static initializer-based registration mechanism not portable #4139
Description
| Bugzilla Link | 3767 |
| Version | unspecified |
| OS | All |
| Reporter | LLVM Bugzilla Contributor |
| CC | @asl |
Extended Description
Throughout the code, LLVM uses statically initialized variables with the expectation that they will run before main. One example is registering the possible backends, and the other is registering command line flags.
Quoth the Standard: It is implementation-defined whether or not the dynamic initialization (8.5, 9.4, 12.1, 12.6.1) of an object of namespace scope is done before the first statement of main. If the initialization is deferred to some point in time after the first statement of main, it shall occur before the first use of any function or object defined in the same translation unit as the object to be initialized.
This mean that a static initializer need not execute until another function in the TU is called. This comes up in MSVC++ and Windows.