Remove Message::to_rule (#18447)

## Summary

As the title says, this PR removes the `Message::to_rule` method by
replacing related uses of `Rule` with `NoqaCode` (or the rule's name in
the case of the cache). Where it seemed a `Rule` was really needed, we
convert back to the `Rule` by parsing either the rule name (with
`str::parse`) or the `NoqaCode` (with `Rule::from_code`).

I thought this was kind of like cheating and that it might not resolve
this part of Micha's
[comment](https://github.com/astral-sh/ruff/pull/18391#issuecomment-2933764275):

> because we can't add Rule to Diagnostic or **have it anywhere in our
shared rendering logic**

but after looking again, the only remaining `Rule` conversion in
rendering code is for the SARIF output format. The other two non-test
`Rule` conversions are for caching and writing a fix summary, which I
don't think fall into the shared rendering logic. That leaves the SARIF
format as the only real problem, but maybe we can delay that for now.

The motivation here is that we won't be able to store a `Rule` on the
new `Diagnostic` type, but we should be able to store a `NoqaCode`,
likely as a string.

## Test Plan

Existing tests

##
[Benchmarks](https://codspeed.io/astral-sh/ruff/branches/brent%2Fremove-to-rule)

Almost no perf regression, only -1% on
`linter/default-rules[large/dataset.py]`.

---------

Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff/src/cache.rs

@@ -439,7 +439,10 @@ impl LintCacheData {
 
         let messages = messages
             .iter()
-            .filter_map(|msg| msg.to_rule().map(|rule| (rule, msg)))
+            // Parse the kebab-case rule name into a `Rule`. This will fail for syntax errors, so
+            // this also serves to filter them out, but we shouldn't be caching files with syntax
+            // errors anyway.
+            .filter_map(|msg| Some((msg.name().parse().ok()?, msg)))
             .map(|(rule, msg)| {
                 // Make sure that all message use the same source file.
                 assert_eq!(

crates/ruff/src/commands/rule.rs

@@ -30,7 +30,7 @@ impl<'a> Explanation<'a> {
         let (linter, _) = Linter::parse_code(&code).unwrap();
         let fix = rule.fixable().to_string();
         Self {
-            name: rule.as_ref(),
+            name: rule.name().as_str(),
             code,
             linter: linter.name(),
             summary: rule.message_formats()[0],
@@ -44,7 +44,7 @@ impl<'a> Explanation<'a> {
 
 fn format_rule_text(rule: Rule) -> String {
     let mut output = String::new();
-    let _ = write!(&mut output, "# {} ({})", rule.as_ref(), rule.noqa_code());
+    let _ = write!(&mut output, "# {} ({})", rule.name(), rule.noqa_code());
     output.push('\n');
     output.push('\n');
 

crates/ruff/src/diagnostics.rs

@@ -165,9 +165,9 @@ impl AddAssign for FixMap {
                 continue;
             }
             let fixed_in_file = self.0.entry(filename).or_default();
-            for (rule, count) in fixed {
+            for (rule, name, count) in fixed.iter() {
                 if count > 0 {
-                    *fixed_in_file.entry(rule).or_default() += count;
+                    *fixed_in_file.entry(rule).or_default(name) += count;
                 }
             }
         }
@@ -305,7 +305,7 @@ pub(crate) fn lint_path(
                     ParseSource::None,
                 );
                 let transformed = source_kind;
-                let fixed = FxHashMap::default();
+                let fixed = FixTable::default();
                 (result, transformed, fixed)
             }
         } else {
@@ -319,7 +319,7 @@ pub(crate) fn lint_path(
                 ParseSource::None,
             );
             let transformed = source_kind;
-            let fixed = FxHashMap::default();
+            let fixed = FixTable::default();
             (result, transformed, fixed)
         };
 
@@ -473,7 +473,7 @@ pub(crate) fn lint_stdin(
                 }
 
                 let transformed = source_kind;
-                let fixed = FxHashMap::default();
+                let fixed = FixTable::default();
                 (result, transformed, fixed)
             }
         } else {
@@ -487,7 +487,7 @@ pub(crate) fn lint_stdin(
                 ParseSource::None,
             );
             let transformed = source_kind;
-            let fixed = FxHashMap::default();
+            let fixed = FixTable::default();
             (result, transformed, fixed)
         };
 

crates/ruff/src/printer.rs

@@ -7,6 +7,7 @@ use bitflags::bitflags;
 use colored::Colorize;
 use itertools::{Itertools, iterate};
 use ruff_linter::codes::NoqaCode;
+use ruff_linter::linter::FixTable;
 use serde::Serialize;
 
 use ruff_linter::fs::relativize_path;
@@ -80,7 +81,7 @@ impl Printer {
             let fixed = diagnostics
                 .fixed
                 .values()
-                .flat_map(std::collections::HashMap::values)
+                .flat_map(FixTable::counts)
                 .sum::<usize>();
 
             if self.flags.intersects(Flags::SHOW_VIOLATIONS) {
@@ -302,7 +303,7 @@ impl Printer {
         let statistics: Vec<ExpandedStatistics> = diagnostics
             .messages
             .iter()
-            .map(|message| (message.to_noqa_code(), message))
+            .map(|message| (message.noqa_code(), message))
             .sorted_by_key(|(code, message)| (*code, message.fixable()))
             .fold(
                 vec![],
@@ -472,13 +473,13 @@ fn show_fix_status(fix_mode: flags::FixMode, fixables: Option<&FixableStatistics
 fn print_fix_summary(writer: &mut dyn Write, fixed: &FixMap) -> Result<()> {
     let total = fixed
         .values()
-        .map(|table| table.values().sum::<usize>())
+        .map(|table| table.counts().sum::<usize>())
         .sum::<usize>();
     assert!(total > 0);
     let num_digits = num_digits(
-        *fixed
+        fixed
             .values()
-            .filter_map(|table| table.values().max())
+            .filter_map(|table| table.counts().max())
             .max()
             .unwrap(),
     );
@@ -498,12 +499,11 @@ fn print_fix_summary(writer: &mut dyn Write, fixed: &FixMap) -> Result<()> {
             relativize_path(filename).bold(),
             ":".cyan()
         )?;
-        for (rule, count) in table.iter().sorted_by_key(|(.., count)| Reverse(*count)) {
+        for (code, name, count) in table.iter().sorted_by_key(|(.., count)| Reverse(*count)) {
             writeln!(
                 writer,
-                "    {count:>num_digits$} × {} ({})",
+                "    {count:>num_digits$} × {code} ({name})",
-                rule.noqa_code().to_string().red().bold(),
+                code = code.to_string().red().bold(),
-                rule.as_ref(),
             )?;
         }
     }

crates/ruff_dev/src/generate_docs.rs

@@ -29,7 +29,7 @@ pub(crate) fn main(args: &Args) -> Result<()> {
         if let Some(explanation) = rule.explanation() {
             let mut output = String::new();
 
-            let _ = writeln!(&mut output, "# {} ({})", rule.as_ref(), rule.noqa_code());
+            let _ = writeln!(&mut output, "# {} ({})", rule.name(), rule.noqa_code());
 
             let (linter, _) = Linter::parse_code(&rule.noqa_code().to_string()).unwrap();
             if linter.url().is_some() {
@@ -101,7 +101,7 @@ pub(crate) fn main(args: &Args) -> Result<()> {
             let filename = PathBuf::from(ROOT_DIR)
                 .join("docs")
                 .join("rules")
-                .join(rule.as_ref())
+                .join(&*rule.name())
                 .with_extension("md");
 
             if args.dry_run {

crates/ruff_dev/src/generate_rules_table.rs

@@ -55,7 +55,7 @@ fn generate_table(table_out: &mut String, rules: impl IntoIterator<Item = Rule>,
             FixAvailability::None => format!("<span {SYMBOL_STYLE}></span>"),
         };
 
-        let rule_name = rule.as_ref();
+        let rule_name = rule.name();
 
         // If the message ends in a bracketed expression (like: "Use {replacement}"), escape the
         // brackets. Otherwise, it'll be interpreted as an HTML attribute via the `attr_list`

crates/ruff_linter/src/codes.rs

@@ -4,13 +4,13 @@
 /// `--select`. For pylint this is e.g. C0414 and E0118 but also C and E01.
 use std::fmt::Formatter;
 
-use strum_macros::{AsRefStr, EnumIter};
+use strum_macros::EnumIter;
 
 use crate::registry::Linter;
 use crate::rule_selector::is_single_rule_selector;
 use crate::rules;
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct NoqaCode(&'static str, &'static str);
 
 impl NoqaCode {

crates/ruff_linter/src/fix/mod.rs

@@ -1,7 +1,7 @@
 use std::collections::BTreeSet;
 
 use itertools::Itertools;
-use rustc_hash::{FxHashMap, FxHashSet};
+use rustc_hash::FxHashSet;
 
 use ruff_diagnostics::{IsolationLevel, SourceMap};
 use ruff_text_size::{Ranged, TextLen, TextRange, TextSize};
@@ -59,13 +59,13 @@ fn apply_fixes<'a>(
     let mut last_pos: Option<TextSize> = None;
     let mut applied: BTreeSet<&Edit> = BTreeSet::default();
     let mut isolated: FxHashSet<u32> = FxHashSet::default();
-    let mut fixed = FxHashMap::default();
+    let mut fixed = FixTable::default();
     let mut source_map = SourceMap::default();
 
-    for (rule, fix) in diagnostics
+    for (code, name, fix) in diagnostics
-        .filter_map(|msg| msg.to_rule().map(|rule| (rule, msg)))
+        .filter_map(|msg| msg.noqa_code().map(|code| (code, msg.name(), msg)))
-        .filter_map(|(rule, diagnostic)| diagnostic.fix().map(|fix| (rule, fix)))
+        .filter_map(|(code, name, diagnostic)| diagnostic.fix().map(|fix| (code, name, fix)))
-        .sorted_by(|(rule1, fix1), (rule2, fix2)| cmp_fix(*rule1, *rule2, fix1, fix2))
+        .sorted_by(|(_, name1, fix1), (_, name2, fix2)| cmp_fix(name1, name2, fix1, fix2))
     {
         let mut edits = fix
             .edits()
@@ -110,7 +110,7 @@ fn apply_fixes<'a>(
         }
 
         applied.extend(applied_edits.drain(..));
-        *fixed.entry(rule).or_default() += 1;
+        *fixed.entry(code).or_default(name) += 1;
     }
 
     // Add the remaining content.
@@ -125,34 +125,44 @@ fn apply_fixes<'a>(
 }
 
 /// Compare two fixes.
-fn cmp_fix(rule1: Rule, rule2: Rule, fix1: &Fix, fix2: &Fix) -> std::cmp::Ordering {
+fn cmp_fix(name1: &str, name2: &str, fix1: &Fix, fix2: &Fix) -> std::cmp::Ordering {
     // Always apply `RedefinedWhileUnused` before `UnusedImport`, as the latter can end up fixing
     // the former. But we can't apply this just for `RedefinedWhileUnused` and `UnusedImport` because it violates
     // `< is transitive: a < b and b < c implies a < c. The same must hold for both == and >.`
     // See https://github.com/astral-sh/ruff/issues/12469#issuecomment-2244392085
-    match (rule1, rule2) {
+    let redefined_while_unused = Rule::RedefinedWhileUnused.name().as_str();
-        (Rule::RedefinedWhileUnused, Rule::RedefinedWhileUnused) => std::cmp::Ordering::Equal,
+    if (name1, name2) == (redefined_while_unused, redefined_while_unused) {
-        (Rule::RedefinedWhileUnused, _) => std::cmp::Ordering::Less,
+        std::cmp::Ordering::Equal
-        (_, Rule::RedefinedWhileUnused) => std::cmp::Ordering::Greater,
+    } else if name1 == redefined_while_unused {
-        _ => std::cmp::Ordering::Equal,
+        std::cmp::Ordering::Less
+    } else if name2 == redefined_while_unused {
+        std::cmp::Ordering::Greater
+    } else {
+        std::cmp::Ordering::Equal
     }
     // Apply fixes in order of their start position.
     .then_with(|| fix1.min_start().cmp(&fix2.min_start()))
     // Break ties in the event of overlapping rules, for some specific combinations.
-    .then_with(|| match (&rule1, &rule2) {
+    .then_with(|| {
+        let rules = (name1, name2);
         // Apply `MissingTrailingPeriod` fixes before `NewLineAfterLastParagraph` fixes.
-        (Rule::MissingTrailingPeriod, Rule::NewLineAfterLastParagraph) => std::cmp::Ordering::Less,
+        let missing_trailing_period = Rule::MissingTrailingPeriod.name().as_str();
-        (Rule::NewLineAfterLastParagraph, Rule::MissingTrailingPeriod) => {
+        let newline_after_last_paragraph = Rule::NewLineAfterLastParagraph.name().as_str();
+        let if_else_instead_of_dict_get = Rule::IfElseBlockInsteadOfDictGet.name().as_str();
+        let if_else_instead_of_if_exp = Rule::IfElseBlockInsteadOfIfExp.name().as_str();
+        if rules == (missing_trailing_period, newline_after_last_paragraph) {
+            std::cmp::Ordering::Less
+        } else if rules == (newline_after_last_paragraph, missing_trailing_period) {
             std::cmp::Ordering::Greater
         }
         // Apply `IfElseBlockInsteadOfDictGet` fixes before `IfElseBlockInsteadOfIfExp` fixes.
-        (Rule::IfElseBlockInsteadOfDictGet, Rule::IfElseBlockInsteadOfIfExp) => {
+        else if rules == (if_else_instead_of_dict_get, if_else_instead_of_if_exp) {
             std::cmp::Ordering::Less
-        }
+        } else if rules == (if_else_instead_of_if_exp, if_else_instead_of_dict_get) {
-        (Rule::IfElseBlockInsteadOfIfExp, Rule::IfElseBlockInsteadOfDictGet) => {
             std::cmp::Ordering::Greater
+        } else {
+            std::cmp::Ordering::Equal
         }
-        _ => std::cmp::Ordering::Equal,
     })
 }
 
@@ -197,7 +207,7 @@ mod tests {
             source_map,
         } = apply_fixes(diagnostics.iter(), &locator);
         assert_eq!(code, "");
-        assert_eq!(fixes.values().sum::<usize>(), 0);
+        assert_eq!(fixes.counts().sum::<usize>(), 0);
         assert!(source_map.markers().is_empty());
     }
 
@@ -234,7 +244,7 @@ print("hello world")
 "#
             .trim()
         );
-        assert_eq!(fixes.values().sum::<usize>(), 1);
+        assert_eq!(fixes.counts().sum::<usize>(), 1);
         assert_eq!(
             source_map.markers(),
             &[
@@ -275,7 +285,7 @@ class A(Bar):
 "
             .trim(),
         );
-        assert_eq!(fixes.values().sum::<usize>(), 1);
+        assert_eq!(fixes.counts().sum::<usize>(), 1);
         assert_eq!(
             source_map.markers(),
             &[
@@ -312,7 +322,7 @@ class A:
 "
             .trim()
         );
-        assert_eq!(fixes.values().sum::<usize>(), 1);
+        assert_eq!(fixes.counts().sum::<usize>(), 1);
         assert_eq!(
             source_map.markers(),
             &[
@@ -353,7 +363,7 @@ class A(object):
 "
             .trim()
         );
-        assert_eq!(fixes.values().sum::<usize>(), 2);
+        assert_eq!(fixes.counts().sum::<usize>(), 2);
         assert_eq!(
             source_map.markers(),
             &[
@@ -395,7 +405,7 @@ class A:
 "
             .trim(),
         );
-        assert_eq!(fixes.values().sum::<usize>(), 1);
+        assert_eq!(fixes.counts().sum::<usize>(), 1);
         assert_eq!(
             source_map.markers(),
             &[

crates/ruff_linter/src/linter.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::collections::hash_map::Entry;
 use std::path::Path;
 
 use anyhow::{Result, anyhow};
@@ -22,6 +23,7 @@ use crate::checkers::imports::check_imports;
 use crate::checkers::noqa::check_noqa;
 use crate::checkers::physical_lines::check_physical_lines;
 use crate::checkers::tokens::check_tokens;
+use crate::codes::NoqaCode;
 use crate::directives::Directives;
 use crate::doc_lines::{doc_lines_from_ast, doc_lines_from_tokens};
 use crate::fix::{FixResult, fix_file};
@@ -84,7 +86,53 @@ impl LinterResult {
     }
 }
 
-pub type FixTable = FxHashMap<Rule, usize>;
+#[derive(Debug, Default, PartialEq)]
+struct FixCount {
+    rule_name: &'static str,
+    count: usize,
+}
+
+/// A mapping from a noqa code to the corresponding lint name and a count of applied fixes.
+#[derive(Debug, Default, PartialEq)]
+pub struct FixTable(FxHashMap<NoqaCode, FixCount>);
+
+impl FixTable {
+    pub fn counts(&self) -> impl Iterator<Item = usize> {
+        self.0.values().map(|fc| fc.count)
+    }
+
+    pub fn entry(&mut self, code: NoqaCode) -> FixTableEntry {
+        FixTableEntry(self.0.entry(code))
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = (NoqaCode, &'static str, usize)> {
+        self.0
+            .iter()
+            .map(|(code, FixCount { rule_name, count })| (*code, *rule_name, *count))
+    }
+
+    pub fn keys(&self) -> impl Iterator<Item = NoqaCode> {
+        self.0.keys().copied()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+pub struct FixTableEntry<'a>(Entry<'a, NoqaCode, FixCount>);
+
+impl<'a> FixTableEntry<'a> {
+    pub fn or_default(self, rule_name: &'static str) -> &'a mut usize {
+        &mut (self
+            .0
+            .or_insert(FixCount {
+                rule_name,
+                count: 0,
+            })
+            .count)
+    }
+}
 
 pub struct FixerResult<'a> {
     /// The result returned by the linter, after applying any fixes.
@@ -581,7 +629,7 @@ pub fn lint_fix<'a>(
     let mut transformed = Cow::Borrowed(source_kind);
 
     // Track the number of fixed errors across iterations.
-    let mut fixed = FxHashMap::default();
+    let mut fixed = FixTable::default();
 
     // As an escape hatch, bail after 100 iterations.
     let mut iterations = 0;
@@ -650,12 +698,7 @@ pub fn lint_fix<'a>(
             // syntax error. Return the original code.
             if has_valid_syntax && has_no_syntax_errors {
                 if let Some(error) = parsed.errors().first() {
-                    report_fix_syntax_error(
+                    report_fix_syntax_error(path, transformed.source_code(), error, fixed.keys());
-                        path,
-                        transformed.source_code(),
-                        error,
-                        fixed.keys().copied(),
-                    );
                     return Err(anyhow!("Fix introduced a syntax error"));
                 }
             }
@@ -670,8 +713,8 @@ pub fn lint_fix<'a>(
         {
             if iterations < MAX_ITERATIONS {
                 // Count the number of fixed errors.
-                for (rule, count) in applied {
+                for (rule, name, count) in applied.iter() {
-                    *fixed.entry(rule).or_default() += count;
+                    *fixed.entry(rule).or_default(name) += count;
                 }
 
                 transformed = Cow::Owned(transformed.updated(fixed_contents, &source_map));
@@ -698,10 +741,10 @@ pub fn lint_fix<'a>(
     }
 }
 
-fn collect_rule_codes(rules: impl IntoIterator<Item = Rule>) -> String {
+fn collect_rule_codes(rules: impl IntoIterator<Item = NoqaCode>) -> String {
     rules
         .into_iter()
-        .map(|rule| rule.noqa_code().to_string())
+        .map(|rule| rule.to_string())
         .sorted_unstable()
         .dedup()
         .join(", ")
@@ -709,7 +752,7 @@ fn collect_rule_codes(rules: impl IntoIterator<Item = Rule>) -> String {
 
 #[expect(clippy::print_stderr)]
 fn report_failed_to_converge_error(path: &Path, transformed: &str, messages: &[Message]) {
-    let codes = collect_rule_codes(messages.iter().filter_map(Message::to_rule));
+    let codes = collect_rule_codes(messages.iter().filter_map(Message::noqa_code));
     if cfg!(debug_assertions) {
         eprintln!(
             "{}{} Failed to converge after {} iterations in `{}` with rule codes {}:---\n{}\n---",
@@ -745,7 +788,7 @@ fn report_fix_syntax_error(
     path: &Path,
     transformed: &str,
     error: &ParseError,
-    rules: impl IntoIterator<Item = Rule>,
+    rules: impl IntoIterator<Item = NoqaCode>,
 ) {
     let codes = collect_rule_codes(rules);
     if cfg!(debug_assertions) {

crates/ruff_linter/src/message/azure.rs

@@ -33,7 +33,7 @@ impl Emitter for AzureEmitter {
                 line = location.line,
                 col = location.column,
                 code = message
-                    .to_noqa_code()
+                    .noqa_code()
                     .map_or_else(String::new, |code| format!("code={code};")),
                 body = message.body(),
             )?;

crates/ruff_linter/src/message/github.rs

@@ -33,7 +33,7 @@ impl Emitter for GithubEmitter {
                 writer,
                 "::error title=Ruff{code},file={file},line={row},col={column},endLine={end_row},endColumn={end_column}::",
                 code = message
-                    .to_noqa_code()
+                    .noqa_code()
                     .map_or_else(String::new, |code| format!(" ({code})")),
                 file = message.filename(),
                 row = source_location.line,
@@ -50,7 +50,7 @@ impl Emitter for GithubEmitter {
                 column = location.column,
             )?;
 
-            if let Some(code) = message.to_noqa_code() {
+            if let Some(code) = message.noqa_code() {
                 write!(writer, " {code}")?;
             }
 

crates/ruff_linter/src/message/gitlab.rs

@@ -90,7 +90,7 @@ impl Serialize for SerializedMessages<'_> {
             }
             fingerprints.insert(message_fingerprint);
 
-            let (description, check_name) = if let Some(code) = message.to_noqa_code() {
+            let (description, check_name) = if let Some(code) = message.noqa_code() {
                 (message.body().to_string(), code.to_string())
             } else {
                 let description = message.body();

crates/ruff_linter/src/message/json.rs

@@ -81,8 +81,8 @@ pub(crate) fn message_to_json_value(message: &Message, context: &EmitterContext)
     }
 
     json!({
-        "code": message.to_noqa_code().map(|code| code.to_string()),
+        "code": message.noqa_code().map(|code| code.to_string()),
-        "url": message.to_rule().and_then(|rule| rule.url()),
+        "url": message.to_url(),
         "message": message.body(),
         "fix": fix,
         "cell": notebook_cell_index,

crates/ruff_linter/src/message/junit.rs

@@ -59,7 +59,7 @@ impl Emitter for JunitEmitter {
                         body = message.body()
                     ));
                     let mut case = TestCase::new(
-                        if let Some(code) = message.to_noqa_code() {
+                        if let Some(code) = message.noqa_code() {
                             format!("org.ruff.{code}")
                         } else {
                             "org.ruff".to_string()

crates/ruff_linter/src/message/mod.rs

@@ -224,30 +224,22 @@ impl Message {
         self.fix().is_some()
     }
 
-    /// Returns the [`Rule`] corresponding to the diagnostic message.
-    pub fn to_rule(&self) -> Option<Rule> {
-        if self.is_syntax_error() {
-            None
-        } else {
-            Some(self.name().parse().expect("Expected a valid rule name"))
-        }
-    }
-
     /// Returns the [`NoqaCode`] corresponding to the diagnostic message.
-    pub fn to_noqa_code(&self) -> Option<NoqaCode> {
+    pub fn noqa_code(&self) -> Option<NoqaCode> {
         self.noqa_code
     }
 
     /// Returns the URL for the rule documentation, if it exists.
     pub fn to_url(&self) -> Option<String> {
-        // TODO(brent) Rule::url calls Rule::explanation, which calls ViolationMetadata::explain,
+        if self.is_syntax_error() {
-        // which when derived (seems always to be the case?) is always `Some`, so I think it's
+            None
-        // pretty safe to inline the Rule::url implementation here, using `self.name()`:
+        } else {
-        //
+            Some(format!(
-        // format!("{}/rules/{}", env!("CARGO_PKG_HOMEPAGE"), self.name())
+                "{}/rules/{}",
-        //
+                env!("CARGO_PKG_HOMEPAGE"),
-        // at least in the case of diagnostics, I guess syntax errors will return None
+                self.name()
-        self.to_rule().and_then(|rule| rule.url())
+            ))
+        }
     }
 
     /// Returns the filename for the message.

crates/ruff_linter/src/message/pylint.rs

@@ -26,7 +26,7 @@ impl Emitter for PylintEmitter {
                 message.compute_start_location().line
             };
 
-            let body = if let Some(code) = message.to_noqa_code() {
+            let body = if let Some(code) = message.noqa_code() {
                 format!("[{code}] {body}", body = message.body())
             } else {
                 message.body().to_string()

crates/ruff_linter/src/message/rdjson.rs

@@ -71,7 +71,7 @@ fn message_to_rdjson_value(message: &Message) -> Value {
                 "range": rdjson_range(start_location, end_location),
             },
             "code": {
-                "value": message.to_noqa_code().map(|code| code.to_string()),
+                "value": message.noqa_code().map(|code| code.to_string()),
                 "url": message.to_url(),
             },
             "suggestions": rdjson_suggestions(fix.edits(), &source_code),
@@ -84,7 +84,7 @@ fn message_to_rdjson_value(message: &Message) -> Value {
                 "range": rdjson_range(start_location, end_location),
             },
             "code": {
-                "value": message.to_noqa_code().map(|code| code.to_string()),
+                "value": message.noqa_code().map(|code| code.to_string()),
                 "url": message.to_url(),
             },
         })

crates/ruff_linter/src/message/sarif.rs

@@ -8,7 +8,7 @@ use serde_json::json;
 use ruff_source_file::OneIndexed;
 
 use crate::VERSION;
-use crate::codes::Rule;
+use crate::codes::NoqaCode;
 use crate::fs::normalize_path;
 use crate::message::{Emitter, EmitterContext, Message};
 use crate::registry::{Linter, RuleNamespace};
@@ -27,7 +27,7 @@ impl Emitter for SarifEmitter {
             .map(SarifResult::from_message)
             .collect::<Result<Vec<_>>>()?;
 
-        let unique_rules: HashSet<_> = results.iter().filter_map(|result| result.rule).collect();
+        let unique_rules: HashSet<_> = results.iter().filter_map(|result| result.code).collect();
         let mut rules: Vec<SarifRule> = unique_rules.into_iter().map(SarifRule::from).collect();
         rules.sort_by(|a, b| a.code.cmp(&b.code));
 
@@ -61,13 +61,19 @@ struct SarifRule<'a> {
     url: Option<String>,
 }
 
-impl From<Rule> for SarifRule<'_> {
+impl From<NoqaCode> for SarifRule<'_> {
-    fn from(rule: Rule) -> Self {
+    fn from(code: NoqaCode) -> Self {
-        let code = rule.noqa_code().to_string();
+        let code_str = code.to_string();
-        let (linter, _) = Linter::parse_code(&code).unwrap();
+        // This is a manual re-implementation of Rule::from_code, but we also want the Linter. This
+        // avoids calling Linter::parse_code twice.
+        let (linter, suffix) = Linter::parse_code(&code_str).unwrap();
+        let rule = linter
+            .all_rules()
+            .find(|rule| rule.noqa_code().suffix() == suffix)
+            .expect("Expected a valid noqa code corresponding to a rule");
         Self {
             name: rule.into(),
-            code,
+            code: code_str,
             linter: linter.name(),
             summary: rule.message_formats()[0],
             explanation: rule.explanation(),
@@ -106,7 +112,7 @@ impl Serialize for SarifRule<'_> {
 
 #[derive(Debug)]
 struct SarifResult {
-    rule: Option<Rule>,
+    code: Option<NoqaCode>,
     level: String,
     message: String,
     uri: String,
@@ -123,7 +129,7 @@ impl SarifResult {
         let end_location = message.compute_end_location();
         let path = normalize_path(&*message.filename());
         Ok(Self {
-            rule: message.to_rule(),
+            code: message.noqa_code(),
             level: "error".to_string(),
             message: message.body().to_string(),
             uri: url::Url::from_file_path(&path)
@@ -143,7 +149,7 @@ impl SarifResult {
         let end_location = message.compute_end_location();
         let path = normalize_path(&*message.filename());
         Ok(Self {
-            rule: message.to_rule(),
+            code: message.noqa_code(),
             level: "error".to_string(),
             message: message.body().to_string(),
             uri: path.display().to_string(),
@@ -178,7 +184,7 @@ impl Serialize for SarifResult {
                     }
                 }
             }],
-            "ruleId": self.rule.map(|rule| rule.noqa_code().to_string()),
+            "ruleId": self.code.map(|code| code.to_string()),
         })
         .serialize(serializer)
     }

crates/ruff_linter/src/message/text.rs

@@ -151,7 +151,7 @@ impl Display for RuleCodeAndBody<'_> {
             if let Some(fix) = self.message.fix() {
                 // Do not display an indicator for inapplicable fixes
                 if fix.applies(self.unsafe_fixes.required_applicability()) {
-                    if let Some(code) = self.message.to_noqa_code() {
+                    if let Some(code) = self.message.noqa_code() {
                         write!(f, "{} ", code.to_string().red().bold())?;
                     }
                     return write!(
@@ -164,7 +164,7 @@ impl Display for RuleCodeAndBody<'_> {
             }
         }
 
-        if let Some(code) = self.message.to_noqa_code() {
+        if let Some(code) = self.message.noqa_code() {
             write!(
                 f,
                 "{code} {body}",
@@ -254,7 +254,7 @@ impl Display for MessageCodeFrame<'_> {
 
         let label = self
             .message
-            .to_noqa_code()
+            .noqa_code()
             .map_or_else(String::new, |code| code.to_string());
 
         let line_start = self.notebook_index.map_or_else(

crates/ruff_linter/src/noqa.rs

@@ -12,13 +12,14 @@ use log::warn;
 use ruff_python_trivia::{CommentRanges, Cursor, indentation_at_offset};
 use ruff_source_file::{LineEnding, LineRanges};
 use ruff_text_size::{Ranged, TextLen, TextRange, TextSize};
+use rustc_hash::FxHashSet;
 
 use crate::Edit;
 use crate::Locator;
 use crate::codes::NoqaCode;
 use crate::fs::relativize_path;
 use crate::message::Message;
-use crate::registry::{Rule, RuleSet};
+use crate::registry::Rule;
 use crate::rule_redirects::get_redirect_target;
 
 /// Generates an array of edits that matches the length of `messages`.
@@ -780,7 +781,7 @@ fn build_noqa_edits_by_diagnostic(
                 if let Some(noqa_edit) = generate_noqa_edit(
                     comment.directive,
                     comment.line,
-                    RuleSet::from_rule(comment.rule),
+                    FxHashSet::from_iter([comment.code]),
                     locator,
                     line_ending,
                 ) {
@@ -816,7 +817,7 @@ fn build_noqa_edits_by_line<'a>(
             offset,
             matches
                 .into_iter()
-                .map(|NoqaComment { rule, .. }| rule)
+                .map(|NoqaComment { code, .. }| code)
                 .collect(),
             locator,
             line_ending,
@@ -829,7 +830,7 @@ fn build_noqa_edits_by_line<'a>(
 
 struct NoqaComment<'a> {
     line: TextSize,
-    rule: Rule,
+    code: NoqaCode,
     directive: Option<&'a Directive<'a>>,
 }
 
@@ -845,13 +846,11 @@ fn find_noqa_comments<'a>(
 
     // Mark any non-ignored diagnostics.
     for message in messages {
-        let Some(rule) = message.to_rule() else {
+        let Some(code) = message.noqa_code() else {
             comments_by_line.push(None);
             continue;
         };
 
-        let code = rule.noqa_code();
-
         match &exemption {
             FileExemption::All(_) => {
                 // If the file is exempted, don't add any noqa directives.
@@ -900,7 +899,7 @@ fn find_noqa_comments<'a>(
                     if !codes.includes(code) {
                         comments_by_line.push(Some(NoqaComment {
                             line: directive_line.start(),
-                            rule,
+                            code,
                             directive: Some(directive),
                         }));
                     }
@@ -912,7 +911,7 @@ fn find_noqa_comments<'a>(
         // There's no existing noqa directive that suppresses the diagnostic.
         comments_by_line.push(Some(NoqaComment {
             line: locator.line_start(noqa_offset),
-            rule,
+            code,
             directive: None,
         }));
     }
@@ -922,7 +921,7 @@ fn find_noqa_comments<'a>(
 
 struct NoqaEdit<'a> {
     edit_range: TextRange,
-    rules: RuleSet,
+    noqa_codes: FxHashSet<NoqaCode>,
     codes: Option<&'a Codes<'a>>,
     line_ending: LineEnding,
 }
@@ -941,18 +940,15 @@ impl NoqaEdit<'_> {
             Some(codes) => {
                 push_codes(
                     writer,
-                    self.rules
+                    self.noqa_codes
                         .iter()
-                        .map(|rule| rule.noqa_code().to_string())
+                        .map(ToString::to_string)
                         .chain(codes.iter().map(ToString::to_string))
                         .sorted_unstable(),
                 );
             }
             None => {
-                push_codes(
+                push_codes(writer, self.noqa_codes.iter().map(ToString::to_string));
-                    writer,
-                    self.rules.iter().map(|rule| rule.noqa_code().to_string()),
-                );
             }
         }
         write!(writer, "{}", self.line_ending.as_str()).unwrap();
@@ -968,7 +964,7 @@ impl Ranged for NoqaEdit<'_> {
 fn generate_noqa_edit<'a>(
     directive: Option<&'a Directive>,
     offset: TextSize,
-    rules: RuleSet,
+    noqa_codes: FxHashSet<NoqaCode>,
     locator: &Locator,
     line_ending: LineEnding,
 ) -> Option<NoqaEdit<'a>> {
@@ -997,7 +993,7 @@ fn generate_noqa_edit<'a>(
 
     Some(NoqaEdit {
         edit_range,
-        rules,
+        noqa_codes,
         codes,
         line_ending,
     })

crates/ruff_linter/src/registry.rs

@@ -1,6 +1,7 @@
 //! Remnant of the registry of all [`Rule`] implementations, now it's reexporting from codes.rs
 //! with some helper symbols
 
+use ruff_db::diagnostic::LintName;
 use strum_macros::EnumIter;
 
 pub use codes::Rule;
@@ -348,9 +349,18 @@ impl Rule {
 
     /// Return the URL for the rule documentation, if it exists.
     pub fn url(&self) -> Option<String> {
-        self.explanation()
+        self.explanation().is_some().then(|| {
-            .is_some()
+            format!(
-            .then(|| format!("{}/rules/{}", env!("CARGO_PKG_HOMEPAGE"), self.as_ref()))
+                "{}/rules/{name}",
+                env!("CARGO_PKG_HOMEPAGE"),
+                name = self.name()
+            )
+        })
+    }
+
+    pub fn name(&self) -> LintName {
+        let name: &'static str = self.into();
+        LintName::of(name)
     }
 }
 
@@ -421,7 +431,7 @@ pub mod clap_completion {
         fn possible_values(&self) -> Option<Box<dyn Iterator<Item = PossibleValue> + '_>> {
             Some(Box::new(Rule::iter().map(|rule| {
                 let name = rule.noqa_code().to_string();
-                let help = rule.as_ref().to_string();
+                let help = rule.name().as_str();
                 PossibleValue::new(name).help(help)
             })))
         }
@@ -443,7 +453,7 @@ mod tests {
             assert!(
                 rule.explanation().is_some(),
                 "Rule {} is missing documentation",
-                rule.as_ref()
+                rule.name()
             );
         }
     }
@@ -460,10 +470,10 @@ mod tests {
             .collect();
 
         for rule in Rule::iter() {
-            let rule_name = rule.as_ref();
+            let rule_name = rule.name();
             for pattern in &patterns {
                 assert!(
-                    !pattern.matches(rule_name),
+                    !pattern.matches(&rule_name),
                     "{rule_name} does not match naming convention, see CONTRIBUTING.md"
                 );
             }

crates/ruff_linter/src/registry/rule_set.rs

@@ -302,9 +302,8 @@ impl Display for RuleSet {
         } else {
             writeln!(f, "[")?;
             for rule in self {
-                let name = rule.as_ref();
                 let code = rule.noqa_code();
-                writeln!(f, "\t{name} ({code}),")?;
+                writeln!(f, "\t{name} ({code}),", name = rule.name())?;
             }
             write!(f, "]")?;
         }

crates/ruff_linter/src/rule_selector.rs

@@ -485,8 +485,7 @@ pub mod clap_completion {
                                     prefix.linter().common_prefix(),
                                     prefix.short_code()
                                 );
-                                let name: &'static str = rule.into();
+                                return Some(PossibleValue::new(code).help(rule.name().as_str()));
-                                return Some(PossibleValue::new(code).help(name));
                             }
 
                             None

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

@@ -3,7 +3,6 @@ pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -18,7 +17,7 @@ mod tests {
     #[test_case(Rule::FastApiNonAnnotatedDependency, Path::new("FAST002_1.py"))]
     #[test_case(Rule::FastApiUnusedPathParameter, Path::new("FAST003.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("fastapi").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),
@@ -32,7 +31,7 @@ mod tests {
     #[test_case(Rule::FastApiNonAnnotatedDependency, Path::new("FAST002_0.py"))]
     #[test_case(Rule::FastApiNonAnnotatedDependency, Path::new("FAST002_1.py"))]
     fn rules_py38(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}_py38", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}_py38", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("fastapi").join(path).as_path(),
             &settings::LinterSettings {

crates/ruff_linter/src/rules/flake8_fixme/mod.rs

@@ -16,7 +16,7 @@ mod tests {
     #[test_case(Rule::LineContainsTodo; "T003")]
     #[test_case(Rule::LineContainsXxx; "T004")]
     fn rules(rule_code: Rule) -> Result<()> {
-        let snapshot = format!("{}_T00.py", rule_code.as_ref());
+        let snapshot = format!("{}_T00.py", rule_code.name());
         let diagnostics = test_path(
             Path::new("flake8_fixme/T00.py"),
             &settings::LinterSettings::for_rule(rule_code),

crates/ruff_linter/src/rules/flake8_gettext/mod.rs

@@ -29,7 +29,7 @@ mod tests {
     #[test_case(Rule::FormatInGetTextFuncCall, Path::new("INT002.py"))]
     #[test_case(Rule::PrintfInGetTextFuncCall, Path::new("INT003.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_gettext").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),

crates/ruff_linter/src/rules/flake8_raise/mod.rs

@@ -3,7 +3,6 @@ pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -15,7 +14,7 @@ mod tests {
 
     #[test_case(Rule::UnnecessaryParenOnRaiseException, Path::new("RSE102.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_raise").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),

crates/ruff_linter/src/rules/flake8_self/mod.rs

@@ -4,7 +4,6 @@ pub mod settings;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use crate::registry::Rule;
@@ -18,7 +17,7 @@ mod tests {
     #[test_case(Rule::PrivateMemberAccess, Path::new("SLF001.py"))]
     #[test_case(Rule::PrivateMemberAccess, Path::new("SLF001_1.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_self").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),

crates/ruff_linter/src/rules/flake8_todos/mod.rs

@@ -2,7 +2,6 @@ pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -20,7 +19,7 @@ mod tests {
     #[test_case(Rule::InvalidTodoCapitalization, Path::new("TD006.py"))]
     #[test_case(Rule::MissingSpaceAfterTodoColon, Path::new("TD007.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_todos").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),

crates/ruff_linter/src/rules/flake8_type_checking/mod.rs

@@ -6,7 +6,6 @@ pub mod settings;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -55,7 +54,7 @@ mod tests {
     #[test_case(Rule::TypingOnlyThirdPartyImport, Path::new("typing_modules_1.py"))]
     #[test_case(Rule::TypingOnlyThirdPartyImport, Path::new("typing_modules_2.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),
@@ -70,7 +69,7 @@ mod tests {
     #[test_case(Rule::QuotedTypeAlias, Path::new("TC008.py"))]
     #[test_case(Rule::QuotedTypeAlias, Path::new("TC008_typing_execution_context.py"))]
     fn type_alias_rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings::for_rules(vec![
@@ -84,11 +83,7 @@ mod tests {
 
     #[test_case(Rule::QuotedTypeAlias, Path::new("TC008_union_syntax_pre_py310.py"))]
     fn type_alias_rules_pre_py310(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!(
+        let snapshot = format!("pre_py310_{}_{}", rule_code.name(), path.to_string_lossy());
-            "pre_py310_{}_{}",
-            rule_code.as_ref(),
-            path.to_string_lossy()
-        );
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -107,7 +102,7 @@ mod tests {
     #[test_case(Rule::RuntimeImportInTypeCheckingBlock, Path::new("quote3.py"))]
     #[test_case(Rule::TypingOnlyThirdPartyImport, Path::new("quote3.py"))]
     fn quote(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("quote_{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("quote_{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -126,7 +121,7 @@ mod tests {
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("init_var.py"))]
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("kw_only.py"))]
     fn strict(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("strict_{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("strict_{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -170,7 +165,7 @@ mod tests {
         Path::new("exempt_type_checking_3.py")
     )]
     fn exempt_type_checking(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -207,7 +202,7 @@ mod tests {
         Path::new("runtime_evaluated_base_classes_5.py")
     )]
     fn runtime_evaluated_base_classes(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -238,7 +233,7 @@ mod tests {
         Path::new("runtime_evaluated_decorators_3.py")
     )]
     fn runtime_evaluated_decorators(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -264,7 +259,7 @@ mod tests {
         Path::new("module/undefined.py")
     )]
     fn base_class_same_file(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {
@@ -282,7 +277,7 @@ mod tests {
     #[test_case(Rule::RuntimeImportInTypeCheckingBlock, Path::new("module/app.py"))]
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("module/routes.py"))]
     fn decorator_same_file(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("flake8_type_checking").join(path).as_path(),
             &settings::LinterSettings {

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

@@ -4,7 +4,6 @@ pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -22,7 +21,7 @@ mod tests {
     #[test_case(Rule::Numpy2Deprecation, Path::new("NPY201_2.py"))]
     #[test_case(Rule::Numpy2Deprecation, Path::new("NPY201_3.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("numpy").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),

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

@@ -4,7 +4,6 @@ pub mod settings;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -20,7 +19,7 @@ mod tests {
 
     #[test_case(Rule::DocstringMissingException, Path::new("DOC501.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("pydoclint").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),
@@ -36,7 +35,7 @@ mod tests {
     #[test_case(Rule::DocstringMissingException, Path::new("DOC501_google.py"))]
     #[test_case(Rule::DocstringExtraneousException, Path::new("DOC502_google.py"))]
     fn rules_google_style(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("pydoclint").join(path).as_path(),
             &settings::LinterSettings {
@@ -58,7 +57,7 @@ mod tests {
     #[test_case(Rule::DocstringMissingException, Path::new("DOC501_numpy.py"))]
     #[test_case(Rule::DocstringExtraneousException, Path::new("DOC502_numpy.py"))]
     fn rules_numpy_style(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("pydoclint").join(path).as_path(),
             &settings::LinterSettings {
@@ -79,7 +78,7 @@ mod tests {
     fn rules_google_style_ignore_one_line(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!(
             "{}_{}_ignore_one_line",
-            rule_code.as_ref(),
+            rule_code.name(),
             path.to_string_lossy()
         );
         let diagnostics = test_path(

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

@@ -776,8 +776,10 @@ mod tests {
         messages.sort_by_key(Ranged::start);
         let actual = messages
             .iter()
-            .filter_map(Message::to_rule)
+            .filter(|msg| !msg.is_syntax_error())
+            .map(Message::name)
             .collect::<Vec<_>>();
+        let expected: Vec<_> = expected.iter().map(|rule| rule.name().as_str()).collect();
         assert_eq!(actual, expected);
     }
 

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

@@ -4,7 +4,6 @@ pub(crate) mod rules;
 
 #[cfg(test)]
 mod tests {
-    use std::convert::AsRef;
     use std::path::Path;
 
     use anyhow::Result;
@@ -25,7 +24,7 @@ mod tests {
     #[test_case(Rule::ErrorInsteadOfException, Path::new("TRY400.py"))]
     #[test_case(Rule::VerboseLogMessage, Path::new("TRY401.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
-        let snapshot = format!("{}_{}", rule_code.as_ref(), path.to_string_lossy());
+        let snapshot = format!("{}_{}", rule_code.name(), path.to_string_lossy());
         let diagnostics = test_path(
             Path::new("tryceratops").join(path).as_path(),
             &settings::LinterSettings::for_rule(rule_code),

crates/ruff_linter/src/test.rs

@@ -20,6 +20,7 @@ use ruff_python_parser::{ParseError, ParseOptions};
 use ruff_python_trivia::textwrap::dedent;
 use ruff_source_file::SourceFileBuilder;
 
+use crate::codes::Rule;
 use crate::fix::{FixResult, fix_file};
 use crate::linter::check_path;
 use crate::message::{Emitter, EmitterContext, Message, TextEmitter};
@@ -233,8 +234,9 @@ Source with applied fixes:
 
     let messages = messages
         .into_iter()
-        .filter_map(|msg| Some((msg.to_rule()?, msg)))
+        .filter_map(|msg| Some((msg.noqa_code()?, msg)))
-        .map(|(rule, mut diagnostic)| {
+        .map(|(code, mut diagnostic)| {
+            let rule = Rule::from_code(&code.to_string()).unwrap();
             let fixable = diagnostic.fix().is_some_and(|fix| {
                 matches!(
                     fix.applicability(),

crates/ruff_macros/src/map_codes.rs

@@ -174,7 +174,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
 
         output.extend(quote! {
             impl #linter {
-                pub fn rules(&self) -> ::std::vec::IntoIter<Rule> {
+                pub(crate) fn rules(&self) -> ::std::vec::IntoIter<Rule> {
                     match self { #prefix_into_iter_match_arms }
                 }
             }
@@ -182,7 +182,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
     }
     output.extend(quote! {
         impl RuleCodePrefix {
-            pub fn parse(linter: &Linter, code: &str) -> Result<Self, crate::registry::FromCodeError> {
+            pub(crate) fn parse(linter: &Linter, code: &str) -> Result<Self, crate::registry::FromCodeError> {
                 use std::str::FromStr;
 
                 Ok(match linter {
@@ -190,7 +190,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
                 })
             }
 
-            pub fn rules(&self) -> ::std::vec::IntoIter<Rule> {
+            pub(crate) fn rules(&self) -> ::std::vec::IntoIter<Rule> {
                 match self {
                     #(RuleCodePrefix::#linter_idents(prefix) => prefix.clone().rules(),)*
                 }
@@ -319,7 +319,7 @@ See also https://github.com/astral-sh/ruff/issues/2186.
                 matches!(self.group(), RuleGroup::Preview)
             }
 
-            pub fn is_stable(&self) -> bool {
+            pub(crate) fn is_stable(&self) -> bool {
                 matches!(self.group(), RuleGroup::Stable)
             }
 
@@ -371,7 +371,7 @@ fn generate_iter_impl(
     quote! {
         impl Linter {
             /// Rules not in the preview.
-            pub fn rules(self: &Linter) -> ::std::vec::IntoIter<Rule> {
+            pub(crate) fn rules(self: &Linter) -> ::std::vec::IntoIter<Rule> {
                 match self {
                     #linter_rules_match_arms
                 }
@@ -385,7 +385,7 @@ fn generate_iter_impl(
         }
 
         impl RuleCodePrefix {
-            pub fn iter() -> impl Iterator<Item = RuleCodePrefix> {
+            pub(crate) fn iter() -> impl Iterator<Item = RuleCodePrefix> {
                 use strum::IntoEnumIterator;
 
                 let mut prefixes = Vec::new();
@@ -436,7 +436,6 @@ fn register_rules<'a>(input: impl Iterator<Item = &'a Rule>) -> TokenStream {
             PartialOrd,
             Ord,
             ::ruff_macros::CacheKey,
-            AsRefStr,
             ::strum_macros::IntoStaticStr,
             ::strum_macros::EnumString,
             ::serde::Serialize,

crates/ruff_server/src/lint.rs

@@ -242,7 +242,7 @@ fn to_lsp_diagnostic(
     let body = diagnostic.body().to_string();
     let fix = diagnostic.fix();
     let suggestion = diagnostic.suggestion();
-    let code = diagnostic.to_noqa_code();
+    let code = diagnostic.noqa_code();
 
     let fix = fix.and_then(|fix| fix.applies(Applicability::Unsafe).then_some(fix));
 

crates/ruff_server/src/server/api/requests/hover.rs

@@ -85,7 +85,7 @@ pub(crate) fn hover(
 
 fn format_rule_text(rule: Rule) -> String {
     let mut output = String::new();
-    let _ = write!(&mut output, "# {} ({})", rule.as_ref(), rule.noqa_code());
+    let _ = write!(&mut output, "# {} ({})", rule.name(), rule.noqa_code());
     output.push('\n');
     output.push('\n');
 

crates/ruff_wasm/src/lib.rs

@@ -208,7 +208,7 @@ impl Workspace {
         let messages: Vec<ExpandedMessage> = messages
             .into_iter()
             .map(|msg| ExpandedMessage {
-                code: msg.to_noqa_code().map(|code| code.to_string()),
+                code: msg.noqa_code().map(|code| code.to_string()),
                 message: msg.body().to_string(),
                 start_location: source_code.line_column(msg.start()).into(),
                 end_location: source_code.line_column(msg.end()).into(),

crates/ruff_workspace/src/configuration.rs

@@ -1098,7 +1098,7 @@ impl LintConfiguration {
         // approach to give each pair it's own `warn_user_once`.
         for (preferred, expendable, message) in INCOMPATIBLE_CODES {
             if rules.enabled(*preferred) && rules.enabled(*expendable) {
-                warn_user_once_by_id!(expendable.as_ref(), "{}", message);
+                warn_user_once_by_id!(expendable.name().as_str(), "{}", message);
                 rules.disable(*expendable);
             }
         }