GH-48074: [C++] Use FetchContent for bundled Abseil

[raulcd]

Rationale for this change

As a follow up of requiring a minimum CMake version >= 3.25 we discussed moving our dependencies from ExternalProject to FetchContent. This can heavily simplify our third party dependency management. Moving abseil is the first step to simplify some of them.

What changes are included in this PR?

The general change is moving from ExternalProject to FetchContent. In more detail this gets rid of all the manual definition of targets for all abseil libraries with it's dependency management. This is removing around 900 lines of custom code which is not necessary with FetchContent.

It also add some required integration due to other dependencies, like grpc, using ExternalProject. We not only have to build but also install in order for those other dependencies to find abseil. This causes some timing issues between config, build, install that requires us to create a custom target to depend on so the other dependencies find abseil. As we have to install abseil for those to find it we also want to not install abseil outside of the build path that's why we override abseil's cmake_install.cmake with no-op.

Are these changes tested?

Yes, the changes are tested locally and on CI.

Are there any user-facing changes?

No

• GitHub Issue: [C++] Use FetchContent for bundled Abseil #48074

[github-actions]

⚠️ GitHub issue #48074 has been automatically assigned in GitHub to PR creator.

[raulcd]

@github-actions crossbow submit -g cpp

[github-actions]

Revision: ffffeb4

Submitted crossbow builds: ursacomputing/crossbow @ actions-f1048dc859

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-cuda-cpp-ubuntu-22.04-cuda-11.7.1
test-debian-12-cpp-amd64
test-debian-12-cpp-i386
test-fedora-42-cpp
test-ubuntu-22.04-cpp
test-ubuntu-22.04-cpp-20
test-ubuntu-22.04-cpp-bundled
test-ubuntu-22.04-cpp-emscripten
test-ubuntu-22.04-cpp-no-threading
test-ubuntu-24.04-cpp
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled
test-ubuntu-24.04-cpp-gcc-14
test-ubuntu-24.04-cpp-minimal-with-formats
test-ubuntu-24.04-cpp-thread-sanitizer

[raulcd]

@github-actions crossbow submit -g cpp

[github-actions]

Revision: ef326eb

Submitted crossbow builds: ursacomputing/crossbow @ actions-b9f2ce761a

Task	Status
example-cpp-minimal-build-static
example-cpp-minimal-build-static-system-dependency
example-cpp-tutorial
test-build-cpp-fuzz
test-conda-cpp
test-conda-cpp-valgrind
test-cuda-cpp-ubuntu-22.04-cuda-11.7.1
test-debian-12-cpp-amd64
test-debian-12-cpp-i386
test-fedora-42-cpp
test-ubuntu-22.04-cpp
test-ubuntu-22.04-cpp-20
test-ubuntu-22.04-cpp-bundled
test-ubuntu-22.04-cpp-emscripten
test-ubuntu-22.04-cpp-no-threading
test-ubuntu-24.04-cpp
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled
test-ubuntu-24.04-cpp-gcc-14
test-ubuntu-24.04-cpp-minimal-with-formats
test-ubuntu-24.04-cpp-thread-sanitizer

[raulcd]

@kou I'd like to discuss this with you once you have some time. There are some challenges mixing FetchContent and ExternalProject but with some custom manipulations I was able to make this work. We will be able to get rid of part of the code once we migrate grpc, gcs to FetchContent too but this can be done after this PR to keep things small instead of trying a big PR approach.
This approach works and we are able to get rid of a lot of custom code to manipulate the abseil targets. This will massively simplify upgrading abseil.
I plan to work on grpc, protobuf, gcs migration to FetchContent next and my plan is to update dependencies once the migration is done. Let me know your thoughts.

[raulcd]

@github actions crossbow submit bundled

[raulcd]

@github-actions crossbow submit bundled

[github-actions]

Revision: b81600c

Submitted crossbow builds: ursacomputing/crossbow @ actions-3868d3fe73

Task	Status
test-r-depsource-bundled
test-ubuntu-22.04-cpp-bundled
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled

[raulcd]

@kou @assignUser I would apprec iate if you could take a look here. I have several PRs aligned after this one, the current plan is to move:
abseil -> c-ares (already on a follow up draft PR) -> protobuf (currently working on it, locally) -> re2 ->grpc

The main problem is that in the interim we have to live with both FetchContent and ExternalProject and their interaction. See the description + comments above.

[kou]

Sorry for missing this! (I saw your comment last week but I attended a conference. So I forgot to review this... Sorry...)

I'll review this today.

[kou]

Could you use function() not macro() to create a variable scope?

We can remove cleanup_fetchcontent() by this change.

[raulcd]

That was a good idea, moving to function help me clean a bunch of things that were not necessary! Thanks for the suggestion @kou

[raulcd]

@github-actions crossbow submit bundled

[github-actions]

Revision: 541ca51

Submitted crossbow builds: ursacomputing/crossbow @ actions-46baf386d7

Task	Status
test-r-depsource-bundled
test-ubuntu-22.04-cpp-bundled
test-ubuntu-24.04-cpp-bundled-offline
test-ubuntu-24.04-cpp-gcc-13-bundled