[`flake8-logging-format`] Add auto-fix for f-string logging calls (`G004`) (#19303)

Closes #19302

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## Summary
This adds an auto-fix for `Logging statement uses f-string` Ruff G004,
so users don't have to resolve it manually.
<!-- What's the purpose of the change? What does it do, and why? -->

## Test Plan
I ran the auto-fixes on a Python file locally and and it worked as
expected.
<!-- How was it tested? -->

---------

Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>

crates/ruff_linter/resources/test/fixtures/flake8_logging_format/G004.py

@@ -17,3 +17,50 @@ info(f"{__name__}")
 # Don't trigger for t-strings
 info(t"{name}")
 info(t"{__name__}")
+
+count = 5
+total = 9
+directory_path = "/home/hamir/ruff/crates/ruff_linter/resources/test/"
+logging.info(f"{count} out of {total} files in {directory_path} checked")
+
+
+
+x = 99
+fmt = "08d"
+logger.info(f"{x:{'08d'}}")
+logger.info(f"{x:>10} {x:{fmt}}")
+
+logging.info(f"")
+logging.info(f"This message doesn't have any variables.")
+
+obj = {"key": "value"}
+logging.info(f"Object: {obj!r}")
+
+items_count = 3
+logging.warning(f"Items: {items_count:d}")
+
+data = {"status": "active"}
+logging.info(f"Processing {len(data)} items")
+logging.info(f"Status: {data.get('status', 'unknown').upper()}")
+
+
+result = 123
+logging.info(f"Calculated result: {result + 100}")
+
+temperature = 123
+logging.info(f"Temperature: {temperature:.1f}°C")
+
+class FilePath:
+    def __init__(self, name: str):
+        self.name = name
+
+logging.info(f"No changes made to {file_path.name}.")
+
+user = "tron"
+balance = 123.45
+logging.error(f"Error {404}: User {user} has insufficient balance ${balance:.2f}")
+
+import logging
+
+x = 1
+logging.error(f"{x} -> %s", x)

crates/ruff_linter/resources/test/fixtures/flake8_logging_format/G004_arg_order.py

@@ -0,0 +1,10 @@
+"""Test f-string argument order."""
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+X = 1
+Y = 2
+logger.error(f"{X} -> %s", Y)
+logger.error(f"{Y} -> %s", X)

crates/ruff_linter/src/preview.rs

@@ -40,6 +40,11 @@ pub(crate) const fn is_bad_version_info_in_non_stub_enabled(settings: &LinterSet
     settings.preview.is_enabled()
 }
 
+/// <https://github.com/astral-sh/ruff/pull/19303>
+pub(crate) const fn is_fix_f_string_logging_enabled(settings: &LinterSettings) -> bool {
+    settings.preview.is_enabled()
+}
+
 // https://github.com/astral-sh/ruff/pull/16719
 pub(crate) const fn is_fix_manual_dict_comprehension_enabled(settings: &LinterSettings) -> bool {
     settings.preview.is_enabled()

crates/ruff_linter/src/rules/flake8_logging_format/mod.rs

@@ -22,6 +22,7 @@ mod tests {
     #[test_case(Path::new("G002.py"))]
     #[test_case(Path::new("G003.py"))]
     #[test_case(Path::new("G004.py"))]
+    #[test_case(Path::new("G004_arg_order.py"))]
     #[test_case(Path::new("G010.py"))]
     #[test_case(Path::new("G101_1.py"))]
     #[test_case(Path::new("G101_2.py"))]
@@ -48,4 +49,24 @@ mod tests {
         assert_diagnostics!(snapshot, diagnostics);
         Ok(())
     }
+
+    #[test_case(Rule::LoggingFString, Path::new("G004.py"))]
+    #[test_case(Rule::LoggingFString, Path::new("G004_arg_order.py"))]
+    fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {
+        let snapshot = format!(
+            "preview__{}_{}",
+            rule_code.noqa_code(),
+            path.to_string_lossy()
+        );
+        let diagnostics = test_path(
+            Path::new("flake8_logging_format").join(path).as_path(),
+            &settings::LinterSettings {
+                logger_objects: vec!["logging_setup.logger".to_string()],
+                preview: settings::types::PreviewMode::Enabled,
+                ..settings::LinterSettings::for_rule(rule_code)
+            },
+        )?;
+        assert_diagnostics!(snapshot, diagnostics);
+        Ok(())
+    }
 }

crates/ruff_linter/src/rules/flake8_logging_format/rules/logging_call.rs

@@ -1,9 +1,11 @@
-use ruff_python_ast::{self as ast, Arguments, Expr, Keyword, Operator};
+use ruff_python_ast::InterpolatedStringElement;
+use ruff_python_ast::{self as ast, Arguments, Expr, Keyword, Operator, StringFlags};
 use ruff_python_semantic::analyze::logging;
 use ruff_python_stdlib::logging::LoggingLevel;
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
+use crate::preview::is_fix_f_string_logging_enabled;
 use crate::registry::Rule;
 use crate::rules::flake8_logging_format::violations::{
     LoggingExcInfo, LoggingExtraAttrClash, LoggingFString, LoggingPercentFormat,
@@ -11,6 +13,87 @@ use crate::rules::flake8_logging_format::violations::{
 };
 use crate::{Edit, Fix};
 
+fn logging_f_string(
+    checker: &Checker,
+    msg: &Expr,
+    f_string: &ast::ExprFString,
+    arguments: &Arguments,
+    msg_pos: usize,
+) {
+    // Report the diagnostic up-front so we can attach a fix later only when preview is enabled.
+    let mut diagnostic = checker.report_diagnostic(LoggingFString, msg.range());
+
+    // Preview gate for the automatic fix.
+    if !is_fix_f_string_logging_enabled(checker.settings()) {
+        return;
+    }
+
+    // If there are existing positional arguments after the message, bail out.
+    // This could indicate a mistake or complex usage we shouldn't try to fix.
+    if arguments.args.len() > msg_pos + 1 {
+        return;
+    }
+
+    let mut format_string = String::new();
+    let mut args: Vec<&str> = Vec::new();
+
+    // Try to reuse the first part's quote style when building the replacement.
+    // Default to double quotes if we can't determine it.
+    let quote_str = f_string
+        .value
+        .f_strings()
+        .next()
+        .map(|f| f.flags.quote_str())
+        .unwrap_or("\"");
+
+    for f in f_string.value.f_strings() {
+        for element in &f.elements {
+            match element {
+                InterpolatedStringElement::Literal(lit) => {
+                    // If the literal text contains a '%' placeholder, bail out: mixing
+                    // f-string interpolation with '%' placeholders is ambiguous for our
+                    // automatic conversion, so don't offer a fix for this case.
+                    if lit.value.as_ref().contains('%') {
+                        return;
+                    }
+                    format_string.push_str(lit.value.as_ref());
+                }
+                InterpolatedStringElement::Interpolation(interpolated) => {
+                    if interpolated.format_spec.is_some()
+                        || !matches!(
+                            interpolated.conversion,
+                            ruff_python_ast::ConversionFlag::None
+                        )
+                    {
+                        return;
+                    }
+                    match interpolated.expression.as_ref() {
+                        Expr::Name(name) => {
+                            format_string.push_str("%s");
+                            args.push(name.id.as_str());
+                        }
+                        _ => return,
+                    }
+                }
+            }
+        }
+    }
+
+    if args.is_empty() {
+        return;
+    }
+
+    let replacement = format!(
+        "{q}{format_string}{q}, {args}",
+        q = quote_str,
+        format_string = format_string,
+        args = args.join(", ")
+    );
+
+    let fix = Fix::safe_edit(Edit::range_replacement(replacement, msg.range()));
+    diagnostic.set_fix(fix);
+}
+
 /// Returns `true` if the attribute is a reserved attribute on the `logging` module's `LogRecord`
 /// class.
 fn is_reserved_attr(attr: &str) -> bool {
@@ -42,7 +125,7 @@ fn is_reserved_attr(attr: &str) -> bool {
 }
 
 /// Check logging messages for violations.
-fn check_msg(checker: &Checker, msg: &Expr) {
+fn check_msg(checker: &Checker, msg: &Expr, arguments: &Arguments, msg_pos: usize) {
     match msg {
         // Check for string concatenation and percent format.
         Expr::BinOp(ast::ExprBinOp { op, .. }) => match op {
@@ -55,8 +138,10 @@ fn check_msg(checker: &Checker, msg: &Expr) {
             _ => {}
         },
         // Check for f-strings.
-        Expr::FString(_) => {
+        Expr::FString(f_string) => {
-            checker.report_diagnostic_if_enabled(LoggingFString, msg.range());
+            if checker.is_rule_enabled(Rule::LoggingFString) {
+                logging_f_string(checker, msg, f_string, arguments, msg_pos);
+            }
         }
         // Check for .format() calls.
         Expr::Call(ast::ExprCall { func, .. }) => {
@@ -168,7 +253,7 @@ pub(crate) fn logging_call(checker: &Checker, call: &ast::ExprCall) {
     // G001, G002, G003, G004
     let msg_pos = usize::from(matches!(logging_call_type, LoggingCallType::LogCall));
     if let Some(format_arg) = call.arguments.find_argument_value("msg", msg_pos) {
-        check_msg(checker, format_arg);
+        check_msg(checker, format_arg, &call.arguments, msg_pos);
     }
 
     // G010

crates/ruff_linter/src/rules/flake8_logging_format/snapshots/ruff_linter__rules__flake8_logging_format__tests__G004.py.snap

@@ -9,6 +9,7 @@ G004 Logging statement uses f-string
   |              ^^^^^^^^^^^^^^^
 5 | logging.log(logging.INFO, f"Hello {name}")
   |
+help: Convert to lazy `%` formatting
 
 G004 Logging statement uses f-string
  --> G004.py:5:27
@@ -20,6 +21,7 @@ G004 Logging statement uses f-string
 6 |
 7 | _LOGGER = logging.getLogger()
   |
+help: Convert to lazy `%` formatting
 
 G004 Logging statement uses f-string
   --> G004.py:8:14
@@ -30,6 +32,7 @@ G004 Logging statement uses f-string
  9 |
 10 | logging.getLogger().info(f"{name}")
    |
+help: Convert to lazy `%` formatting
 
 G004 Logging statement uses f-string
   --> G004.py:10:26
@@ -41,6 +44,7 @@ G004 Logging statement uses f-string
 11 |
 12 | from logging import info
    |
+help: Convert to lazy `%` formatting
 
 G004 Logging statement uses f-string
   --> G004.py:14:6
@@ -51,6 +55,7 @@ G004 Logging statement uses f-string
    |      ^^^^^^^^^
 15 | info(f"{__name__}")
    |
+help: Convert to lazy `%` formatting
 
 G004 Logging statement uses f-string
   --> G004.py:15:6
@@ -61,3 +66,156 @@ G004 Logging statement uses f-string
 16 |
 17 | # Don't trigger for t-strings
    |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:24:14
+   |
+22 | total = 9
+23 | directory_path = "/home/hamir/ruff/crates/ruff_linter/resources/test/"
+24 | logging.info(f"{count} out of {total} files in {directory_path} checked")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:30:13
+   |
+28 | x = 99
+29 | fmt = "08d"
+30 | logger.info(f"{x:{'08d'}}")
+   |             ^^^^^^^^^^^^^^
+31 | logger.info(f"{x:>10} {x:{fmt}}")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:31:13
+   |
+29 | fmt = "08d"
+30 | logger.info(f"{x:{'08d'}}")
+31 | logger.info(f"{x:>10} {x:{fmt}}")
+   |             ^^^^^^^^^^^^^^^^^^^^
+32 |
+33 | logging.info(f"")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:33:14
+   |
+31 | logger.info(f"{x:>10} {x:{fmt}}")
+32 |
+33 | logging.info(f"")
+   |              ^^^
+34 | logging.info(f"This message doesn't have any variables.")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:34:14
+   |
+33 | logging.info(f"")
+34 | logging.info(f"This message doesn't have any variables.")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+35 |
+36 | obj = {"key": "value"}
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:37:14
+   |
+36 | obj = {"key": "value"}
+37 | logging.info(f"Object: {obj!r}")
+   |              ^^^^^^^^^^^^^^^^^^
+38 |
+39 | items_count = 3
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:40:17
+   |
+39 | items_count = 3
+40 | logging.warning(f"Items: {items_count:d}")
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^
+41 |
+42 | data = {"status": "active"}
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:43:14
+   |
+42 | data = {"status": "active"}
+43 | logging.info(f"Processing {len(data)} items")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+44 | logging.info(f"Status: {data.get('status', 'unknown').upper()}")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:44:14
+   |
+42 | data = {"status": "active"}
+43 | logging.info(f"Processing {len(data)} items")
+44 | logging.info(f"Status: {data.get('status', 'unknown').upper()}")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:48:14
+   |
+47 | result = 123
+48 | logging.info(f"Calculated result: {result + 100}")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+49 |
+50 | temperature = 123
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:51:14
+   |
+50 | temperature = 123
+51 | logging.info(f"Temperature: {temperature:.1f}°C")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+52 |
+53 | class FilePath:
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:57:14
+   |
+55 |         self.name = name
+56 |
+57 | logging.info(f"No changes made to {file_path.name}.")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+58 |
+59 | user = "tron"
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:61:15
+   |
+59 | user = "tron"
+60 | balance = 123.45
+61 | logging.error(f"Error {404}: User {user} has insufficient balance ${balance:.2f}")
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+62 |
+63 | import logging
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:66:15
+   |
+65 | x = 1
+66 | logging.error(f"{x} -> %s", x)
+   |               ^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting

crates/ruff_linter/src/rules/flake8_logging_format/snapshots/ruff_linter__rules__flake8_logging_format__tests__G004_arg_order.py.snap

@@ -0,0 +1,23 @@
+---
+source: crates/ruff_linter/src/rules/flake8_logging_format/mod.rs
+---
+G004 Logging statement uses f-string
+  --> G004_arg_order.py:9:14
+   |
+ 7 | X = 1
+ 8 | Y = 2
+ 9 | logger.error(f"{X} -> %s", Y)
+   |              ^^^^^^^^^^^^
+10 | logger.error(f"{Y} -> %s", X)
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004_arg_order.py:10:14
+   |
+ 8 | Y = 2
+ 9 | logger.error(f"{X} -> %s", Y)
+10 | logger.error(f"{Y} -> %s", X)
+   |              ^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting

crates/ruff_linter/src/rules/flake8_logging_format/snapshots/ruff_linter__rules__flake8_logging_format__tests__preview__G004_G004.py.snap

@@ -0,0 +1,291 @@
+---
+source: crates/ruff_linter/src/rules/flake8_logging_format/mod.rs
+---
+G004 [*] Logging statement uses f-string
+ --> G004.py:4:14
+  |
+3 | name = "world"
+4 | logging.info(f"Hello {name}")
+  |              ^^^^^^^^^^^^^^^
+5 | logging.log(logging.INFO, f"Hello {name}")
+  |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+1 1 | import logging
+2 2 | 
+3 3 | name = "world"
+4   |-logging.info(f"Hello {name}")
+  4 |+logging.info("Hello %s", name)
+5 5 | logging.log(logging.INFO, f"Hello {name}")
+6 6 | 
+7 7 | _LOGGER = logging.getLogger()
+
+G004 [*] Logging statement uses f-string
+ --> G004.py:5:27
+  |
+3 | name = "world"
+4 | logging.info(f"Hello {name}")
+5 | logging.log(logging.INFO, f"Hello {name}")
+  |                           ^^^^^^^^^^^^^^^
+6 |
+7 | _LOGGER = logging.getLogger()
+  |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+2 2 | 
+3 3 | name = "world"
+4 4 | logging.info(f"Hello {name}")
+5   |-logging.log(logging.INFO, f"Hello {name}")
+  5 |+logging.log(logging.INFO, "Hello %s", name)
+6 6 | 
+7 7 | _LOGGER = logging.getLogger()
+8 8 | _LOGGER.info(f"{__name__}")
+
+G004 [*] Logging statement uses f-string
+  --> G004.py:8:14
+   |
+ 7 | _LOGGER = logging.getLogger()
+ 8 | _LOGGER.info(f"{__name__}")
+   |              ^^^^^^^^^^^^^
+ 9 |
+10 | logging.getLogger().info(f"{name}")
+   |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+5 5 | logging.log(logging.INFO, f"Hello {name}")
+6 6 | 
+7 7 | _LOGGER = logging.getLogger()
+8   |-_LOGGER.info(f"{__name__}")
+  8 |+_LOGGER.info("%s", __name__)
+9 9 | 
+10 10 | logging.getLogger().info(f"{name}")
+11 11 | 
+
+G004 [*] Logging statement uses f-string
+  --> G004.py:10:26
+   |
+ 8 | _LOGGER.info(f"{__name__}")
+ 9 |
+10 | logging.getLogger().info(f"{name}")
+   |                          ^^^^^^^^^
+11 |
+12 | from logging import info
+   |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+7  7  | _LOGGER = logging.getLogger()
+8  8  | _LOGGER.info(f"{__name__}")
+9  9  | 
+10    |-logging.getLogger().info(f"{name}")
+   10 |+logging.getLogger().info("%s", name)
+11 11 | 
+12 12 | from logging import info
+13 13 | 
+
+G004 [*] Logging statement uses f-string
+  --> G004.py:14:6
+   |
+12 | from logging import info
+13 |
+14 | info(f"{name}")
+   |      ^^^^^^^^^
+15 | info(f"{__name__}")
+   |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+11 11 | 
+12 12 | from logging import info
+13 13 | 
+14    |-info(f"{name}")
+   14 |+info("%s", name)
+15 15 | info(f"{__name__}")
+16 16 | 
+17 17 | # Don't trigger for t-strings
+
+G004 [*] Logging statement uses f-string
+  --> G004.py:15:6
+   |
+14 | info(f"{name}")
+15 | info(f"{__name__}")
+   |      ^^^^^^^^^^^^^
+16 |
+17 | # Don't trigger for t-strings
+   |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+12 12 | from logging import info
+13 13 | 
+14 14 | info(f"{name}")
+15    |-info(f"{__name__}")
+   15 |+info("%s", __name__)
+16 16 | 
+17 17 | # Don't trigger for t-strings
+18 18 | info(t"{name}")
+
+G004 [*] Logging statement uses f-string
+  --> G004.py:24:14
+   |
+22 | total = 9
+23 | directory_path = "/home/hamir/ruff/crates/ruff_linter/resources/test/"
+24 | logging.info(f"{count} out of {total} files in {directory_path} checked")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting
+
+ℹ Safe fix
+21 21 | count = 5
+22 22 | total = 9
+23 23 | directory_path = "/home/hamir/ruff/crates/ruff_linter/resources/test/"
+24    |-logging.info(f"{count} out of {total} files in {directory_path} checked")
+   24 |+logging.info("%s out of %s files in %s checked", count, total, directory_path)
+25 25 | 
+26 26 | 
+27 27 | 
+
+G004 Logging statement uses f-string
+  --> G004.py:30:13
+   |
+28 | x = 99
+29 | fmt = "08d"
+30 | logger.info(f"{x:{'08d'}}")
+   |             ^^^^^^^^^^^^^^
+31 | logger.info(f"{x:>10} {x:{fmt}}")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:31:13
+   |
+29 | fmt = "08d"
+30 | logger.info(f"{x:{'08d'}}")
+31 | logger.info(f"{x:>10} {x:{fmt}}")
+   |             ^^^^^^^^^^^^^^^^^^^^
+32 |
+33 | logging.info(f"")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:33:14
+   |
+31 | logger.info(f"{x:>10} {x:{fmt}}")
+32 |
+33 | logging.info(f"")
+   |              ^^^
+34 | logging.info(f"This message doesn't have any variables.")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:34:14
+   |
+33 | logging.info(f"")
+34 | logging.info(f"This message doesn't have any variables.")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+35 |
+36 | obj = {"key": "value"}
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:37:14
+   |
+36 | obj = {"key": "value"}
+37 | logging.info(f"Object: {obj!r}")
+   |              ^^^^^^^^^^^^^^^^^^
+38 |
+39 | items_count = 3
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:40:17
+   |
+39 | items_count = 3
+40 | logging.warning(f"Items: {items_count:d}")
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^
+41 |
+42 | data = {"status": "active"}
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:43:14
+   |
+42 | data = {"status": "active"}
+43 | logging.info(f"Processing {len(data)} items")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+44 | logging.info(f"Status: {data.get('status', 'unknown').upper()}")
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:44:14
+   |
+42 | data = {"status": "active"}
+43 | logging.info(f"Processing {len(data)} items")
+44 | logging.info(f"Status: {data.get('status', 'unknown').upper()}")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:48:14
+   |
+47 | result = 123
+48 | logging.info(f"Calculated result: {result + 100}")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+49 |
+50 | temperature = 123
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:51:14
+   |
+50 | temperature = 123
+51 | logging.info(f"Temperature: {temperature:.1f}°C")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+52 |
+53 | class FilePath:
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:57:14
+   |
+55 |         self.name = name
+56 |
+57 | logging.info(f"No changes made to {file_path.name}.")
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+58 |
+59 | user = "tron"
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:61:15
+   |
+59 | user = "tron"
+60 | balance = 123.45
+61 | logging.error(f"Error {404}: User {user} has insufficient balance ${balance:.2f}")
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+62 |
+63 | import logging
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004.py:66:15
+   |
+65 | x = 1
+66 | logging.error(f"{x} -> %s", x)
+   |               ^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting

crates/ruff_linter/src/rules/flake8_logging_format/snapshots/ruff_linter__rules__flake8_logging_format__tests__preview__G004_G004_arg_order.py.snap

@@ -0,0 +1,23 @@
+---
+source: crates/ruff_linter/src/rules/flake8_logging_format/mod.rs
+---
+G004 Logging statement uses f-string
+  --> G004_arg_order.py:9:14
+   |
+ 7 | X = 1
+ 8 | Y = 2
+ 9 | logger.error(f"{X} -> %s", Y)
+   |              ^^^^^^^^^^^^
+10 | logger.error(f"{Y} -> %s", X)
+   |
+help: Convert to lazy `%` formatting
+
+G004 Logging statement uses f-string
+  --> G004_arg_order.py:10:14
+   |
+ 8 | Y = 2
+ 9 | logger.error(f"{X} -> %s", Y)
+10 | logger.error(f"{Y} -> %s", X)
+   |              ^^^^^^^^^^^^
+   |
+help: Convert to lazy `%` formatting

crates/ruff_linter/src/rules/flake8_logging_format/violations.rs

@@ -327,10 +327,16 @@ impl Violation for LoggingStringConcat {
 pub(crate) struct LoggingFString;
 
 impl Violation for LoggingFString {
+    const FIX_AVAILABILITY: crate::FixAvailability = crate::FixAvailability::Sometimes;
+
     #[derive_message_formats]
     fn message(&self) -> String {
         "Logging statement uses f-string".to_string()
     }
+
+    fn fix_title(&self) -> Option<String> {
+        Some("Convert to lazy `%` formatting".to_string())
+    }
 }
 
 /// ## What it does