fix: fix illegal decorator check

packages/typescript-estree/src/convert.ts

@@ -8,6 +8,7 @@ import {
   canContainDirective,
   createError,
   findNextToken,
+  getAllAccessorDeclarations,
   getBinaryExpressionType,
   getContainingFunction,
   getDeclarationKind,
@@ -17,6 +18,7 @@ import {
   getRange,
   getTextForTokenKind,
   getTSNodeAccessibility,
+  hasDecorators,
   hasModifier,
   isChainExpression,
   isChildUnwrappableOptionalChain,
@@ -25,6 +27,7 @@ import {
   isESTreeClassMember,
   isOptional,
   isThisInTypeQuery,
+  nodeCanBeDecorated,
   nodeHasIllegalDecorators,
   nodeIsPresent,
   unescapeStringLiteralText,
@@ -3107,14 +3110,45 @@ export class Converter {
       return;
     }
 
+    // typescript<5.0.0
     if (nodeHasIllegalDecorators(node)) {
       this.#throwError(
         node.illegalDecorators[0],
         'Decorators are not valid here.',
       );
     }
 
-    for (const modifier of getModifiers(node) ?? []) {
+    // @ts-expect-error -- this is safe as it's guarded
+    const modifiers: ts.ModifierLike[] = node.modifiers;
+
+    if (!modifiers) {
+      return;
+    }
+
+    for (const modifier of modifiers) {
+      if (ts.isDecorator(modifier)) {
+        // `checkGrammarModifiers` function in typescript
+        if (!nodeCanBeDecorated(node)) {
+          if (ts.isMethodDeclaration(node) && !nodeIsPresent(node.body)) {
+            this.#throwError(
+              modifier,
+              'A decorator can only decorate a method implementation, not an overload.',
+            );
+          } else {
+            this.#throwError(modifier, 'Decorators are not valid here.');
+          }
+        } else if (ts.isSetAccessor(node) || ts.isGetAccessor(node)) {
+          const { firstAccessor, secondAccessor } =
+            getAllAccessorDeclarations(node);
+          if (hasDecorators(firstAccessor) && node === secondAccessor) {
+            this.#throwError(
+              modifier,
+              'Decorators cannot be applied to multiple get/set accessors of the same name.',
+            );
+          }
+        }
+      }
+
       if (modifier.kind !== SyntaxKind.ReadonlyKeyword) {
         if (
           node.kind === SyntaxKind.PropertySignature ||

packages/typescript-estree/src/node-utils.ts

@@ -766,3 +766,41 @@ export function getContainingFunction(
 ): ts.SignatureDeclaration | undefined {
   return ts.findAncestor(node.parent, ts.isFunctionLike);
 }
+
+// `ts.nodeCanBeDecorated`
+export function nodeCanBeDecorated(node: ts.Node): boolean {
+  return [true, false].some(
+    useLegacyDecorators =>
+      // @ts-expect-error -- internal api
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
+      ts.nodeCanBeDecorated?.(
+        useLegacyDecorators,
+        node,
+        node.parent,
+        node.parent.parent,
+      ) ?? true,
+  );
+}
+
+// `ts.hasDecorators`
+export function hasDecorators(node: ts.Node | undefined): boolean {
+  // @ts-expect-error -- internal api
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-return
+  return Boolean(node) && (ts.hasDecorators?.(node) ?? false);
+}
+
+// `ts.getAllAccessorDeclarations`
+export function getAllAccessorDeclarations(
+  accessor: ts.GetAccessorDeclaration | ts.SetAccessorDeclaration,
+): {
+  firstAccessor?: ts.Node;
+  secondAccessor?: ts.Node;
+} {
+  // eslint-disable-next-line  @typescript-eslint/no-unsafe-return
+  return (
+    // @ts-expect-error -- internal api
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
+    ts.getAllAccessorDeclarations?.(accessor.parent.members ?? [], accessor) ??
+    {}
+  );
+}