Skip to content

gh-52188: emit FutureWarning for negative start/end indices #107105

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
anilbey wants to merge 8 commits into
base: main
Choose a base branch
from
Open

gh-52188: emit FutureWarning for negative start/end indices #107105

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
ef0558d
emit FutureWarning for negative start/end indices
anilbey Mar 14, 2023
1ac29f0
added news entry
anilbey Jul 23, 2023
0b59800
update warning text, mention python3.15
anilbey Jul 23, 2023
14359b6
use gh issue in the news item instead of bpo
anilbey Jul 23, 2023
a21c4ee
update docs of re, mention future-warning
anilbey Jul 23, 2023
c98347e
add test to make sure FutureWarnings are raised
anilbey Jul 23, 2023
124d307
update docs FutureWarning: mention start index as well
anilbey Jul 23, 2023
8d661b6
update news item, mention start index as well
anilbey Jul 23, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions Doc/library/re.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -951,6 +951,8 @@ Functions
.. versionchanged:: 3.7
Non-empty matches can now start just after a previous empty match.

.. versionchanged:: 3.13
Negative start and end indices will no longer be truncated to zero in Python 3.15.

.. function:: finditer(pattern, string, flags=0)

Expand All @@ -962,6 +964,8 @@ Functions
.. versionchanged:: 3.7
Non-empty matches can now start just after a previous empty match.

.. versionchanged:: 3.13
Negative start and end indices will no longer be truncated to zero in Python 3.15.

.. function:: sub(pattern, repl, string, count=0, flags=0)

Expand Down
12 changes: 12 additions & 0 deletions Lib/test/test_re.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -441,6 +441,18 @@ def test_bug_117612(self):
self.assertEqual(re.findall(r"(a|(b))", "aba"),
[("a", ""),("b", "b"),("a", "")])

def test_bug_7940_raises_future_warnings(self):
"""Test to ensure the FutureWarnings are raised."""
pat = re.compile(".")
with self.assertWarns(FutureWarning) as cm:
pat.findall("abcd", -1, 1)
self.assertEqual(str(cm.warning), "Negative start index will not "
"be truncated to zero in Python 3.15")
with self.assertWarns(FutureWarning) as cm:
pat.findall("abcd", 1, -1)
self.assertEqual(str(cm.warning), "Negative end index will not "
"be truncated to zero in Python 3.15")

def test_re_match(self):
for string in 'a', S('a'):
self.assertEqual(re.match('a', string).groups(), ())
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2023-07-23-11-57-33.gh-issue-52188.sXC663.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Emit a FutureWarning when truncating negative start and end indices in re.finditer
and re.findall.
13 changes: 11 additions & 2 deletions Modules/_sre/sre.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -453,13 +453,22 @@ state_init(SRE_STATE* state, PatternObject* pattern, PyObject* string,
}

/* adjust boundaries */
if (start < 0)
if (start < 0) {
PyErr_WarnEx(PyExc_FutureWarning,
"Negative start index will not be truncated to zero in Python 3.15",
1);
start = 0;
}
else if (start > length)
start = length;

if (end < 0)

if (end < 0) {
PyErr_WarnEx(PyExc_FutureWarning,
"Negative end index will not be truncated to zero in Python 3.15",
1);
end = 0;
}
else if (end > length)
end = length;

Expand Down