[3.10] bpo-45848: Allow the parser to get error lines from encoded files (GH-29646) (GH-29661)

(cherry picked from commit fdcc46d9554094994f78bedf6dc9220e5d5ee668)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
diff --git a/Python/errors.c b/Python/errors.c
index 600300e..bc1b55e 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -1724,7 +1724,7 @@ PyErr_SyntaxLocationEx(const char *filename, int lineno, int col_offset)
    functionality in tb_displayline() in traceback.c. */
 
 static PyObject *
-err_programtext(PyThreadState *tstate, FILE *fp, int lineno)
+err_programtext(PyThreadState *tstate, FILE *fp, int lineno, const char* encoding)
 {
     int i;
     char linebuf[1000];
@@ -1752,7 +1752,11 @@ err_programtext(PyThreadState *tstate, FILE *fp, int lineno)
     fclose(fp);
     if (i == lineno) {
         PyObject *res;
-        res = PyUnicode_FromString(linebuf);
+        if (encoding != NULL) {
+            res = PyUnicode_Decode(linebuf, strlen(linebuf), encoding, "replace");
+        } else {
+            res = PyUnicode_FromString(linebuf);
+        }
         if (res == NULL)
             _PyErr_Clear(tstate);
         return res;
@@ -1778,7 +1782,7 @@ PyErr_ProgramText(const char *filename, int lineno)
 }
 
 PyObject *
-PyErr_ProgramTextObject(PyObject *filename, int lineno)
+_PyErr_ProgramDecodedTextObject(PyObject *filename, int lineno, const char* encoding)
 {
     if (filename == NULL || lineno <= 0) {
         return NULL;
@@ -1790,7 +1794,13 @@ PyErr_ProgramTextObject(PyObject *filename, int lineno)
         _PyErr_Clear(tstate);
         return NULL;
     }
-    return err_programtext(tstate, fp, lineno);
+    return err_programtext(tstate, fp, lineno, encoding);
+}
+
+PyObject *
+PyErr_ProgramTextObject(PyObject *filename, int lineno)
+{
+    return _PyErr_ProgramDecodedTextObject(filename, lineno, NULL);
 }
 
 #ifdef __cplusplus