Fix #11078: avoid widening F-bounds in type avoidance #11192
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liufengyun
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| /** Deviation from standard tryWiden: | ||
| * - Don't widen F-bounds |
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Maybe the standard tryWiden shouldn't widen f-bounds either?
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Yes, this is a trial to see how it works. It may incur a performance penalty.
If it works, I think we need a more systematic approach here: possible a field in SymDenotation to cache whether a symbol is F-bounded. The field can be set in checkNonCyclic, so we can avoid the computation here (or in ApproximatingTypeMap).
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F-bounded situations are already captured by LazyRefs. Maybe just add a case for LazyRefs to TypeOps.avoid?
Oh, I see you tried that already.
| tp.origin, fromBelow = variance > 0 || variance == 0 && tp.hasLowerBound)(using mapCtx) | ||
| val lo1 = apply(lo) | ||
| if (lo1 ne lo) lo1 else tp | ||
| case tp: LazyRef => |
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I think this should be emptyRange instead of TypeBounds.empty.
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Thanks for the tip, @odersky. I tried emptyRange, the test tests/run/i2895a.scala still fails. The problem is that LazyRef may leak into non-bounds places after asSeenFrom. It seems we need to stop earlier in the handling of bounds.
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test performance please |
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performance test scheduled: 42 job(s) in queue, 1 running. |
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Performance test finished successfully: Visit http://dotty-bench.epfl.ch/11192/ to see the changes. Benchmarks is based on merging with master (35bb073) |
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@odersky Could you have a look at the last trial? Does it make sense? |
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Fix #11078: avoid widening F-bounds in type avoidance