FIR: Allow selector of safe calls to be a FirStatement

It's necessary to allow a?.b += v be interpreted as a?.(b += v)
But currently FirAssignmentOperatorStatement is not FirQualifiedAccess

^KT-41034 In Progress

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirSafeCallExpression.kt

@@ -22,7 +22,7 @@ abstract class FirSafeCallExpression : FirExpression() {
     abstract override val annotations: List<FirAnnotation>
     abstract val receiver: FirExpression
     abstract val checkedSubjectRef: FirExpressionRef<FirCheckedSafeCallSubject>
-    abstract val regularQualifiedAccess: FirQualifiedAccess
+    abstract val selector: FirStatement
 
     override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R = visitor.visitSafeCallExpression(this, data)
 
@@ -32,11 +32,11 @@ abstract class FirSafeCallExpression : FirExpression() {
 
     abstract override fun replaceTypeRef(newTypeRef: FirTypeRef)
 
-    abstract fun replaceRegularQualifiedAccess(newRegularQualifiedAccess: FirQualifiedAccess)
+    abstract fun replaceSelector(newSelector: FirStatement)
 
     abstract override fun <D> transformAnnotations(transformer: FirTransformer<D>, data: D): FirSafeCallExpression
 
     abstract fun <D> transformReceiver(transformer: FirTransformer<D>, data: D): FirSafeCallExpression
 
-    abstract fun <D> transformRegularQualifiedAccess(transformer: FirTransformer<D>, data: D): FirSafeCallExpression
+    abstract fun <D> transformSelector(transformer: FirTransformer<D>, data: D): FirSafeCallExpression
 }

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/builder/FirSafeCallExpressionBuilder.kt

@@ -13,8 +13,8 @@ import org.jetbrains.kotlin.fir.builder.FirBuilderDsl
 import org.jetbrains.kotlin.fir.expressions.FirAnnotation
 import org.jetbrains.kotlin.fir.expressions.FirCheckedSafeCallSubject
 import org.jetbrains.kotlin.fir.expressions.FirExpression
-import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccess
 import org.jetbrains.kotlin.fir.expressions.FirSafeCallExpression
+import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.expressions.builder.FirExpressionBuilder
 import org.jetbrains.kotlin.fir.expressions.impl.FirSafeCallExpressionImpl
 import org.jetbrains.kotlin.fir.types.FirTypeRef
@@ -33,7 +33,7 @@ class FirSafeCallExpressionBuilder : FirAnnotationContainerBuilder, FirExpressio
     override val annotations: MutableList<FirAnnotation> = mutableListOf()
     lateinit var receiver: FirExpression
     lateinit var checkedSubjectRef: FirExpressionRef<FirCheckedSafeCallSubject>
-    lateinit var regularQualifiedAccess: FirQualifiedAccess
+    lateinit var selector: FirStatement
 
     override fun build(): FirSafeCallExpression {
         return FirSafeCallExpressionImpl(
@@ -42,7 +42,7 @@ class FirSafeCallExpressionBuilder : FirAnnotationContainerBuilder, FirExpressio
             annotations,
             receiver,
             checkedSubjectRef,
-            regularQualifiedAccess,
+            selector,
         )
     }
 

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/impl/FirSafeCallExpressionImpl.kt

@@ -10,8 +10,8 @@ import org.jetbrains.kotlin.fir.FirExpressionRef
 import org.jetbrains.kotlin.fir.expressions.FirAnnotation
 import org.jetbrains.kotlin.fir.expressions.FirCheckedSafeCallSubject
 import org.jetbrains.kotlin.fir.expressions.FirExpression
-import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccess
 import org.jetbrains.kotlin.fir.expressions.FirSafeCallExpression
+import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.visitors.*
 
@@ -26,20 +26,20 @@ internal class FirSafeCallExpressionImpl(
     override val annotations: MutableList<FirAnnotation>,
     override var receiver: FirExpression,
     override val checkedSubjectRef: FirExpressionRef<FirCheckedSafeCallSubject>,
-    override var regularQualifiedAccess: FirQualifiedAccess,
+    override var selector: FirStatement,
 ) : FirSafeCallExpression() {
     override fun <R, D> acceptChildren(visitor: FirVisitor<R, D>, data: D) {
         typeRef.accept(visitor, data)
         annotations.forEach { it.accept(visitor, data) }
         receiver.accept(visitor, data)
-        regularQualifiedAccess.accept(visitor, data)
+        selector.accept(visitor, data)
     }
 
     override fun <D> transformChildren(transformer: FirTransformer<D>, data: D): FirSafeCallExpressionImpl {
         typeRef = typeRef.transform(transformer, data)
         transformAnnotations(transformer, data)
         transformReceiver(transformer, data)
-        transformRegularQualifiedAccess(transformer, data)
+        transformSelector(transformer, data)
         return this
     }
 
@@ -53,8 +53,8 @@ internal class FirSafeCallExpressionImpl(
         return this
     }
 
-    override fun <D> transformRegularQualifiedAccess(transformer: FirTransformer<D>, data: D): FirSafeCallExpressionImpl {
-        regularQualifiedAccess = regularQualifiedAccess.transform(transformer, data)
+    override fun <D> transformSelector(transformer: FirTransformer<D>, data: D): FirSafeCallExpressionImpl {
+        selector = selector.transform(transformer, data)
         return this
     }
 
@@ -62,7 +62,7 @@ internal class FirSafeCallExpressionImpl(
         typeRef = newTypeRef
     }
 
-    override fun replaceRegularQualifiedAccess(newRegularQualifiedAccess: FirQualifiedAccess) {
-        regularQualifiedAccess = newRegularQualifiedAccess
+    override fun replaceSelector(newSelector: FirStatement) {
+        selector = newSelector
     }
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -707,7 +707,7 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
     override fun visitSafeCallExpression(safeCallExpression: FirSafeCallExpression) {
         safeCallExpression.receiver.accept(this)
         print("?.{ ")
-        safeCallExpression.regularQualifiedAccess.accept(this)
+        safeCallExpression.selector.accept(this)
         print(" }")
     }
 

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt

@@ -506,7 +506,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             // Special node that might be used as a reference to receiver of a safe call after null check
             +field("checkedSubjectRef", safeCallCheckedSubjectReferenceType)
             // One that uses checkedReceiver as a receiver
-            +field("regularQualifiedAccess", qualifiedAccess, withReplace = true).withTransform()
+            +field("selector", statement, withReplace = true).withTransform()
         }
 
         checkedSafeCallSubject.configure {