[Bug libobjc/48626] New: --enable-objc-gc should be automatic

[Bug libobjc/48626] New: --enable-objc-gc should be automatic

[ro at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

           Summary: --enable-objc-gc should be automatic
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libobjc
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ro@gcc.gnu.org
                CC: nicola@gcc.gnu.org, pinskia@gcc.gnu.org


Currently, --enable-objc-gc, which isn't documented in install.texi, is
required
to enable building libobjc_gc.la.  This could (and should) be automatic: either
automatically build boehm-gc if libobjc is enabled or only build libobjc_gc if
boehm-gc is already built.

The fewer necessary configure options, the better.

[Bug libobjc/48626] --enable-objc-gc should be automatic

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |iains at gcc dot gnu.org

--- Comment #4 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #3)
> I'll probably keep --enable-objc-gc in my configure flags anyways even if it
> becomes automatic, but becoming automatic could help increase test coverage
> of it. I guess I'll confirm this.

Note that Iain Sandoe generally prefers configure detecting things
automatically instead of requiring additional flags; I'm not quite sure how to
go about making this one automatic now that boehm-gc is no longer in-tree,
though.

[Bug libobjc/48626] --enable-objc-gc should be automatic

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

--- Comment #5 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #4)
> (In reply to Eric Gallager from comment #3)
> > I'll probably keep --enable-objc-gc in my configure flags anyways even if it
> > becomes automatic, but becoming automatic could help increase test coverage
> > of it. I guess I'll confirm this.
> 
> Note that Iain Sandoe generally prefers configure detecting things
> automatically instead of requiring additional flags; I'm not quite sure how
> to go about making this one automatic now that boehm-gc is no longer
> in-tree, though.

this seems to be another set of crossed wires.

Darwin only ever used boehm-gc for Java, not for NeXT ObjC

the configure option is related to GC for the GNU runtime.  In that case, the
configuration should work the same as it does for Linux.

===

The NeXT GC support (if it was implemented, which it isn't) on Darwin uses
system-provided libraries (libauto.dylib).  Objective-C GC was retired sometime
around darwin16, so the motivation is low to put effort into implementing it
ahead of more critical missing pieces.

[Bug libobjc/48626] --enable-objc-gc should be automatic

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

--- Comment #6 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Iain Sandoe from comment #5)
> (In reply to Eric Gallager from comment #4)
> > (In reply to Eric Gallager from comment #3)

> > ....  detecting things
> > automatically instead of requiring additional flags; I'm not quite sure how
> > to go about making this one automatic now that boehm-gc is no longer
> > in-tree, though.

detecting automatically (i.e. if the library is in one of the default search
paths) != building automatically (e.g. when it was in tree, it would be built
if objc was configured).

So, in this instance, you could default --enable-objc-gc "on" for darwin, if
the configure machinery [for objc-gc] can cope gracefully with the library
being present or absent.

[Bug libobjc/48626] --enable-objc-gc should be automatic

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

--- Comment #7 from Iain Sandoe <iains at gcc dot gnu.org> ---
now that boehm-gc is no longer in tree

what should we do with this?

I suppose there could be some more sophisticated top-level configuration
(similar to GMP et. al.) which determines if there's a suitable libgc
available?

[Bug libobjc/48626] --enable-objc-gc should be automatic

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

--- Comment #8 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #7 from Iain Sandoe <iains at gcc dot gnu.org> ---
> now that boehm-gc is no longer in tree
>
> what should we do with this?
>
> I suppose there could be some more sophisticated top-level configuration
> (similar to GMP et. al.) which determines if there's a suitable libgc
> available?

On the contrary: I think support for --enable-objc-gc at both the
toplevel and gcc can just go.

* At the toplevel, it's just a preliminary check which I don't think is
  necessary at all since it's redone in more detail in libobjc.

* In gcc, all that --enable-objc-gc does is set OBJC_BOEHM_GC in
  gcc/Makefile, which isn't ever used.

[Bug libobjc/48626] --enable-objc-gc should be automatic

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot gnu.org

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Let me look into that for GCC 15. Note libobjc is not used by many folks even
the GNUStep folks don't use it any more ...

[Bug libobjc/48626] --enable-objc-gc should be automatic

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

--- Comment #10 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> Let me look into that for GCC 15. Note libobjc is not used by many folks even
> the GNUStep folks don't use it any more ...

Thanks.  I only include it (and objc-gc) in my builds to maximize
coverage on uncommon targets: this tends to find bugs that aren't seen
on e.g. Linux.

[Bug libobjc/48626] --enable-objc-gc should be automatic

[doko at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48626

--- Comment #11 from Matthias Klose <doko at gcc dot gnu.org> ---
> Note libobjc is not used by many folks even
> the GNUStep folks don't use it any more ...

that's wrong, looking at least at GNUstep base 1.29.