I have allready persued this problem in Problem with compiling Inline::C on cygwin. In short I was not able to 'make test' of Inline::C under cygwin and Perl 5.8.0. Today I've tried something weired and copied the perlld script from Perl 5.6.1 distribution into the 5.8.0 distribution and that did the trick - it works. I have seen other monks remarks about having troubles with the compilation - that's why I post it here. I do not recommend this technique - but perhaps it can be a start for the real fix.