VM: Implementing the package spec proposal

[sethladd]

Tracking issue for implementing the package spec proposal.

Main issue: dart-archive/dart_enhancement_proposals#5

Proposal: https://github.com/lrhn/dep-pkgspec/blob/master/DEP-pkgspec.md

[iposva-google]

Set owner to @iposva-google.
Added Accepted label.

[sethladd]

Marked this as blocking #23372.

[sethladd]

Added this to the 1.11 milestone.

[nex3]

Milestone 1.11 is in merge mode now. How is this progressing?

[nex3]

Just to make sure: there will also be a --package-spec flag that allows the user to pass in a user-specified package location, right? This is important for pub.

[sethladd]

The DEP specified --package-spec so I would expect that it will be supported. Thanks for raising this.

Curious, how/why would pub use it?

[nex3]

The same way pub uses the --package-root flag now: to compile snapshots from transformed code, to executables in dependencies or globally-activated packages, and to run pub itself for testing.

[sethladd]

PR just landed b07a9dd

[iposva-google]

Fixed with https://codereview.chromium.org//1232593003
and https://codereview.chromium.org//1269643002

[sethladd]

Thanks @iposva-google , very cool!

[nex3]

Three questions:

• Does this support support passing a packages file into Isolate.spawnUri? If not, should we open a new sub-issue of Generate and consume the package spec (.packages) #23372 for that?
• b07a9dd mentions that it doesn't yet support .packages files for HTTP imports. Is that in yet? If not, should we wait to close this issue until it is?
• Where do the tests for this feature live?

[sethladd]

Does this support support passing a packages file into Isolate.spawnUri? If not, should we open a new sub-issue of #23372 for that?

I just checked the bleeding_edge docs for Isolate.spawnUri, and it looks like there isn't a named parameter for packages file. Thanks for the catch. I can open a new sub-issue for that. (cc @lrhn )

b07a9dd mentions that it doesn't yet support .packages files for HTTP imports. Is that in yet? If not, should we wait to close this issue until it is?

I'll open a new tracking issue for that.