From fc144d96580c636001d39a2c06156c5919643f63 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Lozier?= <slozier@users.noreply.github.com>
Date: Sat, 21 Feb 2026 21:58:25 -0500
Subject: [PATCH] Accept positional-only arguments syntax

---
 src/core/IronPython/Compiler/Parser.cs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/core/IronPython/Compiler/Parser.cs b/src/core/IronPython/Compiler/Parser.cs
index 9161912bd..519e4b8da 100644
--- a/src/core/IronPython/Compiler/Parser.cs
+++ b/src/core/IronPython/Compiler/Parser.cs
@@ -1201,6 +1201,7 @@ private Parameter[] ParseParameterList(TokenKind terminator, bool allowAnnotatio
             HashSet<string> names = new HashSet<string>(StringComparer.Ordinal);
             bool needDefault = false;
             bool readMultiply = false;
+            bool readTrueDivide = false;
             bool hasKeywordOnlyParameter = false;
             // we want these to be the last two parameters
             Parameter listParameter = null;
@@ -1221,7 +1222,14 @@ private Parameter[] ParseParameterList(TokenKind terminator, bool allowAnnotatio
                     break;
                 }
 
-                if (MaybeEat(TokenKind.Multiply)) {
+                if (MaybeEat(TokenKind.TrueDivide)) { // accept syntax for positional-only parameters from Python 3.8
+                    if (position == 0 || readMultiply || readTrueDivide) {
+                        ReportSyntaxError(_lookahead);
+                        return null;
+                    }
+
+                    readTrueDivide = true;
+                } else if (MaybeEat(TokenKind.Multiply)) {
                     if (readMultiply) {
                         ReportSyntaxError(_lookahead);
                         return null;