SI-1786 incorporate defined bounds in inference

Also fixes SI-5459.

Look, you don't have to redeclare the bounds, isn't it exciting?
For instance, there are eight places in JavaMirrors with this:

  jTypeVariable[_ <: GenericDeclaration]

After this code is in starr, those can look like this:

  jTypeVariable[_]

Since TypeVariable's definition looks like this:

  interface TypeVariable<D extends GenericDeclaration>

We already know that!

3 files changed, 69 insertions, 5 deletions

diff --git a/test/files/neg/t5687.check b/test/files/neg/t5687.check
index 5096077ee5..f8d02fdcc3 100644
--- a/test/files/neg/t5687.check
+++ b/test/files/neg/t5687.check
@@ -1,8 +1,5 @@
-t5687.scala:4: error: type arguments [T] do not conform to class Template's type parameter bounds [T <: AnyRef]
-  type Repr[T]<:Template[T]
-                ^
-t5687.scala:20: error: overriding type Repr in class Template with bounds[T] <: Template[T];
+t5687.scala:20: error: overriding type Repr in class Template with bounds[T <: AnyRef] <: Template[T];
  type Repr has incompatible type
   type Repr = CurveTemplate[T]
        ^
-two errors found
+one error found
diff --git a/test/files/pos/t1786.scala b/test/files/pos/t1786.scala
new file mode 100644
index 0000000000..22bd659609
--- /dev/null
+++ b/test/files/pos/t1786.scala
@@ -0,0 +1,19 @@
+class SomeClass(val intValue:Int)
+class MyClass[T <: SomeClass](val myValue:T)
+class Flooz[A >: Null <: SomeClass, T >: Null <: A](var value: T)
+
+class A {
+  def f1(i:MyClass[_])                       = i.myValue.intValue
+  def f2(i:MyClass[_ <: SomeClass])          = i.myValue.intValue
+  def f3[T](i: MyClass[T])                   = i.myValue.intValue
+  def f4[T <: SomeClass](i: MyClass[T])      = i.myValue.intValue
+  def f5[T >: Null](i: MyClass[T])           = i.myValue.intValue
+  def f6[T >: Null <: String](i: MyClass[T]) = i.myValue.intValue + i.myValue.charAt(0)
+
+  def g1[A, T](x: Flooz[A, T]) = { x.value = null ; x.value.intValue }
+  def g2(x: Flooz[_, _]) = { x.value = null ; x.value.intValue }
+
+  class MyClass2(x: MyClass[_]) { val p = x.myValue.intValue }
+  class MyClass3[T <: String](x: MyClass[T]) { val p = x.myValue.intValue + x.myValue.length }
+  class MyClass4[T >: Null](x: MyClass[T]) { val p = x.myValue.intValue }
+}
diff --git a/test/files/pos/t5459.scala b/test/files/pos/t5459.scala
new file mode 100644
index 0000000000..971e6f896d
--- /dev/null
+++ b/test/files/pos/t5459.scala
@@ -0,0 +1,48 @@
+trait A1
+trait A2
+trait A3
+trait L1 extends A1 with A2 with A3
+
+object Test {
+  trait T1[-A <: A1]
+  trait T2[-A >: L1]
+  trait T3[ A <: A1]
+  trait T4[ A >: L1]
+  trait T5[+A <: A1]
+  trait T6[+A >: L1]
+
+  def f1(x: T1[_]) = x
+  def f2(x: T2[_]) = x
+  def f3(x: T3[_]) = x
+  def f4(x: T4[_]) = x
+  def f5(x: T5[_]) = x
+  def f6(x: T6[_]) = x
+  // a.scala:22: error: type arguments [Any] do not conform to trait T5's type parameter bounds [+A <: A1]
+  //   def f5(x: T5[_]) = x
+  //       ^
+
+  def g1(x: T1[_ <: A1]) = x
+  def g2(x: T2[_ >: L1]) = x
+  def g3(x: T3[_ <: A1]) = x
+  def g4(x: T4[_ >: L1]) = x
+  def g5(x: T5[_ <: A1]) = x
+  def g6(x: T6[_ >: L1]) = x
+
+  def q1(x: T1[_ >: L1]) = x
+  def q2(x: T2[_ <: A1]) = x
+  def q3(x: T3[_ >: L1]) = x
+  def q4(x: T4[_ <: A1]) = x
+  def q5(x: T5[_ >: L1]) = x
+  def q6(x: T6[_ <: A1]) = x
+  // a.scala:41: error: type arguments [Any] do not conform to trait T5's type parameter bounds [+A <: A1]
+  //   def q5(x: T5[_ >: L1]) = x
+  //       ^
+  // two errors found
+
+  def h1(x: T1[_ >: L1 <: A1]) = x
+  def h2(x: T2[_ >: L1 <: A1]) = x
+  def h3(x: T3[_ >: L1 <: A1]) = x
+  def h4(x: T4[_ >: L1 <: A1]) = x
+  def h5(x: T5[_ >: L1 <: A1]) = x
+  def h6(x: T6[_ >: L1 <: A1]) = x
+}