Recent mingw-w64-clang-aarch64-clang 21.1.7 update is broken

[ntkme]

Ensure the following before filing this issue

• I verified it reproduces with the latest version with - uses: ruby/setup-ruby@v1 (see Versioning policy)

• I tried to reproduce the issue locally by following the workflow steps (including all commands done by ruby/setup-ruby, except for Downloading Ruby & Extracting Ruby),
  and it did not reproduce locally (if it does reproduce locally, it's not a ruby/setup-ruby issue)

Are you running on a GitHub-hosted runner or a self-hosted runner?

GitHub-hosted runner

Link to the failed workflow job (must be a public workflow job, so the necessary information is available)

https://github.com/sass-contrib/sass-embedded-host-ruby/actions/runs/20038850314/job/57467444335

Any other notes?

Windows arm64's clang recently get updated from 21.1.5-1 to 21.1.7-1: https://github.com/ruby/setup-msys2-gcc/releases/tag/v20251205.005709

This change aligns with my daily CI failures: https://github.com/sass-contrib/sass-embedded-host-ruby/actions/workflows/schedule.yml

It appears this new patch release of LLVM is buggy and had an internal crash when compiling google-protobuf:

fatal error: error in backend: Failed to evaluate function length in SEH unwind
info
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and
include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments:
C:\\hostedtoolcache\\windows\\Ruby\\3.4.7\\arm64\\msys64\\clangarm64\\bin\\clang.exe
-I.
-IC:/hostedtoolcache/windows/Ruby/3.4.7/arm64/include/ruby-3.4.0/aarch64-mingw-ucrt
-IC:/hostedtoolcache/windows/Ruby/3.4.7/arm64/include/ruby-3.4.0/ruby/backward
-IC:/hostedtoolcache/windows/Ruby/3.4.7/arm64/include/ruby-3.4.0 -I.
-I./third_party/utf8_range -D_WIN32_WINNT=0x0600 -D__MINGW_USE_VC2005_COMPAT
-D_FILE_OFFSET_BITS=64 -O3 -fstack-protector-strong -fdeclspec -O3
-fno-omit-frame-pointer -fno-fast-math -ggdb3 -Wall -Wextra -Wextra-tokens
-Wdeprecated-declarations -Wdivision-by-zero -Wdiv-by-zero
-Wimplicit-function-declaration -Wimplicit-int -Wpointer-arith
-Wshorten-64-to-32 -Wwrite-strings -Wold-style-definition -Wmissing-noreturn
-Wno-cast-function-type -Wno-constant-logical-operand -Wno-long-long
-Wno-missing-field-initializers -Wno-overlength-strings
-Wno-parentheses-equality -Wno-self-assign -Wno-tautological-compare
-Wno-unused-parameter -Wno-unused-value -Wunused-variable -Wno-shorten-64-to-32
-Wno-dll-attribute-on-redeclaration -Wmisleading-indentation -Wundef -std=gnu99
-O3 -DNDEBUG -fvisibility=hidden -o ruby-upb.o -c ruby-upb.c
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module 'ruby-upb.c'.
4.	Running pass 'AArch64 Assembly Printer' on function '@encode_longvarint'
Exception Code: 0xE0000046
#0 0x00007fffbdac6034 (C:\Windows\System32\KERNELBASE.dll+0x126034)
#1 0x89587fff408030fc
clang: error: clang frontend command failed with exit code 70 (use -v to see
invocation)
clang version 21.1.7
Target: aarch64-w64-windows-gnu
Thread model: posix
InstalledDir: C:/a/_temp/msys64/clangarm64/bin
clang: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg:
C:/Users/RUNNER~1/AppData/Local/Temp/ruby-upb-b5a11f.c
clang: note: diagnostic msg:
C:/Users/RUNNER~1/AppData/Local/Temp/ruby-upb-b5a11f.sh
clang: note: diagnostic msg: 

********************
make: *** [Makefile:251: ruby-upb.o] Error 1

@MSP-Greg Personally I don't mind keep this broken as is and wait for next clang/llvm update on msys2 to fix this. I'm reporting this as an issue, just incase more users are hit. If more users reports issue here, then we can consider temporarily downgrade clang/llvm for windows arm64.

[ntkme]

After a bit more investigation, this seems to be an issue of google-protobuf 4.33.2 release, which coincidentally happened around the same time (within two hours) as the clang update.