allocator: refactor for stabilisation by nia-e · Pull Request #157428 · rust-lang/rust

nia-e · 2026-06-04T11:47:58Z

Adds my current proposal per the doc in #156882 and follow-up Zulip conversations (notably for dyn-compat) unstably.

r? libs

nia-e · 2026-06-04T14:08:19Z

Note that the no-panic bounds introduced close #156490 and #155746. However, if we want to relax them in the future, we may need to adjust our collection types to be more resilient.

clarfonthey · 2026-06-04T19:19:49Z

@rustbot author

(mostly so you can more clearly signal when you think things are ready; I've commented here already so I'll see any additional changes for review as they're made)

clarfonthey · 2026-08-13T12:01:22Z

Final review pass: I think that we've covered enough to merge this now. Everything is still unstable, but this should hopefully close the remaining soundness holes before stabilisation. If there are any minor details that need to be worked out, we can do that on stabilisation.

@bors r+

rust-bors · 2026-08-13T12:01:25Z

📌 Commit 7cab1f0 has been approved by clarfonthey

It is now in the queue for this repository.

allocator: refactor for stabilisation Adds my current proposal per the doc in #156882 and follow-up Zulip conversations (notably for [dyn-compat](https://rust-lang.zulipchat.com/#narrow/channel/197181-t-libs.2Fwg-allocators/topic/Allocator.20dyn-safety/near/599555822)) unstably. r? libs

rust-log-analyzer · 2026-08-13T15:31:18Z

The job aarch64-msvc-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

failures:

---- [debuginfo-cdb] tests\debuginfo\basic-stepping.rs#maximally-steppable stdout ----

error in revision `maximally-steppable`: check directive(s) from `C:\a\rust\rust\tests\debuginfo\basic-stepping.rs#maximally-steppable` not found in debugger output. errors:
    (basic-stepping.rs:130) `   [...]:     let i = [1,2,3,4];`
    (basic-stepping.rs:132) `   [...]:     let j = (23, "hi");`
    (basic-stepping.rs:134) `   [...]:     let k = 2..3;`
    (basic-stepping.rs:136) `   [...]:     let l = &i[k];`
    (basic-stepping.rs:138) `   [...]:     let m: *const() = &a;`
the following subset of check directive(s) was found successfully:
    (basic-stepping.rs:118) `>  147:     let mut c = 27;`
    (basic-stepping.rs:120) `>  148:     let d = c = 99;`
    (basic-stepping.rs:122) `>  149:     let e = "hi bob";`
    (basic-stepping.rs:124) `>  150:     let f = b"hi bob";`
    (basic-stepping.rs:126) `>  151:     let g = b'9';`
    (basic-stepping.rs:128) `>  152:     let h = ["whatever"; 8];`
status: exit code: 0
command: PATH="C:\a\rust\rust\build\aarch64-pc-windows-msvc\stage2\lib\rustlib\aarch64-pc-windows-msvc\lib;C:\Program Files (x86)\Windows Kits\10\bin\arm64;C:\Program Files (x86)\Windows Kits\10\bin\10.0.26100.0\arm64;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\bin\HostARM64\arm64;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\bin\HostARM64\arm64;C:\Program Files\Git\clangarm64\bin;C:\Program Files\Git\usr\bin;C:\Users\runneradmin\bin;C:\a\rust\rust\ninja;C:\a\rust\rust\citools\clang-rust\bin;C:\a\rust\rust\sccache;C:\aliyun-cli;C:\vcpkg;C:\tools\zstd;C:\Program Files (x86)\NSIS;C:\Program Files\Mercurial;C:\hostedtoolcache\windows\stack\3.11.1\x64;C:\mingw64\bin;C:\Program Files\dotnet;C:\Program Files\MySQL\MySQL Server 8.0\bin;C:\Program Files (x86)\R\R-4.6.1\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\SeleniumWebDrivers\EdgeDriver;C:\SeleniumWebDrivers\ChromeDriver;C:\Program Files (x86)\sbt\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\usr\bin;C:\Program Files (x86)\pipx_bin;C:\npm\prefix;C:\hostedtoolcache\windows\go\1.24.13\arm64\bin;C:\hostedtoolcache\windows\Python\3.13.14\arm64\Scripts;C:\hostedtoolcache\windows\Python\3.13.14\arm64;C:\hostedtoolcache\windows\Ruby\3.4.10\aarch64\bin;C:\Program Files\LLVM\bin;C:\Program Files\OpenSSL\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\21.0.12-8.0\aarch64\bin;C:\Tools\Ninja;C:\Program Files (x86)\ImageMagick-7.1.2-Q16-HDRI;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\ProgramData\Chocolatey\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0;C:\Windows\System32\OpenSSH;C:\Program Files\PowerShell\7;C:\Program Files\Microsoft\Web Platform Installer;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn;C:\Program Files\Microsoft SQL Server\150\Tools\Binn;C:\Program Files\dotnet;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit;C:\Program Files\Microsoft SQL Server\130\DTS\Binn;C:\Program Files\Microsoft SQL Server\140\DTS\Binn;C:\Program Files\Microsoft SQL Server\150\DTS\Binn;C:\Program Files\Microsoft SQL Server\160\DTS\Binn;C:\Program Files\Microsoft SQL Server\170\DTS\Binn;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\CMake\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.9.16\bin;C:\Program Files\nodejs;C:\Program Files\Git\cmd;C:\Program Files\Git\clangarm64\bin;C:\Program Files\Git\usr\bin;C:\Program Files\GitHub CLI;C:\tools\php;C:\Program Files (x86)\sbt\bin;C:\Program Files\Amazon\AWSCLIV2;C:\Program Files\Amazon\SessionManagerPlugin\bin;C:\Program Files\Amazon\AWSSAMCLI\bin;C:\Program Files\Microsoft SQL Server\130\Tools\Binn;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\.cargo\bin;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps" "C:\\Program Files (x86)\\Windows Kits\\10\\Debuggers\\arm64\\cdb.exe" "-lines" "-cf" "C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\test\\debuginfo\\basic-stepping.maximally-steppable.cdb\\basic-stepping.debugger.script" "C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\test\\debuginfo\\basic-stepping.maximally-steppable.cdb\\a.exe"
--- stdout -------------------------------

************* Preparing the environment for Debugger Extensions Gallery repositories **************
   ExtensionRepository : Implicit
   UseExperimentalFeatureForNugetShare : true
   AllowNugetExeUpdate : true
   NonInteractiveNuget : true
   AllowNugetMSCredentialProviderInstall : true
   AllowParallelInitializationOfLocalRepositories : true

   EnableRedirectToV8JsProvider : false

   -- Configuring repositories
      ----> Repository : LocalInstalled, Enabled: true
      ----> Repository : UserExtensions, Enabled: true

>>>>>>>>>>>>> Preparing the environment for Debugger Extensions Gallery repositories completed, duration 0.000 seconds

************* Waiting for Debugger Extensions Gallery to Initialize **************

>>>>>>>>>>>>> Waiting for Debugger Extensions Gallery to Initialize completed, duration 0.172 seconds
   ----> Repository : UserExtensions, Enabled: true, Packages count: 0
   ----> Repository : LocalInstalled, Enabled: true, Packages count: 27

Microsoft (R) Windows Debugger Version 10.0.26100.6584 ARM64
Copyright (c) Microsoft Corporation. All rights reserved.

CommandLine: C:\a\rust\rust\build\aarch64-pc-windows-msvc\test\debuginfo\basic-stepping.maximally-steppable.cdb\a.exe

************* Path validation summary **************
Response                         Time (ms)     Location
Deferred                                       srv*
Symbol search path is: srv*
Executable search path is: 
ModLoad: 00007ff6`43260000 00007ff6`43267000   a.exe   
ModLoad: 00007ffc`951b0000 00007ffc`955e7000   ntdll.dll
ModLoad: 00007ffc`92e10000 00007ffc`92f79000   C:\Windows\System32\KERNEL32.DLL
ModLoad: 00007ffc`907a0000 00007ffc`90e79000   C:\Windows\System32\KERNELBASE.dll
ModLoad: 00007ffc`900b0000 00007ffc`901b6000   C:\Windows\SYSTEM32\apphelp.dll
ModLoad: 00007ffc`90500000 00007ffc`90729000   C:\Windows\System32\ucrtbase.dll
ModLoad: 00007ffc`653e0000 00007ffc`654d3000   C:\a\rust\rust\build\aarch64-pc-windows-msvc\stage2\lib\rustlib\aarch64-pc-windows-msvc\lib\std-866f11ed616f593f.dll
ModLoad: 00007ffc`930b0000 00007ffc`93186000   C:\Windows\System32\WS2_32.dll
ModLoad: 00007ffc`93630000 00007ffc`93833000   C:\Windows\System32\RPCRT4.dll
ModLoad: 00007ffc`90e80000 00007ffc`90f7f000   C:\Windows\System32\bcryptprimitives.dll
ModLoad: 00007ffc`79ab0000 00007ffc`79aef000   C:\Windows\SYSTEM32\VCRUNTIME140.dll
ModLoad: 00007ffc`8ec60000 00007ffc`8ecbf000   C:\Windows\SYSTEM32\USERENV.dll
(950.828): Break instruction exception - code 80000003 (first chance)
ntdll!LdrpDoDebuggerBreak+0x34:
00007ffc`9530d5a4 d43e0000 brk         #0xF000
0:000> version
Windows 10 Version 26200 MP (4 procs) Free ARM 64-bit (AArch64)
Product: WinNt, suite: SingleUserTS
Edition build lab: 26100.1.arm64fre.ge_release.240331-1435
Build layer: DesktopEditions -> 26100.1.arm64fre.ge_release.240331-1435
Build layer: OnecoreUAP -> 26100.1.arm64fre.ge_release.240331-1435
Build layer: ShellCommon -> 26100.8875.arm64fre.ge_release_svc_prod1.260710-1804
Build layer: OSClient   -> 26100.8875.arm64fre.ge_release_svc_prod1.260710-1804
Debug session time: Thu Aug 13 15:29:53.443 2026 (UTC + 0:00)
System Uptime: 0 days 2:11:09.134
Process Uptime: 0 days 0:00:01.223
  Kernel time: 0 days 0:00:00.000
  User time: 0 days 0:00:00.000
Live user mode: <Local>

Microsoft (R) Windows Debugger Version 10.0.26100.6584 ARM64
Copyright (c) Microsoft Corporation. All rights reserved.

command line: '"C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\cdb.exe" -lines -cf C:\a\rust\rust\build\aarch64-pc-windows-msvc\test\debuginfo\basic-stepping.maximally-steppable.cdb\basic-stepping.debugger.script C:\a\rust\rust\build\aarch64-pc-windows-msvc\test\debuginfo\basic-stepping.maximally-steppable.cdb\a.exe'  Debugger Process 0x13EC 
dbgeng:  image 10.0.26100.6584, 
        [path: C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\dbgeng.dll]
dbghelp: image 10.0.26100.7705, 
        [path: C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\dbghelp.dll]
        DIA version: 33145
Extension DLL search Path:
    C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\WINXP;C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\winext;C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\winext\arcade;C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\pri;C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64;C:\Users\runneradmin\AppData\Local\Dbg\EngineExtensions;C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64;C:\a\rust\rust\build\aarch64-pc-windows-msvc\stage2\lib\rustlib\aarch64-pc-windows-msvc\lib;C:\Program Files (x86)\Windows Kits\10\bin\arm64;C:\Program Files (x86)\Windows Kits\10\bin\10.0.26100.0\arm64;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\bin\HostARM64\arm64;C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\bin\HostARM64\arm64;C:\Program Files\Git\clangarm64\bin;C:\Program Files\Git\usr\bin;C:\Users\runneradmin\bin;C:\a\rust\rust\ninja;C:\a\rust\rust\citools\clang-rust\bin;C:\a\rust\rust\sccache;C:\aliyun-cli;C:\vcpkg;C:\tools\zstd;C:\Program Files (x86)\NSIS;C:\Program Files\Mercurial;C:\hostedtoolcache\windows\stack\3.11.1\x64;C:\mingw64\bin;C:\Program Files\dotnet;C:\Program Files\MySQL\MySQL Server 8.0\bin;C:\Program Files (x86)\R\R-4.6.1\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\SeleniumWebDrivers\EdgeDriver;C:\SeleniumWebDrivers\ChromeDriver;C:\Program Files (x86)\sbt\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\usr\bin;C:\Program Files (x86)\pipx_bin;C:\npm\prefix;C:\hostedtoolcache\windows\go\1.24.13\arm64\bin;C:\hostedtoolcache\windows\Python\3.13.14\arm64\Scripts;C:\hostedtoolcache\windows\Python\3.13.14\arm64;C:\hostedtoolcache\windows\Ruby\3.4.10\aarch64\bin;C:\Program Files\LLVM\bin;C:\Program Files\OpenSSL\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\21.0.12-8.0\aarch64\bin;C:\Tools\Ninja;C:\Program Files (x86)\ImageMagick-7.1.2-Q16-HDRI;C:\Program Files\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\ProgramData\Chocolatey\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0;C:\Windows\System32\OpenSSH;C:\Program Files\PowerShell\7;C:\Program Files\Microsoft\Web Platform Installer;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn;C:\Program Files\Microsoft SQL Server\150\Tools\Binn;C:\Program Files\dotnet;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit;C:\Program Files\Microsoft SQL Server\130\DTS\Binn;C:\Program Files\Microsoft SQL Server\140\DTS\Binn;C:\Program Files\Microsoft SQL Server\150\DTS\Binn;C:\Program Files\Microsoft SQL Server\160\DTS\Binn;C:\Program Files\Microsoft SQL Server\170\DTS\Binn;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\CMake\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.9.16\bin;C:\Program Files\nodejs;C:\Program Files\Git\cmd;C:\Program Files\Git\clangarm64\bin;C:\Program Files\Git\usr\bin;C:\Program Files\GitHub CLI;C:\tools\php;C:\Program Files (x86)\sbt\bin;C:\Program Files\Amazon\AWSCLIV2;C:\Program Files\Amazon\SessionManagerPlugin\bin;C:\Program Files\Amazon\AWSSAMCLI\bin;C:\Program Files\Microsoft SQL Server\130\Tools\Binn;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\.cargo\bin;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps
Extension DLL chain:
    dbghelp: image 10.0.26100.7705, API 10.0.6, 
        [path: C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\dbghelp.dll]
    exts: image 10.0.26100.6584, API 1.0.0, 
        [path: C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\WINXP\exts.dll]
    uext: image 10.0.26100.6584, API 1.0.0, 
        [path: C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\winext\uext.dll]
    ntsdexts: image 10.0.26100.6584, API 1.0.0, 
        [path: C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\WINXP\ntsdexts.dll]
0:000> .nvlist
Loaded NatVis Files:
    <None Loaded>
0:000> bp `basic-stepping.rs:143`
*** WARNING: Unable to verify checksum for a.exe
*** WARNING: Unable to verify checksum for C:\a\rust\rust\build\aarch64-pc-windows-msvc\stage2\lib\rustlib\aarch64-pc-windows-msvc\lib\std-866f11ed616f593f.dll
0:000>  .lines -e
Line number information will be loaded
0:000>  l+s
Source options are 4:
     4/s - List source code at prompt
0:000>  l+t
Source options are 5:
     1/t - Step/trace by source line
     4/s - List source code at prompt
0:000>  g
Breakpoint 0 hit
>  147:     let mut c = 27;
a!basic_stepping::main+0x10:
00007ff6`432610ec d10203a9 sub         x9,fp,#0x80
0:000>  p
>  148:     let d = c = 99;
a!basic_stepping::main+0x20:
00007ff6`432610fc 52800c68 mov         w8,#0x63
0:000>  p
>  149:     let e = "hi bob";
a!basic_stepping::main+0x30:
00007ff6`4326110c aa0803ea mov         x10,x8
0:000>  p
>  150:     let f = b"hi bob";
a!basic_stepping::main+0x40:
00007ff6`4326111c f9002128 str         x8,[x9,#0x40]
0:000>  p
>  151:     let g = b'9';
a!basic_stepping::main+0x44:
00007ff6`43261120 52800728 mov         w8,#0x39
0:000>  p
>  152:     let h = ["whatever"; 8];
a!basic_stepping::main+0x4c:
00007ff6`43261128 9100a3e8 add         x8,sp,#0x28
0:000>  p
ModLoad: 00007ffc`8e2b0000 00007ffc`8e2e1000   C:\Windows\SYSTEM32\kernel.appcore.dll
ModLoad: 00007ffc`916c0000 00007ffc`91808000   C:\Windows\System32\msvcrt.dll
ntdll!NtTerminateProcess+0x4:
00007ffc`951b1304 d65f03c0 ret
0:000>  p
        ^ No runnable debuggees error in ' p'
0:000>  p
        ^ No runnable debuggees error in ' p'
0:000>  p
        ^ No runnable debuggees error in ' p'
0:000>  p
        ^ No runnable debuggees error in ' p'
0:000>  p
        ^ No runnable debuggees error in ' p'
0:000> qq
quit:
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\atlmfc.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\ObjectiveC.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\concurrency.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\cpp_rest.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\stl.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\Windows.Data.Json.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\Windows.Devices.Geolocation.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\Windows.Devices.Sensors.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\Windows.Media.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\windows.natvis'
NatVis script unloaded from 'C:\Program Files (x86)\Windows Kits\10\Debuggers\arm64\Visualizers\winrt.natvis'
------------------------------------------
stderr: none

---- [debuginfo-cdb] tests\debuginfo\basic-stepping.rs#maximally-steppable stdout end ----

---
Currently active steps:
test::Debuginfo { test_compiler: Compiler { stage: 2, host: aarch64-pc-windows-msvc, forced_compiler: false }, target: aarch64-pc-windows-msvc } at src\bootstrap\src\core\build_steps\test.rs:1953
test::Compiletest { test_compiler: Compiler { stage: 2, host: aarch64-pc-windows-msvc, forced_compiler: false }, target: aarch64-pc-windows-msvc, mode: debuginfo, suite: "debuginfo", path: "tests/debuginfo", compare_mode: Some("split-dwarf") } at src\bootstrap\src\core\build_steps\test.rs:1953
Build completed unsuccessfully in 1:15:35
make: *** [Makefile:115: ci-msvc-py] Error 1
  local time: Thu Aug 13 15:30:28 CUT 2026
  network time: Thu, 13 Aug 2026 15:30:28 GMT
##[error]Process completed with exit code 2.
##[group]Run echo "disk usage:"
echo "disk usage:"

rust-bors · 2026-08-13T15:32:57Z

💔 Test for 34b13a0 failed: CI. Failed job:

auto - aarch64-msvc-1 (web logs, enhanced plaintext logs)

theemathas · 2026-08-13T15:44:31Z

Probably spurious.

@bors r=clarfonthey

rust-bors · 2026-08-13T15:44:35Z

📌 Commit 7cab1f0 has been approved by clarfonthey

It is now in the queue for this repository.

A failed build status on this PR was cleared due to the approval.

…nthey allocator: refactor for stabilisation Adds my current proposal per the doc in rust-lang#156882 and follow-up Zulip conversations (notably for [dyn-compat](https://rust-lang.zulipchat.com/#narrow/channel/197181-t-libs.2Fwg-allocators/topic/Allocator.20dyn-safety/near/599555822)) unstably. r? libs

…uwer Rollup of 17 pull requests Successful merges: - #161045 (stdarch subtree update) - #157428 (allocator: refactor for stabilisation) - #158918 (x86_64-win: Enable f128 on LLVM 23+) - #160288 (rustdoc: use anonymous constant for primitives/keywords/attribute docs) - #160440 (Couple of misc improvements to the unwind infrastructure) - #160441 (PowerPC inline ASM: Fix scalar floats being in the wrong vector lane on little endian) - #160896 (tidy: Update Python version requirements to 3.11) - #160972 (std: map ERROR_NEGATIVE_SEEK to ErrorKind::InvalidInput on Windows) - #161040 (Optimize CStr backing slice bounds checks) - #160928 (check `mut`-restriction when tuple constructor is used as a value) - #160969 (give layout errors from `size_of_val` and `align_of_val` a span) - #161002 (disallow `#[cold]` on `extern "custom"` functions) - #161016 (Fix invalid suggestion from try unlabled block) - #161020 (io: Use `NonNull` for all `Custom` API related to `Box`, update documentation for `Custom`) - #161044 (rustc-dev-guide subtree update) - #161046 (Enable unrolling feature of bors) - #161054 (rustdoc: Fix link title attribute value when field of enum variants)

Rollup of 23 pull requests Successful merges: - #157428 (allocator: refactor for stabilisation) - #158918 (x86_64-win: Enable f128 on LLVM 23+) - #160077 (Don't compute FnAbi for LLVM intrinsics) - #160288 (rustdoc: use anonymous constant for primitives/keywords/attribute docs) - #160440 (Couple of misc improvements to the unwind infrastructure) - #160896 (tidy: Update Python version requirements to 3.11) - #160972 (std: map ERROR_NEGATIVE_SEEK to ErrorKind::InvalidInput on Windows) - #160984 (Fix ICE on { _ } const args in bodies by tracking const-only infer args) - #161036 (Use `with_types_for_suggestion!` in `write_struct_like()`) - #161037 (std: don't clean up the main thread's altstack) - #161040 (Optimize CStr backing slice bounds checks) - #161065 (core: Fix a typo in funnel shift documentation) - #158885 (Add `core::num::Complex`) - #160928 (check `mut`-restriction when tuple constructor is used as a value) - #160969 (give layout errors from `size_of_val` and `align_of_val` a span) - #161002 (disallow `#[cold]` on `extern "custom"` functions) - #161016 (Fix invalid suggestion from try unlabled block) - #161020 (io: Use `NonNull` for all `Custom` API related to `Box`, update documentation for `Custom`) - #161044 (rustc-dev-guide subtree update) - #161046 (Enable unrolling feature of bors) - #161054 (rustdoc: Fix link title attribute value when field of enum variants) - #161055 (`offload!` function-like macro) - #161064 (Revert "riscv: promote d, e, and f target_features to CfgStableToggleUnstable")

Rollup merge of #157428 - nia-e:allocator-refactor, r=clarfonthey allocator: refactor for stabilisation Adds my current proposal per the doc in #156882 and follow-up Zulip conversations (notably for [dyn-compat](https://rust-lang.zulipchat.com/#narrow/channel/197181-t-libs.2Fwg-allocators/topic/Allocator.20dyn-safety/near/599555822)) unstably. r? libs

rust-timer · 2026-08-14T16:15:21Z

Finished benchmarking commit (364c9de): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never rustc-perf
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.5%	[0.4%, 0.6%]	3
Regressions ❌ (secondary)	0.4%	[0.3%, 0.6%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.6%]	1
All ❌✅ (primary)	0.5%	[0.4%, 0.6%]	3

Max RSS (memory usage)

Results (secondary -2.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.1%	[-2.1%, -2.1%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (primary -3.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.7%	[-3.7%, -3.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-3.7%	[-3.7%, -3.7%]	1

Binary size

Results (primary 0.1%, secondary 0.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.2%]	3
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	3
Improvements ✅ (primary)	-0.0%	[-0.0%, -0.0%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[-0.0%, 0.2%]	5

Bootstrap: 455.615s -> 456.684s (0.23%)
Artifact size: 396.47 MiB -> 396.34 MiB (-0.03%)

clarfonthey · 2026-08-14T20:38:19Z

Yeah, that just looks like noise to me.

@rustbot label perf-triaged

rustbot · 2026-08-14T20:38:22Z

Error: Unknown labels: perf-triaged

Please file an issue on GitHub at triagebot if there's a problem with this bot, or reach out on #triagebot on Zulip.

rustbot assigned clarfonthey Jun 4, 2026

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nia-e added the A-allocators Area: Custom and system allocators label Jun 4, 2026

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theemathas mentioned this pull request Jun 5, 2026

Add more safety requirements for Allocator impls #156544

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JonathanBrouwer mentioned this pull request Aug 13, 2026

Rollup of 17 pull requests #161066

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jhpratt mentioned this pull request Aug 13, 2026

Rollup of 23 pull requests #161075

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rust-bors Bot merged commit b5bd618 into rust-lang:main Aug 14, 2026
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rustbot added the perf-regression Performance regression. label Aug 14, 2026

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nia-e mentioned this pull request Aug 14, 2026

Assorted allocator nitpicks #161115

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rust-timer commented Aug 14, 2026

Overall result: ❌✅ regressions and improvements - please read:

Instruction count

Max RSS (memory usage)

Cycles

Binary size

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