[cfe-dev] Out-of-tree CMake dependencies

[Kim Gräsman via cfe-dev]

+sylvestre -- you appear to be working on the Debian packaging of LLVM/Clang

Hey again,

I dug into the Debian packaging a bit more today, and it looks like
there have been changes to accommodate for the install location of
LLVMConfig.cmake, but not ClangConfig.cmake.

I think this might be a bug, but I don't feel confident enough/have a
clear enough problem report to file a package bug.

Could someone confirm/refute that it would make sense to install
LLVMConfig.cmake in /usr/lib/llvm-x.y/cmake/llvm and ClangConfig.cmake
in /usr/lib/llvm-x.y/cmake/clang?

Thanks,
- Kim

On Mon, Oct 30, 2017 at 9:16 PM, Kim Gräsman <kim.grasman at gmail.com> wrote:
> Ping.
>
> Maybe a little too much detail below. TL;DR; why are Clang CMake
> modules for installed separately from LLVM CMake modules in the Debian
> packaging?
>
> Thanks,
> - Kim
>
> On Sun, Oct 8, 2017 at 11:57 AM, Kim Gräsman <kim.grasman at gmail.com> wrote:
>> Hi all,
>>
>> I now have a draft version that seems to be working:
>> https://github.com/kimgr/include-what-you-use/blob/re-cmake/CMakeLists.txt
>>
>> I needed to add `include (HandleLLVMOptions)` to get CFLAGS/CXXFLAGS
>> in place, otherwise I was able to use your example almost verbatim.
>>
>> Both the build and FreeBSD packaging seem to put the LLVM and Clang
>> CMake modules in $PREFIX/lib/cmake, but the apt packages for Ubuntu
>> seem to scatter them:
>>
>>   $ find /usr -name "ClangConfig.cmake" -o -name "LLVMConfig.cmake" 2> /dev/null
>>   /usr/lib/llvm-4.0/lib/cmake/llvm/LLVMConfig.cmake
>>   /usr/share/llvm-4.0/cmake/ClangConfig.cmake
>>
>> The corresponding layout on FreeBSD is:
>>
>>   $ find /usr/local -name "ClangConfig.cmake" -o -name
>> "LLVMConfig.cmake" 2> /dev/null
>>   /usr/local/llvm40/lib/cmake/llvm/LLVMConfig.cmake
>>   /usr/local/llvm40/lib/cmake/clang/ClangConfig.cmake
>>   /usr/local/llvm39/lib/cmake/clang/ClangConfig.cmake
>>   /usr/local/llvm39/lib/cmake/llvm/LLVMConfig.cmake
>>   /usr/local/llvm-devel/lib/cmake/clang/ClangConfig.cmake
>>   /usr/local/llvm-devel/lib/cmake/llvm/LLVMConfig.cmake
>>
>> This makes the UX for IWYU's CMake painful, as we have to specify both
>> CMake search paths:
>>
>>     $ cmake -DIWYU_LLVM_CMAKE_DIR=/usr/lib/llvm-4.0/cmake
>> -DIWYU_CLANG_CMAKE_DIR=/usr/share/llvm-4.0/cmake
>>
>> Could this be improved in the packaging, or is there a benefit to
>> keeping them separate? Am I missing some trick to make system packages
>> easier to pick up?
>>
>> Thanks,
>> - Kim
>>
>> On Thu, Oct 5, 2017 at 7:45 PM, Don Hinton <hintonda at gmail.com> wrote:
>>> You might also want to look at clang's CMakeLists.txt file.  I can be build
>>> either in or out of tree (llvm tree), and handles a lot of this via
>>> llvm-config.
>>>
>>> hth...
>>> don
>>>
>>> On Wed, Oct 4, 2017 at 10:13 PM, Kim Gräsman <kim.grasman at gmail.com> wrote:
>>>>
>>>> Hi Don,
>>>>
>>>> Thanks, that looks like it might work! I'll post back with results
>>>> when I have them.
>>>>
>>>> - Kim
>>>>
>>>> On Wed, Oct 4, 2017 at 9:31 PM, Don Hinton <hintonda at gmail.com> wrote:
>>>> > This might help you get started (this is for out of tree pointing to my
>>>> > development build, but you could also point to the installed version if
>>>> > you
>>>> > have one).
>>>> >
>>>> > # if you only have/need LLVM:
>>>> > #  export
>>>> > LLVM_DIR=/Users/dhinton/projects/llvm_project/build/Debug/lib/cmake/llvm
>>>> > # if you also have/need clang:
>>>> > #  export
>>>> >
>>>> > CLANG_DIR=/Users/dhinton/projects/llvm_project/build/Debug/lib/cmake/clang
>>>> >
>>>> > # While just setting LLVM_DIR will make find_package work, you need to
>>>> > # add it to CMAKE_MODULE_PATH if you want to include AddLLVM, e.g., if
>>>> > # you want to use add_llvm_loadable_module.
>>>> > set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH}
>>>> > "$ENV{LLVM_DIR};$ENV{Clang_DIR}")
>>>> > #find_package(LLVM REQUIRED CONFIG)
>>>> > find_package(Clang REQUIRED CONFIG)
>>>> > include(AddLLVM)
>>>> > add_definitions(${LLVM_DEFINITIONS})
>>>> > include_directories(${LLVM_INCLUDE_DIRS})
>>>> > include_directories(${CLANG_INCLUDE_DIRS})
>>>> > link_directories(${LLVM_LIBRARY_DIRS})
>>>> >
>>>> > message("LLVM_DEFINITIONS = ${LLVM_DEFINITIONS}")
>>>> > message("LLVM_INCLUDE_DIRS = ${LLVM_INCLUDE_DIRS}")
>>>> > message("LLVM_LIBRARY_DIRS = ${LLVM_LIBRARY_DIRS}")
>>>> > message("CLANG_INCLUDE_DIRS = ${CLANG_INCLUDE_DIRS}")
>>>> >
>>>> > On Wed, Oct 4, 2017 at 11:39 AM, Kim Gräsman via cfe-dev
>>>> > <cfe-dev at lists.llvm.org> wrote:
>>>> >>
>>>> >> Hi all,
>>>> >>
>>>> >> In include-what-you-use, we recently had this bug report:
>>>> >> https://github.com/include-what-you-use/include-what-you-use/pull/465
>>>> >>
>>>> >> And it's symptomatic for a whole class of problems where we're
>>>> >> duplicating knowledge from the LLVM/Clang CMake systems to allow both
>>>> >> in-tree and out-of-tree IWYU development.
>>>> >>
>>>> >> (in our terminology, in-tree == cloning the include-what-you-use repo
>>>> >> into a full LLVM and Clang checkout/clone under
>>>> >> llvm/tools/clang/tools/include-what-you-use and out-of-tree == cloning
>>>> >> include-what-you-use anywhere, and giving CMake information about
>>>> >> where to find LLVM/Clang headers and libraries)
>>>> >>
>>>> >> Looking around my system, I see a lot of CMake modules in
>>>> >> /usr/lib/llvm-4.0 and /usr/share/llvm-4.0, but it's not clear to me
>>>> >> how to use them. Also, it would be nice to allow a "next-to-tree"
>>>> >> configuration instead of in-tree, where I can point IWYU at a trunk
>>>> >> checkout of LLVM and Clang and use its CMake modules.
>>>> >>
>>>> >> Is there a correct way to accomplish this?
>>>> >>
>>>> >> Thanks,
>>>> >> - Kim
>>>> >> _______________________________________________
>>>> >> cfe-dev mailing list
>>>> >> cfe-dev at lists.llvm.org
>>>> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>> >
>>>> >
>>>
>>>