bazel merges android resource problem

[leozwang-google]

I ran into android resource problems, the errors are
#1. undefined app elevation
#2. undefined some material items, for example widget.design.textinputlayout

The code is attached in this issue.

The code is straightforward, however, it depends on firebase-UI project https://github.com/firebase/FirebaseUI-Android which also depends on faceback and twitter login aars.

fire.zip

[aj-michael]

/cc @jin @ahumesky @dkelmer

Sorry about the delay on this, I'll try to sort this out early next week.

[aj-michael]

Did some digging, the issue is when Bazel is parsing this stylable attribute:

https://android.googlesource.com/platform/frameworks/support/+/master/design/res/values/attrs.xml#282

Since it doesn't define a format, we assume it a reference instead of a definition. But Bazel can't find an actual definition for it (and neither can I...).

[aj-michael]

Oh, it's inherited from a styleable in appcompat-v7:

https://android.googlesource.com/platform/frameworks/support/+/master/v7/appcompat/res/values/attrs.xml#500

The problem is that maven_aar generates aar_import rules, but there are no deps between those aar_import rules.

This is an ugly manifestation of the fact that Bazel does not have a good solution for transitive maven dependencies.

I'll try and whip up a workaround.

[aj-michael]

so, this issue is a duplicate of #2863.

https://bazel-review.googlesource.com/c/bazel/+/20771 will add a deps attribute to maven_aar that will fix this. However, it will require maintaining the graph of dependencies between the AARs, as opposed to the flat list in the deps of an android_library.