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

[Kim Gräsman via cfe-dev]

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
>>> >
>>> >
>>
>>