FIR IDE: Enable add initializer quickfix for MUST_BE_INITIALIZED.

idea/idea-fir/src/org/jetbrains/kotlin/idea/quickfix/MainKtQuickFixRegistrar.kt

@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.idea.fir.api.fixes.KtQuickFixesList
 import org.jetbrains.kotlin.idea.fir.api.fixes.KtQuickFixesListBuilder
 import org.jetbrains.kotlin.idea.frontend.api.fir.diagnostics.KtFirDiagnostic
 import org.jetbrains.kotlin.idea.quickfix.fixes.*
-import org.jetbrains.kotlin.idea.quickfix.fixes.InitializePropertyQuickFixFactory
 
 class MainKtQuickFixRegistrar : KtQuickFixRegistrar() {
     private val keywords = KtQuickFixesListBuilder.registerPsiQuickFix {
@@ -74,7 +73,7 @@ class MainKtQuickFixRegistrar : KtQuickFixRegistrar() {
             KtFirDiagnostic.MustBeInitializedOrBeAbstract::class,
             AddModifierFix.addAbstractModifier,
         )
-        registerApplicator(InitializePropertyQuickFixFactory.initializePropertyFactory)
+        registerApplicators(InitializePropertyQuickFixFactories.initializePropertyFactory)
         registerApplicator(AddLateInitFactory.addLateInitFactory)
         registerApplicator(AddAccessorsFactories.addAccessorsToUninitializedProperty)
     }

idea/idea-fir/src/org/jetbrains/kotlin/idea/quickfix/fixes/InitializePropertyQuickFixFactories.kt

@@ -11,7 +11,7 @@ import org.jetbrains.kotlin.idea.api.applicator.HLApplicator
 import org.jetbrains.kotlin.idea.api.applicator.HLApplicatorInput
 import org.jetbrains.kotlin.idea.api.applicator.applicator
 import org.jetbrains.kotlin.idea.fir.api.fixes.HLQuickFix
-import org.jetbrains.kotlin.idea.fir.api.fixes.diagnosticFixFactory
+import org.jetbrains.kotlin.idea.fir.api.fixes.diagnosticFixFactories
 import org.jetbrains.kotlin.idea.frontend.api.fir.diagnostics.KtFirDiagnostic
 import org.jetbrains.kotlin.psi.KtClass
 import org.jetbrains.kotlin.psi.KtProperty
@@ -20,7 +20,7 @@ import org.jetbrains.kotlin.psi.psiUtil.containingClassOrObject
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
 
-object InitializePropertyQuickFixFactory {
+object InitializePropertyQuickFixFactories {
 
     data class AddInitializerInput(val initializerText: String?) : HLApplicatorInput
 
@@ -38,8 +38,15 @@ object InitializePropertyQuickFixFactory {
 
     @OptIn(ExperimentalStdlibApi::class)
     val initializePropertyFactory =
-        diagnosticFixFactory(KtFirDiagnostic.MustBeInitializedOrBeAbstract::class) { diagnostic ->
+        diagnosticFixFactories(
+            KtFirDiagnostic.MustBeInitialized::class,
+            KtFirDiagnostic.MustBeInitializedOrBeAbstract::class
+        ) { diagnostic ->
             val property: KtProperty = diagnostic.psi
+
+            // An extension property cannot be initialized because it has no backing field
+            if (property.receiverTypeReference != null) return@diagnosticFixFactories emptyList()
+
             buildList {
                 add(
                     HLQuickFix(

idea/testData/quickfix/addInitializer/memberPropertyVarGetterOnly.kt

@@ -3,4 +3,3 @@ class A {
     <caret>var n: Int
         get() = 1
 }
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/memberPropertyVarGetterOnly.kt.after

@@ -3,4 +3,3 @@ class A {
     var n: Int = <selection>0</selection><caret>
         get() = 1
 }
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/memberPropertyVarSetterOnly.kt

@@ -3,4 +3,3 @@ class A {
     <caret>var n: Int
         set(value: Int) {}
 }
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/memberPropertyVarSetterOnly.kt.after

@@ -3,4 +3,3 @@ class A {
     var n: Int = <selection>0</selection><caret>
         set(value: Int) {}
 }
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelProperty.kt

@@ -1,3 +1,2 @@
 // "Add initializer" "true"
 <caret>val n: Int
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelProperty.kt.after

@@ -1,3 +1,2 @@
 // "Add initializer" "true"
 val n: Int = <selection>0</selection><caret>
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelPropertyVarClass.kt

@@ -2,4 +2,3 @@
 // WITH_RUNTIME
 class A
 <caret>var label: A
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelPropertyVarClass.kt.after

@@ -2,4 +2,3 @@
 // WITH_RUNTIME
 class A
 var label: A = TODO()
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelPropertyVarGetterOnly.kt

@@ -1,4 +1,3 @@
 // "Add initializer" "true"
 <caret>var n: Int
     get() = 1
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelPropertyVarGetterOnly.kt.after

@@ -1,4 +1,3 @@
 // "Add initializer" "true"
 var n: Int = <selection>0</selection><caret>
     get() = 1
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelPropertyVarSetterOnly.kt

@@ -1,4 +1,3 @@
 // "Add initializer" "true"
 <caret>var n: Int
     set(value: Int) {}
-/* IGNORE_FIR */

idea/testData/quickfix/addInitializer/topLevelPropertyVarSetterOnly.kt.after

@@ -1,4 +1,3 @@
 // "Add initializer" "true"
 var n: Int = <selection>0</selection><caret>
     set(value: Int) {}
-/* IGNORE_FIR */