On Sun, Jul 13, 2008 at 11:38 PM, Jens Miltner <email@hidden> wrote:
>
> Am 11.07.2008 um 14:45 schrieb Stéphane Sudre:
>
>>
>> On Jul 11, 2008, at 10:04 AM, Ken Thomases wrote:
>>
>>> On Jul 11, 2008, at 2:48 AM, Stéphane Sudre wrote:
>>>
>>>> "Mac OS X version 10.5 or later is needed for zerocost-exception"
>>>>
>>>> What is this sentence trying to say?
>>>
>>> I'm not entirely sure. Are you trying to compile some Objective-C for
>>> 64-bit architecture but also specifying a deployment target of 10.4?
>>>
>>> Here's some background: With Leopard, Apple revamped the Objective-C ABI
>>> but only for 64-bit. They couldn't do so for 32-bit because it would break
>>> binary compatibility. In the 64-bit ABI, Objective-C exceptions were based
>>> on the same mechanisms as C++ exceptions, which makes them zero-cost unless
>>> an exception actually happens.
>>>
>>> That message seems to suggest you have asked the compiler to emit code
>>> relying on that ABI, but also said you may deploy it on a target not
>>> supporting that ABI.
>>
>>
>> It looks like it's what you're describing.
>>
>> Does this imply that you can not build a project easily on Xcode with
>> exceptions support as soon as you want to test a 32/64-bit Universal Binary
>> application that can run on Tiger and later?
>>
>> It sounds like it might be the return of the
>> "SDK_Deployment_ppc_32_or_something_like_this" options...
>
> I'd assume that there would be an option to specify the exception mechanism
> to use (i.e. allow for backward-compatible exception support in 64-bit
> binaries, too).
Backwards compatible with what? Before Leopard, one couldn't build
64-bit Objective-C binaries.
--
Clark S. Cox III
email@hidden
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