[llvm-dev] Improving deb packages

[Paweł Bylica via llvm-dev]

On Mon, Jul 25, 2016 at 12:28 PM Sylvestre Ledru <sylvestre at debian.org>
wrote:

> Hello,
>
> +Andrew and Brad who did most of the work on cmake.
> To be honest, I am not a cmake expert, any help to improve the situation
> is appreciated.
>
>
> Le 23/07/2016 à 23:42, Paweł Bylica a écrit :
>
> Hi LLVM,
>
> I complained about the deb packages couple of times previously, even fixed
> some issues in packaging. I'm mostly interested in having reliable share
> cmake files available in llvm-dev packages. The version 3.7 was fine, but
> 3.8+ have regressions.
>
> I'm not here to blame anybody. I would like to identify the issues and
> discuss long term solutions.
>
> Sure, thanks for doing that!
>
>
> I started with building very simple test framework that checks different
> Ubuntu/Debian versions and currently supported LLVM versions. The first and
> only test just checks find_package(LLVM CONFIG) cmake function.
> https://github.com/chfast/llvm-apt-tests/blob/master/CMakeLists.txt
>
> I've tested {3.8, 3.9, 4.0} x {xenial, jessie} using docker images and
> Travis CI.
> https://travis-ci.org/chfast/llvm-apt-tests/builds/146508275
> As you can see, only the 3.8 on Jessie passed the test.
>
> Nice work! I am not surprised that 3.8 is passing the test, this is the
> one I focused the most.
> Brad reported this bug https://llvm.org/bugs/show_bug.cgi?id=28325 for
> 3.9 and 4.0
> I just applied them to the branches (I was in holidays before)
>
> Do you mind if I steal that and I add this to my CI to test that we don't
> regress? or are you planning to maintain it?
>

No problem, you can steal whatever you want. What CI do you have in mind? I
could join in and help maintaining it there.


>
> Issues I've identified:
>
>    1. Packaging adds version prefix to binaries, directories, etc. -- eg.
>    llc is renamed to llc-3.8. I'm not sure how it is done, but maybe we should
>    add support for such feature to LLVM's cmake?
>
> This is done in debian/rules, by creating symlink
> http://anonscm.debian.org/viewvc/pkg-llvm/llvm-toolchain/branches/snapshot/debian/rules?revision=2020&view=markup#l319
> We do that to make sure that the different version of llvm/clang are
> co-installable. llc and others are provided by this llvm defaults (
> https://packages.qa.debian.org/l/llvm-defaults.html ).
> Having this available upstream would be good but this hasn't been a source
> of troubles in the past.
>
>
>
>    1. Default install location for cmake shared files is
>    <prefix>/lib/llvm/share/llvm/cmake. find_package() is not able to find them
>    there as it is non-standard path. find_package() needs a hint, like setting
>    LLVM_DIR variable as in
>    https://github.com/chfast/llvm-apt-tests/blob/master/configure.sh#L6
>    If we moved the cmake shared files to <prefix>/lib/llvm/cmake no hint
>    would be needed.
>
> This should be fixed
>
>
>    1. On Ubuntu, packaging script moves cmake shared files to
>    <prefix>/share/llvm-X.Y/cmake. I'm guessing to solve the issue (2).
>    find_package() is able to find LLVMConfig.cmake file without any hint, but
>    this file contains absolute paths referencing previous locations of other
>    files. You usually get issues like this one:
>
>    CMake Error at /usr/share/llvm-3.8/cmake/LLVMConfig.cmake:181
>    (include):
>    include could not find load file:
>    /usr/share/llvm/cmake/LLVM-Config.cmake
>
>    Maybe it is good idea to include other cmake files assuming there are
>    located next to the main file instead of relying on absolute paths.
>
> This is probably related to llvm-defaults behavior.
>
>
>    1. It's a bit weird Debian and Ubuntu packages has different layout of
>    installed shared files.
>
> I don't think it is the case. I am not making any changes in Ubuntu
> packages. In some cases, Ubuntu official packages are patched from Debian's
> but patches are usually forwarded to me.
>

I've rechecked. You are right, however Ubuntu packages it differently, but
we should not care about that. I have to modify my test config to force
installing llvm-3.8-dev from apt.llvm.org.


>
>
>    1. Packages 3.9+ does not have any cmake's shared files, just empty
>    dirs where those files are supposed to be. That might be a bug in the
>    latest packaging script.
>
> Could you report a bug?
>

I think I was wrong about that too.


>
> Thanks for the feedback, this is appreciated!
>

Sorry for late answer, was on holidays and busy with other projects. I will
try proceed with the idea to move cmake shared files withing LLVM dir
structure.

- Paweł
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