On Tue, 22 Oct 2013 10:31:01 +0200, Daniel Höpfl said:
>> Was the old (non-arc) code faulty (but the compiler did not notice
>> this)?
>> Why is the arc-version (with TRIGGER_ERROR defined) wrong?
>
>It is wrong in the non-arc world, too. (ISO/IEC 9899:2011 AKA C11,
>6.8.6.1: "A goto statement shall not jump from outside the scope of an
>identifier having a variably modified type to inside the scope of that
>identifier" - switch is a special case of goto.)
Daniel,
I don't think you can quote the Standard about 'goto' and just wave your hands
and say it applies to 'switch' also. :) The Standard's description of
'switch' should contain the answer.
However, it does seem to me there is a clang bug here somewhere.
I've made a shorter compilable example:
----------------------
#import <Foundation/Foundation.h>
int main (void)
{
int x = 0;
switch(x)
{
case 1:
x++;
#if 0 // toggle me
NSObject* foo = nil;
#else
int* foo = 0;
#endif
(void)foo;
break;
default:
x++;
};
return 0;
}
----------------------
Then build with both:
$ xcrun clang -fsyntax-only -Weverything test.m
$ xcrun clang -fsyntax-only -Weverything -fobjc-arc test.m
If 'foo' is int*, clang has no complaints in non-ARC and ARC.
If 'foo' is NSObject*, clang has no complaints in non-ARC, but errors in ARC.
IMHO, that's pretty weird!
The only bug I can find in llvm bugzilla that looks related was fixed years ago:
<http://llvm.org/PR7789>
Cheers,
--
____________________________________________________________
Sean McBride, B. Eng [email protected]
Rogue Research www.rogue-research.com
Mac Software Developer Montréal, Québec, Canada
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