Fix #1747: Improve error message for Scala/Java type mismatch #1984
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Omit the `=>' if a PolyType has a MethodType as result type.
We used to "fill-in" with zeroes if variances were missing. I now think that;'s too error-prone. Better define all variances explicitly.
| val found1 = dropJavaMethod(found) | ||
| val expected1 = dropJavaMethod(expected) | ||
| if ((found1 eq found) != (expected eq expected1) && (found1 <:< expected1)) | ||
| "\n (Note that Scala's and Java's representation of this type differs)" |
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This might not be enough for the user to understand the issue. In the example we would get
overriding method toArray in trait Collection of type [T](x$0: Array[T])Array[T];
method toArray of type [T](a: Array[T])Array[T] has incompatible type
(Note that Scala's and Java's representation of this type differs)
Would it be possible to hint that to make the representation match one would need to write
def toArray[T](a: Array[T with Object]): Array[T with Object]?
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I thought about it, but it is really tricky and would require quite a bit of code. In short interoperating with Java using arrays requires a lot of context knowledge. Hard to condense that in an error message.
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That is all. Otherwise LGTM. |
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