bpo-44409: Fix error location in tokenizer errors that happen during initialization (GH-26712)

Lib/test/test_exceptions.py

@@ -246,6 +246,7 @@ class ExceptionTests(unittest.TestCase):
         check("pass\npass\npass\n(1+)\npass\npass\npass", 4, 4)
         check("(1+)", 1, 4)
         check("[interesting\nfoo()\n", 1, 1)
+        check(b"\xef\xbb\xbf#coding: utf8\nprint('\xe6\x88\x91')\n", 0, -1)
 
         # Errors thrown by symtable.c
         check('x = [(yield i) for i in range(3)]', 1, 5)

Misc/NEWS.d/next/Core and Builtins/2021-06-13-23-12-18.bpo-44409.eW4LS-.rst

@@ -0,0 +1,2 @@
+Fix error location information for tokenizer errors raised on initialization
+of the tokenizer. Patch by Pablo Galindo.

Parser/pegen.c

@@ -283,6 +283,7 @@ static void
 raise_tokenizer_init_error(PyObject *filename)
 {
     if (!(PyErr_ExceptionMatches(PyExc_LookupError)
+          || PyErr_ExceptionMatches(PyExc_SyntaxError)
           || PyErr_ExceptionMatches(PyExc_ValueError)
           || PyErr_ExceptionMatches(PyExc_UnicodeDecodeError))) {
         return;