generate more correct bytecode for casting Unit to other types

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -3918,7 +3918,10 @@ The "returned" value of try expression with no finally is either the last expres
                     public Unit invoke(InstructionAdapter v) {
                         value.put(boxType(value.type), v);
 
-                        if (opToken != JetTokens.AS_SAFE) {
+                        if (value.type == Type.VOID_TYPE) {
+                            v.aconst(null);
+                        }
+                        else if (opToken != JetTokens.AS_SAFE) {
                             if (!TypeUtils.isNullableType(rightType)) {
                                 v.dup();
                                 Label nonnull = new Label();
@@ -3931,9 +3934,6 @@ The "returned" value of try expression with no finally is either the last expres
                                 v.mark(nonnull);
                             }
                         }
-                        else if (value.type == Type.VOID_TYPE) {
-                            v.aconst(null);
-                        }
                         else {
                             v.dup();
                             generateInstanceOfInstruction(rightType);

compiler/testData/codegen/box/casts/asAny.kt

@@ -0,0 +1,7 @@
+fun println(s: String) {
+}
+
+fun box(): String {
+    println(":Hi!") as Any
+    return "OK"
+}

compiler/testData/codegen/box/casts/asUnit.kt

@@ -0,0 +1 @@
+fun box() = if (4 as? Unit != null) "Fail" else "OK"

compiler/testData/codegen/box/casts/lambdaToUnitCast.kt

@@ -0,0 +1,6 @@
+val foo: () -> Unit = {}
+
+fun box(): String {
+    foo() as Unit
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/generated/BlackBoxCodegenTestGenerated.java

@@ -890,6 +890,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("asAny.kt")
+        public void testAsAny() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/asAny.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("asForConstants.kt")
         public void testAsForConstants() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/asForConstants.kt");
@@ -914,6 +920,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("asUnit.kt")
+        public void testAsUnit() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/asUnit.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("castGenericNull.kt")
         public void testCastGenericNull() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/castGenericNull.kt");
@@ -926,6 +938,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("lambdaToUnitCast.kt")
+        public void testLambdaToUnitCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/lambdaToUnitCast.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("notIs.kt")
         public void testNotIs() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/casts/notIs.kt");