This is the OpenD Programming Language compiler, originally based on Walter Bright's D Programming Language.
This repo contains a Digital Mars based compiler, a LLVM based compiler, the unified runtime, and portions of the standard library.
Download it here:
https://github.com/opendlang/opend/releases/tag/CI
The latest build is always found there.
See: https://docs.github.com/en/get-started/using-git/about-git-subtree-merges
ldc and phobos are both subtrees from upstream.