[kotlin] J2K: Add JKTree processing step to remove redundant type projections #2741
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In the spreadsheet, this one is listed as "REDUNDANT_PROJECTION."
Unfortunately this JKTree processing step isn't sufficient to remove the corresponding diagnostic-based postprocessing step: we need mutability analysis to run before we can remove redundant type projections from collections' type parameters (e.g. we can't remove the
out
fromMutableList<out Foo>
, but we can fromList<out Foo>
). If I omit the postprocessing step, there are 8 failing K1 tests (see attached screenshot).I also tried implementing these changes by modifying JavaToJKTreeBuilder, but that had a bunch of unpleasant side effects, and didn't seem like a natural place to stick this logic.
NB: The test cases added here are largely based on my imagination, and might be overkill.
@abelkov @darthorimar @jocelynluizzi13