Source: qt6-base Followup-For: Bug #1073480 X-Debbugs-Cc: pkg-llvm-t...@lists.alioth.debian.org Control: reassign -1 llvm-17-dev Control: severity -1 important
Hi, after a big of debugging, I think I got to the actual reason for this failure. In particular, starting from LLVM 16, there is a shipped cmake find module to find libzstd: $ dpkg -L llvm-17-dev | grep -i zstd /usr/lib/llvm-17/lib/cmake/llvm/Findzstd.cmake The problem here is that it defines cmake targets with the same name as those defined by the libzstd own cmake config modules: $ dpkg -L libzstd-dev | grep -i cmake /usr/lib/x86_64-linux-gnu/cmake /usr/lib/x86_64-linux-gnu/cmake/zstd /usr/lib/x86_64-linux-gnu/cmake/zstd/zstdConfig.cmake /usr/lib/x86_64-linux-gnu/cmake/zstd/zstdConfigVersion.cmake /usr/lib/x86_64-linux-gnu/cmake/zstd/zstdTargets-none.cmake /usr/lib/x86_64-linux-gnu/cmake/zstd/zstdTargets.cmake This can be easily reproduced on a clean system with only LLVM and libzstd development files, and a very simple CMakeLists.txt file: $ podman run -ti --rm --pull=newer debian:unstable root@514df0e64d7b:/# apt-get update root@514df0e64d7b:/# apt-get -y dist-upgrade root@514df0e64d7b:/# apt-get --no-install-recommends install gcc g++ make cmake libzstd-dev llvm-17-dev root@514df0e64d7b:/# cd /tmp/ root@514df0e64d7b:/tmp# cat >CMakeLists.txt <<EOF > cmake_minimum_required(VERSION 3.20) > project(test) > find_package(LLVM CONFIG) > find_package(zstd CONFIG) > EOF root@514df0e64d7b:/tmp# mkdir build root@514df0e64d7b:/tmp# cd build/ root@514df0e64d7b:/tmp/build# cmake .. -- The C compiler identification is GNU 13.3.0 -- The CXX compiler identification is GNU 13.3.0 -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working C compiler: /usr/bin/cc - skipped -- Detecting C compile features -- Detecting C compile features - done -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Check for working CXX compiler: /usr/bin/c++ - skipped -- Detecting CXX compile features -- Detecting CXX compile features - done -- Performing Test HAVE_FFI_CALL -- Performing Test HAVE_FFI_CALL - Success -- Found FFI: /usr/lib/x86_64-linux-gnu/libffi.so -- Could NOT find LibEdit (missing: LibEdit_INCLUDE_DIRS LibEdit_LIBRARIES) -- Performing Test Terminfo_LINKABLE -- Performing Test Terminfo_LINKABLE - Success -- Found Terminfo: /usr/lib/x86_64-linux-gnu/libtinfo.so -- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found version "1.3.1") -- Found zstd: /usr/lib/x86_64-linux-gnu/libzstd.so -- Found LibXml2: /usr/lib/x86_64-linux-gnu/libxml2.so (found version "2.12.7") -- Could NOT find CURL (missing: CURL_LIBRARY CURL_INCLUDE_DIR) -- Performing Test CMAKE_HAVE_LIBC_PTHREAD -- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success -- Found Threads: TRUE CMake Error at /usr/lib/x86_64-linux-gnu/cmake/zstd/zstdTargets.cmake:42 (message): Some (but not all) targets in this export set were already defined. Targets Defined: zstd::libzstd_shared, zstd::libzstd_static Targets not yet defined: zstd::libzstd Call Stack (most recent call first): /usr/lib/x86_64-linux-gnu/cmake/zstd/zstdConfig.cmake:42 (include) CMakeLists.txt:4 (find_package) -- Configuring incomplete, errors occurred! The order of the bits in the CMakeLists.txt is the key: - the cmake find module shipped by LLVM defines two targets, zstd::libzstd_shared and zstd::libzstd_static - the libzstd cmake config module defines three targets, i.e. zstd::libzstd_shared, zstd::libzstd_static, and zstd::libzstd - the libzstd cmake config module expects a "all or nothing situation", as it assumes that if one is defined, then all the others are too (AFAIK this is done so that multiple calls to find_package(zstd) will not redefine things) This is exactly the situation in qt6-tools: first Clang is searched (which in turns requires LLVM), and then zstd. Hence: - I'm reassigning this to llvm, as it is clearly a bug there; IMHO either the module needs to be taught about the zstd::libzstd target, or it needs to try to use the libzstd config module - I'm lowering the severity of this to important, since it is a not so common situation - I will add a workaround in qt6-tools -- Pino
