[llvm-dev] The clang for centos6 are need GLIBC_2.14, but we only have GLIB 2.12 by default.

[Brian Cain via llvm-dev]

Yonggang,

What's your use case(s) for clang?  If you don't need the {A,T,UB}San
features, you might get much of what you want from ellcc (
http://ellcc.org/releases/).  ellcc is primarily used for cross-target
development.  But there's no reason you can't use it to target x86_64 linux
too.

On Wed, Jun 29, 2016 at 8:28 AM, Brian Cain <brian.cain at gmail.com> wrote:

> It is possible to statically link against libstdc++, yes.  I don't quite
> know all the pieces to the recipe in order to get that to work.  It would
> require changes to the release script in order to get those configuration
> changes all the way through the third phase build.
>
> I don't believe any other tarball release does this, so it would at least
> be an unconventional release.
>
> On Wed, Jun 29, 2016 at 3:47 AM, 罗勇刚(Yonggang Luo) <luoyonggang at gmail.com>
> wrote:
>
>> Well, is that possible to include  libstdc++4.7 into llvm?
>>
>> On Wed, Jun 29, 2016 at 2:26 AM, Brian Cain <brian.cain at gmail.com> wrote:
>>
>>> Sorry if I was unclear, I have no problems building clang against a
>>> newer gcc for my own purpose.  But it doesn't make sense to provide a
>>> release binary for clang that's hosted on llvm.org that's ostensibly
>>> for "centos6" when it would really be bound to "centos6 plus the SCLO
>>> mirror which has the dependency for a newer libstdc++".
>>>
>>> The glibc 2.14 dependency is a result of the binary being built on a
>>> platform new enough to have libstdc++4.7 or newer.  You could eliminate it
>>> if you could find a CentOS release that has libstdc++4.7 and glibc2.12. But
>>> ultimately you're still stuck with a runtime dependency on libstdc++ shared
>>> objects that expect newer GLIBCXX_* symbols.
>>>
>>> The newer gcc release is only needed at build-time.  Its byproduct/side
>>> effect of bringing with it a newer libstdc++ is what creates a runtime
>>> dependency.
>>>
>>> It's my position that a CentOS 6.0-6.x release binary for clang newer
>>> than 3.4.2 is not possible unless CentOS team backports libstdc++4.7
>>> release to that CentOS release.  I'd be happy to learn I'm wrong about that
>>> claim BTW.
>>>
>>> On Tue, Jun 28, 2016 at 1:13 PM, 罗勇刚(Yonggang Luo) <
>>> luoyonggang at gmail.com> wrote:
>>>
>>>> Hell, Brian, I found a way to install Gcc 5.3 on CentOS 6 without the
>>>> need to building it from source. You may try it on CentOS 6.0
>>>> That's makes clang/llvm won't depends on the newer version of glibc 2.14
>>>> The instruction:
>>>>
>>>> vim /etc/yum.repos.d/llvm.repo
>>>>
>>>> The content:
>>>> ```
>>>> [sclo]
>>>> name=SCLO
>>>> baseurl=http://mirror.centos.org/centos/6/sclo/x86_64/rh/
>>>> gpgcheck=0
>>>> enabled=1
>>>> ```
>>>> Installation step:
>>>> ```
>>>> yum clean all
>>>> yum list
>>>> echo y | yum install devtoolset-4
>>>> ```
>>>>
>>>>
>>>> On Wed, Jun 29, 2016 at 1:15 AM, Brian Cain <brian.cain at gmail.com>
>>>> wrote:
>>>>
>>>>> On Tue, Jun 28, 2016 at 11:50 AM, 罗勇刚(Yonggang Luo) <
>>>>> luoyonggang at gmail.com> wrote:
>>>>>
>>>>>> So CentOS before 6.7 is not an option after all?
>>>>>> Is that possible to use clang on CentOS 6.6 and before?
>>>>>>
>>>>>>
>>>>> Not with these binaries, unless you can update your libc/libstdc++.
>>>>> In the general sense -- yes, it's possible if you build from source.
>>>>> There's a couple of potential approaches: build against libc++, build
>>>>> against newer libstdc++.  If you're more adventurous you could also try
>>>>> building with ellcc.  That one requires patches but will yield a statically
>>>>> linked binary.
>>>>>
>>>>> I built clang trunk/tip a few weeks ago on CentOS 6.0.  But I first
>>>>> built the gcc6 suite, then used it to build clang.  I believe clang 3.4.2
>>>>> is the latest version that supports the older libstdc++.  I ran into
>>>>> challenges with using clang so I stuck with gcc6.  The resulting binaries
>>>>> depend on the gcc6 libraries so I can't really use this procedure to make a
>>>>> new official release for centos.  If it's helpful I can publish the steps I
>>>>> used, but really just followed the build instructions.
>>>>>
>>>>> -Brian
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>>          此致
>>>> 礼
>>>> 罗勇刚
>>>> Yours
>>>>     sincerely,
>>>> Yonggang Luo
>>>>
>>>
>>>
>>>
>>> --
>>> -Brian
>>>
>>
>>
>>
>> --
>>          此致
>> 礼
>> 罗勇刚
>> Yours
>>     sincerely,
>> Yonggang Luo
>>
>
>
>
> --
> -Brian
>



-- 
-Brian
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