Dependencies issues when building or-tools 7.0 from Cmake error

[AxelDelsol]

I am sorry if I should have reopened my previous issues. I found more bugs when building and installing the latest version of CMake.

Here is what I tested to "solve" the problem :

TLDR

To build and use or-tools 7.0 when downloading the source code from the latest release (as of 2019/03/29):

1. Change https://github.com/Mizux/Cbc to https://github.com/Mizux/coinor-cbc in cbc.CMakeLists.txt according to Building or-tools 7.0 from Cmake error #1159
2. run cmake and get the following error : includes target "ortools" which requires target "absl_base" that is not in the export set.
3. Change "${CMAKE_INSTALL_LIBDIR}/cmake/" to "${CMAKE_INSTALL_LIBDIR}/cmake/absl" in absl-cpp-src/CMakeLists.txt
4. Change set(ABSL_ENABLE_INSTALL FALSE) to TRUE in in absl-cpp-src/CMakeLists.txt
5. Add find_dependency(absl REQUIRED NO_MODULE) in ortoolsConfig.cmake.in
6. Add set(GFLAGS_USE_TARGET_NAMESPACE TRUE) in ortoolsConfig.cmake.in after include (CMakeFindDependencyMacro)
7. rerun cmake
8. make -j4
9. make install

Detail

With default sources :

/or-tools-7.0-build/cbc-src does not contain a CMakeLists.txt file.

Test 1

1. Change path in cbc.CMakeLists.txt according to Building or-tools 7.0 from Cmake error #1159

Ouput :

CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_base" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_raw_hash_set" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_hash" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_memory" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_meta" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_str_format" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_strings" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_synchronization" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "absl_any" that is not in the export set.
CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.
CMake Error: install(EXPORT "glog-targets" ...) includes target "glog" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.

Building and testing works.
No warning during the installation but will cause an error when trying to use ortools::ortools target (missing targets)

Test 2

0. Change path in cbc.CMakeLists.txt according to Building or-tools 7.0 from Cmake error #1159
1. Tag bf29470 does not exist in https://github.com/abseil/abseil-cpp. Try master instead and remove the patch

-> Same output as before

For the following : tag is bf29470 and the patch is kept.

Test 3

1. Change path in cbc.CMakeLists.txt according to Building or-tools 7.0 from Cmake error #1159

2. Add absl-cpp-src/CMakeLists.txt at line 127 : message(STATUS "ABSL install enabled ? ${ABSL_ENABLE_INSTALL}")
   ABSL install enabled ? FALSE .ABSL_ENABLE_INSTALL is set to false at line 42 because we are using abseil as a subproject in or-tools.

3. Change set(ABSL_ENABLE_INSTALL FALSE) to TRUE in absl-cpp-src/CMakeLists.txt at line 42

Ouput :

CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.
CMake Error: install(EXPORT "glog-targets" ...) includes target "glog" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.

Building and testing works.

When trying to use ortools::ortools after installation in a new project (using the cmake tutorial provided with or-tools):

The following imported targets are referenced, but are missing: absl::base
  absl::raw_hash_set absl::hash absl::memory absl::meta absl::str_format
  absl::strings absl::synchronization absl::any

Test 4

1. Change path in cbc.CMakeLists.txt according to Building or-tools 7.0 from Cmake error #1159
2. Change "${CMAKE_INSTALL_LIBDIR}/cmake/" to "${CMAKE_INSTALL_LIBDIR}/cmake/absl" in absl-cpp-src/CMakeLists.txt
3. Add find_dependency(absl REQUIRED NO_MODULE) in ortoolsConfig.cmake.in

Ouput :

CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.
CMake Error: install(EXPORT "glog-targets" ...) includes target "glog" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.

Building and testing works.

When trying to use ortools::ortools after installation in a new project (using the cmake tutorial provided with or-tools):

Target "CVRP" links to target "gflags::gflags" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?

Test 5

1. Change "${CMAKE_INSTALL_LIBDIR}/cmake/" to "${CMAKE_INSTALL_LIBDIR}/cmake/absl" in absl-cpp-src/CMakeLists.txt
2. Add find_dependency(absl REQUIRED NO_MODULE) in ortoolsConfig.cmake.in
3. Add set(GFLAGS_USE_TARGET_NAMESPACE TRUE) in ortoolsConfig.cmake.in

Ouput :

CMake Error: install(EXPORT "ortoolsTargets" ...) includes target "ortools" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.
CMake Error: install(EXPORT "glog-targets" ...) includes target "glog" which requires target "gflags_nothreads_static" that is not in this export set, but 2 times in others.

Everything works fine even with the CMake error but I could not find why.

[Mizux]

Test 1

Bravo ! you just figure out the limitation of add_subdirectory() vs regular cmake install dependencies ;)
I'm currently in the process of reworking the way we consume our dependencies on CMake-based build
-> #1116

First step was to work for the abseil team to add install rules, second step will be a rework of Cbc then third step I'll rework the way we consume dependencies.

Please note CMake support is still "experimental" so up to now you should use the Make-based build...

note: From CMake release 3.13

The install(TARGETS) command learned to install targets created outside the current directory.

src: https://cmake.org/cmake/help/v3.13/release/3.13.html#commands

Test 2

strange abseil do have this short SHA1 see -> abseil/abseil-cpp@bf29470

Test 3

Yes, related to Test 1, currently we the abseil-team we are changing our mind, we will need to install abseil-cpp first.
good news my patch to install rules have been merged internally and should be all available on github...

Test 4

bear in mind that find_dependency() does not support REQUIRED or NO_MODULE or any find_package() options before CMake 3.9 IIRC

The CMakeFindDependencyMacro module find_dependency macro now forwards all arguments to the underlying find_package() call. Existing uses will continue to function as before, but callers can now access the full suite of arguments that find_package accepts.

src: https://cmake.org/cmake/help/v3.9/release/3.9.html#modules

Test 5

copy/paste you must mean find_dependency(gflag) I guess

note: I marked it as duplicate of #1116

[Mizux]

Everything is on master now, so I'll close this as obsolete/done now.

Thanks for the feedback and don't hesitate to come back if needed...