Smoke test build failures coming from LLVM?

[vanvoorden (Rick van Voorden)]

This smoke test:

[Pull Request] Swift Smoke Test - macOS #24535 [Jenkins]

failed with what looks like an error from llvm:

[2025-11-24T19:10:38.822Z] FAILED: bin/llvm-cas-object-format 
[2025-11-24T19:10:38.822Z] : && /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -Wno-unknown-warning-option -Werror=unguarded-availability-new -arch x86_64 -target x86_64-apple-macosx13.0 -fno-stack-protector -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -O3 -DNDEBUG -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.2.sdk -mmacosx-version-min=13.0 -Wl,-search_paths_first -Wl,-headerpad_max_install_names -Wl,-dead_strip -Wl,-no_warn_duplicate_libraries tools/llvm-cas-object-format/CMakeFiles/llvm-cas-object-format.dir/llvm-cas-object-format.cpp.o -o bin/llvm-cas-object-format  -Wl,-rpath,@loader_path/../lib  lib/libLLVMRemoteCachingService.a  lib/libLLVMMCCAS.a  lib/libLLVMRemoteNullService.a  lib/libLLVMDebugInfoCodeView.a  lib/libLLVMDebugInfoDWARF.a  lib/libLLVMDebugInfoDWARFLowLevel.a  lib/libLLVMObject.a  lib/libLLVMIRReader.a  lib/libLLVMBitReader.a  lib/libLLVMAsmParser.a  lib/libLLVMCore.a  lib/libLLVMRemarks.a  lib/libLLVMBitstreamReader.a  lib/libLLVMMCParser.a  lib/libLLVMTextAPI.a  lib/libLLVMMC.a  lib/libLLVMCASUtil.a  lib/libLLVMCAS.a  lib/libLLVMBinaryFormat.a  lib/libLLVMTargetParser.a  lib/libLLVMSupport.a  -lm  /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.2.sdk/usr/lib/libz.tbd  lib/libLLVMDemangle.a && :
[2025-11-24T19:10:38.823Z] 0  0x104812353  __assert_rtn + 64
[2025-11-24T19:10:38.823Z] 1  0x1046cc995  ld::Fixup::directTargetNoFollow(ld::Atom const*) const + 181
[2025-11-24T19:10:38.823Z] 2  0x1047fe2f4  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 788
[2025-11-24T19:10:38.823Z] 3  0x1047fe31e  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 830
[2025-11-24T19:10:38.823Z] 4  0x1047fe31e  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 830
[2025-11-24T19:10:38.823Z] 5  0x1047fe31e  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 830
[2025-11-24T19:10:38.823Z] 6  0x1047fe31e  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 830
[2025-11-24T19:10:38.823Z] 7  0x1047fe31e  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 830
[2025-11-24T19:10:38.823Z] 8  0x1047fe31e  ld::AtomFileConsolidator::markLive(ld::Atom const*, ld::AtomFileConsolidator::WhyLiveBackChain*) + 830
[2025-11-24T19:10:38.823Z] 9  0x1047fd45f  ___ZN2ld20AtomFileConsolidator9deadStripEb_block_invoke_2 + 111
[2025-11-24T19:10:38.823Z] 10  0x7ff81697c815  _dispatch_client_callout2 + 8
[2025-11-24T19:10:38.823Z] 11  0x7ff81698e2bf  _dispatch_apply_invoke3 + 431
[2025-11-24T19:10:38.823Z] 12  0x7ff81697c7e2  _dispatch_client_callout + 8
[2025-11-24T19:10:38.823Z] 13  0x7ff81697da9e  _dispatch_once_callout + 20
[2025-11-24T19:10:38.823Z] 14  0x7ff81698d408  _dispatch_apply_invoke + 184
[2025-11-24T19:10:38.823Z] 15  0x7ff81697c7e2  _dispatch_client_callout + 8
[2025-11-24T19:10:38.823Z] 16  0x7ff81698beb2  _dispatch_root_queue_drain + 872
[2025-11-24T19:10:38.823Z] 17  0x7ff81698c431  _dispatch_worker_thread2 + 147
[2025-11-24T19:10:38.823Z] 18  0x7ff816b20c3e  _pthread_wqthread + 261
[2025-11-24T19:10:38.823Z] ld: Assertion failed: (_targetIndex < atoms.size()), function directTargetNoFollow, file Fixup.cpp, line 501.
[2025-11-24T19:10:38.823Z] clang++: error: linker command failed with exit code 1 (use -v to see invocation)

My diff was on standard library… and it's not totally clear to me where this failure came from or how exactly this could be related to my code.

A similar diff on different standard library types built smoke tests without the error:

[Pull Request] Swift Smoke Test - macOS #24534 [Jenkins]

Any ideas? I was not able to find any open tasks that might be related.

[al45tair (Alastair Houghton)]

That's an assertion failure in the linker, not an error from LLVM. If you could file a Github issue, that would be helpful; does this problem reproduce locally, do you know? (I've also pinged our linker folks, who are likely out for Thanksgiving and so probably won't be able to do anything until they get back. But filing a Github issue would be very helpful, if you could do that.)

[vanvoorden (Rick van Voorden)]

@al45tair

But filing a Github issue would be very helpful, if you could do that.

Here is my issue. Thanks!

ld: Assertion failed: (_targetIndex < atoms.size()), function directTargetNoFollow, file Fixup.cpp, line 501.