Consider improved messaging when an SDK upgrade would unblock version solving

[matanlurey]

dart --version: Dart SDK version: 2.17.6 (stable) (Tue Jul 12 12:54:37 2022 +0200) on "macos_arm64"

It appears like the analyzer version (v5.0.0) isn't compatible with the state of the package, or am I missing something?

EDIT: After blasting away my pubspec.lock and calling dart pub get:

Resolving dependencies... 
The current Dart SDK version is 2.17.6.

Because test >=1.16.1 <1.16.6 depends on analyzer >=0.39.5 <2.0.0 and test >=1.16.6 <1.17.10 depends on analyzer ^1.0.0, test >=1.16.1 <1.17.10 requires analyzer >=0.39.5 <2.0.0.
And because test >=1.17.10 <1.20.0 depends on analyzer >=1.0.0 <3.0.0 and test >=1.20.0 <1.21.0 depends on analyzer >=2.0.0 <4.0.0, test >=1.16.1 <1.21.0 requires analyzer >=0.39.5 <4.0.0.
And because test >=1.21.0 <1.21.5 depends on analyzer >=2.0.0 <5.0.0 and test >=1.21.5 requires SDK version >=2.18.0-146.0.dev <3.0.0, test >=1.16.1 requires analyzer >=0.39.5 <5.0.0.
So, because linter depends on both analyzer ^5.0.0 and test ^1.16.1, version solving failed.

I think @pq you might have forgot to rev the pubspec dependencies?

Should the github action check that pub get works for stable as a reminder to rev the pubspec?

[srawlins]

Right, I think you might need dart 2.18.0.

[srawlins]

This might be a UX bug for pub? I think it's missing some message like, "Pub version solving would not have failed if you were running with 2.18.0."

[pq]

FYI @jonasfj.

[jonasfj]

A tighter dependency constraint on linter or test would probably have forced a message with less clauses...
It's not obvious for the solver what the right solution is.

But it I agree it would be nice with a heuristic that suggested upgrading the SDK.

[pq]

I'm all for improving the experience. It would be great if the following message could include something actionable.

Resolving dependencies... 
The current Dart SDK version is 2.17.6.

Because test >=1.16.1 <1.16.6 depends on analyzer >=0.39.5 <2.0.0 and test >=1.16.6 <1.17.10 depends on analyzer ^1.0.0, test >=1.16.1 <1.17.10 requires analyzer >=0.39.5 <2.0.0.
And because test >=1.17.10 <1.20.0 depends on analyzer >=1.0.0 <3.0.0 and test >=1.20.0 <1.21.0 depends on analyzer >=2.0.0 <4.0.0, test >=1.16.1 <1.21.0 requires analyzer >=0.39.5 <4.0.0.
And because test >=1.21.0 <1.21.5 depends on analyzer >=2.0.0 <5.0.0 and test >=1.21.5 requires SDK version >=2.18.0-146.0.dev <3.0.0, test >=1.16.1 requires analyzer >=0.39.5 <5.0.0.
So, because linter depends on both analyzer ^5.0.0 and test ^1.16.1, version solving failed.

Something featuring advice like:

... upgrade to a new SDK and try again.

In the short term we could definitely bump our SDK constraint since that would reduce the clauses. In that case we'd get a message more like:

The current Dart SDK version is 2.17.6.

Because linter requires SDK version >=2.18.0-146.0.dev 0 <3.0.0, version solving failed.

(If we agree that this is a lot better, we might consider a test that asserts that the SDK lower bound is at least as high as the highest lower bound of our transitive package dependencies but I haven't thought too hard about that...)

/fyi @InMatrix

[matanlurey]

➕ for improving the UI of pub but not sure this issue is the right place?

[pq]

Agreed. I think this is an opportunity for improvement on the pub client side of things. (I'll transfer the issue for triage there.)

[sigurdm]

The current solver-traces tell you why something doesn't work, but don't tell you what would work.

We could have the solve-failure give you potential solutions:

Resolving dependencies... 
The current Dart SDK version is 2.17.6.

Because test >=1.16.1 <1.16.6 depends on analyzer >=0.39.5 <2.0.0 and test >=1.16.6 <1.17.10 depends on analyzer ^1.0.0, test >=1.16.1 <1.17.10 requires analyzer >=0.39.5 <2.0.0.
And because test >=1.17.10 <1.20.0 depends on analyzer >=1.0.0 <3.0.0 and test >=1.20.0 <1.21.0 depends on analyzer >=2.0.0 <4.0.0, test >=1.16.1 <1.21.0 requires analyzer >=0.39.5 <4.0.0.
And because test >=1.21.0 <1.21.5 depends on analyzer >=2.0.0 <5.0.0 and test >=1.21.5 requires SDK version >=2.18.0-146.0.dev <3.0.0, test >=1.16.1 requires analyzer >=0.39.5 <5.0.0.
So, because linter depends on both analyzer ^5.0.0 and test ^1.16.1, version solving failed.

To make the version solving succeed you could try one of the following potential solutions:
* Upgrade your sdk to at least 2.18.0-146.0.dev.
* Downgrade the constraint on package:test: `dart pub add test:^1.21.41. <--- [This doesn't work today]

I cannot think of a better way of constructing these than:

• for each constraint in the root package (possibly just for each constraint involved in the trace), try to relax it and redo the resolution.
• special handling for the sdk-constraint (try to redo the resolution with an imagined SDK equal to the one required in the trace)...

[jonasfj]

I cannot think of a better way of constructing these than...

Yeah, doing some guesses and running the solver for that is probably what it'll take.
But it's hard to know if such heuristics are useful or not.

[pq]

But it's hard to know if such heuristics are useful or not.

Agreed.

Really this could be a fools errand but I appreciate the conversation.

I'd be curious what @InMatrix thinks?

[pq]

We could have the solve-failure give you potential solutions:

Lest this get lost in the shuffle, I think something like this would be fantastic (even if we could only do it for a subset of cases).