This matches gcc behavior
Hi, you mentioned that this patch aliases __ieee128 to __float128 on PPC. But this seems a target-independent change, right?
The change itself looks reasonable since libstdcxx may refer to __ieee128 type.
Correct. That being said, using an identifier starting with __ is UB in C and C++, so I guess it's not critical (?). I'm open to suggestion on how to implement that behavior in clang though :-)
That seems to be true for __float128 too, even on x86_64. I'll find out what's going on there.
Edit: and also __float80 on x86. Maybe a bug (or "feature") of target-specific built-in types in GCC. I'll find out on Monday.
As Serge said, it's UB to use that as an identifier, so not a show stopper, and Clang and GCC already diverge here for existing types.