FIR: Add problem tests for smart cast within init-section

compiler/fir/resolve/testData/resolve/problems/smartCastInInit.kt

@@ -0,0 +1,14 @@
+interface I
+interface S : I {
+    fun foo()
+}
+
+fun s(): S = TODO()
+
+class Main {
+    private val x: I
+    init {
+        x = s()
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}

compiler/fir/resolve/testData/resolve/problems/smartCastInInit.txt

@@ -0,0 +1,24 @@
+FILE: smartCastInInit.kt
+    public abstract interface I : R|kotlin/Any| {
+    }
+    public abstract interface S : R|I| {
+        public abstract fun foo(): R|kotlin/Unit|
+
+    }
+    public final fun s(): R|S| {
+        ^s R|kotlin/TODO|()
+    }
+    public final class Main : R|kotlin/Any| {
+        public constructor(): R|Main| {
+            super<R|kotlin/Any|>()
+        }
+
+        private final val x: R|I|
+            private get(): R|I|
+
+        init {
+            this@R|/Main|.R|/Main.x| = R|/s|()
+            this@R|/Main|.R|/Main.x|.<Unresolved name: foo>#()
+        }
+
+    }

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsTestGenerated.java

@@ -1166,6 +1166,11 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
             runTest("compiler/fir/resolve/testData/resolve/problems/samConversionInConstructorCall.kt");
         }
 
+        @TestMetadata("smartCastInInit.kt")
+        public void testSmartCastInInit() throws Exception {
+            runTest("compiler/fir/resolve/testData/resolve/problems/smartCastInInit.kt");
+        }
+
         @TestMetadata("syntheticsVsNormalProperties.kt")
         public void testSyntheticsVsNormalProperties() throws Exception {
             runTest("compiler/fir/resolve/testData/resolve/problems/syntheticsVsNormalProperties.kt");

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsWithLightTreeTestGenerated.java

@@ -1166,6 +1166,11 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
             runTest("compiler/fir/resolve/testData/resolve/problems/samConversionInConstructorCall.kt");
         }
 
+        @TestMetadata("smartCastInInit.kt")
+        public void testSmartCastInInit() throws Exception {
+            runTest("compiler/fir/resolve/testData/resolve/problems/smartCastInInit.kt");
+        }
+
         @TestMetadata("syntheticsVsNormalProperties.kt")
         public void testSyntheticsVsNormalProperties() throws Exception {
             runTest("compiler/fir/resolve/testData/resolve/problems/syntheticsVsNormalProperties.kt");