Flaky "failed to remove temporary directory" on Windows

Summary: on Windows rustc can intermittently/flakily fail with: failed to remove temporary directory: The process cannot access the file because it is being used by another process. (os error 32) at path "D:\\b\\s\\w\\ir\\cache\\builder\\src\\out\\f6b4-win32-official\\obj/base/test\\.tmpcZBp3F.temp-archive"

No repro steps, because this error seems to happen flakily :-(. Let me record command-line arguments of rustc that seem most relevant:

• --crate-type rlib
• `--emit=dep-info=obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib.d,link
• -o obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib
• --target=i686-pc-windows-msvc
• -Ccodegen-units=1

Actual behavior (from https://ci.chromium.org/ui/p/chromium/builders/ci/win32-official/10756/overview):

[19104/109285] 5m08.81s F RUST obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib	
FAILED: ff262c98-d6be-4fec-80c3-4043a0ff24d0 "./obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib" RUST obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib
err: exit=1
"D:/b/s/w/ir/cipd_bin_packages/cpython3/bin/python3.exe" "../../build/rust/gni_impl/rustc_wrapper.py" --target-windows --rustc=../../third_party/rust-toolchain/bin/rustc --depfile=obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib.d --rsp=obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib.rsp --  -Clinker=..\..\third_party\llvm-build\Release+Asserts\bin\lld-link.exe --crate-name base_stest_ctest_urust_ulogger_uconsumer ../../base/test/logging/test_rust_logger_consumer.rs --crate-type rlib --edition=2024 -Dunsafe_op_in_unsafe_fn -Dwarnings -Zsplit-lto-unit -Clinker-plugin-lto=yes -Cdefault-linker-libraries -Zdep-info-omit-d-target -Zmacro-backtrace -Zremap-cwd-prefix=. -Zexternal-clangrt --target=i686-pc-windows-msvc -Ccodegen-units=1 -Zunstable-options -Cpanic=immediate-abort -Zpanic_abort_tests --cfg "cr_rustc_revision=\"1920ab925646fae038b02bd462cd328ae9eef1639236-ab925646fae038b02bd462cd328ae9eef1639236-1-22-12326-g8a5f1533\"" -Copt-level=3 -Cllvm-args=-pick-merged-source-locations -g -Zallow-features= -Clinker-plugin-lto=yes -Ccontrol-flow-guard -Ctarget-feature=+crt-static --sysroot=local_rustc_sysroot --emit=dep-info=obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib.d,link -o obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib -Ldependency=obj/third_party/rust/log/v0_4/lib -Ldependency=local_rustc_sysroot/lib/rustlib/i686-pc-windows-msvc/lib -Ldependency=obj/build/rust/allocator -Ldependency=obj/third_party/rust/cxx/v1/lib -Ldependency=win_clang_x86_for_rust_host_build_tools -Ldependency=obj/third_party/rust/foldhash/v0_2/lib -Ldependency=obj/build/rust/chromium_prelude -Clink-arg=-Bdynamic -Clink-arg=obj/base/test/test_rust_logger_consumer_cxx_generated.lib -Clink-arg=obj/build/rust/cxx_cppdeps.lib -Clink-arg=obj/build/rust/allocator/alloc_error_handler_impl.lib -Clink-arg=obj/build/rust/allocator/allocator_impls.lib -Clink-arg=obj/base/allocator/partition_allocator/src/partition_alloc/allocator_base.lib -Clink-arg=obj/base/allocator/partition_allocator/src/partition_alloc/allocator_core.lib -Clink-arg=obj/base/allocator/partition_allocator/src/partition_alloc/allocator_shim.lib -Clink-arg=../../third_party/llvm-build/Release+Asserts/lib/clang/22/lib/windows/clang_rt.builtins-i386.lib -lwinmm.lib --extern log=obj/third_party/rust/log/v0_4/lib/liblog_lib.rlib --extern build_srust_sallocator_callocator=obj/build/rust/allocator/libbuild_srust_sallocator_callocator.rlib --extern cxx=obj/third_party/rust/cxx/v1/lib/libcxx_lib.rlib --extern chromium=obj/build/rust/chromium_prelude/libchromium.rlib LDFLAGS RUSTENV OUT_DIR=gen/base/test/test_rust_logger_consumer
build step: rust_rlib "./obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib"
siso_rule: rust_rlib
stderr:
error: failed to build archive at `obj/base/test/libbase_stest_ctest_urust_ulogger_uconsumer.rlib`: failed to remove temporary directory: The process cannot access the file because it is being used by another process. (os error 32) at path "D:\\b\\s\\w\\ir\\cache\\builder\\src\\out\\f6b4-win32-official\\obj/base/test\\.tmpcZBp3F.temp-archive"

error: aborting due to 1 previous error

IIUC the error above ("failed to remove temporary directory") comes from rustc itself:

• AFAICT Chromium's //build/rust/gni_impl/rustc_wrapper.py does not create temporary directories itself.
• I found an earlier report of a similar issue in https://users.rust-lang.org/t/the-process-cannot-access-the-file-because-it-is-being-used-by-another-process-os-error-32/129335

Given that this happens flakily, I understand that this bug report might be inactionable. Nevertheless, I thought that reporting it may be helpful (sharing details + awareness).

And I wonder if extra logging could help. I am not sure about this myself, because:

• Extra logging may disrupt timing (e.g. the other process using the directory can disappear by the time logging tries to discover it)
• It's unclear what to log:
  • contents of the directory?
  • which exact file path couldn't be deleted (maybe .tmpcZBp3F.temp-archive is "it"?)?
  • which other process prevents deletion (not sure if Windows provides an easy way to get this info)?

Start with the rustc archive-building and temporary-directory cleanup path implicated by the reported error, then compare it with build/rust/gni_impl/rustc_wrapper.py, which the report says does not create temporary directories. Use the recorded Windows command and failing archive path as context; the issue provides no reproduction or named test. Done would be identifying an actionable cause or a justified diagnostic direction.