the _Float16 type is not present on arm g++

Environment

g++ 7.4 7.5 and others

C++ standard mode (e.g. 17, 20, 'latest'):
not applicable

Target arch (e.g. x64):
arm64, arm

Library configuration overrides:
not applicable

Relevant compilation flags:
see steps to reproduce link

Describe the bug

_Float16 is not available desptite gcc documentation saying one should use it
It's only available for C not C++

Steps to reproduce (or a small repro code sample)

https://godbolt.org/z/5e6rdP
The last one shows it's visible for C

Additional information