Add test for #KT-28999

compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject.kt

@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE!
+// ISSUE: KT-28999
+
+fun case_1() {
+    val x = object<T> { } // type of x is <anonymous object><T>
+}
+
+fun case_2() {
+    val x = object<T : Number, K: Comparable<K>> { }
+}
+
+fun case_3() {
+    val x = object<T> <!SYNTAX!>where <!DEBUG_INFO_MISSING_UNRESOLVED!>T<!> : <!DEBUG_INFO_MISSING_UNRESOLVED!>Comparable<!><<!DEBUG_INFO_MISSING_UNRESOLVED!>T<!>><!> { } // ERROR: Where clause is not allowed for objects
+}
+
+val x = object<T, K: Comparable<K>> {
+    fun test() = 10 <!UNCHECKED_CAST!>as T<!> // OK
+}
+
+fun case_4() {
+    val x = object<T> {
+        fun test() = 10 <!UNCHECKED_CAST!>as T<!>
+    }
+
+    val y = x.test() // type y is T
+}
+
+inline fun <reified T> case_5() {
+    val x = object<T> {
+        fun test() = 10 <!UNCHECKED_CAST!>as T<!>
+    }
+
+    val z = x.test()
+
+    if (z is T) {
+        // z is {T!! & T!!} (smart cast from T)
+        <!UNRESOLVED_REFERENCE!>println<!>(z)
+    }
+}

compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject.txt

@@ -0,0 +1,8 @@
+package
+
+public val x: kotlin.Any
+public fun case_1(): kotlin.Unit
+public fun case_2(): kotlin.Unit
+public fun case_3(): kotlin.Unit
+public fun case_4(): kotlin.Unit
+public inline fun </*0*/ reified T> case_5(): kotlin.Unit