[vlc-devel] Regarding building of VLC using clang/LLVM on Linux/Ubuntu

[Steve Lhomme]

Le 30/03/2018 à 09:05, Rémi Denis-Courmont a écrit :
> Le 30 mars 2018 09:25:31 GMT+03:00, Steve Lhomme <robux4 at ycbcr.xyz> a écrit :
>> I ran into a similar issue. Basically when using protobuf from
>> contribs,
>> if it doesn't match exactly the protoc output (as in same A.B.x
>> version)
>> it will not accept the compiled .proto files. To fix that we may build
>> the contribs with the same version reported by `protoc --version`,
>> since
>> there is no way that one version will satisfy everyone on all platforms
>>
>> (including bots).
>>
>>
>> Le 30/03/2018 à 06:39, Raghavan Santhanam a écrit :
>>> Those fat fingers.. eh..
>>>
>>> I found the resolution for this segfault/crashBN - I was able to
>> build
>>> VLC using *clang/LLVM*  on
>>> my *Ubuntu 17.10 x86_64*. The fix was to use the latest *protobuf
>>> v3.5.10* instead of the default Ubuntu repo's
>>> protobuf v3.0.0, specifically, libprotobuf-lite.so was the FN place
>>> where the crash/segfault was happening within its
>>> *google::protobuf::ShutdownProtobufLibrary()*. Will send out the
>>> details of thus successful clang-build of VLC.
>>> I know that this protobuf issue is not specific to clang-usage, but
>>> since that was a roadblock while building VLC
>>> even when using clang/LLVM instead of GCC, I am associating it with
>> my
>>> clang/VLC effort.
>>>
>>> - Raghavan Santhanam
>>>
>>> On Sun, Mar 25, 2018 at 6:52 AM, Rémi Denis-Courmont <remi at remlab.net
>>> <mailto:remi at remlab.net>> wrote:
>>>
>>>      Le 25 mars 2018 20:42:39 GMT+08:00, Raghavan Santhanam
>>>      <raghavanil4m at gmail.com <mailto:raghavanil4m at gmail.com>> a écrit
>> :
>>>      >What is BN, that you mentioned in your first reply? It looks
>> like
>>>      >there's
>>>      >already an open VLC bug for this :
>>>      >https://trac.videolan.org/vlc/ticket/18329
>>>      <https://trac.videolan.org/vlc/ticket/18329>.
>>>      >Yes, I understood that the issues was with something else - same
>> case
>>>      >with
>>>      >GCC. I am trying to resolve this issue in general.
>>>      >
>>>      >On Sun, Mar 25, 2018 at 5:20 AM, Rémi Denis-Courmont
>>>      <remi at remlab.net <mailto:remi at remlab.net>>
>>>      >wrote:
>>>      >
>>>      >> Le 25 mars 2018 20:16:54 GMT+08:00, Raghavan Santhanam <
>>>      >> raghavanil4m at gmail.com <mailto:raghavanil4m at gmail.com>> a
>> écrit :
>>>      >> >Hello,
>>>      >> >
>>>      >> >OK, I am trying to build VLC using clang/LLVM on Ubuntu with
>>>      >necessary
>>>      >> >environment variables for library
>>>      >> >dependencies, etc. But, the make command is failing with a
>>>      segfault
>>>      >> >while
>>>      >> >it reaches "vlc-cache-gen" specific
>>>      >> >command and that doesn't change even after updating Intel
>>>      microcode,
>>>      >> >reboot, etc. So, wanted to know
>>>      >> >the status for Linux/Ubuntu. I saw some reports of clang/VLC
>>>      >> >compatibility.
>>>      >> >BTW, what is BN?!
>>>      >> >
>>>      >> >- Raghavan
>>>      >> >
>>>      >> >2018-03-25 4:35 GMT-07:00 Rémi Denis-Courmont
>> <remi at remlab.net
>>>      <mailto:remi at remlab.net>>:
>>>      >> >
>>>      >> >> Hi,
>>>      >> >>
>>>      >> >> VLC is built using clang on several platforms BN already. I
>>>      can't
>>>      >> >comment
>>>      >> >> on your specific combination.
>>>      >> >> --
>>>      >> >> Envoyé de mon appareil Android avec Courriel K-9 Mail.
>> Veuillez
>>>      >> >excuser ma
>>>      >> >> brièveté.
>>>      >> >>
>>>      >>
>>>      >> That sounds like a bug in an underlying library with no
>>>      relationship
>>>      >to
>>>      >> the compiler. Does it work any better with GCC?
>>>      >> --
>>>      >> Envoyé de mon appareil Android avec Courriel K-9 Mail.
>> Veuillez
>>>      >excuser ma
>>>      >> brièveté.
>>>      >>
>>>
>>>      It was a trivial case of fat fingers.
>>>
>>>      I believe the linked bug already answers your question. Since
>> this
>>>      is a problem with protobuf and triggered by Mir, there are no
>>>      clean fixes within VLC.
>>>      --
>>>      Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez
>>>      excuser ma brièveté.
>>>
>>>
>>>
>>>
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> How about not using that unstable and buggy library in the first place? Why was it imported to begin with?

Rewriting the protocol from scratch may take a while. But if anyone 
volunteers that would be great.