[PATCH] D53670: Revert "Teach __libcpp_is_floating_point that __fp16 and _Float16 are"

[Louis Dionne via Phabricator]

ldionne added a comment.

In https://reviews.llvm.org/D53670#1275188, @rsmith wrote:

> What's the problem with the state of affairs prior to this change? If some compiler / environment is defining a `__FLT16_MANT_DIG__` macro but not providing a `_Float16` type, isn't that just a bug in that environment?


There's also the fact that e.g. `__fp16` doesn't work with the stream's `operator>>` and similar problems. Because of this, we're effectively lying about the fact that `__fp16` is a floating point type. This was Marshall's point, and I agree with it.

@EricWF I do agree that if it quacks like a floating point and it walks like a floating point, then it is a floating point. However, `__fp16` doesn't seem to quack quite right, so it's not a floating point (at least not without additional work).


Repository:
  rL LLVM

https://reviews.llvm.org/D53670