[SIR, FIR generators] Add KDocs for visitor-related methods of elements

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/FirElement.kt

@@ -40,6 +40,11 @@ interface FirElement {
     fun <E : FirElement, D> transform(transformer: FirTransformer<D>, data: D): E =
         transformer.transformElement(this, data) as E
 
+    /**
+     * Runs the provided [visitor] on the FIR subtree with the root at this node.
+     *
+     * @param visitor The visitor to accept.
+     */
     fun accept(visitor: FirVisitorVoid) = accept(visitor, null)
 
     /**
@@ -54,6 +59,15 @@ interface FirElement {
      */
     fun <R, D> acceptChildren(visitor: FirVisitor<R, D>, data: D)
 
+    /**
+     * Runs the provided [visitor] on subtrees with roots in this node's children.
+     *
+     * Basically, calls `accept(visitor)` on each child of this node.
+     *
+     * Does **not** run [visitor] on this node itself.
+     *
+     * @param visitor The visitor for children to accept.
+     */
     fun acceptChildren(visitor: FirVisitorVoid) = acceptChildren(visitor, null)
 
     /**

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

@@ -21,14 +21,15 @@ internal class ElementPrinter(printer: SmartPrinter) : AbstractElementPrinter<El
     override fun SmartPrinter.printAdditionalMethods(element: Element) {
         val kind = element.kind ?: error("Expected non-null element kind")
         with(element) {
-            printAcceptMethod(element, firVisitorType, hasImplementation = true, treeName = "FIR")
+            val treeName = "FIR"
+            printAcceptMethod(element, firVisitorType, hasImplementation = true, treeName = treeName)
 
             printTransformMethod(
                 element = element,
                 transformerClass = firTransformerType,
                 implementation = "transformer.transform${element.name}(this, data)",
                 returnType = TypeVariable("E", listOf(AbstractFirTreeBuilder.baseFirElement)),
-                treeName = "FIR",
+                treeName = treeName,
             )
 
             fun Field.replaceDeclaration(override: Boolean, overridenType: TypeRefWithNullability? = null, forceNullable: Boolean = false) {
@@ -66,7 +67,7 @@ internal class ElementPrinter(printer: SmartPrinter) : AbstractElementPrinter<El
 
             if (element.isRootElement) {
                 println()
-                printAcceptVoidMethod(firVisitorVoidType)
+                printAcceptVoidMethod(firVisitorVoidType, treeName)
                 printAcceptChildrenMethod(
                     element = element,
                     visitorClass = firVisitorType,