[cfe-dev] clang defines __weak as if -fobjc-gc were specified

[jahanian]

I thought I sent out this email earlier. But here it is again.

__weak is always defined for use in blocks. It is unfortunate though that it is def’ed to
objc_gc(weak) though. But for the purpose of use, it doesn’t really matter.

- Fariborz


On Jun 5, 2013, at 10:57 AM, Frank Rehwinkel <frankrehwinkel at gmail.com> wrote:

> Totally agree.  But I'm just coming to the GNUstep project.    And while it used to be supported for Darwin - before clang was an option, it seems an unsupported platform option these days - ironic really.  So I'm a little bit on my own on this one and just trying to make it compile with the minimum of changes to see if it will even work again.
> 
> Just had another look at the code.  Maybe __strong and __weak can be undef'ed when the platform is Darwin/clang.  
> 
> For that matter, now I' curious what is different about this build on FreeBSD, where GNUstep is actively maintained and clang is used.  I know they wouldn't have left these warnings as part of their build.
> 
> Thanks.
> 
> 
> On Wed, Jun 5, 2013 at 1:09 PM, John McCall <rjmccall at apple.com> wrote:
> On Jun 5, 2013, at 10:06 AM, John McCall <rjmccall at apple.com> wrote:
>> On Jun 5, 2013, at 10:04 AM, Frank Rehwinkel <frankrehwinkel at gmail.com> wrote:
>>> Thanks for asking.  I just want to make sure I understand your statement and question.  On Darwin, you've always had __weak defined as __attribute__((objc_gc(weak))), even when __strong is defined as <empty>?
>>> 
>>> If it is intentional, then I would say there is no specific problem.  We can put a comment into the header file for GNUstep to explain why __weak is being undef'ed before it is defined as <empty>.  (Without the undef, the build generates seemingly hundreds of warnings, obscuring other warnings that might be more meaningful.)
>>> 
>>> If it is unintentional, then a change to clang would obviate the additional code in the GNUstep header and save a few seconds every time someone went to read through the logic of those __strong and __weak macro definitions.
>> 
>> Why don't you just not #define __weak and __strong on Darwin?
> 
> Or, for that matter, if they're already defined?
> 
> Headers that randomly change macro state are somewhat evil;  among other things, they tend to introduce nasty order-of-inclusion bugs.
> 
> John.
> 
> 
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