert!(!ptr.is_null());
    let val = *ptr; // Is this line UB?
    assert!(val == 0 || val > 0); // If no, is this line UB? If no, can the assertion fail?
}

Or this code:

#[repr(C)]
struct S {
  f1: u16,
  f2: u32,
}

let s = S { f1: 0, f2: 0 };
let ptr = &s as *const S;
let ptr = s.cast::<u16>().wrapping_offset(1); // now it points at the padding between the fields
let val = unsafe { *ptr }; // Is this line UB?
assert!(val == 0 || val > 0); // If no, is this line UB? If no, can the assertion fail?

Is your objection that this code should also be allowed ("uninit integers should be sound"), or specifically about MaybeUninit::<i32>::uninit().assume_init()? Also I assume you want the integer returned by MaybeUninit::<i32>::uninit().assume_init() to be "sane" in the sense that, e.g. assert!(x < 0 || x >= 0) is well-defined and the assertion passes?

I feel rather strongly that the above two snippets must be UB. IMO supporting such wild things is not sufficient justification for removing noundef benefits for everyone else. That's what we have types for, after all: to express intent and invariants. We could of course have ReallyInitialized<i32> for code that wants to benefit from noundef, but that seems just silly.

scottmcm · 2022-07-16T07:18:20Z

As an example that I conveniently just hit, not being able to use noundef on parameters would penalize everyone using Layout -- which, via Vec/Box, is almost everyone. This optimization https://alive2.llvm.org/ce/z/XdagRK is only sound with the noundef -- remove it and Alive will point out the transformation is unsound. And that optimization is exactly what's needed to improve Layout after #95295. (I filed an LLVM issue for it in llvm/llvm-project#56562.)

I agree that uninit memory should be sound but unsafe. But to me that's called MaybeUninit<_> -- which, conveniently, is even safe to create and write to. That's a much nicer model to work with for both safe and unsafe code, since it means the soundness assertion is needed in the place that's actually capable of knowing that it's been initialized, rather than saying "yeah, yeah, I'll do that later" like mem::uninitialized::<u32>() is.

It's UB to pass uninit to essentially every standard library function, even unsafe fns. So requiring the type-level separation feels absolutely worth it.

I don't think we need freeze to accept this change. If we want freeze, then we could always add a different freeze_assume_valid or something. But a frozen &u32 doesn't really get you anything -- the frozen value could still violate the validity invariant. So really I think "no undef" being part of that validity invariant makes complete sense.

(I suppose we could have a freeze_as_bytes that gave you a [u8; sizeof(T)] that you could then validate yourself decide if it's usable. But that doesn't seem something that most unsafe code wants to do -- it'd much rather not have it get implicitly frozen, and have MIRI be able to say "hey, you didn't initialize this!" at the time it tries to use it.)

scottmcm · 2022-08-09T18:41:48Z

@rfcbot fcp merge

As Ralf said in #98919 (comment), I think we should do this.

For extra clarity, I don't think this says "we'll never have freeze". We can still have the possibility of a "get an unspecified but fixed bit pattern" functionality as a separate method in the future. I just don't think that MaybeUninit::assume_init (or, worse, mem::uninitialized::<i32>()) should be how that's spelled.

If we're defacto going to have to put noundef on non-MaybeUninit function parameters, then trying to carve out some sort of "well integers could be undef but not when you pass them as arguments" feels more troublesome than helpful.

rfcbot · 2022-08-09T18:41:50Z

Team member @scottmcm 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.

RalfJung · 2022-08-09T19:36:56Z

We can still have the possibility of a "get an unspecified but fixed bit pattern" functionality as a separate method in the future.

Definitely. I would imagine something like MaybeUninit::frozen(), which sits half-way between MaybeUninit::uninit() and MaybeUninit::zeroed(). Then MaybeUninit::<i32>::frozen().assume_init() would be defined behavior and return an unspecified but fixed integer, but MaybeUninit::<bool>::frozen().assume_init() would be UB since the arbitrary but fixed value might not be a valid bool.

5225225 · 2022-08-29T18:38:35Z

Checked out the rollup that this PR failed in and realised I do still need to bless some tests here (namely, the sanitizer ones, which aren't run in CI and I didn't have enabled locally either :) )

I'll fix that as soon as I can but for the time being i think it's best to @bors r-

seeing as this will fail rollups it's included in

rustbot · 2022-08-29T20:31:06Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

5225225 · 2022-08-29T20:34:16Z

Okay, that's fixed now, and running the tests locally passes (sanitizer leak.rs fails locally, but I can't see how that can possibly be affected by my change, so I'm just going to ignore that)

thomcc · 2022-08-29T21:02:30Z

I think @RalfJung used the wrong delegate syntax above.

@bors delegate+

bors · 2022-08-29T21:02:32Z

✌️ @5225225 can now approve this pull request

RalfJung · 2022-08-29T21:10:19Z

@bors r+ rollup=iffy

bors · 2022-08-29T21:10:20Z

📌 Commit be32460 has been approved by RalfJung

It is now in the queue for this repository.

bors · 2022-08-30T20:39:04Z

⌛ Testing commit be32460 with merge 02654a0...

bors · 2022-08-30T23:20:33Z

☀️ Test successful - checks-actions
Approved by: RalfJung
Pushing 02654a0 to master...

rust-timer · 2022-08-31T01:43:34Z

Finished benchmarking commit (02654a0): comparison URL.

Overall result: ✅ improvements - 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.

	mean¹	range	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.2%	[-1.2%, -1.2%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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

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.

	mean¹	range	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	6.0%	[6.0%, 6.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.8%	[-4.6%, -2.9%]	2
All ❌✅ (primary)	-	-	0

the arithmetic mean of the percent change ↩ ↩²
number of relevant changes ↩ ↩²

…fJung Strengthen invalid_value lint to forbid uninit primitives, adjust docs to say that's UB For context: rust-lang#66151 (comment) This does not make it a FCW, but it does explicitly state in the docs that uninit integers are UB. This also doesn't affect any runtime behavior, uninit u32's will still successfully be created through mem::uninitialized.

Pkgsrc changes: * We now manage to build for mipsel-unknown-netbsd, but despite the target spec saying cpu = "mips3", the compiler manages to emit 64-bit instructions which cause "illegal instruction" error. Will need more work. The mipsel-unknown-netbsd entry is commentd out since there is no 1.64.0 bootstrap. * Managed to retain the build of aarch64_be, llvm needed a patch to avoid use of neon instructions in the BE case (llvm doesn't support use of neon in BE mode). Ref. patch to src/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h. * The minimum gcc version is now 7.x, and that includes the cross-compiler for the targets. For i386 this also needs to /usr/include/gcc-7 include files in the target root, because immintrin.h from gcc 5 is not compatible with gcc 7.x. This applies for the targets where we build against a root from netbsd-8 (sparc64, powerpc, i386), and files/gcc-wrap gets a hack for this. * Pick up tweak for -latomic inclusion from rust-lang/rust#104220 and rust-lang/rust#104572 * Retain ability to do 32-bit NetBSD, by changing from 64 to 32 bit types in library/std/src/sys/unix/thread_parker/netbsd.rs. * I've struggled a bit to get the "openssl-src" build with -latomic where it's needed. I introduce "NetBSD-generic32" system type and use it for the NetBSD mipsel target. There is another attempt to do the same in the patch to vendor/openssl-sys/build/main.rs. * Bump bootstraps to 1.64.0, checksum updates. Upstream changes: Version 1.65.0 (2022-11-03) ========================== Language -------- - [Error on `as` casts of enums with `#[non_exhaustive]` variants] (rust-lang/rust#92744) - [Stabilize `let else`](rust-lang/rust#93628) - [Stabilize generic associated types (GATs)] (rust-lang/rust#96709) - [Add lints `let_underscore_drop`, `let_underscore_lock`, and `let_underscore_must_use` from Clippy] (rust-lang/rust#97739) - [Stabilize `break`ing from arbitrary labeled blocks ("label-break-value")] (rust-lang/rust#99332) - [Uninitialized integers, floats, and raw pointers are now considered immediate UB](rust-lang/rust#98919). Usage of `MaybeUninit` is the correct way to work with uninitialized memory. - [Stabilize raw-dylib for Windows x86_64, aarch64, and thumbv7a] (rust-lang/rust#99916) - [Do not allow `Drop` impl on foreign ADTs] (rust-lang/rust#99576) Compiler -------- - [Stabilize -Csplit-debuginfo on Linux] (rust-lang/rust#98051) - [Use niche-filling optimization even when multiple variants have data] (rust-lang/rust#94075) - [Associated type projections are now verified to be well-formed prior to resolving the underlying type] (rust-lang/rust#99217) - [Stringify non-shorthand visibility correctly] (rust-lang/rust#100350) - [Normalize struct field types when unsizing] (rust-lang/rust#101831) - [Update to LLVM 15](rust-lang/rust#99464) - [Fix aarch64 call abi to correctly zeroext when needed] (rust-lang/rust#97800) - [debuginfo: Generalize C++-like encoding for enums] (rust-lang/rust#98393) - [Add `special_module_name` lint] (rust-lang/rust#94467) - [Add support for generating unique profraw files by default when using `-C instrument-coverage`] (rust-lang/rust#100384) - [Allow dynamic linking for iOS/tvOS targets] (rust-lang/rust#100636) New targets: - [Add armv4t-none-eabi as a tier 3 target] (rust-lang/rust#100244) - [Add powerpc64-unknown-openbsd and riscv64-unknown-openbsd as tier 3 targets] (rust-lang/rust#101025) - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Don't generate `PartialEq::ne` in derive(PartialEq)] (rust-lang/rust#98655) - [Windows RNG: Use `BCRYPT_RNG_ALG_HANDLE` by default] (rust-lang/rust#101325) - [Forbid mixing `System` with direct system allocator calls] (rust-lang/rust#101394) - [Document no support for writing to non-blocking stdio/stderr] (rust-lang/rust#101416) - [`std::layout::Layout` size must not overflow `isize::MAX` when rounded up to `align`](rust-lang/rust#95295) This also changes the safety conditions on `Layout::from_size_align_unchecked`. Stabilized APIs --------------- - [`std::backtrace::Backtrace`] (https://doc.rust-lang.org/stable/std/backtrace/struct.Backtrace.html) - [`Bound::as_ref`] (https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.as_ref) - [`std::io::read_to_string`] (https://doc.rust-lang.org/stable/std/io/fn.read_to_string.html) - [`<*const T>::cast_mut`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_mut) - [`<*mut T>::cast_const`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_const) These APIs are now stable in const contexts: - [`<*const T>::offset_from`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from) - [`<*mut T>::offset_from`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from) Cargo ----- - [Apply GitHub fast path even for partial hashes] (rust-lang/cargo#10807) - [Do not add home bin path to PATH if it's already there] (rust-lang/cargo#11023) - [Take priority into account within the pending queue] (rust-lang/cargo#11032). This slightly optimizes job scheduling by Cargo, with typically small improvements on larger crate graph builds. Compatibility Notes ------------------- - [`std::layout::Layout` size must not overflow `isize::MAX` when rounded up to `align`] (rust-lang/rust#95295). This also changes the safety conditions on `Layout::from_size_align_unchecked`. - [`PollFn` now only implements `Unpin` if the closure is `Unpin`] (rust-lang/rust#102737). This is a possible breaking change if users were relying on the blanket unpin implementation. See discussion on the PR for details of why this change was made. - [Drop ExactSizeIterator impl from std::char::EscapeAscii] (rust-lang/rust#99880) This is a backwards-incompatible change to the standard library's surface area, but is unlikely to affect real world usage. - [Do not consider a single repeated lifetime eligible for elision in the return type] (rust-lang/rust#103450) This behavior was unintentionally changed in 1.64.0, and this release reverts that change by making this an error again. - [Reenable disabled early syntax gates as future-incompatibility lints] (rust-lang/rust#99935) - [Update the minimum external LLVM to 13] (rust-lang/rust#100460) - [Don't duplicate file descriptors into stdio fds] (rust-lang/rust#101426) - [Sunset RLS](rust-lang/rust#100863) - [Deny usage of `#![cfg_attr(..., crate_type = ...)]` to set the crate type] (rust-lang/rust#99784) This strengthens the forward compatibility lint deprecated_cfg_attr_crate_type_name to deny. - [`llvm-has-rust-patches` allows setting the build system to treat the LLVM as having Rust-specific patches] (rust-lang/rust#101072) This option may need to be set for distributions that are building Rust with a patched LLVM via `llvm-config`, not the built-in LLVM. 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 `x.sh` and `x.ps1` shell scripts] (rust-lang/rust#99992) - [compiletest: use target cfg instead of hard-coded tables] (rust-lang/rust#100260) - [Use object instead of LLVM for reading bitcode from rlibs] (rust-lang/rust#98100) - [Enable MIR inlining for optimized compilations] (rust-lang/rust#91743) This provides a 3-10% improvement in compiletimes for real world crates. See [perf results] (https://perf.rust-lang.org/compare.html?start=aedf78e56b2279cc869962feac5153b6ba7001ed&end=0075bb4fad68e64b6d1be06bf2db366c30bc75e1&stat=instructions:u).

Pkgsrc changes: * pkglint cleanups, bump bootstrap kits to 1.65.0. * New target: mipsel-unknown-netbsd, for cpu=mips32 with soft-float. * Managed to retain the build of aarch64_be, llvm needed a patch to avoid use of neon instructions in the BE case (llvm doesn't support use of neon in BE mode). Ref. patch to src/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h. Also submitted upstream of LLVM to the BLAKE3 maintainers. * The minimum gcc version is now 7.x, and that includes the cross-compiler for the targets. For i386 this also needs to /usr/include/gcc-7 include files in the target root, because immintrin.h from gcc 5 is not compatible with gcc 7.x. This applies for the targets where we build against a root from netbsd-8 (sparc64, powerpc, i386), and files/gcc-wrap gets a hack for this. * Pick up tweak for -latomic inclusion from rust-lang/rust#104220 and rust-lang/rust#104572 * Retain ability to do 32-bit NetBSD, by changing from 64 to 32 bit types in library/std/src/sys/unix/thread_parker/netbsd.rs. * I've tried to get the "openssl-src" build with -latomic where it's needed. I've introduced the "NetBSD-generic32" system type and use it for the NetBSD mipsel target. There is another attempt to do the same in the patch to vendor/openssl-sys/build/main.rs. Upstream changes: Version 1.66.1 (2023-01-10) =========================== - Added validation of SSH host keys for git URLs in Cargo ([CVE-2022-46176](https://www.cve.org/CVERecord?id=CVE-2022-46176)) Version 1.66.0 (2022-12-15) =========================== Language -------- - [Permit specifying explicit discriminants on all `repr(Int)` enums](rust-lang/rust#95710) ```rust #[repr(u8)] enum Foo { A(u8) = 0, B(i8) = 1, C(bool) = 42, } ``` - [Allow transmutes between the same type differing only in lifetimes](rust-lang/rust#101520) - [Change constant evaluation errors from a deny-by-default lint to a hard error](rust-lang/rust#102091) - [Trigger `must_use` on `impl Trait` for supertraits](rust-lang/rust#102287) This makes `impl ExactSizeIterator` respect the existing `#[must_use]` annotation on `Iterator`. - [Allow `..X` and `..=X` in patterns](rust-lang/rust#102275) - [Uplift `clippy::for_loops_over_fallibles` lint into rustc](rust-lang/rust#99696) - [Stabilize `sym` operands in inline assembly](rust-lang/rust#103168) - [Update to Unicode 15](rust-lang/rust#101912) - [Opaque types no longer imply lifetime bounds](rust-lang/rust#95474) This is a soundness fix which may break code that was erroneously relying on this behavior. Compiler -------- - [Add armv5te-none-eabi and thumbv5te-none-eabi tier 3 targets](rust-lang/rust#101329) - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. - [Add support for linking against macOS universal libraries](rust-lang/rust#98736) Libraries --------- - [Fix `#[derive(Default)]` on a generic `#[default]` enum adding unnecessary `Default` bounds](rust-lang/rust#101040) - [Update to Unicode 15](rust-lang/rust#101821) Stabilized APIs --------------- - [`proc_macro::Span::source_text`](https://doc.rust-lang.org/stable/proc_macro/struct.Span.html#method.source_text) - [`uX::{checked_add_signed, overflowing_add_signed, saturating_add_signed, wrapping_add_signed}`](https://doc.rust-lang.org/stable/std/primitive.u8.html#method.checked_add_signed) - [`iX::{checked_add_unsigned, overflowing_add_unsigned, saturating_add_unsigned, wrapping_add_unsigned}`](https://doc.rust-lang.org/stable/std/primitive.i8.html#method.checked_add_unsigned) - [`iX::{checked_sub_unsigned, overflowing_sub_unsigned, saturating_sub_unsigned, wrapping_sub_unsigned}`](https://doc.rust-lang.org/stable/std/primitive.i8.html#method.checked_sub_unsigned) - [`BTreeSet::{first, last, pop_first, pop_last}`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeSet.html#method.first) - [`BTreeMap::{first_key_value, last_key_value, first_entry, last_entry, pop_first, pop_last}`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html#method.first_key_value) - [Add `AsFd` implementations for stdio lock types on WASI.](rust-lang/rust#101768) - [`impl TryFrom<Vec<T>> for Box<[T; N]>`](https://doc.rust-lang.org/stable/std/boxed/struct.Box.html#impl-TryFrom%3CVec%3CT%2C%20Global%3E%3E-for-Box%3C%5BT%3B%20N%5D%2C%20Global%3E) - [`core::hint::black_box`](https://doc.rust-lang.org/stable/std/hint/fn.black_box.html) - [`Duration::try_from_secs_{f32,f64}`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.try_from_secs_f32) - [`Option::unzip`](https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.unzip) - [`std::os::fd`](https://doc.rust-lang.org/stable/std/os/fd/index.html) Rustdoc ------- - [Add Rustdoc warning for invalid HTML tags in the documentation](rust-lang/rust#101720) Cargo ----- - [Added `cargo remove` to remove dependencies from Cargo.toml](https://doc.rust-lang.org/nightly/cargo/commands/cargo-remove.html) - [`cargo publish` now waits for the new version to be downloadable before exiting](rust-lang/cargo#11062) See [detailed release notes](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-166-2022-12-15) for more. Compatibility Notes ------------------- - [Only apply `ProceduralMasquerade` hack to older versions of `rental`](rust-lang/rust#94063) - [Don't export `__heap_base` and `__data_end` on wasm32-wasi.](rust-lang/rust#102385) - [Don't export `__wasm_init_memory` on WebAssembly.](rust-lang/rust#102426) - [Only export `__tls_*` on wasm32-unknown-unknown.](rust-lang/rust#102440) - [Don't link to `libresolv` in libstd on Darwin](rust-lang/rust#102766) - [Update libstd's libc to 0.2.135 (to make `libstd` no longer pull in `libiconv.dylib` on Darwin)](rust-lang/rust#103277) - [Opaque types no longer imply lifetime bounds](rust-lang/rust#95474) This is a soundness fix which may break code that was erroneously relying on this behavior. - [Make `order_dependent_trait_objects` show up in future-breakage reports](rust-lang/rust#102635) - [Change std::process::Command spawning to default to inheriting the parent's signal mask](rust-lang/rust#101077) 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. - [Enable BOLT for LLVM compilation](rust-lang/rust#94381) - [Enable LTO for rustc_driver.so](rust-lang/rust#101403) Version 1.65.0 (2022-11-03) ========================== Language -------- - [Error on `as` casts of enums with `#[non_exhaustive]` variants] (rust-lang/rust#92744) - [Stabilize `let else`](rust-lang/rust#93628) - [Stabilize generic associated types (GATs)] (rust-lang/rust#96709) - [Add lints `let_underscore_drop`, `let_underscore_lock`, and `let_underscore_must_use` from Clippy] (rust-lang/rust#97739) - [Stabilize `break`ing from arbitrary labeled blocks ("label-break-value")] (rust-lang/rust#99332) - [Uninitialized integers, floats, and raw pointers are now considered immediate UB](rust-lang/rust#98919). Usage of `MaybeUninit` is the correct way to work with uninitialized memory. - [Stabilize raw-dylib for Windows x86_64, aarch64, and thumbv7a] (rust-lang/rust#99916) - [Do not allow `Drop` impl on foreign ADTs] (rust-lang/rust#99576) Compiler -------- - [Stabilize -Csplit-debuginfo on Linux] (rust-lang/rust#98051) - [Use niche-filling optimization even when multiple variants have data] (rust-lang/rust#94075) - [Associated type projections are now verified to be well-formed prior to resolving the underlying type] (rust-lang/rust#99217) - [Stringify non-shorthand visibility correctly] (rust-lang/rust#100350) - [Normalize struct field types when unsizing] (rust-lang/rust#101831) - [Update to LLVM 15](rust-lang/rust#99464) - [Fix aarch64 call abi to correctly zeroext when needed] (rust-lang/rust#97800) - [debuginfo: Generalize C++-like encoding for enums] (rust-lang/rust#98393) - [Add `special_module_name` lint] (rust-lang/rust#94467) - [Add support for generating unique profraw files by default when using `-C instrument-coverage`] (rust-lang/rust#100384) - [Allow dynamic linking for iOS/tvOS targets] (rust-lang/rust#100636) New targets: - [Add armv4t-none-eabi as a tier 3 target] (rust-lang/rust#100244) - [Add powerpc64-unknown-openbsd and riscv64-unknown-openbsd as tier 3 targets] (rust-lang/rust#101025) - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Don't generate `PartialEq::ne` in derive(PartialEq)] (rust-lang/rust#98655) - [Windows RNG: Use `BCRYPT_RNG_ALG_HANDLE` by default] (rust-lang/rust#101325) - [Forbid mixing `System` with direct system allocator calls] (rust-lang/rust#101394) - [Document no support for writing to non-blocking stdio/stderr] (rust-lang/rust#101416) - [`std::layout::Layout` size must not overflow `isize::MAX` when rounded up to `align`](rust-lang/rust#95295) This also changes the safety conditions on `Layout::from_size_align_unchecked`. Stabilized APIs --------------- - [`std::backtrace::Backtrace`] (https://doc.rust-lang.org/stable/std/backtrace/struct.Backtrace.html) - [`Bound::as_ref`] (https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.as_ref) - [`std::io::read_to_string`] (https://doc.rust-lang.org/stable/std/io/fn.read_to_string.html) - [`<*const T>::cast_mut`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_mut) - [`<*mut T>::cast_const`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_const) These APIs are now stable in const contexts: - [`<*const T>::offset_from`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from) - [`<*mut T>::offset_from`] (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from) Cargo ----- - [Apply GitHub fast path even for partial hashes] (rust-lang/cargo#10807) - [Do not add home bin path to PATH if it's already there] (rust-lang/cargo#11023) - [Take priority into account within the pending queue] (rust-lang/cargo#11032). This slightly optimizes job scheduling by Cargo, with typically small improvements on larger crate graph builds. Compatibility Notes ------------------- - [`std::layout::Layout` size must not overflow `isize::MAX` when rounded up to `align`] (rust-lang/rust#95295). This also changes the safety conditions on `Layout::from_size_align_unchecked`. - [`PollFn` now only implements `Unpin` if the closure is `Unpin`] (rust-lang/rust#102737). This is a possible breaking change if users were relying on the blanket unpin implementation. See discussion on the PR for details of why this change was made. - [Drop ExactSizeIterator impl from std::char::EscapeAscii] (rust-lang/rust#99880) This is a backwards-incompatible change to the standard library's surface area, but is unlikely to affect real world usage. - [Do not consider a single repeated lifetime eligible for elision in the return type] (rust-lang/rust#103450) This behavior was unintentionally changed in 1.64.0, and this release reverts that change by making this an error again. - [Reenable disabled early syntax gates as future-incompatibility lints] (rust-lang/rust#99935) - [Update the minimum external LLVM to 13] (rust-lang/rust#100460) - [Don't duplicate file descriptors into stdio fds] (rust-lang/rust#101426) - [Sunset RLS](rust-lang/rust#100863) - [Deny usage of `#![cfg_attr(..., crate_type = ...)]` to set the crate type] (rust-lang/rust#99784) This strengthens the forward compatibility lint deprecated_cfg_attr_crate_type_name to deny. - [`llvm-has-rust-patches` allows setting the build system to treat the LLVM as having Rust-specific patches] (rust-lang/rust#101072) This option may need to be set for distributions that are building Rust with a patched LLVM via `llvm-config`, not the built-in LLVM. 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 `x.sh` and `x.ps1` shell scripts] (rust-lang/rust#99992) - [compiletest: use target cfg instead of hard-coded tables] (rust-lang/rust#100260) - [Use object instead of LLVM for reading bitcode from rlibs] (rust-lang/rust#98100) - [Enable MIR inlining for optimized compilations] (rust-lang/rust#91743) This provides a 3-10% improvement in compiletimes for real world crates. See [perf results] (https://perf.rust-lang.org/compare.html?start=aedf78e56b2279cc869962feac5153b6ba7001ed&end=0075bb4fad68e64b6d1be06bf2db366c30bc75e1&stat=instructions:u).

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RalfJung mentioned this pull request Jul 5, 2022

Validity of integers and floating point rust-lang/unsafe-code-guidelines#71

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This was referenced Jul 5, 2022

Tracking issue for panics in mem::uninitialized/zeroed #66151

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Bump itoa version, don't use mem::uninit (0.13 backport) hyperium/hyper#2915

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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 Aug 9, 2022

scottmcm removed the I-lang-nominated Nominated for discussion during a lang team meeting. label Aug 11, 2022

Dylan-DPC mentioned this pull request Aug 27, 2022

Rollup of 7 pull requests #101092

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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 Aug 29, 2022

Fix tests due to stricter invalid_value

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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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 29, 2022

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 30, 2022

bors merged commit 02654a0 into rust-lang:master Aug 30, 2022

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This was referenced Aug 30, 2022

Add generic NonZero type. #100428

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panic-on-uninit: adjust checks to 0x01-filling #101061

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5225225 deleted the stricter-invalid-value branch August 31, 2022 11:02

RalfJung mentioned this pull request Aug 31, 2022

Adjust for supporting more implicit ptr-to-int transmutation rust-lang/miri#2516

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apiraino removed the to-announce Announce this issue on triage meeting label Sep 8, 2022

RalfJung mentioned this pull request Sep 19, 2022

Commit to safety rules for dyn trait upcasting #101336

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StevenJiang1110 mentioned this pull request Jul 17, 2024

The soundness problem in Pod trait due to uninitialized memory asterinas/asterinas#1060

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Strengthen invalid_value lint to forbid uninit primitives, adjust docs to say that's UB #98919

Strengthen invalid_value lint to forbid uninit primitives, adjust docs to say that's UB #98919

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rust-timer commented Aug 31, 2022

Strengthen invalid_value lint to forbid uninit primitives, adjust docs to say that's UB #98919

Strengthen invalid_value lint to forbid uninit primitives, adjust docs to say that's UB #98919

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Overall result: ✅ improvements - no action needed

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