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digitalmars.D.learn - gcc 9 vs. dmd?

reply Andrew Pennebaker <andrew.pennebaker gmail.com> writes:
Given that gcc v9 should have built-in support for compiling D 
code, and that dmd requires gcc, will dmd continue to be 
supported? Or perhaps have its guts incorporated completely into 
gcc?
Nov 29 2018
next sibling parent Adam D. Ruppe <destructionator gmail.com> writes:
On Friday, 30 November 2018 at 00:43:59 UTC, Andrew Pennebaker 
wrote:

 Given that gcc v9 should have built-in support for compiling D 
 code, and that dmd requires gcc, will dmd continue to be 
 supported?


dmd will continue to be supported.
Nov 29 2018
prev sibling parent reply mawk <mawk serveur.io> writes:
On Friday, 30 November 2018 at 00:43:59 UTC, Andrew Pennebaker 
wrote:

 Given that gcc v9 should have built-in support for compiling D 
 code, and that dmd requires gcc, will dmd continue to be 
 supported? Or perhaps have its guts incorporated completely 
 into gcc?


DMD doesn't really require GCC, GCC is in theory used for 
compatibility with modules compiled with gcc according to dmd(1), 
and in practice used for linking.

The linking step could be done with ld alone if you know what to 
type, and it's honestly pretty complicated, and you still need 
components from gcc, for various reasons:

LIBGCCDIR=$(cc -print-file-name=)
CRTDIR=/usr/lib/$(cc -dumpmachine)

ld -L $LIBGCCDIR $CRTDIR/Scrt1.o $CRTDIR/crti.o 
$LIBGCCDIR/crtbeginS.o \
YOUROBJECT.o -E --push-state -static -lphobos2 --pop-state \
-lpthread -lm -lrt -ldl -lc -lgcc -lgcc_s $LIBGCCDIR/crtendS.o 
$CRTDIR/crtn.o
Nov 29 2018
parent reply Andrew Pennebaker <andrew.pennebaker gmail.com> writes:
On Friday, 30 November 2018 at 01:31:12 UTC, mawk wrote:

 On Friday, 30 November 2018 at 00:43:59 UTC, Andrew Pennebaker 
 wrote:

 Given that gcc v9 should have built-in support for compiling D 
 code, and that dmd requires gcc, will dmd continue to be 
 supported? Or perhaps have its guts incorporated completely 
 into gcc?


 DMD doesn't really require GCC, GCC is in theory used for 
 compatibility with modules compiled with gcc according to 
 dmd(1), and in practice used for linking.

 The linking step could be done with ld alone if you know what 
 to type, and it's honestly pretty complicated, and you still 
 need components from gcc, for various reasons:

 LIBGCCDIR=$(cc -print-file-name=)
 CRTDIR=/usr/lib/$(cc -dumpmachine)

 ld -L $LIBGCCDIR $CRTDIR/Scrt1.o $CRTDIR/crti.o 
 $LIBGCCDIR/crtbeginS.o \
 YOUROBJECT.o -E --push-state -static -lphobos2 --pop-state \
 -lpthread -lm -lrt -ldl -lc -lgcc -lgcc_s $LIBGCCDIR/crtendS.o 
 $CRTDIR/crtn.o


gcc is currently required for dmd on FreeBSD, as dmd links to 
libstdc++.
Nov 29 2018
parent reply welkam <wwwelkam gmail.com> writes:
On Friday, 30 November 2018 at 04:47:26 UTC, Andrew Pennebaker 
wrote:

 gcc is currently required for dmd on FreeBSD, as dmd links to 
 libstdc++.


Parts of dmd are still written in C++ but most of it was 
converted recently. More on that here:
"DMD backend now in D"
https://forum.dlang.org/thread/psaekt$tah$1 digitalmars.com
Nov 30 2018
parent Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
On Friday, November 30, 2018 2:43:41 AM MST welkam via Digitalmars-d-learn 
wrote:

 On Friday, 30 November 2018 at 04:47:26 UTC, Andrew Pennebaker

 wrote:

 gcc is currently required for dmd on FreeBSD, as dmd links to
 libstdc++.


 Parts of dmd are still written in C++ but most of it was
 converted recently. More on that here:
 "DMD backend now in D"
 https://forum.dlang.org/thread/psaekt$tah$1 digitalmars.com


That and the C/C++ compiler could be clang rather than gcc. Even without the
backend being ported to D, there shouldn't be an actual dependency on gcc
specifically (especially on FreeBSD where you may not even have gcc
installed). But if I understand correctly, dmd has always used the C
compiler to link on *nix systems rather than using the linker directly. I
don't know why it does, but linking via the C compiler is a completely
different issue from integrating with it.

Regardless, as to the OP's question about gcc integration, that really
doesn't have much to do with dmd. That's a big step forward for gdc, but dmd
is the reference compiler. It's where everything is implemented. gdc and ldc
are then alternate compilers that use the same front-end. but they're
separate projects, and there's really no benefit to us at this point to
removing dmd in favor of either of the other two. With dmd, we're in full
control of the code and the release cycle, which is not true with llvm or
gcc. Honestly, as great as it is for gdc to end up in the official gcc
release, in practice, I expect that it's going to be a recipe for a portion
of the community using an outdated version of the language (especially when
coupled with stuff like LTS releases for Linux distros). That's already been
a problem with gdc even without it being in the official gcc release due to
how long it's taken them to catch up after the front-end was converted to D.

Also, dmd's backend is the backend that Walter wrote and has used for
decades - and it's part of dmc, which he still sells. So, I don't think that
he's going to be in hurry to drop it. And if he were, I honestly expect that
ldc would have become the reference compiler a while ago, not gdc. But dmd
continues to be the reference compiler, and while improving its backend is
not the focus, Walter still does work on it (and part of the reason that
he's converted it to D is so that he can more easily improve it).
Historically, Walter has wanted to stay away from gcc and clang code (or the
code of any other compiler that isn't his), because in the past, he's found
that being able to say that he's never read the source code has been a good
defense against any kind of accusation of code stealing (which definitely
matters when he's selling a C++ compiler). So, all the signs are that we're
going to continue to have the choice of dmd, ldc, and gdc, and none of them
are going anywhere.

- Jonathan M Davis
Nov 30 2018