Fixed bug #470582, using a modified version of patch #527371,
from Greg Chapman.
* Modules/_sre.c
(lastmark_restore): New function, implementing algorithm to restore
a state to a given lastmark. In addition to the similar algorithm used
in a few places of SRE_MATCH, restore lastindex when restoring lastmark.
(SRE_MATCH): Replace lastmark inline restoring by lastmark_restore(),
function. Also include it where missing. In SRE_OP_MARK, set lastindex
only if i > lastmark.
* Lib/test/re_tests.py
* Lib/test/test_sre.py
Included regression tests for the fixed bugs.
* Misc/NEWS
Mention fixes.
diff --git a/Misc/NEWS b/Misc/NEWS
index c57ca1d..cccaff5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -352,6 +352,13 @@
to the value of the PYTHON_API_VERSION macro with which the
interpreter was compiled.
+- Fixed bug #470582: sre module would return a tuple (None, 'a', 'ab')
+ when applying the regular expression '^((a)c)?(ab)$' on 'ab'. It now
+ returns (None, None, 'ab'), as expected. Also fixed handling of
+ lastindex/lastgroup match attributes in a similar cases. For example,
+ when running the expression r'(a)(b)?b' over 'ab', lastindex must be
+ 1, not 2.
+
Library
-------