https://issues.dlang.org/show_bug.cgi?id=17666
--- Comment #9 from Jonathan M Davis <issues.dl...@jmdavisprog.com> --- (In reply to Sebastiaan Koppe from comment #8) > Finally had some time to take a look. Pretty awesome. Thanks. > > But why in core.sys.linux.netinet.in_ is some stuff behind static > if(__USE_MISC)? As far as I can tell that conditional evaluates to false, > and there is a structure in there - ip_mreq - that I need. Unless I screwed it up, it follows what's defined in the header file. And yes, looking at core.sys.posix.config, it looks like it always evaluates to false. It needs either _BSD_SOURCE or _SVID_SOURCE to be true, but they're both false. I don't know whether that's correct or not. But if __USE_MISC is normally defined on a Linux system using glibc, then that implies that either how we're defining it is wrong or that we're doing the wrong thing with _BSD_SOURCE and/or _SVID_SOURCE. > Also, the static if(__USE_MISC) at > https://github.com/dlang/druntime/blob/master/src/core/sys/linux/netinet/in_. > d#L168 is already inside a static if (__USE_MISC) conditional block. That does look odd. Rechecking the file, it looks like I missed an #endif when reading it and thought that that section went longer than it did (braces with staci if are _so_ much better for figuring out when a section begins and ends). I've created a PR to fix it: https://github.com/dlang/druntime/pull/1911 That doesn't get you ip_mreq though. It's clearly in the __USE_MISC section. So, if we're going to have it, we need to figure out what the deal with __USE_MISC is and how we should be handling it such that it's true if it's true on Linux, but I really don't know anything about it. --