From f5d456f6e716f78b5b350dd30dba956142986cae Mon Sep 17 00:00:00 2001
From: magiccwarss <matem.mayreni@gmail.com>
Date: Sat, 7 Nov 2026 16:57:22 +0400
Subject: [PATCH] Require an unquoted identifier immediately before function
 calls

---
 jmespath/parser.py                         |  3 +-
 tests/compliance/function_name_syntax.json | 72 ++++++++++++++++++++++
 2 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 tests/compliance/function_name_syntax.json

diff --git a/jmespath/parser.py b/jmespath/parser.py
index cc8e804e..b744b5a6 100644
--- a/jmespath/parser.py
+++ b/jmespath/parser.py
@@ -282,7 +282,8 @@ def _token_led_and(self, left):
         return ast.and_expression(left, right)
 
     def _token_led_lparen(self, left):
-        if left['type'] != 'field':
+        if (left['type'] != 'field' or
+                self._lookahead(-2) != 'unquoted_identifier'):
             #  0 - first func arg or closing paren.
             # -1 - '(' token
             # -2 - invalid function "name".
diff --git a/tests/compliance/function_name_syntax.json b/tests/compliance/function_name_syntax.json
new file mode 100644
index 00000000..52e4c9b7
--- /dev/null
+++ b/tests/compliance/function_name_syntax.json
@@ -0,0 +1,72 @@
+[
+  {
+    "given": {
+      "foo": 1,
+      "bar": 2,
+      "items": [
+        {
+          "foo": 2
+        },
+        {
+          "foo": 1
+        }
+      ],
+      "length": "value"
+    },
+    "cases": [
+      {
+        "expression": "(length)(@)",
+        "error": "syntax"
+      },
+      {
+        "expression": "(\"length\")(@)",
+        "error": "syntax"
+      },
+      {
+        "expression": "((length))(@)",
+        "error": "syntax"
+      },
+      {
+        "expression": "((\"length\"))(@)",
+        "error": "syntax"
+      },
+      {
+        "expression": "to_array((length)(@))",
+        "error": "syntax"
+      },
+      {
+        "expression": "[(\"length\")(@)]",
+        "error": "syntax"
+      },
+      {
+        "expression": "\"length\"(@)",
+        "error": "syntax"
+      },
+      {
+        "expression": "length(@)",
+        "result": 4
+      },
+      {
+        "expression": "(length(@))",
+        "result": 4
+      },
+      {
+        "expression": "to_array(length(@))",
+        "result": [
+          4
+        ]
+      },
+      {
+        "expression": "items[].length(@)",
+        "result": [
+          1,
+          1
+        ]
+      },
+      {
+        "expression": "\"length\"",
+        "result": "value"
+      }
+    ]
+  }
+]