Wow. This is big news for C++.

For background -- and I am not an expert here -- their C++ frontend is widely known. I first heard of it because Visual C++'s Intellisense uses it, which was notable because VC does not use the msvc frontend for its own completion. I understand it's been either used or evaluated for other frontends in the past too. I worked as PM for one C++ product, and was fortunate to be able to learn a lot from our engineers; we didn't use it, but they thought highly of EDG.

It has a very strong reputation for being correct. And as such, I think open sourcing it will be a very beneficial thing for the C++ community.

Announcement: https://edgcpp.org/#transition

The source code itself: https://github.com/edgcpp/compiler

Documentation: https://edgcpp.org/doc/

And for those curious the license SPDX is: Apache-2.0 WITH LLVM-exception

i.e.

- https://spdx.org/licenses/Apache-2.0.html

- https://spdx.org/licenses/LLVM-exception.html

Ah, I used EDG for static analysis, but joined when we were switching over to using Clang for the frontend. I can't say for sure, but part of it was definitely just to save money using open source. The code that was hacked on top of EDG was also ridiculous, so there was a lot of accumulated tech debt there.

Looking back at that code definitely brings back memories. As a consumer of both frontends, I will say I much preferred working with Clang's. Both needed extra work on top to support everything we needed. Maybe I'm just not as acquainted with C as I would like to be. It's cool to look at this again, though.

"Three tracks, one codebase" this is such an LLM written sentence.

EDIT: But in this case it seems something significant is being released, it would be better with less writing and more human if possible.

It's got history! That's really unusual for moves to open-source; the dates on the earliest commits are in 1990 and they do go forward in time so that's really unusual to have that much history. I bet there's some fun stuff in there.

Despite using C++ for a few years now, the EDG source code is still mostly C code (and in fact, the C++ code is still using the old .c file names). In particular, there's no usage of the C++ standard library.

Where other languages might use inheritance, EDG still uses the C-style `union { ... } variant;`.

On a related note, compiling EDG is extremely fast: on my machine, the EDG frontend compiles in <10s; whereas clang takes >10min (caution unfair comparison: clang includes much more than just a frontend).

If I remember correctly, EDG was the only C++ implementation that actually attempted to implement the export keyword for templates in old C++. It was this implementation experience that informed the deprecation of export. EDG is a major influence in the development of C++.

Ooh, fond (and some not so fond) memories of when Silicon Graphics' (MIPS) C and C++ compilers were based on EDG's frontend, with a custom ucode-generating backend, and integrated into CASEVision. Early 1990s.

EDG was just 3 guys back then.

It has an interesting code style, the comments go _after_ the function definition but before the opening bracket.

It looks weird, but it actually makes sense! The flow is more natural - first the function definition, and then the explanation of what it does. It also avoids repeating the function name.

What is this?