This may be wrong way to do this since the comment at the top of global.sym says it's auto generated by "make regen_headers". However there doesn't seem to be a make target for that, so I don't know. It's a workaround for this particular module anyway.
Now, whether this is a good idea or not, I can't tell you. I have no clue about those issues.
I do know, however, that I would very, very much like Devel::Cover to build on Windows.
What did work was to add the following symbols to global.sym ....
Seems that's one way to make those symbols public. Nice hack - though if you ever need to access a different private symbol, you'll have to rebuild perl again.
I'm curious to know whether the Devel::Cover that you built with this hacked perl-5.10.0 will work on an unhacked perl-5.10.0. (Others would probably know the answer to that without needing to test it.) Have you tried that out ? If it works on the unhacked version of perl, then it could be handy for others if the binary of your build of Devel::Cover (either ppm package or just a tar.gz of blib) was made available.
That did not work. Devel::Cover unsurprisingly needs access to the symbols during both build and run time. Tried it with a 5.8.8 because that's my existing installation with lots of modules I don't care to reinstall.
Instead I patched the current installation by building a Perl 5.8.8 with the exported symbols, and then: