c++ - 是否明确定义了哪个线程调用thread_local存储的构造函数？

Question

C++标准是否定义了如何，何时以及通过哪个线程调用thread_local变量的构造函数？例如，是否总是为线程本身分配了thread_local数据？还是产生新线程的线程？还是过程的第一个线程？还是取决于编译器？

Answer 1

[basic.start.dynamic] It is implementation-defined whether the dynamic initialization of a non-local non-inline variable with thread storage duration is sequenced before the first statement of the initial function of a thread or is deferred. If it is deferred, the initialization associated with the entity for thread t is sequenced before the first non-initialization odr-use by t of any non-inline variable with thread storage duration defined in the same translation unit as the variable to be initialized. It is implementation-defined in which threads and at which points in the program such deferred dynamic initialization occurs.