ExclusiveData implements a move constructor that both has a misspelled variable and attempts to move a Mutex, which contains a member variable that deletes its move constructor. Clang 19 is able to recognize that this issue occurs independently of the template arguments and is present in every possible template instantiation, and diagnoses the issue as an error. Since this code has compiled on older compilers, I would imagine that it just never gets instantiated with template arguments, so we may be able to just delete the move constructor to silence the issue on Clang 19.