KT-549 type inference failed

KT-580 Type inference failed
KT-600 Problem with 'sure' extension function type inference
KT-571 Type inference failed

compiler/testData/checkerWithErrorTypes/full/kt600.jet

@@ -0,0 +1,8 @@
+//KT-600 Problem with 'sure' extension function type inference
+
+fun <T : Any> T?.sure() : T { if (this != null) return this else throw NullPointerException() }
+
+fun test() {
+    val i : Int? = 10
+    val <!UNUSED_VARIABLE!>i2<!> : Int = i.sure() // inferred type is Int? but Int was excepted
+}

compiler/testData/checkerWithErrorTypes/full/regression/kt549.jet

@@ -0,0 +1,16 @@
+//KT-549 type inference failed
+namespace demo
+
+  fun filter<T>(list : Array<T>, filter : fun (T) : Boolean) : java.util.List<T> {
+    val answer = java.util.ArrayList<T>();
+    for (l in list) {
+      if (filter(l)) answer.add(l)
+    }
+    return answer;
+  }
+
+fun main(args : Array<String>) {
+  for (a in filter(args, {it.length > 1})) {
+    System.out?.println("Hello, ${a}!")
+  }
+}

compiler/testData/checkerWithErrorTypes/full/regression/kt580.jet

@@ -0,0 +1,20 @@
+//KT-580 Type inference failed
+namespace whats.the.difference
+
+import java.util.*
+
+fun iarray(vararg a : String) = a // BUG
+
+fun main(vals : IntArray) {
+    val vals = iarray("789", "678", "567")
+    val diffs = ArrayList<Int>
+    for (i in vals.indices) {
+        for (j in i..vals.lastIndex())  // Type inference failed
+             diffs.add(vals[i].length - vals[j].length)
+        for (j in i..vals.lastIndex)  // Type inference failed
+             diffs.add(vals[i].length - vals[j].length)
+    }
+}
+
+fun <T> Array<T>.lastIndex() = size - 1
+val <T> Array<T>.lastIndex : Int get() = size - 1

compiler/testData/checkerWithErrorTypes/quick/regressions/kt571.jet

@@ -0,0 +1,3 @@
+//KT-571 Type inference failed
+fun <T, R> let(t : T, body : fun(T) : R) = body(t)
+private fun double(d : Int) : Int = let(d * 2) {it / 10 + it * 2 % 10}

compiler/testData/codegen/regressions/kt247.jet

@@ -19,7 +19,7 @@ fun t3() {
 
 fun t4() {
     val e: E? = E()
-    System.out?.println(e?.foo() == e) //verify error
+    System.out?.println(e?.bar() == e) //verify error
     System.out?.println(e?.foo())  //verify error
 }
 
@@ -35,4 +35,5 @@ class C(val x: Int)
 class D(val s: String)
 class E() {
     fun foo() = 1
+    fun bar() = this
 }