Uninitialized scalar field

The field will contain an arbitrary value left over from earlier computations. A scalar field is not initialized by the constructor
/src/mongo/util/pcre.cpp:311: UNINIT_CTOR 122354 Class member declaration for "_errorPos".
/src/mongo/util/pcre.cpp:166: UNINIT_CTOR 122354 Non-static class member "_errorPos" is not initialized in this constructor nor in any functions that it calls.