Use WildcardType in place of a type variable in pretypeArgs
#3974
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allanrenucci
commented
Feb 7, 2018
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| def combine(f: (Char, Int) => Int): Int = ??? | ||
| def combine(f: (String, Int) => String): String = ??? | ||
| val r5 = combine((x: Char, y) => x + y) | ||
| val t5: Int = r5 | ||
| val r6 = combine((x: String, y) => x ++ y.toString) | ||
| val t6: String = r6 | ||
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| // Errors: The argument types of an anonymous function must be fully known |
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@odersky Is this intended? Should I open an issue for it?
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I think it's fine; we don't look inside tuples here. What does scalac say?
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Tested on Scala 2.13.0-M2:
[error] constructor cannot be instantiated to expected type;
[error] found : (T1, T2)
[error] required: Char
[error] bar { case (x, y) => () }
[error] ^
[warn] match may not be exhaustive.
[warn] It would fail on the following input: (_, _)
[warn] val rp5 = combine { case (x: Char, y) => x + y }
[warn] ^
[warn] match may not be exhaustive.
[warn] It would fail on the following input: (_, _)
[warn] val rp6 = combine { case (x: String, y) => x ++ y.toString }
[warn] ^
[warn] two warnings foundIn two out of tree of the cases scalac is able to find the correct overload. It emits a spurious exhaustivity warning though
odersky
approved these changes
Feb 7, 2018
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| def combine(f: (Char, Int) => Int): Int = ??? | ||
| def combine(f: (String, Int) => String): String = ??? | ||
| val r5 = combine((x: Char, y) => x + y) | ||
| val t5: Int = r5 | ||
| val r6 = combine((x: String, y) => x ++ y.toString) | ||
| val t6: String = r6 | ||
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| // Errors: The argument types of an anonymous function must be fully known |
There was a problem hiding this comment.
I think it's fine; we don't look inside tuples here. What does scalac say?
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As discussed during the meeting. Let's see if it passes the tests