abseil: fix build in environments without CMake

[Artalus]

Specify library name and version: abseil/X

abseil requires CMake to be built, but does it without respect 🙂

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• I've read the contributing guidelines.
• I've used a recent Conan client version close to the currently deployed.
• I've tried at least one configuration locally with the conan-center hook activated.

[github-actions]

🤖 Beep Boop! This pull request is making changes to 'recipes/abseil//'.

👋 @Hopobcn you might be interested. 😉

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 3 (c9c461760baa413f855609c8543b5251079924c1):

• abseil/20230125.3:
  All packages built successfully! (All logs)

• abseil/20230802.1:
  All packages built successfully! (All logs)

• abseil/20230125.2:
  All packages built successfully! (All logs)

• abseil/20230125.1:
  All packages built successfully! (All logs)

• abseil/20220623.0:
  All packages built successfully! (All logs)

• abseil/20230125.0:
  All packages built successfully! (All logs)

• abseil/20220623.1:
  All packages built successfully! (All logs)

• abseil/20211102.0:
  All packages built successfully! (All logs)

---

Conan v2 pipeline ✔️

Note: Conan v2 builds are now mandatory. Please read our discussion about it.

All green in build 3 (c9c461760baa413f855609c8543b5251079924c1):

• abseil/20230802.1:
  All packages built successfully! (All logs)

• abseil/20230125.3:
  All packages built successfully! (All logs)

• abseil/20230125.0:
  All packages built successfully! (All logs)

• abseil/20230125.2:
  All packages built successfully! (All logs)

• abseil/20230125.1:
  All packages built successfully! (All logs)

• abseil/20220623.1:
  All packages built successfully! (All logs)

• abseil/20211102.0:
  All packages built successfully! (All logs)

• abseil/20220623.0:
  All packages built successfully! (All logs)

[ghost]

I detected other pull requests that are modifying abseil/all recipe:

• abseil: add version 20240116.2 #23588

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[valgur]

Abseil requires CMake v3.10 (https://github.com/abseil/abseil-cpp/blob/20240116.1/CMakeLists.txt#L19). We generally don't add CMake as a tool_requires unless v3.16 or newer is needed.

[uilianries]

Hello @Artalus! Thank you for submitting your PR, but having CMake installed is something expected already by CCI: https://github.com/conan-io/conan-center-index/blob/master/docs/developing_recipes_locally.md#setup-your-environment

In case we follow your idea, then any recipe in CCI using CMake should have it listed as tool requirement too ...

The CI service in CCI has CMake 3.15 installed due Conan 2.x design: https://github.com/conan-io/tribe/blob/a36de8dd33852f43091e9f5eb5a7ad83618089f2/design/004-tools-cmake.md?plain=1#L2

For those projects that need a new version, then we list CMake as tool requirement to install a newer version. This is not the case for Abseil, it uses CMake 3.10: https://github.com/abseil/abseil-cpp/blob/master/CMakeLists.txt#L19

If don't have CMake installed in your environment and want to use Conan to install it, I would recommend configuring it directly in your profile instead: https://docs.conan.io/2/reference/config_files/profiles.html#tool-requires

[Artalus]

Cheers for such a detailed explanation! Being able to declare tool-require in the profile might be of service later.

I might argue that if a package depends on buildtool X that is easily available from Conan, it should declare one as such - esp. since CMake now climbed upon a track of slowly shedding off some of its legacy components. But this would be a large change in CCI policies outside the scope of this PR :) I guess we can safely close it then 👍

[uilianries]

@Artalus Thank you for understanding! Indeed other build tools we still need to list, like meson, but because CMake is used largely in ConanCenterIndex and most adopted.