The D ecosystem in Debian with free-as-in-freedom DMD

[Marco Leise via Digitalmars-d]

Am Tue, 11 Apr 2017 07:40:12 -0700
schrieb Jonathan M Davis via Digitalmars-d
<digitalmars-d at puremagic.com>:

> It could always just be distributed as a static library. There arguably
> isn't much point in distributing it as a shared library anyway -
> particularly when it's not ABI compatible across versions. I actively avoid
> having phobos as a shared library on my systems, because it just causes
> versioning problems when programs are built against it. All of those
> problems go away with a static library. And so much of Phobos is templated
> anyway that there isn't even much to share.
> 
> - Jonathan M Davis

I see what you're doing there, but your last point is wishful
thinking. Dynamically linked binaries can share megabytes of
code. Even Phobos - although heavily templated - has proven to
be very amenable to sharing. For example, a "Hello world!"
program using `writeln()` has these sizes when compiled with
`dmd -O -release -inline`:

     static Phobos2 : 806968 bytes
    dynamic Phobos2 :  18552 bytes

That's about 770 KiB to share or 97.7% of its total size!
Awesome!

Another package we have on Gentoo now is the tiling terminal
emulator Tilix, compiled with its default `dmd -O`:

     static Phobos2+GtkD : 14828272 bytes
    dynamic Phobos2+GtkD :  6126464 bytes

So here we get ~8.3 megabytes in binary size reduction due to
sharing. (Though 6 MiB for a terminal is still a lot - are
we slim yet? :P )

Some forms of proprietary code and GPL code need clean
shared library interfaces, free from templates and attribute
inference. I mentioned this before: As far as feasible have
full attribute inference for non-exported functions and
reliance on only explicit attributes for exported functions,
so that code changes can't break the public API (due to
mangling changes).

When Dlang's ABI changes, release a major version and make a
public announcement so that everyone can schedule the system
update to a convenient time as is done with GCC C++ ABI
changes.

-- 
Marco