matplotlib in cygwin

The VERBOSE flags generate runtime, not compile time information, so
try reimporting a module that fails and see if you get any extra
info. Eg matplotlib.backends._backend_agg

Also, please confirm that matplotlib._agg also dumps.

Oh! Ok, yeah, they all still dump, including matplotlib._agg, and the verbose compile doesn't seem to add any new info.

I find it odd that an extension built with SWIG, and one built with
PYCXX, have the same behavior, since their is almost no overlap in
these tools. It suggests something may be wrong with your setup
rather than matplotlib. In your current environment, can you still
build and run an older mpl?

No, as I said before, matplotlib 0.72 does the same thing, and I have installed and run matplotlib-0.72 under cygwin before, so I assume this means that cygwin is at fault somehow. I'm just trying to see if I can find where it is at fault so I have something specific to pester the cygwin devs about.