MSVC 19.xx has had some serious teething problems with its new "improvements" to how it handles templates.  Many have been fixed.

We should rev the supported version from 19.16 to some more recent version.  I'm asking for people to add comments to this ticket with links to godbolt examples of where gcc, clang, and a more recent MSVC do the right thing but MSVC 19.16 does the wrong thing.

The godbolt examples should run across 4 compilers:  MSVC 19.16, a later MSVC 19.xx where the feature works (if possible), gcc 8.3 and clang 7.0.  The expectation is that clang and gcc are doing the right thing, in these examples.