bpo-30858: Improve error location for expressions with assignments (GH-23753)

Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 91ca1db..d825560 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -802,6 +802,13 @@ def _check_error(self, code, errtext,
         else:
             self.fail("compile() did not raise SyntaxError")
 
+    def test_expression_with_assignment(self):
+        self._check_error(
+            "print(end1 + end2 = ' ')",
+            'expression cannot contain assignment, perhaps you meant "=="?',
+            offset=19
+        )
+
     def test_curly_brace_after_primary_raises_immediately(self):
         self._check_error("f{", "invalid syntax", mode="single")