P2374R4 `views::cartesian_product`

[StephanTLavavej]

P2374R4 views::cartesian_product
P2540R1 Empty Product For Certain Views
LWG-3760 cartesian_product_view::iterator's parent_ is never valid
LWG-3761 cartesian_product_view::iterator::operator- should pass by reference
LWG-3801 cartesian_product_view::iterator::distance-from ignores the size of last underlying range
LWG-3820 cartesian_product_view::iterator::prev is not quite right
LWG-3849 cartesian_product_view::iterator's default constructor is overconstrained

Feature-test macro (expected):

#define __cpp_lib_ranges_cartesian_product 202207L

[StephanTLavavej]

I saw that @JMazurkiewicz is investigating this (thanks! 😻); marking accordingly to avoid duplicated work.