Fix #8012: Disallow conversion to underspecified SAM type #8013
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We cannot write
class C extends B[?]
By the same token, we cannot do a SAM type conversion to B[?]
since this would create code like the one above.
Traits are OK, since traits with wildcard arguments can be produced in source.
odersky
added
the
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@odersky if you have a reference (Scala spec, perhaps?) for why we don't allow wildcards in extends clauses, I'd be interested in reading it. I seem to remember that I ran across some Java compatibility problems where a class in Java was extending a class with a wildcard as a parameter and as a result, was not extensible in Scala. |
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We cannot write
By the same token, we cannot do a SAM type conversion to B[?]
since this would create code like the one above.