Reported as an 'issue' on the blackhole tracker (http://github.com/pereckerdal/blackhole/issues/#issue/6), but I figured I'd copy it to the list in case anyone else was interested/being-affected, or on the offhand chance that this isn't a responsibility of blackhole to correct for a change in gambit...
upgrading to 4.5.3 kills import dead in it's tracks whenever you have a module that uses the C FFI and thus requires compilation.
As demonstrated below (only change is upgrade to 4.5.3 and re-build of 'build.scm'/removal of ns.dat)
[nikki@vbox src]$ bsc Loaded Black Hole... Gambit v4.5.2
(import test-c)
/home/nikki/src/test-c is being compiled...
(c-print)
Hello world
=====
[nikki@vbox src]$ bsc Loaded Black Hole... Gambit v4.5.3
(import test-c)
/home/nikki/src/test-c is being compiled... *** ERROR -- Operator is not a PROCEDURE (#("test-c.o1" ##2 http://github.com/pereckerdal/blackhole/issues/#issue/2 | test-c.o1|>))
At a guess, this is likely caused by something in the following commit :
http://www.iro.umontreal.ca/~gambit/repo/.cgit.cgi/Gambit/commit/?id=5bae3cb... http://www.iro.umontreal.ca/%7Egambit/repo/.cgit.cgi/Gambit/commit/?id=5bae3cb2db90f90ae9fbe16374f4c44fdb3106fe