Context: Walter Bright created the first native C++ compiler, Zortech C++. This pull request actually implements its own C compiler! For Walter, considering he's implemented C++98 alone, implementing C must be nothing :)

He implemented the ANSI C compiler here in just 5 days.

Semi-related project, using libclang to import C++ directly (with C++ templates and all the other features, regular D has C++ linking and exception support built-in): https://github.com/Syniurge/Calypso

Some quotes from the forum https://forum.dlang.org/post/s7a37h$2bbv$1@digitalmars.com :

- Writing a C preprocessor is a nightmare. Fortunately, I already did that https://github.com/facebookarchive/warp and we can use it if we choose.

- The D code will be able to inline C code, and even CTFE it.

- There are a lot of wacky C extensions out there. We only need to implement currently used ones (not the 16 bit stuff), and only the stuff that appears in C headers.

- Without a C compiler, we're stuck with, wedded to, and beholden to libclang. I wouldn't be surprised that the eventual cost of adapting ourselves to libclang will exceed the cost of doing our own C compiler.