Synthetic 'field' variable is no more created in extension property accessors #KT-9303 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java

@@ -776,11 +776,11 @@ public class BodyResolver {
         );
 
         // Synthetic "field" creation
-        if (functionDescriptor instanceof PropertyAccessorDescriptor) {
+        if (functionDescriptor instanceof PropertyAccessorDescriptor && functionDescriptor.getExtensionReceiverParameter() == null) {
             PropertyAccessorDescriptor accessorDescriptor = (PropertyAccessorDescriptor) functionDescriptor;
             JetProperty property = (JetProperty) function.getParent();
             final SyntheticFieldDescriptor fieldDescriptor = new SyntheticFieldDescriptor(accessorDescriptor, property);
-            innerScope = new LexicalScopeImpl(innerScope, functionDescriptor, true, functionDescriptor.getExtensionReceiverParameter(),
+            innerScope = new LexicalScopeImpl(innerScope, functionDescriptor, true, null,
                                               "Accessor inner scope with synthetic field",
                                               RedeclarationHandler.DO_NOTHING, new Function1<LexicalScopeImpl.InitializeHandler, Unit>() {
                 @Override

compiler/testData/diagnostics/tests/backingField/ExtensionProperty.kt

@@ -0,0 +1,17 @@
+// See KT-9303: synthetic field variable does not exist for extension properties
+val String.foo: Int
+    get() {
+        // No shadowing here
+        val field = 42
+        return field
+    }
+
+val String.bar: Int = <!PROPERTY_INITIALIZER_NO_BACKING_FIELD!>13<!>
+    // Error
+    get() = <!UNRESOLVED_REFERENCE!>field<!>
+
+class My {
+    val String.x: Int = <!PROPERTY_INITIALIZER_NO_BACKING_FIELD!>7<!>
+        // Error
+        get() = <!UNRESOLVED_REFERENCE!>field<!>
+}

compiler/testData/diagnostics/tests/backingField/ExtensionProperty.txt

@@ -0,0 +1,12 @@
+package
+
+public val kotlin.String.bar: kotlin.Int = 13
+public val kotlin.String.foo: kotlin.Int
+
+public final class My {
+    public constructor My()
+    public final val kotlin.String.x: kotlin.Int = 7
+    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/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -1374,6 +1374,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("ExtensionProperty.kt")
+            public void testExtensionProperty() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/backingField/ExtensionProperty.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("FieldAsParam.kt")
             public void testFieldAsParam() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/backingField/FieldAsParam.kt");