Using cuda::std::complex <<, >> (ostream,istream) operators cause to compilation error

I can confirm that it compiles successfully on CUDA 12.4.1 (but not 12.5.1)

Suggestion: retest with the latest available CUDA, currently 12.6.1. if it still fails to compile, file a bug, or you could file a CCCL issue. Ah, it looks like you already did.