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Re: Newer features in Objective C

From: David Chisnall
Subject: Re: Newer features in Objective C
Date: Mon, 13 Feb 2023 10:32:17 +0000
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On 13/02/2023 00:52, Gregory Casamento wrote:

On Wed, Feb 8, 2023 at 09:57 Richard Stallman < <>> wrote:

    [[[ To any NSA and FBI agents reading my email: please consider    ]]]
    [[[ whether defending the US Constitution against all enemies,     ]]]
    [[[ foreign or domestic, requires you to follow Snowden's example. ]]]

    GNU Objective C supports the features that Objective C had in 1989.
    It would be nice to add the newer Objective C features.
    Is anyone interested in doing that?
    Please write to me personally if you sare intested in working on this.

This is not true. Nicola Pero added declared properties a while ago, and exceptions were already there. GCC is more or less feature-complete with respect to Objective-C circa 2005. Apple subsequently invested quite a few person-years of engineering effort on adding more modern features, the largest of which is ARC. Subscripting is a fairly simple transform, which would probably be quite easy to add to GCC. Some of the other things, such as direct methods, require some careful design work (the interaction between +initialize and direct methods is annoying and I haven't yet come up with an ABI that would cause them to be a performance win).

I, personally, have the knowledge, but not the time.  I think that is the situation with a number of us, but I certainly don’t speak for us all.  We had hoped that someone in the existing GCC community might be willing to take this on if it’s to be done on a volunteer basis.

I have tried to persuade GCC folks to do this a few times, but there are a few problems:

- The current Objective-C code in GCC is *awful*. I started working on Objective-C support in clang because it was less work to add Objective-C codegen to clang *from scratch* than it was to add fairly simple features that it was missing at the time (declared properties) to GCC. If anything, that code has become even harder to work with in the intervening years.

- The license for GCC means that none of the companies that might have funded this work 10 years ago were willing to touch it. This has not improved.

It’s my belief that this is a pretty large effort.  It will likely be multiple weeks or months of effort for one person to do as it involves adding a number of missing features.  In your email you say that GCC supports the features from 1989… that’s true but there are also SOME 2.0 features that have been implemented but it is not complete so we have, in effect, Objective C 1.5. :)

That is *incredibly* optimistic. Adding ARC support requires some very subtle work related to lifetimes and has a lot of interactions with other features (e.g. C++ copy constructors). I would put the estimate in person-years, not less.

I am wondering if it might be necessary for the FSF to hire someone to do this outside of the community (or within if that’s an option).

I am not sure what the way forward on this is at this point.

I see two viable options:

- Publicly acknowledge that GCC has not supported Objective-C for 15+ years, remove Objective-C support from the next release of GCC, and let GNUstep focus on working with compilers that do support the language.

- Ensure that there is a pot of at least half a million dollars available to properly fund the work on GCC and contract an experienced developer to work on it full time for the next two years (or a company with a team of developers for a shorter period) and then be on retainer to fix the bugs going forward.

If the FSF has half a million to spend on Objective-C support in GCC then that money could be *far* better spent on improving other bits of GNUstep.


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