P4150 R0 Multidimensional Index-based For Each

[wg21bot]

P4150R0 Multidimensional Index-based For Each (Nicolas Morales, Mark Hoemmen, Bryce Adelstein Lelbach, Damien Lebrun-Grandie)

[foonathan]

Should SG9 take a look at this (and presumably other algorithms proposed for mdalgorithm?) They're range-ish, even if - they don't have iterators.