Antonio Sanchez 9816fe59b4 Fix assignment operator issue for latest MSVC+NVCC.
Details are scattered across #920, #1000, #1324, #2291.

Summary: some MSVC versions have a bug that requires omitting explicit
`operator=` definitions (leads to duplicate definition errors), and
some MSVC versions require adding explicit `operator=` definitions
(otherwise implicitly deleted errors).  This mess tries to cover
all the cases encountered.

Fixes #2291.
2021-08-03 00:26:10 +00:00
..
2021-03-15 18:42:04 +00:00