I am not sure if this is the right place to ask this question. Please redirect me if not.
I downloaded the latest main Swift toolchain (org.swift.62202510171a) and tried to compile a simple C++ program with the new LLVM 20 realtime sanitizer:
xcrun -toolchain "org.swift.62202510171a" clang main.cpp -lstdc++ -fsanitize=realtime
This results in the following error:
ld: file cannot be open()ed, errno=2 path=/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-10-17-a.xctoolchain/usr/lib/clang/21/lib/darwin/libclang_rt.rtsan_osx_dynamic.dylib in '/Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2025-10-17-a.xctoolchain/usr/lib/clang/21/lib/darwin/libclang_rt.rtsan_osx_dynamic.dylib'
When I look there, rtsan dylib is indeed missing.