Build errors with clang were observed due to the use of __sync_add_and_fetch, which is legacy and will be deprecated in the future.
It can be reproduced by building macos-x86-zero or linux-x86-zero with clang.
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/jdk/src/hotspot/os_cpu/bsd_zero/atomic_bsd_zero.hpp:199:37: error: cannot initialize a parameter of type 'char *' with an lvalue of type 'unsigned long'
  return __sync_add_and_fetch(dest, add_value);
                                    ^~~~~~~~~
/jdk/src/hotspot/os_cpu/bsd_zero/atomic_bsd_zero.hpp:170:12: note: in instantiation of function template specialization 'Atomic::PlatformAdd<8>::add_and_fetch<char *, unsigned long>' requested here
    return add_and_fetch(dest, add_value, order) - add_value;
           ^
./src/hotspot/share/runtime/atomic.hpp:706:38: note: in instantiation of function template specialization 'Atomic::PlatformAdd<8>::fetch_and_add<char *, unsigned long>' requested here
    return PlatformAdd<sizeof(P*)>().fetch_and_add(dest, scale_addend(addend), order);
                                     ^
   ... (rest of output omitted)
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