Fix compound assignment on arbitrary expression in LHS

(with a convention compound assignment operator defined).

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/AssignmentGenerator.kt

@@ -127,7 +127,7 @@ class AssignmentGenerator(statementGenerator: StatementGenerator) : StatementGen
             is VariableDescriptor ->
                 VariableLValue(ktLeft.startOffset, ktLeft.endOffset, descriptor, operator)
             else ->
-                TODO("Other cases of LHS")
+                OnceExpressionValue(statementGenerator.generateExpression(ktLeft))
         }
     }
 

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/intermediate/OnceExpressionValue.kt

@@ -21,7 +21,7 @@ import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.psi2ir.generators.CallGenerator
 import org.jetbrains.kotlin.types.KotlinType
 
-class OnceExpressionValue(val irExpression: IrExpression) : IntermediateValue {
+class OnceExpressionValue(val irExpression: IrExpression) : LValue, AssignmentReceiver {
     private var instantiated = false
 
     override fun load(): IrExpression {
@@ -31,4 +31,11 @@ class OnceExpressionValue(val irExpression: IrExpression) : IntermediateValue {
     }
 
     override val type: KotlinType get() = irExpression.type
+
+    override fun store(irExpression: IrExpression): IrExpression {
+        throw AssertionError("Expression value ${irExpression.render()} can't be used in store operation")
+    }
+
+    override fun assign(withLValue: (LValue) -> IrExpression): IrExpression =
+            withLValue(this)
 }

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/intermediate/VariableLValue.kt

@@ -40,8 +40,7 @@ class VariableLValue(
             IrGetVariableImpl(startOffset, endOffset, descriptor, irOperator)
 
     override fun store(irExpression: IrExpression): IrExpression =
-            IrSetVariableImpl(startOffset, endOffset, descriptor,
-                                                                  irExpression, irOperator)
+            IrSetVariableImpl(startOffset, endOffset, descriptor, irExpression, irOperator)
 
     override fun assign(withLValue: (LValue) -> IrExpression): IrExpression =
             withLValue(this)

compiler/testData/ir/irText/expressions/augmentedAssignmentWithExpression.kt

@@ -0,0 +1,21 @@
+class Host {
+    operator fun plusAssign(x: Int) {}
+
+    fun test1() {
+        this += 1
+    }
+}
+
+fun foo() = Host()
+
+fun Host.test2() {
+    this += 1
+}
+
+fun test3() {
+    foo() += 1
+}
+
+fun test4(a: () -> Host) {
+    a() += 1
+}

compiler/testData/ir/irText/expressions/augmentedAssignmentWithExpression.txt

@@ -0,0 +1,33 @@
+FILE /augmentedAssignmentWithExpression.kt
+  CLASS CLASS Host
+    CONSTRUCTOR public constructor Host()
+      BLOCK_BODY
+        DELEGATING_CONSTRUCTOR_CALL 'constructor Any()'
+        INSTANCE_INITIALIZER_CALL classDescriptor='Host'
+    FUN public final operator fun plusAssign(x: kotlin.Int): kotlin.Unit
+      BLOCK_BODY
+    FUN public final fun test1(): kotlin.Unit
+      BLOCK_BODY
+        CALL 'plusAssign(Int): Unit' type=kotlin.Unit operator=PLUSEQ
+          $this: THIS of 'Host' type=Host
+          x: CONST Int type=kotlin.Int value='1'
+  FUN public fun foo(): Host
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='foo(): Host'
+        CALL 'constructor Host()' type=Host operator=null
+  FUN public fun Host.test2(): kotlin.Unit
+    BLOCK_BODY
+      CALL 'plusAssign(Int): Unit' type=kotlin.Unit operator=PLUSEQ
+        $this: $RECEIVER of 'test2() on Host: Unit' type=Host
+        x: CONST Int type=kotlin.Int value='1'
+  FUN public fun test3(): kotlin.Unit
+    BLOCK_BODY
+      CALL 'plusAssign(Int): Unit' type=kotlin.Unit operator=PLUSEQ
+        $this: CALL 'foo(): Host' type=Host operator=null
+        x: CONST Int type=kotlin.Int value='1'
+  FUN public fun test4(a: () -> Host): kotlin.Unit
+    BLOCK_BODY
+      CALL 'plusAssign(Int): Unit' type=kotlin.Unit operator=PLUSEQ
+        $this: CALL 'invoke(): Host' type=Host operator=INVOKE
+          $this: GET_VAR 'value-parameter a: () -> Host' type=() -> Host operator=VARIABLE_AS_FUNCTION
+        x: CONST Int type=kotlin.Int value='1'

compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java

@@ -310,6 +310,12 @@ public class IrTextTestCaseGenerated extends AbstractIrTextTestCase {
             doTest(fileName);
         }
 
+        @TestMetadata("augmentedAssignmentWithExpression.kt")
+        public void testAugmentedAssignmentWithExpression() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/expressions/augmentedAssignmentWithExpression.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("badBreakContinue.kt")
         public void testBadBreakContinue() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/expressions/badBreakContinue.kt");