Tests for already working KT-3993 and KT-5427. These test cases pass at least since M11

compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt3993.kt

@@ -0,0 +1,10 @@
+class User(val login : Boolean) {}
+
+fun currentAccess(user: User?): Int {
+    return when {
+        user == null -> 0
+        // We should get smartcast here
+        <!DEBUG_INFO_SMARTCAST!>user<!>.login -> 1 
+        else -> -1
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt3993.txt

@@ -0,0 +1,11 @@
+package
+
+internal fun currentAccess(/*0*/ user: User?): kotlin.Int
+
+internal final class User {
+    public constructor User(/*0*/ login: kotlin.Boolean)
+    internal final val login: kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt5427.kt

@@ -0,0 +1,5 @@
+fun foo(p: String?): Int {
+    // We should get smart cast here
+    val x = if (p != null) { <!DEBUG_INFO_SMARTCAST!>p<!> } else "a"
+    return x.length()
+}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt5427.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun foo(/*0*/ p: kotlin.String?): kotlin.Int

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -11187,12 +11187,24 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/smartCasts/varnotnull"), Pattern.compile("^(.+)\\.kt$"), true);
                 }
 
+                @TestMetadata("kt3993.kt")
+                public void testKt3993() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt3993.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("kt4409.kt")
                 public void testKt4409() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt4409.kt");
                     doTest(fileName);
                 }
 
+                @TestMetadata("kt5427.kt")
+                public void testKt5427() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt5427.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("kt5907.kt")
                 public void testKt5907() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/kt5907.kt");