[headers]/5 especially mentions "names which are defined as macros in C", which include floating-point classification/comparison functions (fpclassify, isless, etc.).
So, is <cmath> disallowed to declare them in the global namespace as they seem to be excluded from "these names"?
Also, [headers]/6 states
Names which are defined as macros in C shall be defined as macros in the C++ standard library, even if C grants license for implementation as functions.
Does this mean that despite being functions, these names also need to be defined as macros in C++?
I think both answers are "no". Not sure whether this needs an LWG issue.