Fix false SyntaxError for named expression as positional argument (f(a := 1, b))

AUTHORS.txt

@@ -53,6 +53,7 @@ Simon Ruggier (@sruggier)
 Tim Gates (@timgates42) <tim.gates@iress.com>
 Batuhan Taskaya (@isidentical) <isidentical@gmail.com>
 Jocelyn Boullier (@Kazy) <jocelyn@boullier.bzh>
+Apoorv Darshan (@apoorvdarshan) <ad13dtu@gmail.com>
 
 
 Note: (@user) means a github user name.

CHANGELOG.rst

@@ -6,6 +6,9 @@ Changelog
 Unreleased
 ++++++++++
 
+- Fix a false ``SyntaxError`` for named expressions used as positional
+  arguments in a call, e.g. ``f(a := 1, b)``
+
 0.8.7 (2026-05-02)
 ++++++++++++++++++
 

parso/python/errors.py

@@ -933,6 +933,18 @@ def is_issue(self, node):
                             self.add_issue(argument, message=message)
                     else:
                         kw_unpacking_only = True
+                elif argument.children[1] == ':=':
+                    # f(a := 1) is a named expression, i.e. a positional
+                    # argument, not a keyword argument.
+                    if kw_unpacking_only:
+                        # f(**x, a := 1)
+                        message = "positional argument follows " \
+                                  "keyword argument unpacking"
+                        self.add_issue(argument, message=message)
+                    elif kw_only:
+                        # f(x=2, a := 1)
+                        message = "positional argument follows keyword argument"
+                        self.add_issue(argument, message=message)
                 else:  # Is a keyword argument.
                     kw_only = True
                     if first.type == 'name':

test/failing_examples.py

@@ -49,6 +49,8 @@ def build_nested(code, depth, base='def f():\n'):
     'f(x=1, x=2)',
     'f(**x, y)',
     'f(x=2, y)',
+    'f(x=2, a := 1)',
+    'f(**x, a := 1)',
     'f(**x, *y)',
     'f(**x, y=3, z)',
     # augassign

test/test_python_errors.py

@@ -362,6 +362,12 @@ def test_valid_fstrings(code):
         'a[(b:=0)]',
         'a[(b:=0, c:=0)]',
         'a[(b:=0):1:2]',
+        'f(a := 1, b)',
+        'f(a := 1, b=2)',
+        'f(a := 1, *b)',
+        'f(a := 1, **b)',
+        'f(b, a := 1)',
+        'f(*b, a := 1)',
     ]
 )
 def test_valid_namedexpr(code):