D-Programming-Language/dmd — pull request #3397 by Yoplitein (2014-03-22 17:59:42+00:00)
Title: Recognize shared libraries as valid files when linking

Fixes commands like `dmd -ofmain main.o libfoo.so` outputting `Error: unrecognized file extension so`
Doesn't have code for windows, but I have a feeling that linking DLLs is completely different.