data identity changes for stl-variant in 50.12

[ab9rf]

this is arguably a better approach for the change in #4090

[lethosor]

So this is basically letting the preprocessor split arguments by commas, then joining them with __VA_ARGS__.

I agree it looks cleaner. Haven't tested.

[ab9rf]

So this is basically letting the preprocessor split arguments by commas, then joining them with __VA_ARGS__.

actually think that __VA_ARGS__ bypasses splitting entirely, but that's a compiler implementation detail that frankly i don't care about here. __VA_ARGS__ and the ... meta-argument in macros have been in the standard since C++11, and all of the compilers we care about implement it in the standard way