[FIR/IR generator] Add kDoc property to AbstractElement & AbstractField

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/AbstractElement.kt

@@ -16,6 +16,8 @@ abstract class AbstractElement<Element, Field> : ElementOrRef<Element, Field>, F
 
     abstract val name: String
 
+    abstract val kDoc: String?
+
     abstract val fields: Set<Field>
 
     abstract val params: List<TypeVariable>

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/AbstractField.kt

@@ -14,6 +14,8 @@ abstract class AbstractField {
     val nullable: Boolean
         get() = typeRef.nullable
 
+    var kDoc: String? = null
+
     abstract val isVolatile: Boolean
 
     abstract val isFinal: Boolean

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/printer/printUtils.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.generators.tree.printer
 
 import org.jetbrains.kotlin.generators.tree.AbstractElement
 import org.jetbrains.kotlin.generators.tree.ImplementationKind
+import org.jetbrains.kotlin.utils.SmartPrinter
 
 /**
  * The angle bracket-delimited list of type parameters to print, or empty string if the element has no type parameters.
@@ -51,3 +52,18 @@ val AbstractElement<*, *>.generics: String
     get() = params.takeIf { it.isNotEmpty() }
         ?.let { it.joinToString(", ", "<", ">") { it.name } }
         ?: ""
+
+fun SmartPrinter.printKDoc(kDoc: String?) {
+    if (kDoc == null) return
+    println("/**")
+    for (line in kDoc.lineSequence()) {
+        print(" *")
+        if (line.isBlank()) {
+            println()
+        } else {
+            print(" ")
+            println(line)
+        }
+    }
+    println(" */")
+}