a)

[NSNumber numberWithDouble:somevalue] seems to always return nil.
[NSNumber numberWithInt:someintvalue]  however works.

I couldn't figure out where the error occurs but it looks like the generic NSNumber object gets allocated instead of the subclassed NSNumber_double or something like that.

b) Foundation code inside pthreads don't work if you create them using pthread library calls. In our case it did crash at the first NSAutoreleasePool alloc/init sequence. The workaround was to use NSThread instead

b) Another problem we run into is @synchronized not working if its cascaded. But only in threads apparently. This might be compiler specific or runtime library specific. We did compile cocotron under Linux with LLVM Clang 3.2 using the gnustep-libobjc2 runtime. While doing all this , we did also run into some crash of svn clang which got fixed within a couple of days by the clang developers and the stock version of gdb was also terribly confused until gdb was installed from source. We have it now compiling natively under CentOS, Debian and Ubuntu (and probably others). If anyone wants to have the Makefiles, let me know.