CMake Superbuild: Tarball

[ax3l]

Cloning whole repos can be quite slow and CMake does not support shallow clones yet. We can use release tarballs instead.

Follow-up to #1583

Configure from scratch time:

• Before: 50.2s
• Now: 9.7s

Todo list:

• rebase after CMake Superbuild: Repo & Local Source #1667
• docs update
• catch
• json
• pybind11
• toml11

[DerNils-git]

Reducing the configure time by a factor of almost five is significant so an obvious improvement.
Just a small disadvantage. One has to remember to update two lines if the version of a dependency should be updated instead of one.

We are working on a wrapper for FetchContent_Declare to add a few features which should improve usability if the SOURCE_DIR directory is defined. We want to reduce the amount of downloads. If you are interested we could discuss this separately.

[ax3l]

We are working on a wrapper for FetchContent_Declare to add a few features which should improve usability if the SOURCE_DIR directory is defined. We want to reduce the amount of downloads. If you are interested we could discuss this separately.

Thanks! That sounds very interesting as a follow-up, happy to take a look on what you are working on 👍

Just a small disadvantage. One has to remember to update two lines if the version of a dependency should be updated instead of one.

I would not wait for this extra update for the 0.16.0 release, since it is not critical and we do change the superbuild dependencies very, very seldomly. The superbuild is really just a developer convenience feature and should be deactivated for non-development deployments in favor of a proper external package/module.

[franzpoeschel]

Will openPMD_catch_branch, openPMD_catch_repo and openPMD_catch_src be removed?

[ax3l]

We will support both. The order now of precedence is:

• src
• tar, or if openPMD_catch_tar is set to off/false/empty/etc.
• git

[ax3l]

Docs added that explain the precedence.