Re: [avr-gcc-list] using exceptions

[Gabriel Dos Reis]

On Tue, May 1, 2012 at 12:15 PM, Weddington, Eric
<address@hidden> wrote:
>> -----Original Message-----
>> From: address@hidden [mailto:avr-
>> address@hidden On Behalf Of Gabriel
>> Dos Reis
>> Sent: Tuesday, May 01, 2012 9:18 AM
>> To: Georg-Johann Lay
>> Cc: address@hidden
>> Subject: Re: [avr-gcc-list] using exceptions
>>
>>
>> My recent interests in AVR grew out of educational and research
>> activities -- as I explained in a relatively recent post on libstdc++.  I am
>> still learning AVR and its toolsets but I can definitely help with the C++
>> part.
>>
>> We are in the situation where we would like to compile a restricted
>> subset of Haskell to AVR via C++ intermediate codes.
>>
>> I will have a look at PR50925.
>>
>> -- Gaby
>
> Hi Gaby,
>
> I've seen your name extensively on the gcc mailing list. I've also been to a 
> number of the GCC Summit events in the past few years; I don't know if you've 
> attended them also.

Unfortunately, I've (consistently :-/) missed GCC Summit because of
my daytime job -- despite being a libstdc++ maintainer, and maintainer
of other parts of the compiler, and having been a GCC Release Manager
for a while.

>
> I'm sorry but I've missed your recent post on libstdc++ that explained your 
> educational and research activities. Do you have a link? Please let me know 
> if there's anything we can do to help you with these activities.

Essentially, we would like to:
  (1) "spice up" our programming class projects with
        robots programming -- many of our students are native C++ speakers,
        and AVR-based robots are cheap :-)

  (2) as a research project, some of my students would like to
        program AVR microcontrollers in Haskell to explore the
        "functional reactive programming" paradigm.  However, GHC,
        the most popular Haskell compiler does not support AVR and I
        do not think it is going to do so in the near future, based on
discussions
         I have had with GHC key developers.  So, a subgroup
        of students (under my direction) has set up to write a
compiler for a subset
        of Haskell targetting AVR.  This is quite an exciting research project.

>
> Johann is pretty much right in his description. Historically, there haven't 
> been very many AVR developers on GCC. Joerg Wunsch (CC) and I, who are both 
> admins on the avr-libc project, have had an open request for years for a 
> volunteer to help with the C++ side of things, and specifically to help build 
> libsupc++ support for the AVR. None of us are experts in C++, but relatively 
> good experience in C.
>

I am a maintainer for libstdc++ and would be happy to help here.
But, I must also confess that there has been some confusion among
us (libstdc++ maintainers) about exactly what is needed for AVR to get
basic stuff started.  See for example:

    http://gcc.gnu.org/ml/libstdc++/2012-01/msg00098.html

I am not expert in AVR -- I know just enough to be dangerous, so I
would definitely do with some education here.


> C++ on the AVR has had more attention recently, mainly because of the Arduino 
> community. The Arduino language is translated into C++ and then compiled for 
> the AVR. So any help with C++ will also affect that community in a positive 
> way.
>

Thanks, that is good to know.

> Also let us know if there's anything we can do to help you get up to speed on 
> the AVR toolset.

I guess I would need to get my feet wet with
   1. minimal free-standing  C++ implementations without exceptions
   2. get support for RTTI (without exceptions)
   3. exceptions (assuming 1 and 2 are done successfully)

Regarding 2., I would like to understand the general policy:  RTTI
data are generally const
and should be best stored in read only location.  What is the general
preference for AVR?  Put
read only data in program memory or data segment?  Apologies for the
triviality but
the recent discussion about __func__ got me thinking.

Is Johann my main entry point as GCC AVR maintainer?

-- Gaby