Free the DMD backend

[Matthias Klumpp via Digitalmars-d]

On Wednesday, 1 June 2016 at 01:26:53 UTC, Eugene Wissner wrote:
> On Tuesday, 31 May 2016 at 20:12:33 UTC, Russel Winder wrote:
>> On Tue, 2016-05-31 at 10:09 +0000, Atila Neves via 
>> Digitalmars-d wrote:
>>> […]
>>> 
>>> No, no, no, no. We had LDC be the default already on Arch 
>>> Linux for a while and it was a royal pain. I want to choose 
>>> to use LDC when and if I need performance. Otherwise, I want 
>>> my projects to compile as fast possible and be able to use 
>>> all the shiny new features.
>>
>> So write a new backend for DMD the licence of which allows DMD 
>> to be in Debian and Fedora.
>
> LDC shouldn't be the default compiler to be included in Debian 
> or Fedora. Reference compiler and the default D compiler in a 
> particular distribution are two independent things.

Exactly. But since we can legally distribute DMD in e.g. Debian, 
and DMD is the reference compiler, we will build software in 
Debian with a compiler that upstream might not have tested.
Additionally, new people usually try out a language with the 
default compiler found in their Linux distribution, and there is 
a chance that the reference compiler and default free compiler 
differ, which is just additional pain and plain weird in the 
Linux world.

E.g. think of Python. Everyone uses and tests with CPython, 
although there are other interpreters available. If CPython would 
be non-free, distros would need to compile with a free compiler, 
e.g. PyPy, which is potentially not feature complete, leading to 
a split in the Python ecosystem between what the reference 
compiler (CPython) does, and what people actually use in Linux 
distributions (PyPy). Those compilers might use different 
language versions, or have a different standard library or 
runtime, making the issue worse.
Fortunately, CPython is completely free, so we don't really have 
that issue ;-)