Android: Add nonTransitiveRClasses Option

[souvlakias]

#5862
This feature affects multi-module android applications. This blog helps on understanding its benefits.

The basic idea is compilation avoidance: in a dependency tree that’s at least three levels deep, modifying a node causes only that node and its parent to recompile, instead of propagating all the way up to the root.
(Test Branch)

Default value is set to true, like AGP>=8

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[vaslabs]

Can we have a comparison of the difference? E.g. a line count for the file input on the aapt2 compile or/and linking for each configuration

[souvlakias]

Can we have a comparison of the difference? E.g. a line count for the file input on the aapt2 compile or/and linking for each configuration

transitiveRClasses:

NonTransitiveRClasses:

Comments

The line count difference on the aapt2 link args is not significant, since the ModuleCompiledResources are way less compared to the CompiledLibResources.
Nevertheless the goal of Compilation Avoidance is achieved here, since modules only depend on their direct dependencies.
E.g. modifying Database's resources would only cause itself and network to recompile and not any other modules which was the case before.

[lefou]

We now have androidDirectCompiledResources and androidTransitiveCompiledResources. The latter is a super-set of the former.

I was thinking, if it makes sense to have two disjunct sets, meaning, the transitive set contains only those resources not already in the direct resources? That way, we could easily spot what resources we potentially miss with mill show _.androidTransitiveCompiledResources. But it also makes reasoning a bit easier, since the direct resources are always used. Meaning, we have a more stable task dependency tree.