Improve error messages when transformer plugins fail to load

[yjbanov]

What steps will reproduce the problem?

1. Create two projects A and B
2. B depends on A
3. Create a transformer in project A
4. Add it to B's pubspec.yaml
5. 'pub serve' project B

What is the expected output? What do you see instead?

Expecting 'pub serve' not to crash. Instead, it crashes (stderr output from pub --trace 'serve' attached).

What version of the product are you using? On what operating system?

barback 0.11.1
Tried two Dart VM versions:
1.3.0-dev.0.0 (Wed Feb 26 07:39:42 2014) on "macos_x64"
1.2.0-dev.5.15 (Mon Feb 24 02:12:58 2014) on "macos_x64"

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Attachment:
barback-sterr.log (146.37 KB)

[iposva-google]

Added Pkg-Barback, Area-Pkg, Triaged labels.

[nex3]

I can't reproduce this locally. Can you confirm this is still happening on the latest bleeding edge pub version, and if so can you provide a tarball of an app where this happens?

[nex3]

Added CannotReproduce label.

[yjbanov]

So, it turns out I was incorrectly referring to the transformer. I needed to specify full path to the file where the transformer is defined, but instead I just used the package name. Bob N. says for that to work I have to name the file transformer.dart. I'll try that later.

However, that's not an excuse to produce illegible errors. It should clearly say "your transformer cannot be found" or sth like that, preferably w/o stack traces. So, I tried again. I cannot reproduce the exact same error, but I get a different error, this time even less legible that the last. Attaching both the stderr and the archived sample projects.

Dart VM version: 1.3.0-dev.3.2 (Mon Mar 10 11:06:13 2014) on "macos_x64"
Pub 1.3.0-dev.3.2

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Attachments:
stderr.txt (929 Bytes)
sample-projects.zip (4.64 KB)

[nex3]

It would be nice to improve these error messages, but currently the IsolateSpawnException API doesn't expose any information we can use to do so. I've filed issue #17492 to track that.

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Removed Pkg-Barback, Area-Pkg labels.
Added Area-Pub, Triaged labels.
Marked this as being blocked by #17492.
Changed the title to: "Improve error messages when transformer plugins fail to load".

[nex3]

Oops, I mean issue #17501.

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Marked this as being blocked by #17501.
Unmarked this as being blocked by #17492.

[munificent]

Issue #15594 has been merged into this issue.

[nex3]

Issue #19961 has been merged into this issue.

[DartBot]

This issue has been moved to dart-lang/pub#896.