Clang compiler does not support IEC 559 math functionality. Clang does not
control and honor the definition of the __STDC_IEC_559__ macro. Under specific
options, such as -Ofast and -ffast-math, Clang will enable a range of optimizations that provide
faster mathematical operations that may not conform to the IEEE-754 specifications.
The __STDC_IEC_559__ macro value may be defined but ignored when these faster
optimizations are enabled.