[llvm-dev] Question about compiler-rt builtins targets

[Chris Bieneman via llvm-dev]

If Ardi has a working libc++ with C++ 11 support and a compiler that supports C++ 11, I would expect that building on OS X 10.6.8 should work.

If it doesn’t that’s a bug. Our checks for the host system *should* be (and maybe aren’t) written in a way that they test the capabilities of the host system, not the version.

Either way let me reiterate. One of the complications with supporting old OS releases is that they aren’t always as well tested as the newer releases, and sometimes they get bugs that linger for a long time because none of the core developers really care. If there are bugs impacting your ability to use an older OS or toolchain, we will always accept patches to fix them as long as they’re reasonable and don’t introduce undue burden to the community.

We do not actively try to break running on older operating systems, and generally when we do deliberately break it there is a long discussion (as there was with dropping Windows XP). I do believe there are other people in the community that care about OS X 10.6.x, and even some that I know go back to 10.4 for PPC.

-Chris

> On Apr 26, 2016, at 2:39 PM, Bruce Hoult <bruce at hoult.org> wrote:
> 
> On Wed, Apr 27, 2016 at 4:15 AM, Chris Bieneman via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> The other thing I wanted to touch on is you mentioned in your email you think there is a disconnect in mindset. I think you’re misunderstanding. The LLVM community supports very old OS versions. In fact, we still use CMake 2.8.12 because that’s what comes on the Ubuntu 14.04 LTS. I suspect we’ll be moving off that soon as there is a new LTS release imminent, but we generally support developing on 2-3 year old OS releases, and deploying to even older releases.
> 
> The version ardi is targeting, OS X 10.6.8, is quite a bit older than that :-) 10.6 came out in 2009, and the .8 final release in mid 2011. However a significant number of machines have not been upgraded past it for the rather annoying reason that it's the last one that supports the built in "Rosetta" PowerPC emulator. Systems supported by 10.6.8 include reasonably modern ones such as the quad core Nehalem i7 17" laptop I'm typing this on, which is not a lot slower than the current models with Haswell. I've got the latest OS on the aftermarket Samsung Pro SSD, but 10.6.8 is on the original 750 GB hard disk and I can boot into it any time.
> 
> I think it's reasonable to say that an OS version is "supported" in that the various tools that come with it (or are readily downloadable) are good enough to build current LLVM.
> 
> However, I don't see any reason that you should not be able to run a compiler which, let's face it, primarily reads a few disk files and writes other disk files, on anything Unix-like, no matter how old, provided that the utility programs needed for the build process have already been installed in a suitable version.
> 
> Of course you don't want to have to support system compilers that don't do C++11, but ardi has already gone to the trouble of making a working LLVM 3.5 for his 10.6.8 system.
> 

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