[FIR] Make FirImport an abstract class

This change is necessary in order to make `FirElement` abstract class. To do it we need to remove all `accept` and `transform` methods from fir interfaces. So we have to make sure that all fir element implementations have their `accept` and `transform` implementations in their super classes. In particular this change makes `FirImport` abstract class in order to preserve `accept` and `transform` methods after removing them from fir interfaces.

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/FirErrorImport.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.fir.declarations
 
 import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.fir.FirElement
-import org.jetbrains.kotlin.fir.FirPureAbstractElement
 import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
 import org.jetbrains.kotlin.fir.diagnostics.FirDiagnosticHolder
 import org.jetbrains.kotlin.name.FqName
@@ -19,7 +18,7 @@ import org.jetbrains.kotlin.fir.visitors.*
  * DO NOT MODIFY IT MANUALLY
  */
 
-abstract class FirErrorImport : FirPureAbstractElement(), FirImport, FirDiagnosticHolder {
+abstract class FirErrorImport : FirImport(), FirDiagnosticHolder {
     abstract override val source: KtSourceElement?
     abstract override val importedFqName: FqName?
     abstract override val isAllUnder: Boolean

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/FirImport.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.fir.declarations
 
 import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.fir.FirPureAbstractElement
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.fir.visitors.*
@@ -16,12 +17,12 @@ import org.jetbrains.kotlin.fir.visitors.*
  * DO NOT MODIFY IT MANUALLY
  */
 
-interface FirImport : FirElement {
-    override val source: KtSourceElement?
-    val importedFqName: FqName?
-    val isAllUnder: Boolean
-    val aliasName: Name?
-    val aliasSource: KtSourceElement?
+abstract class FirImport : FirPureAbstractElement(), FirElement {
+    abstract override val source: KtSourceElement?
+    abstract val importedFqName: FqName?
+    abstract val isAllUnder: Boolean
+    abstract val aliasName: Name?
+    abstract val aliasSource: KtSourceElement?
 
     override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R = visitor.visitImport(this, data)
 

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/FirResolvedImport.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.fir.declarations
 
 import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.fir.FirElement
-import org.jetbrains.kotlin.fir.FirPureAbstractElement
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
@@ -18,7 +17,7 @@ import org.jetbrains.kotlin.fir.visitors.*
  * DO NOT MODIFY IT MANUALLY
  */
 
-abstract class FirResolvedImport : FirPureAbstractElement(), FirImport {
+abstract class FirResolvedImport : FirImport() {
     abstract override val source: KtSourceElement?
     abstract override val importedFqName: FqName?
     abstract override val isAllUnder: Boolean

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/builder/FirImportBuilder.kt

@@ -9,7 +9,6 @@ package org.jetbrains.kotlin.fir.declarations.builder
 
 import kotlin.contracts.*
 import org.jetbrains.kotlin.KtSourceElement
-import org.jetbrains.kotlin.fir.FirPureAbstractElement
 import org.jetbrains.kotlin.fir.builder.FirBuilderDsl
 import org.jetbrains.kotlin.fir.declarations.FirImport
 import org.jetbrains.kotlin.fir.declarations.impl.FirImportImpl

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/impl/FirImportImpl.kt

@@ -8,7 +8,6 @@
 package org.jetbrains.kotlin.fir.declarations.impl
 
 import org.jetbrains.kotlin.KtSourceElement
-import org.jetbrains.kotlin.fir.FirPureAbstractElement
 import org.jetbrains.kotlin.fir.declarations.FirImport
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
@@ -25,7 +24,7 @@ internal class FirImportImpl(
     override val isAllUnder: Boolean,
     override val aliasName: Name?,
     override val aliasSource: KtSourceElement?,
-) : FirPureAbstractElement(), FirImport {
+) : FirImport() {
     override fun <R, D> acceptChildren(visitor: FirVisitor<R, D>, data: D) {}
 
     override fun <D> transformChildren(transformer: FirTransformer<D>, data: D): FirImportImpl {

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

@@ -509,6 +509,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +booleanField("isAllUnder")
             +field("aliasName", nameType, nullable = true)
             +field("aliasSource", sourceElementType, nullable = true)
+            shouldBeAbstractClass()
         }
 
         resolvedImport.configure {