[C++] StructArray::field() is not thread safe #48134
Description
Describe the bug, including details regarding any error messages, version, and platform.
It is possible for two threads calling StructArray::field() with the same index at the same time to cause a race on the stored entry in boxed_fields_. I.e. if a second thread goes into the path that calls MakeArray() before the first thread stored its own new array, the second thread would also write to the same shared_ptr and invalidate the shared_ptr from the first thread, thereby also invalidating the returned reference.
Component(s)
C++