Re: How to get warnings for missing methods in older SDKs
Re: How to get warnings for missing methods in older SDKs
- Subject: Re: How to get warnings for missing methods in older SDKs
- From: Jean-Daniel Dupas <email@hidden>
- Date: Mon, 28 Mar 2011 22:31:39 +0200
Le 28 mars 2011 à 22:09, Chris Hanson a écrit :
> On Mar 27, 2011, at 10:39 AM, Quincey Morris wrote:
>
>> So, again, the approach to give you what you want -- an app that's written "for" an older OS -- is to build against its SDK. The only difficulty you have now is that you'll have to use Xcode 3.2 to build against 10.5, because Xcode 4 unfortunately can't do it.
>
> It’s important to understand that this is only new in Xcode 4 for Mac OS X. iOS developers have worked this way for quite a while.
>
> In fact, as of Xcode 3.2.5 there is a way to specify you want to use the “latest” SDK, without tying the SDK you want to build against to any specific version.
>
> Things work this way so developers have an easier time adopting the features of new operating systems, without being confused into thinking “I can’t adopt feature Z because I need to run on older operating systems.”
>
> Insisting that you MUST use an older SDK to target an older OS is - in the vast majority of cases - both incorrect and counterproductive. (I’m still looking into the cases where it’s been claimed it won’t work, which could be bugs or require documentation updates.)
>
Easy: linking on libcrypto on 10.6 SDK with deployment target set to 10.5 produces an executable that crashes at launch on Leopard.
And there is not a single symbol in the BSD library that uses availability macro, so not a single function is declared using the weak_symbol attribute, whatever the OS version it was introduced.
For example, libxml contains symbols introduced in 10.6. If you try to use one (and nothing tell you which symbol is new of course), the produced executable will crash at launch time on Leopard.
> -- Chris
-- Jean-Daniel
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