Add ruff rules-json subcommand

crates/ruff_cli/src/args.rs

@@ -45,6 +45,8 @@ pub enum Command {
         #[arg(long, value_enum, default_value = "text")]
         format: HelpFormat,
     },
+    /// Print a JSON document explaining all of the rules known to Ruff.
+    RulesJSON,
     /// List or describe the available configuration options
     Config { option: Option<String> },
     /// List all supported upstream linters

crates/ruff_cli/src/commands/mod.rs

@@ -3,6 +3,7 @@ pub(crate) mod clean;
 pub(crate) mod config;
 pub(crate) mod linter;
 pub(crate) mod rule;
+pub(crate) mod rules_json;
 pub(crate) mod run;
 pub(crate) mod run_stdin;
 pub(crate) mod show_files;

crates/ruff_cli/src/commands/rules_json.rs

@@ -0,0 +1,47 @@
+//! Generate a JSON file describing supported lint rules.
+//! NB: the format may change in the future.
+
+use anyhow::Error;
+use std::io::{stdout, Write};
+
+use serde::ser::{SerializeMap, Serializer};
+
+use serde_json::json;
+
+use strum::IntoEnumIterator;
+
+use ruff::registry::{Linter, RuleNamespace};
+use ruff_diagnostics::AutofixKind;
+
+fn write_rules_json(writer: &mut dyn Write) -> Result<(), Error> {
+    let mut ser = serde_json::Serializer::pretty(writer);
+    let mut map = ser.serialize_map(None)?;
+    for linter in Linter::iter() {
+        for rule in &linter {
+            let code = format!(
+                "{}{}",
+                linter.common_prefix(),
+                linter.code_for_rule(rule).unwrap()
+            );
+            let fixable = match rule.autofixable() {
+                AutofixKind::Sometimes => "sometimes",
+                AutofixKind::Always => "always",
+                AutofixKind::None => "none",
+            };
+            let value = json!({
+                "name": rule.as_ref(),
+                "message": rule.message_formats()[0],
+                "explanation": rule.explanation(),
+                "fixable": fixable,
+                "linter": linter.name(),
+            });
+            map.serialize_entry(&code, &value)?;
+        }
+    }
+    map.end()?;
+    Ok(())
+}
+
+pub(crate) fn rules_json() -> Result<(), Error> {
+    write_rules_json(&mut stdout())
+}

crates/ruff_cli/src/lib.rs

@@ -113,6 +113,7 @@ quoting the executed command, along with the relevant file contents and `pyproje
 
     match command {
         Command::Rule { rule, format } => commands::rule::rule(rule, format)?,
+        Command::RulesJSON => commands::rules_json::rules_json()?,
         Command::Config { option } => return Ok(commands::config::config(option.as_deref())),
         Command::Linter { format } => commands::linter::linter(format)?,
         Command::Clean => commands::clean::clean(log_level)?,

docs/configuration.md

@@ -162,12 +162,13 @@ Ruff: An extremely fast Python linter.
 Usage: ruff [OPTIONS] <COMMAND>
 
 Commands:
-  check   Run Ruff on the given files or directories (default)
-  rule    Explain a rule
-  config  List or describe the available configuration options
-  linter  List all supported upstream linters
-  clean   Clear any caches in the current directory and any subdirectories
-  help    Print this message or the help of the given subcommand(s)
+  check       Run Ruff on the given files or directories (default)
+  rule        Explain a rule
+  rules-json  Print a JSON document explaining all of the rules known to Ruff
+  config      List or describe the available configuration options
+  linter      List all supported upstream linters
+  clean       Clear any caches in the current directory and any subdirectories
+  help        Print this message or the help of the given subcommand(s)
 
 Options:
   -h, --help     Print help