As of this writing (but perhaps not for very much longer!) the four mainstream compilers on Godbolt Compiler Explorer give four different answers for this simple C++ program:
J. Berner, P. Grohs, G. Kutyniok, and P. Petersen. (2021)cite arxiv:2105.04026Comment: This review paper will appear as a book chapter in the book "Theory of Deep Learning" by Cambridge University Press.