[Test] Add regression tests for issues which are fixed in K2

Related issues:
KT-10879, KT-18055, KT-20617, KT-23873
KT-25668, KT-31191, KT-33108, KT-41013
KT-51827, KT-53886, KT-56624, KT-58447
KT-58458, KT-58751, KT-58814, KT-60597
KT-62806, KT-63258, KT-63444, KT-65101
KT-65408, KT-65844, KT-66186

^KT-65926 Fixed

compiler/testData/diagnostics/tests/smartCasts/smartcastBetweenClassAndTypeParameter.fir.kt

@@ -0,0 +1,16 @@
+// FULL_JDK
+// WITH_REFLECT
+// ISSUE: KT-58814
+
+open class A
+class B : A()
+class C : A()
+
+fun <T : A> createObj(implementedBy: Class<T>): T {
+    val obj = when (implementedBy) {
+        B::class.java -> B()
+        else -> throw Exception("unsupported class")
+    }
+    val castObj = implementedBy.cast(obj)
+    return castObj // should be OK
+}

compiler/testData/diagnostics/tests/smartCasts/smartcastBetweenClassAndTypeParameter.kt

@@ -0,0 +1,16 @@
+// FULL_JDK
+// WITH_REFLECT
+// ISSUE: KT-58814
+
+open class A
+class B : A()
+class C : A()
+
+fun <T : A> createObj(implementedBy: Class<T>): T {
+    val obj = when (implementedBy) {
+        B::class.java -> B()
+        else -> throw Exception("unsupported class")
+    }
+    val castObj = <!DEBUG_INFO_SMARTCAST!>implementedBy<!>.cast(obj)
+    return <!TYPE_MISMATCH!>castObj<!> // should be OK
+}

compiler/testData/diagnostics/tests/smartCasts/syntheticAccessorOnSmartcastedReceiver.fir.kt

@@ -0,0 +1,17 @@
+// ISSUE: KT-10879
+// FILE: A.java
+public interface A {
+    A getFoo();
+}
+
+// FILE: main.kt
+interface B : A
+interface C : A
+
+fun test(x: A) {
+    if (x !is C) return
+    if (x is B) {
+        x.foo.foo
+        x.getFoo().foo
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/syntheticAccessorOnSmartcastedReceiver.kt

@@ -0,0 +1,17 @@
+// ISSUE: KT-10879
+// FILE: A.java
+public interface A {
+    A getFoo();
+}
+
+// FILE: main.kt
+interface B : A
+interface C : A
+
+fun test(x: A) {
+    if (x !is C) return
+    if (x is B) {
+        x.<!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>.<!DEBUG_INFO_MISSING_UNRESOLVED!>foo<!>
+        x.getFoo().foo
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertyOfLocalClass.fir.kt

@@ -0,0 +1,13 @@
+// ISSUE: KT-18055
+
+fun main() {
+    data class Stat(val link: String? = null)
+
+    var stat = Stat()
+
+    if (stat.link != null) {
+        takeString(stat.link)
+    }
+}
+
+fun takeString(link: String) {}

compiler/testData/diagnostics/tests/smartCasts/variables/propertyOfLocalClass.kt

@@ -0,0 +1,13 @@
+// ISSUE: KT-18055
+
+fun main() {
+    data class Stat(val link: String? = null)
+
+    var stat = Stat()
+
+    if (stat.link != null) {
+        takeString(<!SMARTCAST_IMPOSSIBLE!>stat.link<!>)
+    }
+}
+
+fun takeString(link: String) {}