From 9881e4e5386bf6a74b4a542321c23a7c396035ef Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Thu, 30 Nov 2017 23:21:45 -0800
Subject: [PATCH] Don't hide unexpected errors in PyErr_WarnExplicitObject().
 (GH-4585) (#4662)

(cherry picked from commit a561862048555d555fa4850eaf832ae5474c7e1f)
---
 Python/ast.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/Python/ast.c b/Python/ast.c
index d2710259ac..ede7f4fd99 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -4136,18 +4136,19 @@ warn_invalid_escape_sequence(struct compiling *c, const node *n,
     }
     if (PyErr_WarnExplicitObject(PyExc_DeprecationWarning, msg,
                                    c->c_filename, LINENO(n),
-                                   NULL, NULL) < 0 &&
-        PyErr_ExceptionMatches(PyExc_DeprecationWarning))
+                                   NULL, NULL) < 0)
     {
-        const char *s;
+        if (PyErr_ExceptionMatches(PyExc_DeprecationWarning)) {
+            const char *s;
 
-        /* Replace the DeprecationWarning exception with a SyntaxError
-           to get a more accurate error report */
-        PyErr_Clear();
+            /* Replace the DeprecationWarning exception with a SyntaxError
+               to get a more accurate error report */
+            PyErr_Clear();
 
-        s = PyUnicode_AsUTF8(msg);
-        if (s != NULL) {
-            ast_error(c, n, s);
+            s = PyUnicode_AsUTF8(msg);
+            if (s != NULL) {
+                ast_error(c, n, s);
+            }
         }
         Py_DECREF(msg);
         return -1;
-- 
2.40.0