Enable `pycodestyle` rules under new "nursery" category (#4407)

crates/ruff/src/rule_selector.rs

@@ -119,8 +119,7 @@ impl Visitor<'_> for SelectorVisitor {
 
     fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
         formatter.write_str(
-            "expected a string code identifying a linter or specific rule, or a partial rule code \
-             or ALL to refer to all rules",
+            "expected a string code identifying a linter or specific rule, or a partial rule code or ALL to refer to all rules",
         )
     }
 
@@ -141,13 +140,22 @@ impl From<RuleCodePrefix> for RuleSelector {
     }
 }
 
+/// Returns `true` if the given rule should be selected by the `RuleSelector::All` selector.
+fn select_all(rule: Rule) -> bool {
+    // Nursery rules have to be explicitly selected, so we ignore them when looking at
+    // prefixes.
+    !rule.is_nursery()
+}
+
 impl IntoIterator for &RuleSelector {
-    type IntoIter = RuleSelectorIter;
     type Item = Rule;
+    type IntoIter = RuleSelectorIter;
 
     fn into_iter(self) -> Self::IntoIter {
         match self {
-            RuleSelector::All => RuleSelectorIter::All(Rule::iter()),
+            RuleSelector::All => {
+                RuleSelectorIter::All(Rule::iter().filter(|rule| select_all(*rule)))
+            }
             RuleSelector::C => RuleSelectorIter::Chain(
                 Linter::Flake8Comprehensions
                     .into_iter()
@@ -165,7 +173,7 @@ impl IntoIterator for &RuleSelector {
 }
 
 pub enum RuleSelectorIter {
-    All(RuleIter),
+    All(std::iter::Filter<RuleIter, fn(&Rule) -> bool>),
     Chain(std::iter::Chain<std::vec::IntoIter<Rule>, std::vec::IntoIter<Rule>>),
     Vec(std::vec::IntoIter<Rule>),
 }

crates/ruff_cli/src/commands/rule.rs

@@ -43,6 +43,17 @@ pub(crate) fn rule(rule: Rule, format: HelpFormat) -> Result<()> {
                 output.push('\n');
             }
 
+            if rule.is_nursery() {
+                output.push_str(&format!(
+                    r#"This rule is part of the **nursery**, a collection of newer lints that are
+still under development. As such, it must be enabled by explicitly selecting
+{}."#,
+                    rule.noqa_code()
+                ));
+                output.push('\n');
+                output.push('\n');
+            }
+
             if let Some(explanation) = rule.explanation() {
                 output.push_str(explanation.trim());
             } else {

crates/ruff_cli/tests/integration_test.rs

@@ -12,7 +12,7 @@ use path_absolutize::path_dedot;
 const BIN_NAME: &str = "ruff";
 
 #[test]
-fn test_stdin_success() -> Result<()> {
+fn stdin_success() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     cmd.args(["-", "--format", "text", "--isolated"])
         .write_stdin("")
@@ -22,7 +22,7 @@ fn test_stdin_success() -> Result<()> {
 }
 
 #[test]
-fn test_stdin_error() -> Result<()> {
+fn stdin_error() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args(["-", "--format", "text", "--isolated"])
@@ -40,7 +40,7 @@ Found 1 error.
 }
 
 #[test]
-fn test_stdin_filename() -> Result<()> {
+fn stdin_filename() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args([
@@ -66,7 +66,7 @@ Found 1 error.
 
 #[cfg(unix)]
 #[test]
-fn test_stdin_json() -> Result<()> {
+fn stdin_json() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args([
@@ -127,7 +127,7 @@ fn test_stdin_json() -> Result<()> {
 }
 
 #[test]
-fn test_stdin_autofix() -> Result<()> {
+fn stdin_autofix() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args(["-", "--format", "text", "--fix", "--isolated"])
@@ -142,7 +142,7 @@ fn test_stdin_autofix() -> Result<()> {
 }
 
 #[test]
-fn test_stdin_autofix_when_not_fixable_should_still_print_contents() -> Result<()> {
+fn stdin_autofix_when_not_fixable_should_still_print_contents() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args(["-", "--format", "text", "--fix", "--isolated"])
@@ -157,7 +157,7 @@ fn test_stdin_autofix_when_not_fixable_should_still_print_contents() -> Result<(
 }
 
 #[test]
-fn test_stdin_autofix_when_no_issues_should_still_print_contents() -> Result<()> {
+fn stdin_autofix_when_no_issues_should_still_print_contents() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args(["-", "--format", "text", "--fix", "--isolated"])
@@ -172,7 +172,7 @@ fn test_stdin_autofix_when_no_issues_should_still_print_contents() -> Result<()>
 }
 
 #[test]
-fn test_show_source() -> Result<()> {
+fn show_source() -> Result<()> {
     let mut cmd = Command::cargo_bin(BIN_NAME)?;
     let output = cmd
         .args(["-", "--format", "text", "--show-source", "--isolated"])
@@ -217,3 +217,63 @@ fn show_statistics() -> Result<()> {
     );
     Ok(())
 }
+
+#[test]
+fn nursery_prefix() -> Result<()> {
+    let mut cmd = Command::cargo_bin(BIN_NAME)?;
+
+    // `--select E` should detect E741, but not E225, which is in the nursery.
+    let output = cmd
+        .args(["-", "--format", "text", "--isolated", "--select", "E"])
+        .write_stdin("I=42\n")
+        .assert()
+        .failure();
+    assert_eq!(
+        str::from_utf8(&output.get_output().stdout)?,
+        r#"-:1:1: E741 Ambiguous variable name: `I`
+Found 1 error.
+"#
+    );
+
+    Ok(())
+}
+
+#[test]
+fn nursery_all() -> Result<()> {
+    let mut cmd = Command::cargo_bin(BIN_NAME)?;
+
+    // `--select ALL` should detect E741, but not E225, which is in the nursery.
+    let output = cmd
+        .args(["-", "--format", "text", "--isolated", "--select", "E"])
+        .write_stdin("I=42\n")
+        .assert()
+        .failure();
+    assert_eq!(
+        str::from_utf8(&output.get_output().stdout)?,
+        r#"-:1:1: E741 Ambiguous variable name: `I`
+Found 1 error.
+"#
+    );
+
+    Ok(())
+}
+
+#[test]
+fn nursery_direct() -> Result<()> {
+    let mut cmd = Command::cargo_bin(BIN_NAME)?;
+
+    // `--select E225` should detect E225.
+    let output = cmd
+        .args(["-", "--format", "text", "--isolated", "--select", "E225"])
+        .write_stdin("I=42\n")
+        .assert()
+        .failure();
+    assert_eq!(
+        str::from_utf8(&output.get_output().stdout)?,
+        r#"-:1:2: E225 Missing whitespace around operator
+Found 1 error.
+"#
+    );
+
+    Ok(())
+}

crates/ruff_dev/src/generate_docs.rs

@@ -43,6 +43,17 @@ pub(crate) fn main(args: &Args) -> Result<()> {
                 output.push('\n');
             }
 
+            if rule.is_nursery() {
+                output.push_str(&format!(
+                    r#"This rule is part of the **nursery**, a collection of newer lints that are
+still under development. As such, it must be enabled by explicitly selecting
+{}."#,
+                    rule.noqa_code()
+                ));
+                output.push('\n');
+                output.push('\n');
+            }
+
             process_documentation(explanation.trim(), &mut output);
 
             let filename = PathBuf::from(ROOT_DIR)
@@ -116,7 +127,7 @@ mod tests {
 
     #[test]
     fn test_process_documentation() {
-        let mut out = String::new();
+        let mut output = String::new();
         process_documentation(
             "
 See also [`mccabe.max-complexity`].
@@ -127,10 +138,10 @@ Something [`else`][other].
 - `mccabe.max-complexity`
 
 [other]: http://example.com.",
-            &mut out,
+            &mut output,
         );
         assert_eq!(
-            out,
+            output,
             "
 See also [`mccabe.max-complexity`][mccabe.max-complexity].
 Something [`else`][other].

crates/ruff_diagnostics/src/violation.rs

@@ -1,6 +1,6 @@
 use std::fmt::{Debug, Display};
 
-#[derive(Copy, Clone)]
+#[derive(Debug, Copy, Clone)]
 pub enum AutofixKind {
     Sometimes,
     Always,
@@ -30,7 +30,7 @@ pub trait Violation: Debug + PartialEq + Eq {
         None
     }
 
-    // TODO micha: Move `autofix_title` to `Fix`, add new `advice` method that is shown as an advice.
+    // TODO(micha): Move `autofix_title` to `Fix`, add new `advice` method that is shown as an advice.
     // Change the `Diagnostic` renderer to show the advice, and render the fix message after the `Suggested fix: <here>`
 
     /// Returns the title for the autofix. The message is also shown as an advice as part of the diagnostics.

crates/ruff_macros/src/lib.rs

@@ -15,7 +15,7 @@ mod rule_namespace;
 mod violation;
 
 #[proc_macro_derive(ConfigurationOptions, attributes(option, doc, option_group))]
-pub fn derive_config(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+pub fn derive_config(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
 
     config::derive_impl(input)
@@ -43,13 +43,12 @@ pub fn cache_key(input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro]
-pub fn register_rules(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
+pub fn register_rules(item: TokenStream) -> TokenStream {
     let mapping = parse_macro_input!(item as register_rules::Input);
     register_rules::register_rules(&mapping).into()
 }
 
-/// Adds an `explanation()` method from the doc comment and
-/// `#[derive(Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize)]`
+/// Adds an `explanation()` method from the doc comment.
 #[proc_macro_attribute]
 pub fn violation(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let violation = parse_macro_input!(item as ItemStruct);
@@ -59,7 +58,7 @@ pub fn violation(_attr: TokenStream, item: TokenStream) -> TokenStream {
 }
 
 #[proc_macro_derive(RuleNamespace, attributes(prefix))]
-pub fn derive_rule_namespace(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+pub fn derive_rule_namespace(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
 
     rule_namespace::derive_impl(input)

crates/ruff_macros/src/map_codes.rs

@@ -8,21 +8,25 @@ use syn::{
     Ident, ItemFn, LitStr, Pat, Path, Stmt, Token,
 };
 
-use crate::rule_code_prefix::{get_prefix_ident, if_all_same};
+use crate::rule_code_prefix::{get_prefix_ident, if_all_same, is_nursery};
 
 pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
     let Some(last_stmt) = func.block.stmts.last() else {
         return Err(Error::new(func.block.span(), "expected body to end in an expression"));
     };
     let Stmt::Expr(Expr::Call(ExprCall{args: some_args, ..}), _) = last_stmt else {
-        return Err(Error::new(last_stmt.span(), "expected last expression to be Some(match (..) { .. })"))
+        return Err(Error::new(last_stmt.span(), "expected last expression to be `Some(match (..) { .. })`"))
     };
     let mut some_args = some_args.into_iter();
     let (Some(Expr::Match(ExprMatch { arms, .. })), None) = (some_args.next(), some_args.next()) else {
-        return Err(Error::new(last_stmt.span(), "expected last expression to be Some(match (..) { .. })"))
+        return Err(Error::new(last_stmt.span(), "expected last expression to be `Some(match (..) { .. })`"))
     };
 
-    let mut linters: BTreeMap<Ident, BTreeMap<String, (Path, Vec<Attribute>)>> = BTreeMap::new();
+    // Map from: linter (e.g., `Flake8Bugbear`) to rule code (e.g.,`"002"`) to rule data (e.g.,
+    // `(Rule::UnaryPrefixIncrement, RuleGroup::Unspecified, vec![])`).
+    #[allow(clippy::type_complexity)]
+    let mut linter_to_rules: BTreeMap<Ident, BTreeMap<String, (Path, Path, Vec<Attribute>)>> =
+        BTreeMap::new();
 
     for arm in arms {
         if matches!(arm.pat, Pat::Wild(..)) {
@@ -30,15 +34,15 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         }
 
         let entry = syn::parse::<Entry>(arm.into_token_stream().into())?;
-        linters
+        linter_to_rules
             .entry(entry.linter)
             .or_default()
-            .insert(entry.code.value(), (entry.rule, entry.attrs));
+            .insert(entry.code.value(), (entry.rule, entry.group, entry.attrs));
     }
 
-    let linter_idents: Vec<_> = linters.keys().collect();
+    let linter_idents: Vec<_> = linter_to_rules.keys().collect();
 
-    let mut out = quote! {
+    let mut output = quote! {
         #[derive(Debug, Clone, PartialEq, Eq, Hash)]
         pub enum RuleCodePrefix {
             #(#linter_idents(#linter_idents),)*
@@ -47,7 +51,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         impl RuleCodePrefix {
             pub fn linter(&self) -> &'static Linter {
                 match self {
-                    #(Self::#linter_idents(..) => &crate::registry::Linter::#linter_idents,)*
+                    #(Self::#linter_idents(..) => &Linter::#linter_idents,)*
                 }
             }
 
@@ -59,13 +63,15 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         }
     };
 
-    for (linter, map) in &linters {
-        out.extend(super::rule_code_prefix::expand(
+    for (linter, rules) in &linter_to_rules {
+        output.extend(super::rule_code_prefix::expand(
             linter,
-            map.iter().map(|(k, v)| (k.as_str(), &v.1)),
+            rules
+                .iter()
+                .map(|(code, (.., group, attrs))| (code.as_str(), group, attrs)),
         ));
 
-        out.extend(quote! {
+        output.extend(quote! {
             impl From<#linter> for RuleCodePrefix {
                 fn from(linter: #linter) -> Self {
                     Self::#linter(linter)
@@ -81,32 +87,44 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
 
     let mut all_codes = Vec::new();
 
-    for (linter, map) in &linters {
-        let mut full_map: HashMap<_, _> = map
-            .iter()
-            .map(|(code, rule)| (code.clone(), vec![rule.clone()]))
-            .collect();
-        for code in map.keys() {
+    for (linter, rules) in &linter_to_rules {
+        // Group the rules by their common prefixes.
+        // TODO(charlie): Why do we do this here _and_ in `rule_code_prefix::expand`?
+        let mut rules_by_prefix = BTreeMap::new();
+
+        for (code, (rule, group, attrs)) in rules {
+            // Nursery rules have to be explicitly selected, so we ignore them when looking at
+            // prefixes.
+            if is_nursery(group) {
+                rules_by_prefix.insert(code.clone(), vec![(rule.clone(), attrs.clone())]);
+                continue;
+            }
+
             for i in 1..=code.len() {
                 let prefix = code[..i].to_string();
-                let rules: Vec<_> = map
+                let rules: Vec<_> = rules
                     .iter()
-                    .filter_map(|(code, rules)| {
+                    .filter_map(|(code, (rule, group, attrs))| {
+                        // Nursery rules have to be explicitly selected, so we ignore them when
+                        // looking at prefixes.
+                        if is_nursery(group) {
+                            return None;
+                        }
+
                         if code.starts_with(&prefix) {
-                            Some(rules)
+                            Some((rule.clone(), attrs.clone()))
                         } else {
                             None
                         }
                     })
-                    .cloned()
                     .collect();
-                full_map.insert(prefix, rules);
+                rules_by_prefix.insert(prefix, rules);
             }
         }
 
-        for (code, names) in &full_map {
-            let prefix_ident = get_prefix_ident(code);
-            let attr = match if_all_same(names.iter().map(|(_, attrs)| attrs)) {
+        for (prefix, rules) in &rules_by_prefix {
+            let prefix_ident = get_prefix_ident(prefix);
+            let attr = match if_all_same(rules.iter().map(|(.., attrs)| attrs)) {
                 Some(attr) => quote!(#(#attr)*),
                 None => quote!(),
             };
@@ -117,10 +135,12 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
 
         let mut prefix_into_iter_match_arms = quote!();
 
-        for (code, rules) in full_map {
-            let rule_paths = rules.iter().map(|(path, attrs)| quote!(#(#attrs)* #path));
-            let prefix_ident = get_prefix_ident(&code);
-            let attr = match if_all_same(rules.iter().map(|(_, attrs)| attrs)) {
+        for (prefix, rules) in rules_by_prefix {
+            let rule_paths = rules
+                .iter()
+                .map(|(path, .., attrs)| quote!(#(#attrs)* #path));
+            let prefix_ident = get_prefix_ident(&prefix);
+            let attr = match if_all_same(rules.iter().map(|(.., attrs)| attrs)) {
                 Some(attr) => quote!(#(#attr)*),
                 None => quote!(),
             };
@@ -129,7 +149,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
             });
         }
 
-        out.extend(quote! {
+        output.extend(quote! {
             impl IntoIterator for &#linter {
                 type Item = Rule;
                 type IntoIter = ::std::vec::IntoIter<Self::Item>;
@@ -141,7 +161,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         });
     }
 
-    out.extend(quote! {
+    output.extend(quote! {
         impl IntoIterator for &RuleCodePrefix {
             type Item = Rule;
             type IntoIter = ::std::vec::IntoIter<Self::Item>;
@@ -154,7 +174,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         }
     });
 
-    out.extend(quote! {
+    output.extend(quote! {
         impl RuleCodePrefix {
             pub fn parse(linter: &Linter, code: &str) -> Result<Self, crate::registry::FromCodeError> {
                 use std::str::FromStr;
@@ -166,16 +186,22 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         }
     });
 
+    // Map from rule to codes that can be used to select it.
+    // This abstraction exists to support a one-to-many mapping, whereby a single rule could map
+    // to multiple codes (e.g., if it existed in multiple linters, like Pylint and Flake8, under
+    // different codes). We haven't actually activated this functionality yet, but some work was
+    // done to support it, so the logic exists here.
     #[allow(clippy::type_complexity)]
-    let mut rule_to_codes: HashMap<&Path, Vec<(&Ident, &str, &[Attribute])>> = HashMap::new();
+    let mut rule_to_codes: HashMap<&Path, Vec<(&Ident, &str, &Path, &[Attribute])>> =
+        HashMap::new();
     let mut linter_code_for_rule_match_arms = quote!();
 
-    for (linter, map) in &linters {
-        for (code, (rule, attrs)) in map {
+    for (linter, map) in &linter_to_rules {
+        for (code, (rule, group, attrs)) in map {
             rule_to_codes
                 .entry(rule)
                 .or_default()
-                .push((linter, code, attrs));
+                .push((linter, code, group, attrs));
             linter_code_for_rule_match_arms.extend(quote! {
                 #(#attrs)* (Self::#linter, #rule) => Some(#code),
             });
@@ -183,50 +209,66 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
     }
 
     let mut rule_noqa_code_match_arms = quote!();
+    let mut rule_group_match_arms = quote!();
 
     for (rule, codes) in rule_to_codes {
-        assert!(
-            codes.len() == 1,
+        assert_eq!(
+            codes.len(),
+            1,
             "
-            The mapping of multiple codes to one rule has been disabled due to UX concerns (it would
-            be confusing if violations were reported under a different code than the code you selected).
+{} is mapped to multiple codes.
 
-            We firstly want to allow rules to be selected by their names (and report them by name),
-            and before we can do that we have to rename all our rules to match our naming convention
-            (see CONTRIBUTING.md) because after that change every rule rename will be a breaking change.
+The mapping of multiple codes to one rule has been disabled due to UX concerns (it would
+be confusing if violations were reported under a different code than the code you selected).
 
-            See also https://github.com/charliermarsh/ruff/issues/2186.
+We firstly want to allow rules to be selected by their names (and report them by name),
+and before we can do that we have to rename all our rules to match our naming convention
+(see CONTRIBUTING.md) because after that change every rule rename will be a breaking change.
 
-            (this was triggered by {} being mapped to multiple codes)
-            ",
+See also https://github.com/charliermarsh/ruff/issues/2186.
+",
             rule.segments.last().unwrap().ident
         );
 
-        let (linter, code, attrs) = codes
+        let (linter, code, group, attrs) = codes
             .iter()
-            .sorted_by_key(|(l, ..)| *l == "Pylint") // TODO: more sophisticated sorting
+            .sorted_by_key(|(l, ..)| *l == "Pylint")
             .next()
             .unwrap();
 
         rule_noqa_code_match_arms.extend(quote! {
             #(#attrs)* #rule => NoqaCode(crate::registry::Linter::#linter.common_prefix(), #code),
         });
+
+        rule_group_match_arms.extend(quote! {
+            #(#attrs)* #rule => #group,
+        });
     }
 
-    out.extend(quote! {
-        impl crate::registry::Rule {
+    output.extend(quote! {
+        impl Rule {
             pub fn noqa_code(&self) -> NoqaCode {
                 use crate::registry::RuleNamespace;
 
                 match self {
                     #rule_noqa_code_match_arms
-                    // TODO: support rules without codes
-                    // rule => rule.as_ref()
                 }
             }
+
+            pub fn group(&self) -> RuleGroup {
+                use crate::registry::RuleNamespace;
+
+                match self {
+                    #rule_group_match_arms
+                }
+            }
+
+            pub fn is_nursery(&self) -> bool {
+                matches!(self.group(), RuleGroup::Nursery)
+            }
         }
 
-        impl crate::registry::Linter {
+        impl Linter {
             pub fn code_for_rule(&self, rule: Rule) -> Option<&'static str> {
                 match (self, rule) {
                     #linter_code_for_rule_match_arms
@@ -237,16 +279,17 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
     });
 
     let mut linter_into_iter_match_arms = quote!();
-    for (linter, map) in &linters {
-        let rule_paths = map.values().map(|(path, attrs)| quote!(#(#attrs)* #path));
+    for (linter, map) in &linter_to_rules {
+        let rule_paths = map
+            .values()
+            .map(|(path, .., attrs)| quote!(#(#attrs)* #path));
         linter_into_iter_match_arms.extend(quote! {
-            crate::registry::Linter::#linter => vec![#(#rule_paths,)*].into_iter(),
+            Linter::#linter => vec![#(#rule_paths,)*].into_iter(),
         });
     }
 
-    out.extend(quote! {
-
-        impl IntoIterator for &crate::registry::Linter {
+    output.extend(quote! {
+        impl IntoIterator for &Linter {
             type Item = Rule;
             type IntoIter = ::std::vec::IntoIter<Self::Item>;
 
@@ -259,7 +302,7 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
 
     });
 
-    out.extend(quote! {
+    output.extend(quote! {
         impl RuleCodePrefix {
             pub fn iter() -> ::std::vec::IntoIter<RuleCodePrefix> {
                 vec![ #(#all_codes,)* ].into_iter()
@@ -267,18 +310,19 @@ pub(crate) fn map_codes(func: &ItemFn) -> syn::Result<TokenStream> {
         }
     });
 
-    Ok(out)
+    Ok(output)
 }
 
 struct Entry {
     linter: Ident,
     code: LitStr,
+    group: Path,
     rule: Path,
     attrs: Vec<Attribute>,
 }
 
 impl Parse for Entry {
-    /// Parses a match arm such as `(Pycodestyle, "E101") => Rule::MixedSpacesAndTabs,`
+    /// Parses a match arm such as `(Pycodestyle, "E112") => (RuleGroup::Nursery, Rule::NoIndentedBlock),`
     fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
         let attrs = Attribute::parse_outer(input)?;
         let pat_tuple;
@@ -287,11 +331,16 @@ impl Parse for Entry {
         let _: Token!(,) = pat_tuple.parse()?;
         let code: LitStr = pat_tuple.parse()?;
         let _: Token!(=>) = input.parse()?;
-        let rule: Path = input.parse()?;
+        let pat_tuple;
+        parenthesized!(pat_tuple in input);
+        let group: Path = pat_tuple.parse()?;
+        let _: Token!(,) = pat_tuple.parse()?;
+        let rule: Path = pat_tuple.parse()?;
         let _: Token!(,) = input.parse()?;
         Ok(Entry {
             linter,
             code,
+            group,
             rule,
             attrs,
         })

crates/ruff_macros/src/rule_code_prefix.rs

@@ -2,35 +2,34 @@ use std::collections::{BTreeMap, BTreeSet};
 
 use proc_macro2::Span;
 use quote::quote;
-use syn::{Attribute, Ident};
-
-pub(crate) fn get_prefix_ident(prefix: &str) -> Ident {
-    let prefix = if prefix.as_bytes()[0].is_ascii_digit() {
-        // Identifiers in Rust may not start with a number.
-        format!("_{prefix}")
-    } else {
-        prefix.to_string()
-    };
-    Ident::new(&prefix, Span::call_site())
-}
+use syn::{Attribute, Ident, Path};
 
 pub(crate) fn expand<'a>(
     prefix_ident: &Ident,
-    variants: impl Iterator<Item = (&'a str, &'a Vec<Attribute>)>,
+    variants: impl Iterator<Item = (&'a str, &'a Path, &'a Vec<Attribute>)>,
 ) -> proc_macro2::TokenStream {
     // Build up a map from prefix to matching RuleCodes.
     let mut prefix_to_codes: BTreeMap<String, BTreeSet<String>> = BTreeMap::default();
     let mut code_to_attributes: BTreeMap<String, &[Attribute]> = BTreeMap::default();
 
-    for (variant, attr) in variants {
+    for (variant, group, attr) in variants {
         let code_str = variant.to_string();
-        for i in 1..=code_str.len() {
-            let prefix = code_str[..i].to_string();
+        // Nursery rules have to be explicitly selected, so we ignore them when looking at prefixes.
+        if is_nursery(group) {
             prefix_to_codes
-                .entry(prefix)
+                .entry(code_str.clone())
                 .or_default()
                 .insert(code_str.clone());
+        } else {
+            for i in 1..=code_str.len() {
+                let prefix = code_str[..i].to_string();
+                prefix_to_codes
+                    .entry(prefix)
+                    .or_default()
+                    .insert(code_str.clone());
+            }
         }
+
         code_to_attributes.insert(code_str, attr);
     }
 
@@ -115,3 +114,25 @@ pub(crate) fn if_all_same<T: PartialEq>(iter: impl Iterator<Item = T>) -> Option
         None
     }
 }
+
+/// Returns an identifier for the given prefix.
+pub(crate) fn get_prefix_ident(prefix: &str) -> Ident {
+    let prefix = if prefix.as_bytes()[0].is_ascii_digit() {
+        // Identifiers in Rust may not start with a number.
+        format!("_{prefix}")
+    } else {
+        prefix.to_string()
+    };
+    Ident::new(&prefix, Span::call_site())
+}
+
+/// Returns true if the given group is the "nursery" group.
+pub(crate) fn is_nursery(group: &Path) -> bool {
+    let group = group
+        .segments
+        .iter()
+        .map(|segment| segment.ident.to_string())
+        .collect::<Vec<String>>()
+        .join("::");
+    group == "RuleGroup::Nursery"
+}

ruff.schema.json

@@ -1688,7 +1688,6 @@
         "E1",
         "E10",
         "E101",
-        "E11",
         "E111",
         "E112",
         "E113",
@@ -1696,14 +1695,10 @@
         "E115",
         "E116",
         "E117",
-        "E2",
-        "E20",
         "E201",
         "E202",
         "E203",
-        "E21",
         "E211",
-        "E22",
         "E221",
         "E222",
         "E223",
@@ -1712,17 +1707,13 @@
         "E226",
         "E227",
         "E228",
-        "E23",
         "E231",
-        "E25",
         "E251",
         "E252",
-        "E26",
         "E261",
         "E262",
         "E265",
         "E266",
-        "E27",
         "E271",
         "E272",
         "E273",

scripts/add_rule.py

@@ -181,9 +181,10 @@ pub fn {rule_name_snake}(checker: &mut Checker) {{}}
         while (line := next(fp)).strip() != "":
             lines.append(line)
 
-        linter_variant = pascal_case(linter)
+        variant = pascal_case(linter)
         lines.append(
-            " " * 8 + f"""({linter_variant}, "{code}") => Rule::{name},\n""",
+            " " * 8
+            + f"""({variant}, "{code}") => (RuleGroup::Unspecified, Rule::{name}),\n""",
         )
         lines.sort()
 

scripts/pyproject.toml

@@ -11,13 +11,12 @@ line-length = 88
 line-length = 88
 select = ["ALL"]
 ignore = [
-  "C901", # McCabe complexity
-  "PL",   # pylint
-  "S",    # bandit
-  "G",    # flake8-logging
-  "T",    # flake8-print
-  "FBT",  # flake8-boolean-trap
-  "E203",
+  "C901",  # McCabe complexity
+  "PL",    # pylint
+  "S",     # bandit
+  "G",     # flake8-logging
+  "T",     # flake8-print
+  "FBT",   # flake8-boolean-trap
 ]
 
 [tool.ruff.pydocstyle]