check for --expt-relaxed-constexpr

is there any way to know via preprocessor macros if nvcc is being run with the --expt-relaxed-constexpr flag ?

Thank you,

Found it

F.3.16.4. Constexpr functions and function templates

By default, a constexpr function cannot be called from a function with incompatible execution space. The experimental nvcc flag --expt-relaxed-constexpr removes this restriction. When this flag is specified, host code can invoke a device constexpr function and device code can invoke a host constexpr function. nvcc will define the macro CUDACC_RELAXED_CONSTEXPR when --expt-relaxed-constexpr has been specified.