Postfix expression code generation fixed as per KT-7561.

A set of tests for KT-7561 on codegen side, including exotic inc() functions().
 #KT-7561 Fixed.

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

@@ -3239,7 +3239,9 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
         final boolean isPrimitiveNumberClassDescriptor = isPrimitiveNumberClassDescriptor(cls);
         if (isPrimitiveNumberClassDescriptor && AsmUtil.isPrimitive(asmBaseType)) {
             JetExpression operand = expression.getBaseExpression();
-            if (operand instanceof JetReferenceExpression && asmResultType == Type.INT_TYPE) {
+            // Optimization for j = i++, when j and i are Int without any smart cast: we just work with primitive int
+            if (operand instanceof JetReferenceExpression && asmResultType == Type.INT_TYPE &&
+                bindingContext.get(BindingContext.SMARTCAST, operand) == null) {
                 int index = indexOfLocal((JetReferenceExpression) operand);
                 if (index >= 0) {
                     return StackValue.postIncrement(index, increment);
@@ -3247,7 +3249,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
             }
         }
 
-        return StackValue.operation(asmResultType, new Function1<InstructionAdapter, Unit>() {
+        return StackValue.operation(asmBaseType, new Function1<InstructionAdapter, Unit>() {
             @Override
             public Unit invoke(InstructionAdapter v) {
                 StackValue value = gen(expression.getBaseExpression());

compiler/testData/codegen/box/increment/assignPlusOnSmartCast.kt

@@ -0,0 +1,8 @@
+public fun box() : String {
+    var i : Int?
+    i = 10
+    // assignPlus on a smart cast should work
+    i += 1
+
+    return if (11 == i) "OK" else "fail i = $i"
+}

compiler/testData/codegen/box/increment/postfixIncrementDoubleSmartCast.kt

@@ -0,0 +1,10 @@
+public fun box() : String {
+    var i : Int?
+    i = 10
+    // We have "double" smart cast here:
+    // first on i and second on i++
+    // Back-end should NOT think that both i and j are Int
+    val j: Int = i++
+
+    return if (j == 10 && 11 == i) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/postfixIncrementOnClass.kt

@@ -0,0 +1,12 @@
+trait Base
+class Derived: Base
+class Another: Base
+fun Base.inc(): Derived { return Derived() }
+
+public fun box() : String {
+    var i : Base
+    i = Another()
+    val j = i++
+
+    return if (j is Another && i is Derived) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/postfixIncrementOnClassSmartCast.kt

@@ -0,0 +1,11 @@
+open class Base
+class Derived: Base()
+fun Derived.inc(): Derived { return Derived() }
+
+public fun box() : String {
+    var i : Base
+    i = Derived()
+    val j = i++
+
+    return if (j is Derived && i is Derived) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/postfixIncrementOnShortSmartCast.kt

@@ -0,0 +1,8 @@
+public fun box() : String {
+    var i : Short?
+    i = 10
+    // Postfix increment on a smart casted short should work
+    val j = i++
+
+    return if (j!!.toInt() == 10 && i!!.toInt() == 11) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/postfixIncrementOnSmartCast.kt

@@ -0,0 +1,9 @@
+public fun box() : String {
+    var i : Int?
+    i = 10
+    // Postfix increment on a smart cast should work
+    // Specific: i.inc() type is Int but i and j types are both Int?
+    val j = i++
+
+    return if (j == 10 && 11 == i) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/postfixNotnullClassIncrement.kt

@@ -0,0 +1,12 @@
+class MyClass
+
+// In principle it is not correct, MyClass? is not a subtype of MyClass
+fun MyClass.inc(): MyClass? = null
+
+public fun box() : String {
+    var i : MyClass? 
+    i = MyClass()
+    val j = i++
+
+    return if (j is MyClass && null == i) "OK" else "fail i = $i j = $j"
+}

compiler/testData/codegen/box/increment/postfixNullableClassIncrement.kt

@@ -0,0 +1,11 @@
+class MyClass
+
+fun MyClass?.inc(): MyClass? = null
+
+public fun box() : String {
+    var i : MyClass? 
+    i = MyClass()
+    val j = i++
+
+    return if (j is MyClass && null == i) "OK" else "fail i = $i j = $j"
+}

compiler/testData/codegen/box/increment/postfixNullableIncrement.kt

@@ -0,0 +1,10 @@
+fun Int?.inc(): Int? = this
+
+fun init(): Int? { return 10 }
+
+public fun box() : String {
+    var i : Int? = init()
+    val j = i++
+
+    return if (j == 10 && 10 == i) "OK" else "fail i = $i j = $j"
+}

compiler/testData/codegen/box/increment/prefixIncrementOnClass.kt

@@ -0,0 +1,12 @@
+trait Base
+class Derived: Base
+class Another: Base
+fun Base.inc(): Derived { return Derived() }
+
+public fun box() : String {
+    var i : Base
+    i = Another()
+    val j = ++i
+
+    return if (j is Derived && i is Derived) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/prefixIncrementOnClassSmartCast.kt

@@ -0,0 +1,11 @@
+open class Base
+class Derived: Base()
+fun Derived.inc(): Derived { return Derived() }
+
+public fun box() : String {
+    var i : Base
+    i = Derived()
+    val j = ++i
+
+    return if (j is Derived && i is Derived) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/prefixIncrementOnSmartCast.kt

@@ -0,0 +1,8 @@
+public fun box() : String {
+    var i : Int?
+    i = 10
+    // Prefix increment on a smart cast should work
+    val j = ++i
+
+    return if (j == 11 && 11 == i) "OK" else "fail j = $j i = $i"
+}

compiler/testData/codegen/box/increment/prefixNotnullClassIncrement.kt

@@ -0,0 +1,12 @@
+class MyClass
+
+// In principle it is not correct, MyClass? is not a subtype of MyClass
+fun MyClass.inc(): MyClass? = null
+
+public fun box() : String {
+    var i : MyClass? 
+    i = MyClass()
+    val j = ++i
+
+    return if (j == null && null == i) "OK" else "fail i = $i j = $j"
+}

compiler/testData/codegen/box/increment/prefixNullableClassIncrement.kt

@@ -0,0 +1,11 @@
+class MyClass
+
+fun MyClass?.inc(): MyClass? = null
+
+public fun box() : String {
+    var i : MyClass? 
+    i = MyClass()
+    val j = ++i
+
+    return if (j == null && null == i) "OK" else "fail i = $i j = $j"
+}

compiler/testData/codegen/box/increment/prefixNullableIncrement.kt

@@ -0,0 +1,10 @@
+fun Int?.inc(): Int? = this
+
+fun init(): Int? { return 10 }
+
+public fun box() : String {
+    var i : Int? = init()
+    val j = ++i
+
+    return if (j == 10 && 10 == i) "OK" else "fail i = $i j = $j"
+}

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

@@ -4049,6 +4049,105 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
         }
     }
 
+    @TestMetadata("compiler/testData/codegen/box/increment")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Increment extends AbstractBlackBoxCodegenTest {
+        public void testAllFilesPresentInIncrement() throws Exception {
+            JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/increment"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+
+        @TestMetadata("assignPlusOnSmartCast.kt")
+        public void testAssignPlusOnSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/assignPlusOnSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixIncrementDoubleSmartCast.kt")
+        public void testPostfixIncrementDoubleSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixIncrementDoubleSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixIncrementOnClass.kt")
+        public void testPostfixIncrementOnClass() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixIncrementOnClass.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixIncrementOnClassSmartCast.kt")
+        public void testPostfixIncrementOnClassSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixIncrementOnClassSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixIncrementOnShortSmartCast.kt")
+        public void testPostfixIncrementOnShortSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixIncrementOnShortSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixIncrementOnSmartCast.kt")
+        public void testPostfixIncrementOnSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixIncrementOnSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixNotnullClassIncrement.kt")
+        public void testPostfixNotnullClassIncrement() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixNotnullClassIncrement.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixNullableClassIncrement.kt")
+        public void testPostfixNullableClassIncrement() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixNullableClassIncrement.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("postfixNullableIncrement.kt")
+        public void testPostfixNullableIncrement() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/postfixNullableIncrement.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("prefixIncrementOnClass.kt")
+        public void testPrefixIncrementOnClass() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/prefixIncrementOnClass.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("prefixIncrementOnClassSmartCast.kt")
+        public void testPrefixIncrementOnClassSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/prefixIncrementOnClassSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("prefixIncrementOnSmartCast.kt")
+        public void testPrefixIncrementOnSmartCast() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/prefixIncrementOnSmartCast.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("prefixNotnullClassIncrement.kt")
+        public void testPrefixNotnullClassIncrement() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/prefixNotnullClassIncrement.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("prefixNullableClassIncrement.kt")
+        public void testPrefixNullableClassIncrement() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/prefixNullableClassIncrement.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("prefixNullableIncrement.kt")
+        public void testPrefixNullableIncrement() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/box/increment/prefixNullableIncrement.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("compiler/testData/codegen/box/innerNested")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)