[FIR] Add test for smartcast with return in elvis

compiler/fir/resolve/testData/resolve/smartcasts/elvis.cfg.dot

@@ -0,0 +1,96 @@
+digraph elvis_kt {
+subgraph foo {
+  0 [shape=box label="Enter function foo"];
+  1 [shape=box label="Exit function foo"];
+
+  0 -> {1};
+}
+
+subgraph val_b {
+  2 [shape=box label="Enter property"];
+  3 [shape=box label="Exit property"];
+
+  2 -> {3};
+}
+
+subgraph test_1 {
+  4 [shape=box label="Enter function test_1"];
+  5 [shape=box label="Enter block"];
+  6 [shape=box label="Enter when"];
+  7 [shape=box label="Enter when branch condition "];
+  8 [shape=box label="Enter when"];
+  9 [shape=box label="Access variable R|<local>/x|"];
+  10 [shape=box label="Access variable R|/A.b|"];
+  11 [shape=box label="Variable declaration: lval <elvis>: R|kotlin/Boolean?|"];
+  12 [shape=box label="Enter when branch condition "];
+  13 [shape=box label="Const: Null(null)"];
+  14 [shape=box label="Operator =="];
+  15 [shape=box label="Exit when branch condition"];
+  16 [shape=box label="Enter block"];
+  17 [shape=box label="Jump: ^test_1 Unit"];
+  18 [shape=box label="Stub[DEAD]"];
+  19 [shape=box label="Exit block[DEAD]"];
+  20 [shape=box label="Exit when branch result[DEAD]"];
+  21 [shape=box label="Enter when branch condition else"];
+  22 [shape=box label="Exit when branch condition"];
+  23 [shape=box label="Enter block"];
+  24 [shape=box label="Access variable R|<local>/<elvis>|"];
+  25 [shape=box label="Exit block"];
+  26 [shape=box label="Exit when branch result"];
+  27 [shape=box label="Exit when"];
+  28 [shape=box label="Exit when branch condition"];
+  29 [shape=box label="Enter block"];
+  30 [shape=box label="Access variable R|<local>/x|"];
+  31 [shape=box label="Function call: R|<local>/x|.R|/A.foo|()"];
+  32 [shape=box label="Exit block"];
+  33 [shape=box label="Exit when branch result"];
+  34 [shape=box label="Enter when branch condition else"];
+  35 [shape=box label="Exit when branch condition"];
+  36 [shape=box label="Enter block"];
+  37 [shape=box label="Exit block"];
+  38 [shape=box label="Exit when branch result"];
+  39 [shape=box label="Exit when"];
+  40 [shape=box label="Exit block"];
+  41 [shape=box label="Exit function test_1"];
+
+  4 -> {5};
+  5 -> {6};
+  6 -> {7};
+  7 -> {8};
+  8 -> {9};
+  9 -> {10};
+  10 -> {11};
+  11 -> {12};
+  12 -> {13};
+  13 -> {14};
+  14 -> {15};
+  15 -> {16 21};
+  16 -> {17};
+  17 -> {41};
+  17 -> {18} [style=dotted];
+  18 -> {19} [style=dotted];
+  19 -> {20} [style=dotted];
+  20 -> {27} [style=dotted];
+  21 -> {22};
+  22 -> {23};
+  23 -> {24};
+  24 -> {25};
+  25 -> {26};
+  26 -> {27};
+  27 -> {28};
+  28 -> {29 34};
+  29 -> {30};
+  30 -> {31};
+  31 -> {32};
+  32 -> {33};
+  33 -> {39};
+  34 -> {35};
+  35 -> {36};
+  36 -> {37};
+  37 -> {38};
+  38 -> {39};
+  39 -> {40};
+  40 -> {41};
+}
+
+}

compiler/fir/resolve/testData/resolve/smartcasts/elvis.kt

@@ -0,0 +1,10 @@
+interface A {
+    fun foo()
+    val b: Boolean
+}
+
+fun test_1(x: A?) {
+    if (x?.b ?: return) {
+        x.foo()
+    }
+}

compiler/fir/resolve/testData/resolve/smartcasts/elvis.txt

@@ -0,0 +1,26 @@
+FILE: elvis.kt
+    public abstract interface A : R|kotlin/Any| {
+        public abstract fun foo(): R|kotlin/Unit|
+
+        public abstract val b: R|kotlin/Boolean|
+            public get(): R|kotlin/Boolean|
+
+    }
+    public final fun test_1(x: R|A?|): R|kotlin/Unit| {
+        when () {
+            when (lval <elvis>: R|kotlin/Boolean?| = R|<local>/x|?.R|/A.b|) {
+                ==($subj$, Null(null)) ->  {
+                    ^test_1 Unit
+                }
+                else ->  {
+                    R|<local>/<elvis>|!
+                }
+            }
+             ->  {
+                R|<local>/x|.R|/A.foo|()
+            }
+            else ->  {
+            }
+        }
+
+    }

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

@@ -109,6 +109,11 @@ public class FirCfgBuildingTestGenerated extends AbstractFirCfgBuildingTest {
             runTest("compiler/fir/resolve/testData/resolve/smartcasts/casts.kt");
         }
 
+        @TestMetadata("elvis.kt")
+        public void testElvis() throws Exception {
+            runTest("compiler/fir/resolve/testData/resolve/smartcasts/elvis.kt");
+        }
+
         @TestMetadata("equalsAndIdentity.kt")
         public void testEqualsAndIdentity() throws Exception {
             runTest("compiler/fir/resolve/testData/resolve/smartcasts/equalsAndIdentity.kt");