Beside the known ones, like computed gotos and __builtin_expect(), GCC has other less known extensions, you can find some of them here: http://www.ibm.com/developerworks/linux/library/l-gcc-hacks/
They are used by Linux. If D wants to be a system language, such small things may be useful if you want to build a kernel with D. One of them is the Range extension, it seems GCC devs think that 3 points are better after all: switch (major_idx) { case 0: return SCSI_DISK0_MAJOR; case 1 ... 7: return SCSI_DISK1_MAJOR + major_idx - 1; case 8 ... 15: return SCSI_DISK8_MAJOR + major_idx - 8; default: BUG(); return 0; } Triple points can be used for initializations too: int widths[] = { [0 ... 9] = 1, [10 ... 99] = 2, [100] = 3 }; The __builtin_return_address() looks interesting, but I don't understand where it can be useful. The Constant detection done with __builtin_constant_p(exp) is what I was asking for in one of my recent posts here. It seems I was "right" again. The article also shows some of the function attributes, in truth in GCC there are many other of such attributes. Some of them are useful for D too. The good thing of adding some of those things to D is that they can be put in the specs, so they don't become nonstandard extensions as in GCC, this avoids several troubles. Bye, bearophile