Fix #2675: Properly handle undetermined type variables in unapply #3889
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In non-variant contexts, we used to always maximize them, but this is unsound. See neg/patternUnsoundness.scala. We now create fresh abstract types in these situations.
Make bind-defined symbols forward-referencable. This is necessary to support more interesting patterns of Binds. E.g. in case (bla: List[t]) the bound symbol `bla` refers to the bound type `t` in its info. Previously we used BindDefinedType for that, but that cannot work in general, because it does not distinguish between a reference and a binding.
Have to modify the way templates are scanned, so far, all non-member definitions inside a template were forgotten. Strangely enough this caused a completely unrelated fromTastyTest to fail.
A clause was accidentally disabled fir debugging purposes.
smarter
reviewed
Jan 23, 2018
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| x match { | ||
| case x: C[u] => | ||
| def x: u = x |
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Is the self-recursive call intended here?
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I assume so, it was an old test in pos. The new test in pickling adds more variations that exercise forward binds in pickling.
With the changes in the last commit, the symbol of a Bind always exists.
This was referenced Jan 24, 2018
smarter
approved these changes
Feb 1, 2018
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In non-variant contexts, we used to always maximize undetermined type variables, but this is unsound. See neg/patternUnsoundness.scala. We now create fresh abstract types in
these situations. This forced us to also fix the pickling and unpickling of Bind nodes.