Flutter SDK dependency support for <flutter>/bin/cache/pkg

[mit-mit]

Pub currently supports resolving packages located in <flutter>/packages when using an SDK dependency:

flutter:
    description: flutter
    source: sdk
    version: "0.0.41-dev"

This bug requests that it additionally also looks for matching packages in <flutter>/bin/cache/pkg when using a sdk_cache dependency:

sky_engine:
    description: flutter
    source: sdk_cache

[nex3]

Do the packages in bin/cache/pkg ever overlap with the packages in packages? If not, can we just update the logic for the Flutter SDK to check in both place? Adding an entirely new source that only makes sense for Flutter is something I'd like to avoid.

[mit-mit]

I don't think so; @Hixie ?

[Hixie]

The version on sky_engine has never been updated as far as I'm aware. IMHO we should just drop it, not add any more dependencies on it. FWIW, we're about to drop all the version numbers in the flutter packages in the framework repo too. (It doesn't make sense to have these version numbers since the version will eventually change with every commit.) (see go/flutter-release)

Also currently the SDK dependency check is broken because we're publishing the version with the wrong file name, but we're planning on fixing that in the coming days.

[nex3]

The version on sky_engine has never been updated as far as I'm aware. IMHO we should just drop it, not add any more dependencies on it.

Does this mean we should close out this issue?

[Hixie]

I don't know what led to this issue, so there may be underlying issues that need resolving? But yeah, as described I would recommend probably not supporting this.

[nex3]

I believe the only motivating case was sky_engine, so I'll close this.

[mit-mit]

@Hixie, flutter/flutter#13559 was the motivation for this. So we no longer depend on sky_engine?

[Hixie]

I assume we still depend on sky_engine (that's basically dart:ui), but there's only one sky_engine per checkout of the flutter repo (in bin/cache), so if we have established which Flutter SDK we're using, we know which engine to use as well, it shouldn't be ambiguous.

[mit-mit]

Sure, but this bug wasn't meant to help with resolving the version, it was meant to help resolve the location of the package.

[Hixie]

The source: sdk_cache part seems fine to me. (If a little magical.)