Re: DragonEgg has been revived

["Dan'l Miller" <optikos@verizon.net>]

On Tuesday, May 22, 2018 at 2:40:24 PM UTC-5, Shark8 wrote:
> On Tuesday, May 22, 2018 at 6:29:10 AM UTC-6, Simon Clubley wrote:
> > 
> > What I would like to see is an Ada compiler that can generate code
> > for a wide range of targets without any GPL restrictions on the
> > generated code.
> 
> I'm getting ready to restart work on Byron. I figure that perhaps an Implementation Manual/Design Document would help explain the design underneath it and welcome new contributors. 
> 
> > 
> > I'm not really bothered how that happens but LLVM seems like an
> > interesting option.
> 
> I have mixed feelings on LLVM -- it would be nice to grab all the targets for it, but I also think it's a stupid
> idea to build the compiler specifically for it.

Writing a compiler “specifically for” LLVM?  I thought that the whole premise of Byron was to write an Ada compiler for multiple back-ends:
1) libFirm:  https://pp.ipd.kit.edu/firm
2) LLVM
3) GCC
4) Graal for JVM:  http://www.graalvm.org
5) CLR for .NET & Mono
and so forth.

Compared to Byron's laudable long-term clean-room-design goals, my GELI proposal* for an LLVM-backended GNAT is an interim stop-gap, focusing only on likely-not-clean-room generation of LLVM bitcode IR within a single GPLv3 GNAT executable, causing only ISAs' machine-code (not the IR) to be generated by LLVM-embedded-within-GNAT.

* described in a prior reply above

> Yeah; that's one of the big problems Byron [Ada 2012 in Ada 2012] is intended to address; the other big
> one is to escape the stupid morass of licensing issues.

What is so bad about GPLv3 with Runtime Exception …

1) … unless a person really really wants to re-work GCC-emitted machine code as lifted to LLVM bitcode IR via, say, McSema as not-GPLv3ed derivative works, needing disclosure of all source code?**
or

2) … unless a person really really wants to write LLVM bitcode IR out to a file to execute it on Sulong/GraalVM as not-GPLv3ed derivative works, needing disclosure of all source code?**
or

3) Can anyone think of any other precise downsides of GPLv3 •with• Runtime Exception?

I think all the downsides other than those 2 listed above are with GPL •without• Runtime Exception, correct?

** Due to the Target Code clauses of GPLv3 and the Eligible Compilation Process of GPLv3's Runtime Exception, all downstream derivative works are staunchly GPLv3 with the Runtime Exception overtly revoking itself due to the (clearly) IR or the machine-code-as-IR.