From 6174474bea9fe6f5f12f05a16004eabb817ce721 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Tue, 22 Sep 2015 01:01:17 +0200
Subject: [PATCH] _PyUnicodeWriter_PrepareInternal(): make the assertion more
 strict

---
 Objects/unicodeobject.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 7c079e0799..d0b285abac 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -13307,7 +13307,8 @@ _PyUnicodeWriter_PrepareInternal(_PyUnicodeWriter *writer,
     PyObject *newbuffer;
 
     /* ensure that the _PyUnicodeWriter_Prepare macro was used */
-    assert(maxchar > writer->maxchar || length > 0);
+    assert((maxchar > writer->maxchar && length >= 0)
+           || length > 0);
 
     if (length > PY_SSIZE_T_MAX - writer->pos) {
         PyErr_NoMemory();
-- 
2.40.0