assimpTargets.cmake issue on Linux

[umlaeute]

the cmake-configuration for 3rd-party consumers is somewhat broken on Linux.

I'm currently preparing the Debian packages for assimp-5.0.0, and test-compiling 3rd-party software (ros-*) that uses assimp/cmake now fails.

I narrowed it down to cmake to being able to find the libassimp.so.5 file (which of course is present on the system).

• assimp's cmake configuration is installed into /usr/lib/x86_64-linux-gnu/cmake/assimp-5.0/

• assimp's shared library is installed as /usr/lib/x86_64-linux-gnu/libassimp.so.5

• assimpTargets.cmake calculates the _IMPORT_PREFIX as /usr/lib/x86_64-linux-gnu/cmake/assimp-5.0/../../../ which in the end resolves to /usr/lib: https://github.com/assimp/assimp/blob/v5.0.0/assimpTargets.cmake.in#L44-L48

• for shared-lib builds on non-windows systems, a file-check is added for ${_IMPORT_PREFIX}/lib/${sharedLibraryName}, which really resolves to /usr/lib/lib/libassimp.so.5: https://github.com/assimp/assimp/blob/v5.0.0/assimpTargets-release.cmake.in#L79

• since there is no /usr/lib/lib/libassimp.so.5 file (esp. note the /lib/lib) , any call to find_package(ASSIMP) fails :-(

[umlaeute]

I don't really know much CMake, but it seems to me that the proper path to search for libassimp.so.5 would be ASSIMP_LIBRARY_DIRS instead.
So for now, I will just change https://github.com/assimp/assimp/blob/v5.0.0/assimpTargets-release.cmake.in#L79 to:

list(APPEND _IMPORT_CHECK_FILES_FOR_assimp::assimp "${ASSIMP_ROOT_DIR}/@ASSIMP_LIB_INSTALL_DIR@/${sharedLibraryName}" )

[umlaeute]

see https://salsa.debian.org/debian/assimp/blob/master/debian/patches/cmake.patch for the full patch.

The patch is of course a bit hack-and-slash, as we only need to care about "proper" installations.

[arakis]

I get the same problem while compiling https://github.com/dfranx/SHADERed on Gentoo.

The problem is mentioned here, also: https://bugs.gentoo.org/701912

CMake Warning (dev) at /usr/lib64/cmake/assimp-5.0/assimpTargets.cmake:54 (if):
  if given arguments:

    "ON"

  An argument named "ON" appears in a conditional statement.  Policy CMP0012
  is not set: if() recognizes numbers and boolean constants.  Run "cmake
  --help-policy CMP0012" for policy details.  Use the cmake_policy command to
  set the policy and suppress this warning.
Call Stack (most recent call first):
  /usr/lib64/cmake/assimp-5.0/assimp-config.cmake:1 (include)
  CMakeLists.txt:147 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Error at /usr/lib64/cmake/assimp-5.0/assimpTargets.cmake:85 (message):
  The imported target "assimp::assimp" references the file

     "/usr/lib/libassimp.so.5"

  but this file does not exist.  Possible reasons include:

  * The file was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and contained

     "/usr/lib64/cmake/assimp-5.0/assimpTargets.cmake"

  but not all the files it references.

Call Stack (most recent call first):
  /usr/lib64/cmake/assimp-5.0/assimp-config.cmake:1 (include)
  CMakeLists.txt:147 (find_package)


-- Configuring incomplete, errors occurred!

[vmatare]

Why not just use GNUInstallDirs and get rid of all this hackery that breaks down on every other corner?

[kimkulling]

Is in, good luck!