Here's another open-source contribution for Microsoft's list of unusual open-source/Linux announcements this year: they've added a CodeView library to LLVM.

CodeView is a Microsoft debugger dating back to the 1980's with it still existing today in the form of a debugging information format for Microsoft's compiler. This newly-added library to LLVM is for allowing this open-source compiler stack to generate debugging information that's compatible with the CodeView format. Some details are explained by this commit.

This is just the latest LLVM/Clang activity by Microsoft developers and part of their effort of new debug support and hooking up Clang's parsers to the rest of their compiler stack.