Fix #360: Improve avoidance algorithm #2078
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The essential change is that we do not throw away more precise info of the avoided type if the expected type is fully defined.
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Oh, it was SI-1569, not our issues. |
odersky
changed the title
| val tree1 = ascribeType(tree, avoid(tree.tpe, localSyms)) | ||
| ensureNoLocalRefs(tree1, pt, localSyms, forcedDefined = true) | ||
| } else | ||
| val avoidingType = avoid(tree.tpe, localSyms) |
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The comment on top of this method needs to be updated now that the order of operations changed.
No more try-again business necessary.
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@smarter I investigated whether we could base TypeAssigner#avoid on ApproximatingTypeMap. But it seems to be pretty tricky to do so, so for the moment I abandoned the effort. See branch change-avoid-via-approx on staging for the current state of the effort. We still get discrepancies where the new avoid is not as good as the old one. I am going to let it be for now, but if you want to take a look please go ahead. |
| /** Ensure that an expression's type can be expressed without references to locally defined | ||
| * symbols. This is done by adding a type ascription of a widened type that does | ||
| * not refer to the locally defined symbols. The widened type is computed using | ||
| * `TyperAssigner#avoid`. However, if the expected type is fully defined and not |
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typo: TyperAssigner -> TypeAssigner
Thanks! I'll see if I have time to have a look. |
The essential change is that we do not throw away more
precise info of the avoided type if the expected type
is fully defined.