Do not miss implicits in type parameters of parents

This did not work before because we incorrectly looked for their value
in the prefix of the type instead of the type itself.

Author: smarter

src/dotty/tools/dotc/typer/Implicits.scala

@@ -323,7 +323,7 @@ trait ImplicitRunInfo { self: RunInfo =>
               def addParentScope(parent: TypeRef): Unit = {
                 iscopeRefs(parent) foreach addRef
                 for (param <- parent.typeParams)
-                  comps ++= iscopeRefs(pre.member(param.name).info)
+                  comps ++= iscopeRefs(tp.member(param.name).info)
               }
               val companion = cls.companionModule
               if (companion.exists) addRef(companion.valRef)

tests/pos/implicit_tparam.scala

@@ -0,0 +1,12 @@
+class Foo[T]
+class Bar extends Foo[A]
+
+class A
+object A {
+  implicit val bar: Bar = new Bar
+}
+
+object Test {
+  def getBar(implicit bar: Bar) = bar
+  getBar
+}