`*aarch64-msvc*` job logs sometimes become massive
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A-CI
A-spurious
C-bug
O-aarch64-pc-windows-msvc
T-bootstrap
T-infra
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- Rust
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Description
If I download the jobs log for e.g. https://github.com/rust-lang/rust/actions/runs/24973805754/job/73121722739, I notice that the *aarch64-msvc* jobs are massive (approx. 245 MiB give or take). Other jobs are usually 2 orders of magnitude smaller (around a few MiBs).
Key observations:
- Only happens for
*aarch64-msvc*, not*x86_64-msvc* - Seems to be a lot of logs when building LLVM
dust -F -r
1.0G └─┬ . │██████████████████████████████████████████████████████████████████████ │ 100%
247M ├── 24_auto - aarch64-msvc-1.txt │█████████████████ │ 23%
244M ├── 7_auto - aarch64-msvc-2.txt │█████████████████ │ 23%
243M ├── 10_auto - dist-aarch64-msvc.txt │████████████████ │ 23%
12M ├── 51_auto - dist-arm-linux-gnueabi.txt │█ │ 1%
12M ├── 80_auto - dist-armv7-linux.txt │█ │ 1%
12M ├── 78_auto - dist-armhf-linux.txt │█ │ 1%
9.0M ├── 71_auto - dist-i586-gnu-i586-i686-musl.txt │█ │ 1%
8.6M ├── 27_auto - test-various.txt │█ │ 1%
8.1M ├── 60_auto - dist-x86_64-linux.txt │█ │ 1%
7.8M ├── 77_auto - aarch64-gnu.txt │█ │ 1%
7.7M ├── 21_auto - aarch64-apple.txt │█ │ 1%
7.7M ├── 56_auto - x86_64-gnu-llvm-21-3.txt │█ │ 1%
7.7M ├── 49_auto - x86_64-gnu-llvm-22-3.txt │█ │ 1%
7.1M ├── 9_auto - dist-x86_64-msvc.txt │█ │ 1%
7.0M ├── 85_auto - dist-aarch64-linux.txt │█ │ 1%
6.9M ├── 50_auto - x86_64-gnu-llvm-21-2.txt │█ │ 1%
6.9M ├── 37_auto - x86_64-gnu-llvm-22-2.txt │█ │ 1%
6.5M ├── 28_auto - x86_64-gnu-nopt.txt │█ │ 1%
6.4M ├── 35_auto - optional-x86_64-gnu-parallel-frontend.txt│█ │ 1%
6.4M ├── 23_auto - x86_64-gnu-stable.txt │█ │ 1%
6.4M ├── 33_auto - x86_64-gnu.txt │█ │ 1%
5.8M ├── 25_auto - x86_64-msvc-1.txt │█ │ 1%
5.7M ├── 18_auto - i686-msvc-1.txt │█ │ 1%
5.6M ├── 12_auto - x86_64-mingw-1.txt │█ │ 1%
5.6M ├── 43_auto - i686-gnu-nopt-1.txt │█ │ 1%
5.6M ├── 72_auto - i686-gnu-1.txt │█ │ 1%
4.7M ├── 6_auto - aarch64-gnu-llvm-21-1.txt │█ │ 0%
4.5M ├── 82_auto - armhf-gnu.txt │█ │ 0%
4.3M ├── 63_auto - arm-android.txt │█ │ 0%
4.3M └── 54_auto - x86_64-gnu-debug.txt │█ │ 0%
What the huge amounts of LLVM build logs look like:
2026-04-27T02:45:26.1438350Z running: "cmake" "--build" "C:\\a\\rust\\rust\\build\\aarch64-pc-windows-msvc\\llvm\\build" "--target" "install" "--config" "Release" "--" "-j" "4"
2026-04-27T02:45:27.9450288Z [1/3993] Building CXX object lib\Demangle\CMakeFiles\LLVMDemangle.dir\Demangle.cpp.obj
2026-04-27T02:45:27.9451762Z Note: including file: C:\a\rust\rust\src\llvm-project\llvm\include\llvm/Demangle/Demangle.h
2026-04-27T02:45:27.9452384Z Note: including file: C:\a\rust\rust\src\llvm-project\llvm\include\llvm/Demangle\DemangleConfig.h
2026-04-27T02:45:27.9453070Z Note: including file: C:\a\rust\rust\build\aarch64-pc-windows-msvc\llvm\build\include\llvm/Config/llvm-config.h
2026-04-27T02:45:27.9454351Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\cassert
2026-04-27T02:45:27.9455233Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\yvals_core.h
2026-04-27T02:45:27.9456341Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\yvals_core.h
2026-04-27T02:45:27.9457192Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\vcruntime.h
2026-04-27T02:45:27.9457987Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\sal.h
2026-04-27T02:45:27.9459246Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\concurrencysal.h
2026-04-27T02:45:27.9459977Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\vadefs.h
2026-04-27T02:45:27.9460934Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\vadefs.h
2026-04-27T02:45:27.9461787Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\xkeycheck.h
2026-04-27T02:45:27.9462506Z Note: including file: C:\Program Files (x86)\Windows Kits\10\include\10.0.26100.0\ucrt\assert.h
2026-04-27T02:45:27.9463115Z Note: including file: C:\Program Files (x86)\Windows Kits\10\include\10.0.26100.0\ucrt\corecrt.h
2026-04-27T02:45:27.9463844Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\cstddef
2026-04-27T02:45:27.9464933Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\yvals_core.h
2026-04-27T02:45:27.9465501Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\stddef.h
2026-04-27T02:45:27.9466617Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_header_macro.h
2026-04-27T02:45:27.9467527Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_ptrdiff_t.h
2026-04-27T02:45:27.9468217Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_size_t.h
2026-04-27T02:45:27.9469217Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_wchar_t.h
2026-04-27T02:45:27.9469828Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_null.h
2026-04-27T02:45:27.9470896Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_nullptr_t.h
2026-04-27T02:45:27.9471526Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_max_align_t.h
2026-04-27T02:45:27.9472522Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\__stddef_offsetof.h
2026-04-27T02:45:27.9473280Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\xtr1common
2026-04-27T02:45:27.9473972Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\yvals_core.h
2026-04-27T02:45:27.9474655Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\optional
2026-04-27T02:45:27.9475689Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\yvals.h
2026-04-27T02:45:27.9476603Z Note: including file: C:\a\rust\rust\citools\clang-rust\lib\clang\20\include\yvals_core.h
2026-04-27T02:45:27.9477532Z Note: including file: C:\Program Files (x86)\Windows Kits\10\include\10.0.26100.0\ucrt\crtdbg.h
2026-04-27T02:45:27.9478291Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\vcruntime_new_debug.h
2026-04-27T02:45:27.9479155Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\vcruntime_new.h
2026-04-27T02:45:27.9480302Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\crtdefs.h
2026-04-27T02:45:27.9481097Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\use_ansi.h
2026-04-27T02:45:27.9482040Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44.35207\include\exception
2026-04-27T02:45:27.9482835Z Note: including file: C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.44
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked GitHub Actions job log and compare the aarch64-msvc and x86_64-msvc LLVM build output, especially the CMake invocation and verbose include tracing. Trace that behavior into the repository's CI and LLVM build configuration; done means aarch64-msvc jobs no longer emit unexpectedly massive LLVM logs without losing necessary build diagnostics.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cmake, github-actions, rust
- Domain
- build-system, ci-cd, compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 45/100