From c3007eefae300d27beb938cf7f3a12a28fb2e42b Mon Sep 17 00:00:00 2001
From: ruchi-mish90 <officialruchimish@gmail.com>
Date: Fri, 17 Jul 2026 12:29:52 +0530
Subject: [PATCH] fix patch_name IndexError when @patch_to uses cls= kwarg

---
 nbdev/doclinks.py         |  2 +-
 nbs/api/05_doclinks.ipynb | 12 +++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/nbdev/doclinks.py b/nbdev/doclinks.py
index 09a9104c1..c340f369c 100644
--- a/nbdev/doclinks.py
+++ b/nbdev/doclinks.py
@@ -48,7 +48,7 @@ def patch_name(o):
     if nm=='patch': 
         a = o.args.args[0].annotation
         if isinstance(a, ast.BinOp): return _binop_leafs(a, o)
-    elif nm=='patch_to': a = d.args[0]
+    elif nm=='patch_to': a = d.args[0] if d.args else next(k.value for k in d.keywords if k.arg=='cls')
     else: return o.name
     return _sym_nm(a,o)
 
diff --git a/nbs/api/05_doclinks.ipynb b/nbs/api/05_doclinks.ipynb
index 30ebf7c54..42a94c9ba 100644
--- a/nbs/api/05_doclinks.ipynb
+++ b/nbs/api/05_doclinks.ipynb
@@ -100,7 +100,7 @@
     "    if nm=='patch': \n",
     "        a = o.args.args[0].annotation\n",
     "        if isinstance(a, ast.BinOp): return _binop_leafs(a, o)\n",
-    "    elif nm=='patch_to': a = d.args[0]\n",
+    "    elif nm=='patch_to': a = d.args[0] if d.args else next(k.value for k in d.keywords if k.arg=='cls')\n",
     "    else: return o.name\n",
     "    return _sym_nm(a,o)"
    ]
@@ -128,6 +128,16 @@
     "test_eq('_T._g', _test_patch(s))"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "s = \"@patch_to(cls=_T)\\ndef _h(self): ...\"\n",
+    "test_eq('_T._h', _test_patch(s))"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,