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author | Jason Zaugg <jzaugg@gmail.com> | 2015-03-17 18:14:08 -0700 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2015-03-17 18:44:37 -0700 |
commit | d0181ab3810f1e063b33e79b43f183a098de2aab (patch) | |
tree | ef6db3de02c81de1aef428debec5b34b96e35348 /test/files/run | |
parent | fa33395a25c87115c910e8d4a4124aee6134062b (diff) | |
download | scala-d0181ab3810f1e063b33e79b43f183a098de2aab.tar.gz scala-d0181ab3810f1e063b33e79b43f183a098de2aab.tar.bz2 scala-d0181ab3810f1e063b33e79b43f183a098de2aab.zip |
Resurrect a test for type inference
This test was removed in ... when case class extension was disallowed.
But the intent of the test was actually to exercise a path through
type inference, described in `Infer#exprTypeArgs`.
When I remove that special case, the test still fails:
```
test/files/pos/jesper.scala:29: error: No implicit view available from Pair.Cons[Int,Pair.Cons[Boolean,Pair.End]] => Boolean.
val x2 : Boolean = p.find[Boolean] // Doesn't compile
^
one error found
```
This special case is important to understand when deciphering
the inference in this program:
```
object Test {
trait Cov[+A]
def cov[A](implicit ev: Cov[A]): A = ???
implicit def covImp[A]: Cov[A] = ???
trait Inv[A]
def inv[A](implicit ev: Inv[A]): A = ???
implicit def invImp[A]: Inv[A] = ???
trait Con[-A]
def con[A](implicit ev: Con[A]): A = ???
implicit def conImp[A]: Con[A] = ???
cov : String // (Test.this.cov[String](Test.this.covImp[Nothing]): String);
// (Test.this.cov[Nothing](Test.this.covImp[Nothing]): String) (or, without the special case in exprTypeArgs)
inv : String // (Test.this.inv[Nothing](Test.this.invImp[Nothing]): String);
con : String // (Test.this.con[Any](Test.this.conImp[Any]): String)
}
```
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