http://hg.python.org/cpython/rev/5a1cb8506cea changeset: 72461:5a1cb8506cea branch: 2.7 parent: 72456:0f5b64630fda user: Mark Dickinson <mdickinson@enthought.com> date: Sat Sep 24 09:01:16 2011 +0100 summary: Backport issue #12973 itertools fix from 3.x. files: Misc/NEWS | 6 +++--- Modules/itertoolsmodule.c | 4 +++- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/Misc/NEWS b/Misc/NEWS --- a/Misc/NEWS +++ b/Misc/NEWS @@ -15,9 +15,9 @@ - Issue #12973: Fix overflow checks that invoked undefined behaviour in int.__pow__. These overflow checks were causing int.__pow__ to produce incorrect results with recent versions of Clang, as a result of the - compiler optimizing the check away. Also fix similar overflow check - in list_repeat (which caused test_list to fail with recent versions - of Clang). + compiler optimizing the check away. Also fix similar overflow checks + in list_repeat (listobject.c) and islice_next (itertoolsmodule.c). These + bugs caused test failures with recent versions of Clang. - Issue #12266: Fix str.capitalize() to correctly uppercase/lowercase titlecased and cased non-letter characters. diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c --- a/Modules/itertoolsmodule.c +++ b/Modules/itertoolsmodule.c @@ -1234,7 +1234,9 @@ return NULL; lz->cnt++; oldnext = lz->next; - lz->next += lz->step; + /* The (size_t) cast below avoids the danger of undefined + behaviour from signed integer overflow. */ + lz->next += (size_t)lz->step; if (lz->next < oldnext || (stop != -1 && lz->next > stop)) lz->next = stop; return item; -- Repository URL: http://hg.python.org/cpython