It's one of the 4 big remaining C++ compiler frontends: gcc, clang, MSVC, EDG. Most other C++ compilers are based on either EDG or clang. (e.g. the Intel C++ compiler used to be based on the EDG frontend, though modern versions are based on clang instead)

The "frontend" is the part of the compiler that understands the input language: lexer, parser, template instantiation, constexpr evaluation, ... The EDG frontend produces an intermediate representation (IL) that is then used by the different compiler vendors to generate machine code. Or do code analysis.

EDG can also be used as a C++-to-C compiler.

> EDG can also be used as a C++-to-C compiler.

Nice to see this still exists!

After all, this is how it all started back in the days of - what was it called again ? - yeah, cfront

https://en.wikipedia.org/wiki/Cfront