[GSoC 2019] Interested in Baremetal D Runtime and project ideas

[Mike Franklin]

On Saturday, 6 April 2019 at 20:22:19 UTC, Stefanos Baziotis 
wrote:

> I totally agree with all of these. What I roughly got from the 
> project
> description was to achieve what Andrei said but without the 
> dependencies to
> so much existing C/C++ code.

I don't see that Andrei objects much to the C/C++ dependency.  
Afterall, he recently approved adding the C++ standard library to 
the druntime: https://github.com/dlang/druntime/pull/2286

In fact, I find I'm in the minority when it comes to wanting to 
replace `memcpy` and friends with templates.  It's hard to 
advocate for it right now because there isn't actually a way to 
utilize it.  That's why Dan's project is so important.  Once Dan 
is done and the other runtime hooks are converted to templates 
the benefit of replacing `memcpy` and friend will become more 
apparent.  Until that work happens, we can't really utilize the 
templatized versions of `memcpy` and friends and so it will be 
difficult to measure real-world benefits.  Once done however, 
could replace `memcpy` and friends in the runtime and run some 
real-world benchmarks on the DMD compiler, Phobos, and other D 
projects to measure real benefit.  And that's not to mention 
turtles-all-the-way-down safety and purity guarantees provided by 
the compiler.

I'm not sure who posted the original GSoC idea, so they'd have to 
speak for themselves, but it appears to be a synthesis of things 
I have been advocating for for a long time.  It's not really 
about creating a bare metal runtime, it's mostly just about being 
able to use D for bare-metal programming in a pay-as-you-go 
fashion.

> So what do you believe is the best way I can help?

Where to begin?  There's so much work that needs to be done, I'm 
not even sure where to start.  At the moment, I'm just trying to 
clean up some unfinished business in the compiler like converting 
the last remaining C files in DMD to D, following through on 
deprecations so we can be liberated from some technical debt, and 
hopefully getting around to finishing 
https://github.com/dlang/dmd/pull/9068 which is a prerequisite to 
refactoring druntime enabling much of what I've been talking 
about.

Probably the best thing you can do is focus on your proposal and 
make it great.  I hope those reviewing the proposals will be able 
to see the relationship and natural progression with Dan's 
proposal and yours and both will be selected.

For the past 5 years this has been my experience working on D:  
https://www.youtube.com/watch?v=AbSehcT19u0

If you're anxious to get your hands dirty, you can start by 
choosing a not-yet-converted runtime hook from 
https://wiki.dlang.org/Runtime_Hooks and have at it.  See 
https://github.com/dlang/druntime/pull/2508 for another recent 
example of another contributor getting busy.

https://github.com/dlang/dmd/pull/9068 is a low barrier to entry 
task that would help us out a lot.

You can also start stripping out utilities from Phobos (e.g. 
std.traits, std.meta, std.conv, etc.) to create a no-dependency 
utility library.  Basically my "Suggestion 2" here: 
https://forum.dlang.org/post/qooasdrdlrqdhghjwmus@forum.dlang.org 
  It could potentially serve as a starting point for std.v2 and 
the opt-in continuum.  See 
https://forum.dlang.org/post/mailman.7799.1553797857.29801.digitalmars-d@puremagic.com for the thread where that was first proposed.

Mike