Resolve "EXTERN: Adapt to Conan 2"

Summary

Updating from Conan 1 to Conan 2.5 required several changes, both on the conanfile.py as well as the CMakeLists.txt file(s).

Related to

• #73 (closed)
• #80 (closed)
• #82 (closed)
• #83 (closed)

Related MR for integration tests: caosdb-cppinttest!35 (merged)

Focus

The biggest changes are in conanfile.py and CMakeLists.txt all according to the migration guide. Crucial here are

• Conan now doesn't appear in the CMakeLists.txt files anymore. Instead, Conan generates CMakeToolChain files, which handle all the necessary includes etc. The toolchain files are passed to CMake as arguments.
• Packages are included in our CMakeLists.txt using CMake's FindPackage
• Conan 2.0 builds into build/<build_type>, i.e. build/Release or build/Debug

Test Environment

How to set up a test environment for manual testing?

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Up-to-date JSON schema (or not necessary)
• Appropriate user and developer documentation (or not necessary)
  • How do I use the software? Assume "stupid" users.
  • How do I develop or debug the software? Assume novice developers.
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

For further good practices have a look at our review guidelines.

doc/CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 
 - Updated dependency versions.
+- Updated Python dependencies for Conan 2 and support Python 3.12.
+- Updated C++ package manager Conan to 2.5.0.
 
 ### Deprecated