[LLVMdev] [RFC] Progress report on CMake build system's ability to replace autoconf

[Jack Howarth]

On Tue, Feb 3, 2015 at 4:50 PM, Nick Kledzik <kledzik at apple.com> wrote:
>
> On Feb 3, 2015, at 1:40 PM, Duncan P. N. Exon Smith <dexonsmith at apple.com> wrote:
>
>>
>>> On 2015 Feb 3, at 13:26, Chris Bieneman <beanz at apple.com> wrote:
>>>
>>>
>>>> On Feb 3, 2015, at 1:06 PM, Jonathan Roelofs <jroelofs.lists at gmail.com> wrote:
>>>>
>>>>
>>>>
>>>> On 2/3/15 12:08 PM, Chris Bieneman wrote:
>>>>
>>>>> Other issues not tracked by bugs:
>>>>>
>>>>> * CMake builds for libc++?
>>>> Can you elaborate... what do you mean by this? AFAIK this already works.
>>>
>>> Duncan made a comment on IRC about being libc++, but I’m not aware of what the specific issues were (hence the ?).
>>>
>>> -Chris
>>
>> +kledzik and bogner, who looked into this last.
> Duncan was concerned about libc++ on darwin.
>
> The problem was/is that the shipping Apple libc++.dylib did not use CMake (or the previous buildit script). It used its own Xcode project which passed a bunch of special linker flags.  Building libc++ for darwin without the special flags produced a dylib that only partially worked.
>
> I have not recently tried to build libc++ for darwin from the LLVM repository.  So, I don’t know if anyone has updated CMake files for libcxx to build something that works on darwin.
>
> -Nick

Nick,
        David Fang's packaging of the llvm 3.5.1 release for the fink
project uses a cmake build of libc++ (as did the prior llvm 3.4.2
packaging). The libc++ changes are at…

http://fink.cvs.sourceforge.net/viewvc/fink/dists/10.7/stable/main/finkinfo/languages/llvm35-libcxx.patch

but has some changes for support ppc builds and earlier darwin
releases mixed in the patch.
                Jack

>
>
>
>
>>
>> I don't remember quite what the issue is; perhaps Nick or Justin knows.  I
>> remember the repro though:
>>
>> 1. Complete a CMake build of clang+libcxx+compiler-rt.
>> 2. Add DYLD_LIBRARY_PATH=path/to/lib to the environment (so that ld64 finds
>>    the just-built libLTO.dylib).
>> 3. Everything, including `/bin/ls` IIRC, crashes, since the just-built
>>    libcxx.dylib doesn't "work".
>>
>> I work around this by not checking out libcxx in my CMake source trees (at
>> least, not when I'm using LTO).
>
>
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