Track caller of slice split and swap

[kornelski]

Improves error location for slice.split_at*() and slice.swap().

These are generic inline functions, so the #[track_caller] on them is free — only changes a value of an argument already passed to panicking code.

[rust-highfive]

r? @kennytm

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[joshtriplett]

@bors r+ rollup=never

[bors]

📌 Commit 084ea21 has been approved by joshtriplett

[nrc]

I'm not clear on the motivation for this change - aiui, track_caller is meant for functions like unwrap which are basically panic boilerplate. In the case of the split/swap functions, this isn't the case. The justification I can thing of is that these are small functions in the standard library and we can assume they don't have bugs in, therefore the bug must be in the calling code. But that seems like an argument that can be made about half of std. So, is this part of a larger plan to apply track_caller across std, or is there something special about split/swap which I'm missing?

[kornelski]

The reason is exactly the same as for unwrap: these methods are also panicking, and the panic needs a proper location.

Currently these methods report invalid input as their own internal failure:

'assertion failed: mid <= self.len()', /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/slice/mod.rs:1537:9

Which is unhelpful and from user perspective shows an irrelevant location.

Other slice methods like clone_from_slice and swap_with_slice have already been fixed to report better locations.

I think from usability perspective track_caller should be used on all std functions that check user input using assertions. However, I'm not adding these wholesale out of caution, in case it added runtime overhead. For the functions I've checked that it doesn't.

[nrc]

Thanks for the explanation, so to paraphrase for my own understanding, the plan is to add track_caller to all functions which potentially panic only on precondition violations and where there is no runtime overhead?

[kornelski]

Yes, I think it would be good to add track_caller to all functions that need it and can have it at zero cost.

However, I'm sensing you're pushing back against this, so I'm not insisting that all of them need to be changed, I'm just focusing on the cases I've ran into in the real world.

[bors]

⌛ Testing commit 084ea21 with merge 3f5b002ff05dc01626010327a03456bbc2d122a5...

[rust-log-analyzer]

The job x86_64-msvc-2 failed! Check out the build log: (web) (plain)

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

9 note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
10 


The actual run.stderr differed from the expected run.stderr.
Actual run.stderr saved to D:\a\rust\rust\build\x86_64-pc-windows-msvc\test\ui\panics\panic-short-backtrace-windows-x86_64\panic-short-backtrace-windows-x86_64.run.stderr
error: 1 errors occurred comparing run output.
status: exit code: 101
status: exit code: 101
command: PATH="D:\a\rust\rust\build\x86_64-pc-windows-msvc\stage2\lib\rustlib\x86_64-pc-windows-msvc\lib;C:\Program Files (x86)\Windows Kits\10\bin\x64;C:\Program Files (x86)\Windows Kits\10\bin\10.0.22000.0\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.29.30133\bin\HostX64\x64;C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.29.30133\bin\HostX64\x64;D:\a\rust\rust\build\x86_64-pc-windows-msvc\stage0-bootstrap-tools\x86_64-pc-windows-msvc\release\deps;D:\a\rust\rust\build\x86_64-pc-windows-msvc\stage0\bin;D:\a\rust\rust\ninja;D:\a\rust\rust\msys2\mingw64\bin;C:\hostedtoolcache\windows\Python\3.10.0\x64\Scripts;C:\hostedtoolcache\windows\Python\3.10.0\x64;C:\msys64\usr\bin;D:\a\rust\rust\sccache;C:\Program Files\MongoDB\Server\5.0\bin;C:\aliyun-cli;C:\vcpkg;C:\cf-cli;C:\Program Files (x86)\NSIS;C:\tools\zstd;C:\Program Files\Mercurial;C:\hostedtoolcache\windows\stack\2.7.3\x64;C:\cabal\bin;C:\ghcup\bin;C:\tools\ghc-9.2.1\bin;C:\Program Files\dotnet;C:\mysql\bin;C:\Program Files\R\R-4.1.2\bin\x64;C:\SeleniumWebDrivers\GeckoDriver;C:\Program Files (x86)\sbt\bin;C:\Rust\.cargo\bin;C:\Program Files (x86)\GitHub CLI;C:\Program Files\Git\bin;C:\Program Files (x86)\pipx_bin;C:\hostedtoolcache\windows\go\1.15.15\x64\bin;C:\hostedtoolcache\windows\Python\3.7.9\x64\Scripts;C:\hostedtoolcache\windows\Python\3.7.9\x64;C:\hostedtoolcache\windows\Ruby\2.5.9\x64\bin;C:\tools\kotlinc\bin;C:\hostedtoolcache\windows\Java_Temurin-Hotspot_jdk\8.0.312-7\x64\bin;C:\npm\prefix;C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\wbin;C:\ProgramData\kind;C:\Program Files\Eclipse Foundation\jdk-8.0.302.8-hotspot\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0;C:\Windows\System32\OpenSSH;C:\ProgramData\Chocolatey\bin;C:\Program Files\Docker;C:\Program Files\PowerShell\7;C:\Program Files\Microsoft\Web Platform Installer;C:\Program Files\dotnet;C:\Program Files\Microsoft SQL Server\130\Tools\Binn;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit;C:\Program Files (x86)\Microsoft SQL Server\110\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\120\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\130\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\140\DTS\Binn;C:\Program Files (x86)\Microsoft SQL Server\150\DTS\Binn;C:\Program Files\nodejs;C:\Program Files\OpenSSL\bin;C:\Strawberry\c\bin;C:\Strawberry\perl\site\bin;C:\Strawberry\perl\bin;C:\ProgramData\chocolatey\lib\pulumi\tools\Pulumi\bin;C:\Program Files\TortoiseSVN\bin;C:\Program Files\CMake\bin;C:\ProgramData\chocolatey\lib\maven\apache-maven-3.8.4\bin;C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code;C:\Program Files\Microsoft SDKs\Service Fabric\Tools\ServiceFabricLocalClusterManager;C:\Program Files\Git\cmd;C:\Program Files\Git\mingw64\bin;C:\Program Files\Git\usr\bin;C:\tools\php;C:\Program Files (x86)\sbt\bin;C:\SeleniumWebDrivers\ChromeDriver;C:\SeleniumWebDrivers\EdgeDriver;C:\Program Files\Amazon\AWSCLIV2;C:\Program Files\Amazon\SessionManagerPlugin\bin;C:\Program Files\Amazon\AWSSAMCLI\bin;C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\bin;C:\Program Files (x86)\Microsoft BizTalk Server;C:\Program Files\LLVM\bin;C:\Users\runneradmin\.dotnet\tools;C:\Users\runneradmin\AppData\Local\Microsoft\WindowsApps" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\test\\ui\\panics\\panic-short-backtrace-windows-x86_64\\a.exe"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
thread 'main' panicked at 'd was called', D:\a\rust\rust\src/test\ui\panics\panic-short-backtrace-windows-x86_64.rs:48:5
   0: std::panicking::begin_panic
   1: d
   2: c
   3: b
---

Some tests failed in compiletest suite=ui mode=ui host=x86_64-pc-windows-msvc target=x86_64-pc-windows-msvc


command did not execute successfully: "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\stage0-tools-bin\\compiletest.exe" "--compile-lib-path" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\stage2\\bin" "--run-lib-path" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\stage2\\lib\\rustlib\\x86_64-pc-windows-msvc\\lib" "--rustc-path" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\stage2\\bin\\rustc.exe" "--src-base" "D:\\a\\rust\\rust\\src/test\\ui" "--build-base" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\test\\ui" "--stage-id" "stage2-x86_64-pc-windows-msvc" "--suite" "ui" "--mode" "ui" "--target" "x86_64-pc-windows-msvc" "--host" "x86_64-pc-windows-msvc" "--llvm-filecheck" "D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\llvm\\build\\bin\\FileCheck.exe" "--nodejs" "C:\\Program Files\\nodejs\\node" "--npm" "C:\\Program Files\\nodejs\\npm" "--host-rustcflags" "-Crpath -O -Cdebuginfo=0  -Lnative=D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\native\\rust-test-helpers" "--target-rustcflags" "-Crpath -O -Cdebuginfo=0  -Lnative=D:\\a\\rust\\rust\\build\\x86_64-pc-windows-msvc\\native\\rust-test-helpers" "--docck-python" "C:\\hostedtoolcache\\windows\\Python\\3.10.0\\x64\\python3.exe" "--lldb-python" "C:\\hostedtoolcache\\windows\\Python\\3.10.0\\x64\\python3.exe" "--gdb" "C:\\msys64\\usr\\bin\\gdb" "--llvm-version" "13.0.0-rust-1.59.0-nightly" "--llvm-components" "aarch64 aarch64asmparser aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils aggressiveinstcombine all all-targets analysis arm armasmparser armcodegen armdesc armdisassembler arminfo armutils asmparser asmprinter avr avrasmparser avrcodegen avrdesc avrdisassembler avrinfo binaryformat bitreader bitstreamreader bitwriter bpf bpfasmparser bpfcodegen bpfdesc bpfdisassembler bpfinfo cfguard codegen core coroutines coverage debuginfocodeview debuginfodwarf debuginfogsym debuginfomsf debuginfopdb demangle dlltooldriver dwarflinker dwp engine executionengine extensions filecheck frontendopenacc frontendopenmp fuzzmutate globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo instcombine instrumentation interfacestub interpreter ipo irreader jitlink libdriver lineeditor linker lto m68k m68kasmparser m68kcodegen m68kdesc m68kdisassembler m68kinfo mc mca mcdisassembler mcjit mcparser mips mipsasmparser mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmparser msp430codegen msp430desc msp430disassembler msp430info native nativecodegen nvptx nvptxcodegen nvptxdesc nvptxinfo objcarcopts object objectyaml option orcjit orcshared orctargetprocess passes powerpc powerpcasmparser powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata remarks riscv riscvasmparser riscvcodegen riscvdesc riscvdisassembler riscvinfo runtimedyld scalaropts selectiondag sparc sparcasmparser sparccodegen sparcdesc sparcdisassembler sparcinfo support symbolize systemz systemzasmparser systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target textapi transformutils vectorize webassembly webassemblyasmparser webassemblycodegen webassemblydesc webassemblydisassembler webassemblyinfo webassemblyutils windowsmanifest x86 x86asmparser x86codegen x86desc x86disassembler x86info xray" "--cc" "" "--cxx" "" "--cflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--channel" "nightly" "--color" "always"


Build completed unsuccessfully in 0:40:42
Build completed unsuccessfully in 0:40:42
make: *** [Makefile:74: ci-subset-2] Error 1

[bors]

💔 Test failed - checks-actions

[kornelski]

It needs a "bless" of UI tests on Windows. Unfortunately, I'm having problems getting x.py to work on Windows. Can someone "bless" it for me?

[the8472]

You might want to ask on zulip to find a windows user.

[matthiaskrgr]

Might as well be #92000
@bors retry #92000

[bors]

⌛ Testing commit 084ea21 with merge 82418f9...

[bors]

☀️ Test successful - checks-actions
Approved by: joshtriplett
Pushing 82418f9 to master...

[rust-timer]

Finished benchmarking commit (82418f9): comparison url.

Summary: This benchmark run did not return any relevant changes.

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

@rustbot label: -perf-regression