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add more gadt exhaustivity check tests #3999

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Merged
merged 5 commits into from
Feb 20, 2018
Merged

add more gadt exhaustivity check tests #3999

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e1a068a
add gadt exhaustivity check test
liufengyun Feb 14, 2018
dcc3822
add more tests
liufengyun Feb 15, 2018
a1a9cc5
Delete dead comment
Blaisorblade Feb 15, 2018
ab0a7c3
Add call site causing MatchError that Fengyun hinted at
Blaisorblade Feb 15, 2018
50d91c1
small refactoring of code
liufengyun Feb 19, 2018
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16 changes: 16 additions & 0 deletions tests/patmat/gadt2.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
sealed trait Nat[+T]
case class Zero() extends Nat[Nothing]
case class Succ[T]() extends Nat[T]
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This is not intended to be a correct representation of Peano numerals, right? Not only for the +T but also because T in Succ is completely unconstrained...


// +N is incorrect, as in `foo` we can have `N = Zero | Succ[Zero]`,
// then it's correct for exhaustivity check to produce two warnings.
sealed trait Vect[N <: Nat[_], +T]
case class VN[T]() extends Vect[Zero, T]
case class VC[T, N <: Nat[_]](x: T, xs: Vect[N, T]) extends Vect[Succ[N], T]

object Test {
def foo[N <: Nat[_], A, B](v1: Vect[N, A], v2: Vect[N, B]) = (v1, v2) match {
case (VN(), VN()) => 1
case (VC(x, xs), VC(y, ys)) => 2
}
}
1 change: 1 addition & 0 deletions tests/patmat/gadt4.check
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12: Pattern Match Exhaustivity: (VC(_, _), VN()), (VN(), VC(_, _))
2 changes: 2 additions & 0 deletions tests/patmat/gadt2.scala.ignore → tests/patmat/gadt4.scala
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Expand Up @@ -2,6 +2,8 @@ sealed trait Nat[+T]
case class Zero() extends Nat[Nothing]
case class Succ[T]() extends Nat[T]

// +N is incorrect, as in `foo` we can have `N = Zero | Succ[Zero]`,
// then it's correct for exhaustivity check to produce two warnings.
sealed trait Vect[+N <: Nat[_], +T]
case class VN[T]() extends Vect[Zero, T]
case class VC[T, N <: Nat[_]](x: T, xs: Vect[N, T]) extends Vect[Succ[N], T]
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