How to make formula resolve git submodules?

[itsmattkc]

I'm trying to write a formula that uses Git submodules to resolve dependencies. If I download a zip or tar.gz from GitHub, there's no .git folder so this submodule information is missing and CMake can't resolve them. If I set the head with a tag, then brew considers it a "head only"/unstable formula (despite the tag) and I get errors trying to make a tap out of it.

What are my options here? The only thing I can think of is to maintain/upload my own archive of the repo with the submodules already there, and that seems unnecessarily inconvenient.

[carlocab]

You can use a Git clone which automatically resolves submodules. You will need to specify both tag and revision. If the version information isn't recovered correctly from the tag you can also specify the version in the formula manually. For example:

  url "https://github.com/grpc/grpc.git",
      tag:      "v1.39.1",
      revision: "2d6b8f61cfdd1c4d2d7c1aae65a4fbf00e3e0981"
  version "1391"

Note that Git clones are much slower and worse for caching than tarballs.

[nandahkrishna]

You can take a look at arduino-cli or other formulae which specify the stable URL with a tag and revision:

url "https://github.com/arduino/arduino-cli.git",
    tag:      "0.18.3",
    revision: "d710b642ef7992a678053e9d68996c02f5863721"

This is less preferable and more expensive compared to using a tarball (which can be cached), but a fair few formulae do use this approach.

[itsmattkc]

Ah thanks, I didn't know the url could just be a Git repository.