[KSP] Incremental symbol processing not working (or working poorly)

[mar3kk]

Does dagger/hilt KSP actually support incremental symbol processing? It seems changing any java or kotlin file in our project, even one that seemingly shouldn't contribute to the output, causes the ksp to re-run completely.
Analyzing the KSP log files kspDirtySet.log and kspSourceToOutputs.log turns out most of the times the files considered dirty are only used to produce some proguard rules. There are a lot of entries ending _HiltModules_KeyModule_LazyClassKeys.pro. Feels like something that could be skipped when minification is disabled.

[bcorso]

Does dagger/hilt KSP actually support incremental symbol processing?

Hmm, yes, it should support incremental processing.

In KSP the incremantal processing is determined by the mode of each output (isolating/aggregating). For the LazyClassKey proguard files, this is setup here.

If you're seeing an issue specifically with the .pro files it could be a bug related specifically to resource file outputs (since most of Dagger's outputs are source files, it could explain why we didn't hit this before now). However, that would be something we'd need to get fixed in KSP rather than Dagger.

We're a little back logged right now, so if you could provide a minimal repro example that could help get this rolling.

[bcorso]

Actually, nm. @Chang-Eric pointed out that we were forgetting the originating element for the resource file (https://github.com/google/dagger/blob/master/java/dagger/internal/codegen/processingstep/LazyClassKeyProcessingStep.java#L114).

I'll send out a fix for that soon.