no need to initiate an empty comments array for every single node, prettier will create them if needed and only a few places need to check if it's defined

Author: Janther

src/slang-nodes/ContractMembers.ts

@@ -30,7 +30,7 @@ export class ContractMembers extends SlangNode {
     print: PrintFunction,
     options: ParserOptions<AstNode>
   ): Doc {
-    return this.items.length > 0 || this.comments.length > 0
+    return this.items.length > 0 || (this.comments?.length || 0) > 0
       ? printSeparatedItem(printPreservingEmptyLines(path, print, options), {
           firstSeparator: hardline
         })

src/slang-nodes/IfStatement.ts

@@ -51,7 +51,7 @@ export class IfStatement extends SlangNode {
       this.elseBranch
         ? [
             bodyKind !== NonterminalKind.Block || // else on a new line if body is not a block
-            bodyComments.some(
+            bodyComments?.some(
               (comment) =>
                 !isBlockComment(comment) || comment.placement === 'ownLine'
             ) // or if body has trailing single line comments or a block comment on a new line

src/slang-nodes/InterfaceMembers.ts

@@ -30,7 +30,7 @@ export class InterfaceMembers extends SlangNode {
     print: PrintFunction,
     options: ParserOptions<AstNode>
   ): Doc {
-    return this.items.length > 0 || this.comments.length > 0
+    return this.items.length > 0 || (this.comments?.length || 0) > 0
       ? printSeparatedItem(printPreservingEmptyLines(path, print, options), {
           firstSeparator: hardline
         })

src/slang-nodes/LibraryMembers.ts

@@ -30,7 +30,7 @@ export class LibraryMembers extends SlangNode {
     print: PrintFunction,
     options: ParserOptions<AstNode>
   ): Doc {
-    return this.items.length > 0 || this.comments.length > 0
+    return this.items.length > 0 || (this.comments?.length || 0) > 0
       ? printSeparatedItem(printPreservingEmptyLines(path, print, options), {
           firstSeparator: hardline
         })

src/slang-nodes/SlangNode.ts

@@ -37,7 +37,7 @@ function reversedIterator<T>(children: T[]): Iterable<T> {
 }
 
 export class SlangNode {
-  comments: Comment[] = [];
+  comments?: Comment[];
 
   loc: AstLocation;
 

src/slang-nodes/Statements.ts

@@ -30,7 +30,7 @@ export class Statements extends SlangNode {
     print: PrintFunction,
     options: ParserOptions<AstNode>
   ): Doc {
-    return this.items.length > 0 || this.comments.length > 0
+    return this.items.length > 0 || (this.comments?.length || 0) > 0
       ? printSeparatedItem(printPreservingEmptyLines(path, print, options), {
           firstSeparator: hardline
         })

src/slang-nodes/YulStatements.ts

@@ -30,7 +30,7 @@ export class YulStatements extends SlangNode {
     print: PrintFunction,
     options: ParserOptions<AstNode>
   ): Doc {
-    return this.items.length > 0 || this.comments.length > 0
+    return this.items.length > 0 || (this.comments?.length || 0) > 0
       ? printSeparatedItem(printPreservingEmptyLines(path, print, options), {
           firstSeparator: hardline
         })

src/slang-printers/print-comments.ts

@@ -3,7 +3,11 @@ import { printComment } from '../slang-comments/printer.js';
 import { joinExisting } from '../slang-utils/join-existing.js';
 
 import type { AstPath, Doc, ParserOptions } from 'prettier';
-import type { AstNode, Comment } from '../slang-nodes/types.d.ts';
+import type {
+  AstNode,
+  Comment,
+  StrictAstNode
+} from '../slang-nodes/types.d.ts';
 import { locEnd } from '../slang-utils/loc.js';
 
 const { hardline, line } = doc.builders;
@@ -13,9 +17,10 @@ function isPrintable(comment: Comment): boolean {
 }
 
 export function printComments(
-  path: AstPath<AstNode>,
+  path: AstPath<StrictAstNode>,
   options: ParserOptions<AstNode>
 ): Doc[] {
+  if (typeof path.node.comments === 'undefined') return [];
   return joinExisting(
     line,
     path.map((commentPath, index, comments: Comment[]) => {

src/slangPrinter.ts

@@ -8,11 +8,13 @@ import type { PrintFunction } from './types.d.ts';
 function hasNodeIgnoreComment({ comments }: StrictAstNode): boolean {
   // Prettier sets SourceUnit's comments to undefined after assigning comments
   // to each node.
-  return comments?.some(
-    (comment) =>
-      comment.value
-        .slice(2, isBlockComment(comment) ? -2 : undefined)
-        .trim() === 'prettier-ignore'
+  return Boolean(
+    comments?.some(
+      (comment) =>
+        comment.value
+          .slice(2, isBlockComment(comment) ? -2 : undefined)
+          .trim() === 'prettier-ignore'
+    )
   );
 }