Insight Toolkit (ITK) -- Official Repository. ITK builds on a proven, spatially-oriented architecture for processing, segmentation, and registration of scientific images in two, three, or more dimensions.
ITK already dropped Visual C++ 2013 in 2018, with commit 0067eee541994d6f977490bee521b9f6f0adfc64 "COMP: Require MSVC VS14 2015 for C++11 compatibility", by Bradley Lowekamp (@blowekamp).
While I still don't fully understand the problem, it looks like Bradley's PR #4961 will remove the obsolete _MSC_VER < 1900 check anyway. So close without merging. Thanks for all your comments!
ITK already dropped Visual C++ 2013 in 2018, with commit 0067eee541994d6f977490bee521b9f6f0adfc64 "COMP: Require MSVC VS14 2015 for C++11 compatibility", by Bradley Lowekamp (@blowekamp).
For the record, Microsoft also dropped VS2013: https://learn.microsoft.com/en-us/lifecycle/products/visual-studio-2013