From c9d369f1bf78c48083679b2afa5f31d8378ea94d Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Sat, 16 Jun 2012 02:22:37 +0200
Subject: Optimize _PyUnicode_FastCopyCharacters() when maxchar(from) >
 maxchar(to)

---
 Python/formatter_unicode.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'Python/formatter_unicode.c')

diff --git a/Python/formatter_unicode.c b/Python/formatter_unicode.c
index fdb587d073..cd6667053e 100644
--- a/Python/formatter_unicode.c
+++ b/Python/formatter_unicode.c
@@ -786,8 +786,10 @@ format_string_internal(PyObject *value, const InternalFormatSpec *format,
         goto done;
 
     /* Then the source string. */
-    _PyUnicode_FastCopyCharacters(writer->buffer, writer->pos,
-                                  value, 0, len);
+    if (len) {
+        _PyUnicode_FastCopyCharacters(writer->buffer, writer->pos,
+                                      value, 0, len);
+    }
     writer->pos += (len + rpad);
     result = 0;
 
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