From aefa49471c294db34aa4a5ee146553d9d5f7609f Mon Sep 17 00:00:00 2001
From: Pablo Galindo <pablogsal@gmail.com>
Date: Thu, 4 May 2023 14:24:08 +0100
Subject: [PATCH] gh-104169: Ensure the tokenizer doesn't overwrite previous
 errors

---
 Parser/tokenizer.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Parser/tokenizer.c b/Parser/tokenizer.c
index 7c07d2011fda61..52d0d9a534cb6a 100644
--- a/Parser/tokenizer.c
+++ b/Parser/tokenizer.c
@@ -1277,6 +1277,12 @@ _syntaxerror_range(struct tok_state *tok, const char *format,
                    int col_offset, int end_col_offset,
                    va_list vargs)
 {
+    // In release builds, we don't want to overwrite a previous error, but in debug builds we
+    // want to fail if we are not doing it so we can fix it.
+    assert(tok->done != E_ERROR);
+    if (tok->done == E_ERROR) {
+        return ERRORTOKEN;
+    }
     PyObject *errmsg, *errtext, *args;
     errmsg = PyUnicode_FromFormatV(format, vargs);
     if (!errmsg) {