transient--set-layout: Symbol’s function definition is void

[jman-schief]

Follow-up to #391

I am using the latest stable Emacs 30.2 on Debian testing/forky and is using transient version 0.7.2.2

When I start Emacs a few packages (among which also magit) show this error:

■  Error (use-package): magit/:catch: Symbol’s function definition is void: transient--set-layout

I configured magit with use-package:

(use-package magit)

and it pulls magit-20260226.1808

If I understand correctly transient--set-layout was merged in Emacs in commit https://cgit.git.savannah.gnu.org/cgit/emacs.git/commit/?id=680fa61b5989b84c0e19ac568be012afd8345f0c which updates transient to version 0.9.1. That patch has not yet landed on stable Emacs.

And magit was updated to using a version of transient not yet released on stable Emacs distribution and installing magit without requiring a version will break my installation.

@tarsius can you help me understand this?

Thanks

[tarsius]

You have to install a newer version of Transient.

The package manager should do that automatically since the Melpa package specifies the Transient version, which it needs, but because Transient is a built-in package, some package managers refuse to honor that automatically. (The maintainers of these package managers know about this, but last I checked, they considered this a feature, not a bug.) So you have to explicitly update Transient.

[jman-schief]

ok updating transient works but I am pretty confused: what is exactly the "feature" here? We have a package built-in (transient) in Emacs stable which is compatible up to version x.y. of an external package (example magit). Clearly you are free to evolve magit but use-package shouldn't pull just any version of it. There must be a compatibility matrix or something.

You are releasing semver versions of transient and magit, correct? Are you clarifying if new versions of magit need a version bump of transient? Shouldn't be that complicated to handle dependencies. Or am I not seeing the whole picture? I mean, obviously there's something wrong because I came here with a broken Emacs config, right?

Thanks for your help!

[tarsius]

what is exactly the "feature" here?

The Emacs maintainers decided that the package manager should not update a built-in package A, even if an externally installed package B needs a newer version of that package A and says so in its dependency list. The "feature" is "the user might not want that" because theoretically another built-in package C, might not be compatible with the more recent external version of package A.

I am trying hard to prevent that from happening in the case of Transient. There actually is one unaddressed compatibility issue breaking a minor feature in the built-in emoji.el bundled with an older Emacs release (29.* but not 30.*) . So I guess they have a point.

In case it is not clear, I don't think the Emacs maintainers made the right choice here. It's much worse to break Magit completely for everyone than to break one minor feature of a built-in package (which otherwise remains usable), whose purpose it is to insert emoji, and which is used by way fewer users than Magit.

Please just install the latest version (or snapshot) of Transient if you want to use the latest version (or snapshot) of Magit. It is unfortunate that you and many/most other Magit users have to explicitly update Transient, but the behavior of package.el is beyond my control.

[tarsius]

You should also (setq package-install-upgrade-built-in t), but if I remember correctly, that doesn't actually work in 30 yet.

[jman-schief]

You should also (setq package-install-upgrade-built-in t), but if I remember correctly, that doesn't actually work in 30 yet.

Yes, C-h v says it's available since 29.1 and I agree with Emacs that I don't want to upgrade built-in packages. But the compatibility check of use-package is broken because it pulls incompatible versions of external packages. As a package author, you should not be concerned about these issues.

I want something like this:

(use-package magit
  :version "x.y")

where x.y is a semver version known to work with built-in transient and I'd rather not use hacks like pinning git tags with straight. On the other hand magit should declare which version of transient it requires to hint use-package about incompatibilities. Why isn't there such a check is beyond my comprehension.

Anyway, I should bring this conversation elsewhere :)