llvm-project

abd10578 - [Clang] Minimal support for availability attributes on partial specializations (#138426)

[Clang] Minimal support for availability attributes on partial specializations (#138426) There are some limitations. Because we only know which partial specialization to refer to when instantiating, and because we can't instantiate the class before we require a complete type, we can only use the partial specialization once we have a complete class. Similarly, because we don't know if a class is ever going to be complete, we always warn on availability of the primary. Therefore, we only warn for the partial specialization if we did not warn on the primary. I considered alternatives to address that second limitation: - Delay warnings to the end of the TU - Tracking where each availability attribute originally comes from. However, both of these have drawbacks, and the use case is probably less motivated than wanting to deprecate the use of a specific specialization. Fixes #44496