UP031 (printf-string-formatting) difference between Ruff and pyupgrade

[tdulcet]

I ran Ruff on medium sized project and then pyupgrade. Ruff missed one UP031 autofix that pyupgrade fixed. Both Ruff and pyupgrade missed 96 UP031 (a known problem) and 23 UP032 (a few of these may be caused by #8106).

Ruff command:

ruff --target-version py310 --select UP --line-length 320 --unsafe-fixes --fix .

pyupgrade command:

pyupgrade --py310-plus **/*.py

Diff:

-       path = "%s-%s-%s.pem" % (
+       path = "{}-{}-{}.pem".format(
		safe_domain_name(cn), # common name, which should be filename safe because it is IDNA-encoded, but in case of a malformed cert make sure it's ok to use as a filename
		cert.not_valid_after.date().isoformat().replace("-", ""), # expiration date
		hexlify(cert.fingerprint(hashes.SHA256())).decode("ascii")[0:8], # fingerprint prefix
		)

(There were some additional differences due to Ruff not supporting the newer pyupgrade rules.)

Ruff version:

ruff 0.1.1

[dhruvmanila]

Thanks for reporting! It's because of the comments which is a known limitation:

ruff/crates/ruff_linter/src/rules/pyupgrade/rules/printf_string_formatting.rs

Lines 493 to 498 in 87772c2

	// Avoid fix if there are comments within the right-hand side:
	// ```
	// "%s" % (
	// 0, # 0
	// )
	// ```

Relevant issue: #6336

\cc @zanieb Do we want to downgrade the applicability level as suggested (#6342 (comment)) now that we support them?

[charliermarsh]

Yeah, I'd suggest flagging the diagnostic, and using an unsafe fix personally.