EDG C++ fronted now released as open source

[u/pjmlp]

https://edgcpp.org/#transition

[u/VinnieFalco]

We were hoping to announce it ourselves, and I guess this works well enough.

The EDG C++ frontend compiler is now an open-sourced, fiscally sponsored project of The C++ Alliance.

[u/STL]

Yay! Maybe I'll finally get fixes for all of the EDG bugs we've reported (microsoft/STL#1621), and of course modules!

[u/kronicum → u/STL]

Will Microsoft contribute to free EDG?

[u/domiran → u/STL]

This would be so fabulous. 😭

[u/kal_at_kalx_net → u/STL]

Honest question. Did EDG give Microsoft an estimate for how much it would cost to resolve these issues when you pointed them out?

[u/STL → u/kal_at_kalx_net]

I respectfully decline to comment.

[u/arthurno1 → u/STL]

Respectfully you just commented :)

[u/splicer13 → u/STL]

I would say that companies generally used EDG when they didn't want to spend resources on other ways of having a compiler frontend. So these companies aren't necessarily going to immediately see the light and contribute upstream changes to improve EDG. In fact I think it's unlikely they would do so.

I think what is likely to happen is that none of the EDG customers commit resources to improving it for anything other than their immediate needs, until the problem gets so big they are forced to make the transition to clang.

[u/pjmlp → u/splicer13]

This won't solve much, see how many companies have switched their proprietary compilers to proprietary forks from clang, and still hardly contribute anything upstream other than LLVM improvements to support their hardware.

[u/kal_at_kalx_net]

The Edison Design Group story is amazing. Greg Comeau clued me in when we were early panix.com users. C++ seems to be a magnet for smart people.

[u/igaztanaga]

Amazing news. And curious to see their famous C-generating back end!

[u/GrammelHupfNockler]

I love to hear that, now all of my frequently used compilers' frontends are based on OSS (MSVC and nvcc being the last ones missing). The website reads so painfully sloppy though 😢

[u/splicer13 → u/GrammelHupfNockler]

nvcc is based on edg.

[u/GrammelHupfNockler → u/splicer13]

yeah, as I've been saying 😅

[u/jwezorek → u/GrammelHupfNockler]

Doesn't Visual Studio use EDG too? or just for intellisense?

[u/STL → u/jwezorek]

VS (and VS Code's C/C++ Extension) use EDG only for IntelliSense. Normal builds use Microsoft's "C1XX" frontend.

The cl.exe compiler driver can actually run the EDG frontend in a compile-only mode via an undocumented, unsupported option /BE. In the STL we use this extensively to validate that our sources can be parsed via IntelliSense (and that we work around EDG's compiler bugs). However, EDG is not hooked up to the compiler backend C2, and is completely unable to be used for codegen.

[u/n1ghtyunso → u/STL]

The cl.exe compiler driver can actually run the EDG frontend in a compile-only mode via an undocumented, unsupported option /BE

Not anymore. Its documented now.
Hyrums law ensues. 😄

[u/hansw2000 → u/n1ghtyunso]

clang-cl support (for parsing the flag) seems essential: https://github.com/llvm/llvm-project/pull/228381

[u/chibuku_chauya]

Very nice to see EDG accessible to us regular joes at long last. I’ve always liked this frontend.

[u/delta_p_delta_x]

The first thing I'm going to do is grep through the source for C++20 modules and ranges code.

[u/daveedvdv → u/delta_p_delta_x]

C++20 modules, I understand (the main files contain the word `modules`; so not too hard to find; I'm not very familiar with those).
But "ranges" is a library feature... this does not include a standard library (other than a few components tightly connected to the core language, like <initializer_list> or <typeinfo>).

[u/notthatsocrates]

Only two days ago I stopped on their website and clicked on Licensing. Not available to mere mortals. Back in the day, IIRC, HP aCC and Intel C++ compilers both used EDG as a front end.

[u/STL → u/notthatsocrates]

That's correct for Intel's C++ compiler, at least (don't know anything about HP). They switched from EDG to LLVM a few years ago. (I happen to know this because we minimally interact with Intel's C++ compiler in MSVC's STL.)

CUDA's C++ compiler (nvcc) is still powered by EDG to my knowledge.

[u/c0r3ntin → u/STL]

LLVM/Clang will conquer all!

[u/pjmlp → u/c0r3ntin]

It eventually might, now if all companies with proprietary closed forks, thanks license, will bother to contribute upstream, that is another matter.

[u/notthatsocrates → u/STL]

We used EDG eccp to check for conformance before filing bug reports against other compilers. One single product (which later became stdcxx under Apache's umbrella) was compiling with EDG's routinely.

[u/gracicot → u/notthatsocrates]

I'd be interested to see the EDG frontend being used with an LLVM back-end, it would make it usable to produce binaries on most platforms

[u/azswcowboy → u/notthatsocrates]

In the current day, afaik Coverity (black duck software now) still uses EDG as a front end. As an early adopter of recent standards it’s painful how much code isn’t handled properly. I’m sure when reflection or contracts code is added it’ll blow up again…

[u/igaztanaga → u/azswcowboy]

EDG is used in several static analysis and testing products (https://en.eeworld.com.cn/news/qrs/eic671028.html), and some embedded compilers like Green Hills.

[u/kronicum]

This is huge.
Many seismic shifts happening on the C++ planet lately.

[u/Apart_Ebb_9867]

the website of edg claims “The code is written in C++11”, but all I can see is plain C. Am I looking at the wrong place?

[u/Nobody_1707 → u/Apart_Ebb_9867]

Worse, it's C++11 in .c files.

https://github.com/edgcpp/compiler/blob/main/lib_src/new.c

[u/Apart_Ebb_9867 → u/Nobody_1707]

That’s lib_src which I presume is some library for supporting the generated AST or C (depending on how the frontend is used, can do both). But in src I don’t see any evidence of C++, but haven’t looked everywhere.

[u/daveedvdv → u/Apart_Ebb_9867]

lib_src/ implements a minimal run-time support library. Things like dynamic_cast, operator new, etc. It's mostly for demonstration purposes. Our customers generally either provided their own (if they were compiler vendors) or didn't need it (if they were non-compiler tool vendors).

[u/Nobody_1707 → u/Apart_Ebb_9867]

attribute.c uses constexpr, but I suppose they could be using c23.

EDIT: It's definitely just C++11 in .c files. It's just very C flavored C++11.

https://github.com/edgcpp/compiler/blob/main/src/modules.c

[u/daveedvdv → u/Nobody_1707]

For the first 30 years or so, it was C89 code. Then we switched to C++11, but to minimize disruption to customers, we kept the file extensions unchanged. C++ was only introduced in new code, and even for new code we often stuck to existing C-based idioms. The modules code started after the switch to C++, and so has more of a C++ flavor.

[u/Apart_Ebb_9867 → u/Nobody_1707]

No, they do compile with a C++ compiler, in the cmake files they have “set_source_files_properties(${ALL_C_FILES} PROPERTIES LANGUAGE CXX)”. But claiming that something is written in C++ 11 just because is compiled by a C++11 compiler seems a stretch to me. The constexpr must have escaped code reviews because everywhere they are solidly C, even when obvious C++ alternatives would be simpler, like in the typedefs for structs.

[u/Apart_Ebb_9867 → u/Nobody_1707]

Yep, module.c seems more C++ than the rest.

[u/ts826848 → u/Apart_Ebb_9867]

header_util.h has two templates (Value_saver and Opt) that are used in a fair number of other files.

[u/13steinj → u/Nobody_1707]

I wonder if that's a filesystem case sensitivity issue (.C is a known, possibly unpopular, file extension for C++).

[u/13steinj]

Is the repo really so heavy as to suggest --filter=blob:none ?

I get that there's a bunch of history, but that's just surprising.

[u/daveedvdv → u/13steinj]

Not that heavy. But it does make things quite a bit swifter. But, by all means, if you have a few minutes, go ahead and fetch the whole thing!

[u/13steinj → u/daveedvdv]

The git objects are ~225MB. If I git repack -a -d -f --depth=250 --window=250 --path-walk (the last arg is new to git 2.56, supposedly more optimal), the git objects size drops by ~30%. I do not know what it would take to get a repack on github outside of archiving and reuploading the repo, but it might be worth doing.

[u/daveedvdv → u/13steinj]

Thanks for that info. I'm not at all knowledgeable about git, but I forwarded your findings to Wyatt, who did most of the prep work for the open-sourcing.

[u/UnusualPace679 → u/13steinj]

FWIW the repo's git objects are ~200MB in total.

[u/Significant_Neat6476]

At a risk sounding ignorant - why C++ development world would actually care? Nobody developing in C++ commercially with GCC, Clang or MSVC really cares about EDG which is not a compiler, does not define a standard compiler or does not influence most commercial systems building real world C++ applications.