KT-313 Bug in substitutions in a function returning its type parameter T

compiler/testData/checkerWithErrorTypes/full/Variance.jet

@@ -18,8 +18,8 @@ fun foo(c: Consumer<Int>, p: Producer<Int>, u: Usual<Int>) {
 }
 
 //Arrays copy example
-class Array<T>(val length : Int) {
-    fun get(index : Int) : T { return null }
+class Array<T>(val length : Int, val t : T) {
+    fun get(index : Int) : T { return t }
     fun set(index : Int, value : T) { /* ... */ }
 }
 

compiler/testData/checkerWithErrorTypes/full/regression/kt313.jet

@@ -0,0 +1,11 @@
+// KT-313 Bug in substitutions in a function returning its type parameter T
+
+fun <T> Iterable<T>.join(separator : String?) : String {
+    return separator.npe()
+}
+
+fun <T : Any> T?.npe() : T {
+    if (this == null)
+      throw NullPointerException()
+    return this;
+}

compiler/testData/codegen/regressions/kt326.jet

@@ -1,7 +1,7 @@
 namespace test
 
 class List<T>(len: Int) {
-  val a : Array<T> = Array<T>(len)
+  val a : Array<T?> = Array<T?>(len)
 
   fun reverse() {
     var i = 0
@@ -29,7 +29,7 @@ fun box() : String {
 
   val c = List<Array<Int>>(1)
   c.a[0] = Array<Int>(4,{-1})
-  println(c.a[0].size)
+  println(c.a[0]?.size)
 
   val e = List<Int>(5)
   e.a[0] = 0

compiler/testData/codegen/traits/stdlib.jet

@@ -36,8 +36,8 @@ trait WriteOnlyArray<in T> : ISized {
   }
 }
 
-class MutableArray<T>(length: Int) : ReadOnlyArray<T>, WriteOnlyArray<T> {
-    private val array = Array<T>(length)
+class MutableArray<T>(length: Int, init : fun(Int) : T) : ReadOnlyArray<T>, WriteOnlyArray<T> {
+    private val array = Array<T>(length, init)
 
     override fun get(index : Int) : T = array[index]
     override fun set(index : Int, value : T) : Unit { array[index] = value }
@@ -47,7 +47,7 @@ class MutableArray<T>(length: Int) : ReadOnlyArray<T>, WriteOnlyArray<T> {
 }
 
 fun box() : String {
-    var a = MutableArray<Int> (4)
+    var a = MutableArray<Int> (4, {0})
     a [0] = 10
     a.set(1, 2, 13)
     a [3] = 40