Skip to content

[ruff] Suppress diagnostic for invalid f-strings before Python 3.12 (RUF027) #23480

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

Merged
ntBre merged 8 commits into from
Feb 25, 2026
Merged

[ruff] Suppress diagnostic for invalid f-strings before Python 3.12 (RUF027) #23480

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
e4e4d47
fix(RUF027): suppress fix when interpolation contains comments on Pyt…
Feb 23, 2026
4a32020
fix: update snapshots for comment_test case
Feb 23, 2026
7a4e919
fix(RUF027): only suppress fix when '#' is a comment, not when inside…
Feb 23, 2026
56aae78
Merge remote-tracking branch 'upstream/main' into fix/ruf027-comment-…
Feb 24, 2026
daddca5
fix(RUF027): exclude format spec from comment-hash check; merge upstream
stakeswky Feb 24, 2026
8e45af2
fix(RUF027): use parser unsupported-syntax errors for pre-3.12 backsl…
stakeswky Feb 25, 2026
365bce2
fix: use wildcard match for Pep701FString to cover all PEP 701 variants
stakeswky Feb 25, 2026
bb534aa
address review: trim comment, update snapshots for format spec cases
stakeswky Feb 25, 2026
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
7 changes: 7 additions & 0 deletions crates/ruff_linter/resources/test/fixtures/ruff/RUF027_0.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -90,3 +90,10 @@ def fuzz_bug():
def backslash_test():
x = "test"
print("Hello {'\\n'}{x}") # Should not trigger RUF027 for Python < 3.12

# Test case for comment handling in f-string interpolations
# Should not trigger RUF027 for Python < 3.12 due to comments in interpolations
def comment_test():
x = "!"
print("""{x # }
}""")
8 changes: 5 additions & 3 deletions crates/ruff_linter/src/rules/ruff/rules/missing_fstring_syntax.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -226,10 +226,12 @@ fn should_be_fstring(
for f_string in value.f_strings() {
let mut has_name = false;
for element in f_string.elements.interpolations() {
// Check if the interpolation expression contains backslashes
// F-strings with backslashes in interpolations are only valid in Python 3.12+
// Check if the interpolation expression contains backslashes or comments
// F-strings with backslashes or comments in interpolations are only valid in Python 3.12+
let interpolation_text = &fstring_expr[element.range()];
if target_version < PythonVersion::PY312 && interpolation_text.contains('\\') {
if target_version < PythonVersion::PY312
&& (interpolation_text.contains('\\') || interpolation_text.contains('#'))
{

@dscorbett dscorbett Feb 23, 2026

Copy link
Copy Markdown

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Number signs are only problematic when they would start comments. f"{'#'}" is fine in Python 3.11.

@stakeswky stakeswky Feb 23, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Good catch! Updated the check to use a has_comment_hash() helper that tracks string nesting — # inside a nested string literal (e.g., f"{'#'}") is now correctly recognized as not a comment.

return false;
}

Expand Down
Loading