Fix #6849: support irrefutable sequence match #6850
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liufengyun
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Jul 15, 2019
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liufengyun
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- Fix Document irrefutable unapply in pattern matching #6490: Add spec for irrefutable extractors
- Fix Compiler crash on irrefutable unapplySeq #6849: support irrefutable sequence match
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@liufengyun Can we revive this before the release? It seems this is important functionality. |
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| def unapplySeq(x: Any): ThreeStringExtract = new ThreeStringExtract("" + x) | ||
| def unapplySeq(x: Any): Option[(List[Int], Double, Seq[Char])] = | ||
| if ((x == null) || (x == "")) then None | ||
| else Some(new ThreeStringExtract("" + x).get) |
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Should add extra tests rather than modify the old ones
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We added extra tests in other files. This test has to be adapted, as it does not conform to the protocol: the result type conforms to sequence match, thus it is irrefutable.
tests/patmat/i6490.check
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| @@ -0,0 +1 @@ | |||
| 8: Pattern Match Exhaustivity: Foo(Nil) | |||
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Shouldn’t it be Pattern Match Exhaustivity: Foo()?
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Now it prints Foo().
The mismatch is caused by an additional ConstFold during unpickling.
Now if the result type of an unapplySeq conforms to a sequence match, it will be taken as an irrefutable sequence match --- `isEmpty` and `get` defined on the type are ignored. Thus, we need to rewrite the test.
It's accidentally removed in conflict resolution.
| def unapplySeq(x: Any): ThreeStringExtract = new ThreeStringExtract("" + x) | ||
| def unapplySeq(x: Any): Option[(List[Int], Double, Seq[Char])] = | ||
| if ((x == null) || (x == "")) then None | ||
| else Some(new ThreeStringExtract("" + x).get) |
There was a problem hiding this comment.
We added extra tests in other files. This test has to be adapted, as it does not conform to the protocol: the result type conforms to sequence match, thus it is irrefutable.
