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Re: RFC: FSF GCC, #import (and #pragma once)

From: David Ayers
Subject: Re: RFC: FSF GCC, #import (and #pragma once)
Date: Fri, 07 Mar 2003 11:17:52 +0100
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.3b) Gecko/20030210

Hi Adam,

Thanks for the reply!

Adam Fedor wrote:

It's probably useful to at least make your opinion known.

Yes, I just wanted to avoid GNUstep developers arguing amongst each other on GCC's list, rather than here.

#import has been depreciated for some time (even by Apple) ...

I must admit, I was very surprised to hear this! A quick search on Apple's pages did in fact reveal:

"GCC permits the use of |#import| in C and C++ as well as Objective-C. However, it is not in standard C or C++ and should therefore not be used by portable programs."

and :

     "Changes in Warnings

Some warnings are now off by default, but can be turned on again with a compiler switch. They are as follows:

The directives #pragma once and #import. GCC handles them correctly, even though they're *obsolete*. Use -Wpragma-once and -Wimport to see the warnings about them."

But these don't seems like a prominent deprecationby Apple. The former seems like a advisory for dedicated implementation languages, yet ignores ObjC++, while the later is a release note bullet under the title of "Changes in Warnings". They are more weak acknowledgements that they recognize the issues. And most important of all, because they have not guarded their headers against multipleinclusion and continue to use #import within their headers themselves, it remains an academic discussion in relation to existing code base. Do you, or anyone else, have a reference to a more prominentstatement?

In my view, before the FSF should consider removing the support for #import, Apple must guard their headers, (probably stop using #import themselves), prominently deprecatethe usage, and maybe even remove it from their version of GCC. And even then, if FSF GCC still supported the (then old) Apple semantics of #import, the FSF might still consider continuing the support for a while just in case this might spur some projects to switch to GNUstep. (I do recognize that in the real world Apple will most certainly not remove the feature as long as FSF GCC has it.)

I believe the technical implications, of whether this or that implementation is correct or not, is secondary to that fact that the FSF GCC should encourage the use of free software by implementing a widely used feature. And this alone should cause the FSF to embrace the work of anyone syncing FSF's and Apple's semantics, no matter how broken Apple's semantics might be. This of course only applies to features that the FSF discourages anyway and are merely provided for compatibility, as is the case here. And I have no problem if this potentially broken feature were turned off by default and must be enabled explicitly..


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