+ , "-optc-DDYNAMIC"
+#if defined(mingw32_TARGET_OS)
+ -- On Windows, code that is to be linked into a dynamic library must be compiled
+ -- with -fPIC. Labels not in the current package are assumed to be in a DLL
+ -- different from the current one.
+ , "-fPIC"
+#elif defined(openbsd_TARGET_OS)
+ -- Without this, linking the shared libHSffi fails because
+ -- it uses pthread mutexes.
+ , "-optl-pthread"
+#endif
+ ],