Merge pull request #2354 from adriaanm/ticket-7289

SI-7289 Less strict type application for TypeVar.

4 files changed, 88 insertions, 0 deletions

diff --git a/test/files/neg/t7289.check b/test/files/neg/t7289.check
new file mode 100644
index 0000000000..e4aeebbc6c
--- /dev/null
+++ b/test/files/neg/t7289.check
@@ -0,0 +1,4 @@
+t7289.scala:8: error: could not find implicit value for parameter e: Test.Schtroumpf[scala.collection.immutable.Nil.type]
+  implicitly[Schtroumpf[Nil.type]]
+            ^
+one error found
diff --git a/test/files/neg/t7289.scala b/test/files/neg/t7289.scala
new file mode 100644
index 0000000000..f4ed3daf76
--- /dev/null
+++ b/test/files/neg/t7289.scala
@@ -0,0 +1,39 @@
+object Test extends App {
+  trait Schtroumpf[T]
+
+  implicit def schtroumpf[T, U <: Coll[T], Coll[X] <: Traversable[X]]
+    (implicit minorSchtroumpf: Schtroumpf[T]): Schtroumpf[U] = ???
+
+  implicit val qoo: Schtroumpf[Int] = new Schtroumpf[Int]{}
+  implicitly[Schtroumpf[Nil.type]]
+}
+
+/*
+info1 = {scala.tools.nsc.typechecker.Implicits$ImplicitInfo@3468}"qoo: => Test.Schtroumpf[Int]"
+info2 = {scala.tools.nsc.typechecker.Implicits$ImplicitInfo@3469}"schtroumpf: [T, U <: Coll[T], Coll[_] <: Traversable[_]](implicit minorSchtroumpf: Test.Schtroumpf[T])Test.Schtroumpf[U]"
+isStrictlyMoreSpecific(info1, info2)
+  isSubType(Test.Schtroumpf[Int], Test.Schtroumpf[U] forSome { T; U <: Coll[T]; Coll[_] <: Traversable[_] })
+    isAsSpecificValueType(Test.Schtroumpf[Int], Test.Schtroumpf[U], undef2 = List(type T, type U, type Coll))
+
+      val et: ExistentialType = Test.Schtroumpf[U] forSome { T; U <: Coll[T]; Coll[_] <: Traversable[_] }
+      val tp1 = Test.Schtroumpf[Int]
+      et.withTypeVars(isSubType(tp1, _, depth))
+        solve()
+        tvars = tList(=?Nothing, =?Int, =?=?Int)
+
+
+[    create] ?T                       ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[    create] ?U                       ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[    create] ?Coll                    ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[   setInst] Nothing                  ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], T=Nothing )
+[   setInst] scala.collection.immutable.Nil.type( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], U=scala.collection.immutable.Nil.type )
+[   setInst] =?scala.collection.immutable.Nil.type( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], Coll==?scala.collection.immutable.Nil.type )
+[    create] ?T                       ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[   setInst] Int                      ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], T=Int )
+[    create] ?T                       ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[    create] ?U                       ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[    create] ?Coll                    ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]] )
+[   setInst] Nothing                  ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], T=Nothing )
+[   setInst] Int                      ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], U=Int )
+[   setInst] =?Int                    ( In Test#schtroumpf[T,U <: Coll[T],Coll[_] <: Traversable[_]], Coll==?Int )
+*/
\ No newline at end of file
diff --git a/test/files/neg/t7289_status_quo.check b/test/files/neg/t7289_status_quo.check
new file mode 100644
index 0000000000..31c072e969
--- /dev/null
+++ b/test/files/neg/t7289_status_quo.check
@@ -0,0 +1,22 @@
+t7289_status_quo.scala:9: error: could not find implicit value for parameter e: Test1.Ext[List[Int]]
+  implicitly[Ext[List[Int]]]                    // fails - not found
+            ^
+t7289_status_quo.scala:11: error: could not find implicit value for parameter e: Test1.Ext[List[List[List[Int]]]]
+  implicitly[Ext[List[List[List[Int]]]]]        // fails - not found
+            ^
+t7289_status_quo.scala:15: error: ambiguous implicit values:
+ both method f in object Test1 of type [A, Coll <: CC[A], CC[X] <: Traversable[X]](implicit xi: Test1.Ext[A])Test1.Ext[Coll]
+ and value m in object Test1 of type => Test1.Ext[List[List[Int]]]
+ match expected type Test1.Ext[_ <: List[List[Int]]]
+  implicitly[Ext[_ <: List[List[Int]]]]         // fails - ambiguous
+            ^
+t7289_status_quo.scala:20: error: could not find implicit value for parameter e: Test1.ExtCov[List[Int]]
+  implicitly[ExtCov[List[Int]]]                 // fails - not found
+            ^
+t7289_status_quo.scala:21: error: could not find implicit value for parameter e: Test1.ExtCov[List[List[Int]]]
+  implicitly[ExtCov[List[List[Int]]]]           // fails - not found
+            ^
+t7289_status_quo.scala:22: error: could not find implicit value for parameter e: Test1.ExtCov[List[List[List[Int]]]]
+  implicitly[ExtCov[List[List[List[Int]]]]]     // fails - not found
+            ^
+6 errors found
diff --git a/test/files/neg/t7289_status_quo.scala b/test/files/neg/t7289_status_quo.scala
new file mode 100644
index 0000000000..39621429a1
--- /dev/null
+++ b/test/files/neg/t7289_status_quo.scala
@@ -0,0 +1,23 @@
+// record the status quo after this fix
+// not clear to @adriaanm why an upper-bounded existential in an invariant position
+// is different from putting that upper bound in a covariant position
+object Test1 {
+  trait Ext[T]
+  implicit def f[A, Coll <: CC[A], CC[X] <: Traversable[X]](implicit xi: Ext[A]): Ext[Coll] = ???
+  implicit val m: Ext[List[List[Int]]] = new Ext[List[List[Int]]]{}
+
+  implicitly[Ext[List[Int]]]                    // fails - not found
+  implicitly[Ext[List[List[Int]]]]              // compiles
+  implicitly[Ext[List[List[List[Int]]]]]        // fails - not found
+
+  // Making Ext[+T] should incur the same behavior as these. (so says @paulp)
+  implicitly[Ext[_ <: List[Int]]]               // compiles
+  implicitly[Ext[_ <: List[List[Int]]]]         // fails - ambiguous
+  implicitly[Ext[_ <: List[List[List[Int]]]]]   // compiles
+
+  // But, we currently get:
+  trait ExtCov[+T]
+  implicitly[ExtCov[List[Int]]]                 // fails - not found
+  implicitly[ExtCov[List[List[Int]]]]           // fails - not found
+  implicitly[ExtCov[List[List[List[Int]]]]]     // fails - not found
+}
\ No newline at end of file