Guile 2.9.9, like .8 and .7, does not build on Cygwin (64 bit).  Configure runs without error, but make crashes with this (truncated to just the tail):

Making all in bootstrap
make[2]: Entering directory '/cygdrive/c/Users/rr828893/Downloads/guile-2.9.9/bootstrap'
  BOOTSTRAP GUILEC ice-9/eval.go
  BOOTSTRAP GUILEC ice-9/psyntax-pp.go
  BOOTSTRAP GUILEC language/cps/intmap.go
  BOOTSTRAP GUILEC language/cps/intset.go
  BOOTSTRAP GUILEC language/cps/graphs.go
  BOOTSTRAP GUILEC ice-9/vlist.go
  BOOTSTRAP GUILEC srfi/srfi-1.go
/bin/sh: line 6:  4294 Segmentation fault      (core dumped) GUILE_AUTO_COMPILE=0 ../meta/build-env guild compile --target="x86_64-unknown-cygwin" -O1 -Oresolve-primitives -L "/home/rr828893/Downloads/guile-2.9.9/module" -L "/home/rr828893/Downloads/guile-2.9.9/guile-readline" -o "srfi/srfi-1.go" "../module/srfi/srfi-1.scm"
make[2]: *** [Makefile:1930: srfi/srfi-1.go] Error 139
make[2]: Leaving directory '/cygdrive/c/Users/rr828893/Downloads/guile-2.9.9/bootstrap'
make[1]: *** [Makefile:1849: all-recursive] Error 1
make[1]: Leaving directory '/cygdrive/c/Users/rr828893/Downloads/guile-2.9.9'
make: *** [Makefile:1735: all] Error 2

All previous problems (which were easy to work around) have gone away in this release, which is progress, but it doesn't get me past Guile 2.2.

John Cowan
Your worships will perhaps be thinking that it is an easy thing
to blow up a dog? [Or] to write a book?
    --Don Quixote, Introduction