I don't know enough to understand if the "hard" troubles described by John Meacham are real, but I think that even if they are not, the current situation violates the "principle of least surprise" for the author of a module. Such author may be unaware of the need to take special steps to make his module use the same file API as the builtin language functions, and that will lead to situations when the modules bundled with the compiler can deal with >4Gb files but the new module cannot. It may be even worse for instance with respect to reentrancy of the code: the author of the module may not realize that he needs to take special steps or e.g. the handling of errno will be broken in multithreaded environment. In extreme case, even the opposite situation is possible: the module's autoconf may detect some obscure incompatible feature of the system that the base build did not know about (even if this is a pure theoretical danger). I think it would be a right thing to provide the author of an external module with "baseline" C environment by default, compatible with the environment under which the modules bundled with the compiler where built. And on top of that, allow them to use autoconf/whatever else to deviate from that if they need to. Eugene