[llvm-dev] LLVM and XCode 7.0.0

[Chris Bieneman via llvm-dev]

It is also worth pointing out that when upgrading Xcode you will almost always need to clear out your CMake build directory. CMake only runs the compiler & SDK checks once, and changing Xcode can change compilers, headers, and libraries.

-Chris

> On Sep 18, 2015, at 12:00 PM, Tim Northover via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Hi Larry,
> 
> On 18 September 2015 at 00:02, Larry Gritz via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> First of all, can anybody say definitively which LLVM/Clang version corresponds to what Apple calls 7.0.0? Is there a web page somewhere with the list of correspondences?
> 
> I'm afraid there is no real correspondence. Xcode's clang & LLVM gets
> branched at a fairly arbitrary point in time, and then many patches
> are cherry-picked over time before it actually gets released.
> 
> That 3.6.0 just means that the initial branch happened some time
> between the release of OSS 3.5 and OSS 3.6; it says nothing about what
> bugs were fixed (or added!) before release, what features were ported
> before release, or what features were implemented first in Xcode and
> then made their way to OSS LLVM.
> 
> Because there's virtually no useful information to be gained from the
> "based on LLVM ...", we've stopped reporting it in the version string.
> 
>> Or am I missing something obvious that I should be doing to detect versions more robustly?
> 
> Checking for the actual features you need is usually recommended. But
> if that's not possible for some reason, you'll probably have to treat
> Xcode Clang and OSS Clang as two different compilers.
> 
> Cheers.
> 
> Tim.
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