• the default install used djgpp for the compiler, aliased to gcc. djgpp has all kinds of issues with absolute paths (e.g. /usr/include/sys/socket.h when configure -ing rsync). But I went back to the cygwin installer, and found that if I select the 'gcc: C compiler helper' and the packages that get auto-selected with it, I get good old gcc back again and all is well.

-- MattWalsh - 30 Dec 2005