FirSyntheticPropertiesScope: support case with derived getter

#KT-42496 Fixed

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Synthetics.kt

@@ -18,9 +18,11 @@ import org.jetbrains.kotlin.fir.symbols.CallableId
 import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.symbols.SyntheticSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
+import org.jetbrains.kotlin.fir.typeContext
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.ConeNullability.NOT_NULL
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.types.AbstractTypeChecker
 
 class SyntheticPropertySymbol(
     callableId: CallableId,
@@ -72,8 +74,28 @@ class FirSyntheticPropertiesScope(
                     val parameter = setter.valueParameters.singleOrNull() ?: return
                     if (setter.typeParameters.isNotEmpty() || setter.isStatic) return
                     val parameterType = (parameter.returnTypeRef as? FirResolvedTypeRef)?.type ?: return
-                    if (getterReturnType.withNullability(NOT_NULL) != parameterType.withNullability(NOT_NULL)) {
+                    if (getter.symbol.callableId.classId == setter.symbol.callableId.classId) {
-                        return
+                        if (getterReturnType.withNullability(NOT_NULL) != parameterType.withNullability(NOT_NULL)) {
+                            return
+                        }
+                    } else {
+                        // TODO: at this moment it works for cases like
+                        // class Base {
+                        //     void setSomething(Object value) {}
+                        // }
+                        // class Derived extends Base {
+                        //     String getSomething() { return ""; }
+                        // }
+                        // In FE 1.0, we should have also Object getSomething() in class Base for this to work
+                        // I think details here are worth designing
+                        if (!AbstractTypeChecker.isSubtypeOf(
+                                session.typeContext,
+                                getterReturnType.withNullability(NOT_NULL),
+                                parameterType.withNullability(NOT_NULL)
+                            )
+                        ) {
+                            return
+                        }
                     }
                     matchingSetter = setter
                 })

compiler/testData/codegen/boxAgainstJava/syntheticExtensions/overrideOnlyGetter.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // FILE: JavaClass2.java
 
 class JavaClass1 {

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.fir.kt

@@ -5,7 +5,7 @@ fun foo(o: JavaClass2) {
     o.something = ""
     o.setSomething(1)
     o.something = 1 // we generate extension property for JavaClass2 with more specific type
-    o.<!VARIABLE_EXPECTED!>something<!> += "1"
+    o.something += "1"
 }
 
 fun useString(i: String) {}

compiler/testData/ir/irText/firProblems/kt42496.fir.txt

@@ -0,0 +1,11 @@
+FILE fqName:<root> fileName:/kt42496.kt
+  FUN name:box visibility:public modality:FINAL <> () returnType:kotlin.String
+    BLOCK_BODY
+      VAR name:javaClass type:<root>.JavaClass2 [val]
+        CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in <root>.JavaClass2' type=<root>.JavaClass2 origin=null
+      CALL 'public open fun setSomething (value: kotlin.Any?): kotlin.Unit declared in <root>.JavaClass1' type=kotlin.Unit origin=EQ
+        $this: GET_VAR 'val javaClass: <root>.JavaClass2 [val] declared in <root>.box' type=<root>.JavaClass2 origin=null
+        value: CONST String type=kotlin.String value="OK"
+      RETURN type=kotlin.Nothing from='public final fun box (): kotlin.String declared in <root>'
+        CALL 'public open fun getSomething (): kotlin.String? declared in <root>.JavaClass2' type=kotlin.String? origin=GET_PROPERTY
+          $this: GET_VAR 'val javaClass: <root>.JavaClass2 [val] declared in <root>.box' type=<root>.JavaClass2 origin=null