• timotheecour (33/33) Jan 18 2013 I'm wondering whether it would make sense to do compiler

"timotheecour" <thelastmammoth gmail.com> writes:

I'm wondering whether it would make sense to do compiler 
bootstrapping to speedup further development and bugfixing?

This is inspired by a recent comment from Andrei 
(https://github.com/D-Programming-Language/dmd/pull/1489) ("I 
think we're getting closer to the point we could and should do 
some bootstrapping inside the compiler. Using D for tools may be 
a simple entry point."). This came up regarding the difficulty in 
doing simple things in portable way in C (eg vergen.c).

Here's how this could work relatively easily:

1) define a good enough D specs (called D_specs_frozen). We could 
use a dumbed-down version (D1) but might as well use specs from 
the latest D2.061 release, which includes UDA etc. Compile 
corresponding source code (D_src_frozen) to obtain dmd_frozen 
executable. Development on D_src_frozen stops (only very critical 
bugfixes, see below).

2) start a new fork of dmd (D_src_bootstrap) from latest dmd 
version and gradually rewrite most/all of dmd in D_specs_frozen 
language. This can be done incrementally, using a mix of c and d 
files as intermediate stage and converting them one by one (can 
be semi-automated). I counted "only" 181 C files, which is not 
excessive. Compile dmd_bootstrap executable using dmd_frozen. The 
D specs can continue to evolve at that point, new features get 
added and bugs fixed.

Note, D_src_frozen still contains bugs, but a majority of which 
won't have to be fixed in the D_src_frozen branch. That's because 
there'll be only 1 project that depends on D_src_frozen, which is 
  D_src_bootstrap, so bugs or language limitations can be dealt 
with for that one project. Any other project will be based on the 
continuously improving new D branch.
Instead, people can focus on fixing bugs and enhancing features 
in the D_src_bootstrap branch, which should be orders of 
magnitude easier given that it'll be written in D D_specs_frozen 
instead of C++.