From: Benjamin Peterson <benjamin@python.org>
Date: Wed, 27 Nov 2013 01:22:36 +0000 (-0600)
Subject: fix format spec recursive expansion (closes #19729)
X-Git-Tag: v3.4.0b2~459^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0ee22bf7743dc9a6d593c432f787d7bfe70be199;p=thirdparty%2FPython%2Fcpython.git

fix format spec recursive expansion (closes #19729)
---

diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 9dc3438bea0f..502d39368d62 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -955,6 +955,7 @@ class UnicodeTest(string_tests.CommonTest,
                          '')
 
         self.assertEqual("{[{}]}".format({"{}": 5}), "5")
+        self.assertEqual("0x{:0{:d}X}".format(0x0,16), "0x0000000000000000")
 
     def test_format_map(self):
         self.assertEqual(''.format_map({}), '')
diff --git a/Misc/NEWS b/Misc/NEWS
index 59db14f3e2d2..defbf25fa877 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,8 @@ What's New in Python 3.3.4 release candidate 1?
 Core and Builtins
 -----------------
 
+- Issue #19729: In str.format(), fix recursive expansion in format spec.
+
 - Issue #19638: Fix possible crash / undefined behaviour from huge (more than 2
   billion characters) input strings in _Py_dg_strtod.
 
diff --git a/Objects/stringlib/unicode_format.h b/Objects/stringlib/unicode_format.h
index c1c2cf37812a..d4719a578bb5 100644
--- a/Objects/stringlib/unicode_format.h
+++ b/Objects/stringlib/unicode_format.h
@@ -727,8 +727,10 @@ MarkupIterator_next(MarkupIterator *self, SubString *literal,
     while (self->str.start < self->str.end) {
         switch (c = PyUnicode_READ_CHAR(self->str.str, self->str.start++)) {
         case ':':
-            hit_format_spec = 1;
-            count = 1;
+            if (!hit_format_spec) {
+                count = 1;
+                hit_format_spec = 1;
+            }
             break;
         case '{':
             /* the format spec needs to be recursively expanded.