rule 5/8: Remove FromStr impl for Rule

Cargo.lock

@@ -1951,6 +1951,7 @@ dependencies = [
  "strum_macros",
  "test-case",
  "textwrap",
+ "thiserror",
  "titlecase",
  "toml_edit",
  "wasm-bindgen",

Cargo.toml

@@ -61,6 +61,7 @@ strum_macros = { version = "0.24.3" }
 textwrap = { version = "0.16.0" }
 titlecase = { version = "2.2.1" }
 toml_edit = { version = "0.17.1", features = ["easy"] }
+thiserror = { version = "1.0" }
 
 # https://docs.rs/getrandom/0.2.7/getrandom/#webassembly-support
 # For (future) wasm-pack support

ruff_cli/src/cli.rs

@@ -4,7 +4,7 @@ use clap::{command, Parser};
 use regex::Regex;
 use ruff::fs;
 use ruff::logging::LogLevel;
-use ruff::registry::{RuleCode, RuleCodePrefix};
+use ruff::registry::{Rule, RuleCodePrefix};
 use ruff::resolver::ConfigProcessor;
 use ruff::settings::types::{
     FilePattern, PatternPrefixPair, PerFileIgnore, PythonVersion, SerializationFormat,
@@ -169,6 +169,7 @@ pub struct Cli {
     /// Explain a rule.
     #[arg(
         long,
+        value_parser=Rule::from_code,
         // Fake subcommands.
         conflicts_with = "add_noqa",
         conflicts_with = "clean",
@@ -180,7 +181,7 @@ pub struct Cli {
         conflicts_with = "stdin_filename",
         conflicts_with = "watch",
     )]
-    pub explain: Option<RuleCode>,
+    pub explain: Option<Rule>,
     /// Generate shell completion
     #[arg(
         long,
@@ -302,7 +303,7 @@ pub struct Arguments {
     pub config: Option<PathBuf>,
     pub diff: bool,
     pub exit_zero: bool,
-    pub explain: Option<RuleCode>,
+    pub explain: Option<Rule>,
     pub files: Vec<PathBuf>,
     pub generate_shell_completion: Option<clap_complete_command::Shell>,
     pub isolated: bool,

ruff_cli/src/main.rs

@@ -157,8 +157,8 @@ quoting the executed command, along with the relevant file contents and `pyproje
         PyprojectDiscovery::Hierarchical(settings) => settings.cli.clone(),
     };
 
-    if let Some(code) = cli.explain {
-        commands::explain(&code, format)?;
+    if let Some(rule) = cli.explain {
+        commands::explain(&rule, format)?;
         return Ok(ExitCode::SUCCESS);
     }
     if cli.show_settings {

ruff_macros/src/define_rule_mapping.rs

@@ -9,6 +9,7 @@ pub fn define_rule_mapping(mapping: &Mapping) -> proc_macro2::TokenStream {
     let mut rule_kind_match_arms = quote!();
     let mut rule_origin_match_arms = quote!();
     let mut rule_code_match_arms = quote!();
+    let mut rule_from_code_match_arms = quote!();
     let mut diagkind_code_match_arms = quote!();
     let mut diagkind_body_match_arms = quote!();
     let mut diagkind_fixable_match_arms = quote!();
@@ -25,6 +26,7 @@ pub fn define_rule_mapping(mapping: &Mapping) -> proc_macro2::TokenStream {
         rule_origin_match_arms.extend(quote! {Self::#code => RuleOrigin::#origin,});
         let code_str = LitStr::new(&code.to_string(), Span::call_site());
         rule_code_match_arms.extend(quote! {Self::#code => #code_str,});
+        rule_from_code_match_arms.extend(quote! {#code_str => Ok(&RuleCode::#code), });
         diagkind_code_match_arms.extend(quote! {Self::#name(..) => &RuleCode::#code, });
         diagkind_body_match_arms.extend(quote! {Self::#name(x) => Violation::message(x), });
         diagkind_fixable_match_arms
@@ -49,7 +51,6 @@ pub fn define_rule_mapping(mapping: &Mapping) -> proc_macro2::TokenStream {
     quote! {
         #[derive(
             EnumIter,
-            EnumString,  // TODO(martin): Remove
             Debug,
             PartialEq,
             Eq,
@@ -67,6 +68,11 @@ pub fn define_rule_mapping(mapping: &Mapping) -> proc_macro2::TokenStream {
         #[derive(AsRefStr, Debug, PartialEq, Eq, Serialize, Deserialize)]
         pub enum DiagnosticKind { #diagkind_variants }
 
+        #[derive(thiserror::Error, Debug)]
+        pub enum FromCodeError {
+            #[error("unknown rule code")]
+            Unknown,
+        }
 
         impl Rule {
             /// A placeholder representation of the `DiagnosticKind` for the diagnostic.
@@ -81,6 +87,13 @@ pub fn define_rule_mapping(mapping: &Mapping) -> proc_macro2::TokenStream {
             pub fn code(&self) -> &'static str {
                 match self { #rule_code_match_arms }
             }
+
+            pub fn from_code(code: &str) -> Result<&'static Self, FromCodeError> {
+                match code {
+                    #rule_from_code_match_arms
+                    _ => Err(FromCodeError::Unknown),
+                }
+            }
         }
 
 

src/checkers/noqa.rs

@@ -1,14 +1,12 @@
 //! `NoQA` enforcement and validation.
 
-use std::str::FromStr;
-
 use nohash_hasher::IntMap;
 use rustpython_parser::ast::Location;
 
 use crate::ast::types::Range;
 use crate::fix::Fix;
 use crate::noqa::{is_file_exempt, Directive};
-use crate::registry::{Diagnostic, DiagnosticKind, RuleCode, CODE_REDIRECTS};
+use crate::registry::{Diagnostic, DiagnosticKind, Rule, RuleCode, CODE_REDIRECTS};
 use crate::settings::{flags, Settings};
 use crate::violations::UnusedCodes;
 use crate::{noqa, violations};
@@ -134,8 +132,8 @@ pub fn check_noqa(
                         if matches.contains(&code) || settings.external.contains(code) {
                             valid_codes.push(code);
                         } else {
-                            if let Ok(rule_code) = RuleCode::from_str(code) {
-                                if settings.rules.enabled(&rule_code) {
+                            if let Ok(rule) = Rule::from_code(code) {
+                                if settings.rules.enabled(rule) {
                                     unmatched_codes.push(code);
                                 } else {
                                     disabled_codes.push(code);

src/registry.rs

@@ -5,7 +5,7 @@ use once_cell::sync::Lazy;
 use rustc_hash::FxHashMap;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
-use strum_macros::{AsRefStr, EnumIter, EnumString};
+use strum_macros::{AsRefStr, EnumIter};
 
 use crate::ast::types::Range;
 use crate::fix::Fix;
@@ -712,8 +712,6 @@ pub static CODE_REDIRECTS: Lazy<FxHashMap<&'static str, RuleCode>> = Lazy::new(|
 
 #[cfg(test)]
 mod tests {
-    use std::str::FromStr;
-
     use strum::IntoEnumIterator;
 
     use crate::registry::Rule;
@@ -722,7 +720,7 @@ mod tests {
     fn check_code_serialization() {
         for rule in Rule::iter() {
             assert!(
-                Rule::from_str(rule.code()).is_ok(),
+                Rule::from_code(rule.code()).is_ok(),
                 "{rule:?} could not be round-trip serialized."
             );
         }