Odd ubsan issue when building on macOS

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
macos, shell
Domain
build-system, operating-systems

Research direction

Start with fuzzbuild.sh and the generic arguments shown in the issue, then reproduce by launching out/fuzzbuild/d8 from the build directory and from another working directory on macOS. The work is done when d8 no longer fails to locate libclang_rt.ubsan_osx_dynamic.dylib when launched outside out/fuzzbuild/.

Written by the indexing model from the issue text.

Description

I've noticed that when building d8 on macOS using the generic fuzzbuild.sh args. 'is_debug=false dcheck_always_on=true v8_static_library=true v8_enable_verify_heap=true v8_fuzzilli=true sanitizer_coverage_flags="trace-pc-guard" target_cpu="x64"' It tries to statically load a ubsan library via a ../../ path which works fine when d8 is launched from <v8>/out/fuzzbuild/ but fails when launching from anywhere else.

 % ~/project/v8/out/fuzzbuild/d8
dyld[30191]: Library not loaded: @rpath/libclang_rt.ubsan_osx_dynamic.dylib
  Referenced from: <4C4C4449-5555-3144-A1CD-576D2F414F8F> /Users/emma/project/v8/out/fuzzbuild/d8
  Reason: tried: '/Users/emma/project/v8/out/fuzzbuild/libclang_rt.ubsan_osx_dynamic.dylib' (no such file), '../../third_party/llvm-build/Release+Asserts/lib/clang/21/lib/darwin/libclang_rt.ubsan_osx_dynamic.dylib' (no such file), '/Users/emma/project/v8/out/fuzzbuild/libclang_rt.ubsan_osx_dynamic.dylib' (no such file), '../../third_party/llvm-build/Release+Asserts/lib/clang/21/lib/darwin/libclang_rt.ubsan_osx_dynamic.dylib' (no such file)
zsh: abort      ~/project/v8/out/fuzzbuild/d8

I've temporarily solved this problem by copying third_party to ~/ and then launching fuzzilli from two nested folders. Not sure why this occurring though

Dominant language
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