Add rendering of rule markdown for terminal output (#2747)

Add rendering of rule markdown for terminal output
    
This is achieved by making use of the `mdcat` crate.
    
See the following links for details:
    
- https://crates.io/crates/mdcat
- https://github.com/swsnr/mdcat
- https://docs.rs/mdcat/latest/mdcat/

crates/ruff/src/registry.rs

@@ -896,7 +896,7 @@ mod tests {
         for rule in Rule::iter() {
             let code = rule.code();
             let (linter, rest) =
-                Linter::parse_code(code).unwrap_or_else(|| panic!("couldn't parse {:?}", code));
+                Linter::parse_code(code).unwrap_or_else(|| panic!("couldn't parse {code:?}"));
             assert_eq!(code, format!("{}{rest}", linter.common_prefix()));
         }
     }

crates/ruff/src/rules/pylint/rules/bad_str_strip_call.rs

@@ -94,7 +94,7 @@ fn has_duplicates(s: &str) -> bool {
     for ch in s.chars() {
         if escaped {
             escaped = false;
-            let pair = format!("\\{}", ch);
+            let pair = format!("\\{ch}");
             if !seen.insert(pair) {
                 return true;
             }

crates/ruff/src/source_code/generator.rs

@@ -915,7 +915,7 @@ impl<'a> Generator<'a> {
             }
             Constant::None => self.p("None"),
             Constant::Bool(b) => self.p(if *b { "True" } else { "False" }),
-            Constant::Int(i) => self.p(&format!("{}", i)),
+            Constant::Int(i) => self.p(&format!("{i}")),
             Constant::Tuple(tup) => {
                 if let [elt] = &**tup {
                     self.p("(");

crates/ruff_cli/Cargo.toml

@@ -41,8 +41,10 @@ glob = { version = "0.3.0" }
 ignore = { version = "0.4.18" }
 itertools = { version = "0.10.5" }
 log = { version = "0.4.17" }
+mdcat = { version = "1.0.0", default-features = false }
 notify = { version = "5.0.0" }
 path-absolutize = { version = "3.0.14", features = ["once_cell_cache"] }
+pulldown-cmark = { version = "0.9.2", default-features = false, features = ['simd'] }
 quick-junit = { version = "0.3.2" }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
@@ -50,9 +52,10 @@ rustc-hash = { version = "1.1.0" }
 serde = { version = "1.0.147", features = ["derive"] }
 serde_json = { version = "1.0.87" }
 similar = { version = "2.2.1" }
+strum = { version = "0.24.1" }
+syntect = { version = "5.0.0", default-features = false, features = ["parsing", "regex-fancy", "default-themes", "default-syntaxes"] }
 textwrap = { version = "0.16.0" }
 walkdir = { version = "2.3.2" }
-strum = "0.24.1"
 
 [dev-dependencies]
 assert_cmd = { version = "2.0.4" }

crates/ruff_cli/src/args.rs

@@ -41,7 +41,7 @@ pub enum Command {
         rule: Rule,
 
         /// Output format
-        #[arg(long, value_enum, default_value = "text")]
+        #[arg(long, value_enum, default_value = "markdown")]
         format: HelpFormat,
     },
     /// List all supported upstream linters
@@ -284,6 +284,7 @@ pub struct CheckArgs {
 pub enum HelpFormat {
     Text,
     Json,
+    Markdown,
 }
 
 #[allow(clippy::module_name_repetitions)]

crates/ruff_cli/src/commands.rs

@@ -4,11 +4,15 @@ use std::path::{Path, PathBuf};
 use std::time::Instant;
 
 use anyhow::{bail, Result};
+use colored::control::SHOULD_COLORIZE;
 use colored::Colorize;
 use ignore::Error;
 use itertools::Itertools;
 use log::{debug, error};
+use mdcat::terminal::{TerminalProgram, TerminalSize};
+use mdcat::{Environment, ResourceAccess, Settings};
 use path_absolutize::path_dedot;
+use pulldown_cmark::{Options, Parser};
 #[cfg(not(target_family = "wasm"))]
 use rayon::prelude::*;
 use ruff::cache::CACHE_DIR_NAME;
@@ -20,6 +24,7 @@ use ruff::resolver::PyprojectDiscovery;
 use ruff::settings::flags;
 use ruff::{fix, fs, packaging, resolver, warn_user_once, AutofixAvailability, IOError};
 use serde::Serialize;
+use syntect::parsing::SyntaxSet;
 use walkdir::WalkDir;
 
 use crate::args::{HelpFormat, Overrides};
@@ -281,9 +286,10 @@ struct Explanation<'a> {
 pub fn rule(rule: &Rule, format: HelpFormat) -> Result<()> {
     let (linter, _) = Linter::parse_code(rule.code()).unwrap();
     let mut stdout = BufWriter::new(io::stdout().lock());
-    match format {
-        HelpFormat::Text => {
     let mut output = String::new();
+
+    match format {
+        HelpFormat::Text | HelpFormat::Markdown => {
             output.push_str(&format!("# {} ({})", rule.as_ref(), rule.code()));
             output.push('\n');
             output.push('\n');
@@ -308,22 +314,46 @@ pub fn rule(rule: &Rule, format: HelpFormat) -> Result<()> {
                 output.push_str("Message formats:");
                 for format in rule.message_formats() {
                     output.push('\n');
-                    output.push_str(&format!("* {}", format));
+                    output.push_str(&format!("* {format}"));
                 }
             }
-
-            writeln!(stdout, "{}", output)?;
         }
         HelpFormat::Json => {
-            writeln!(
+            output.push_str(&serde_json::to_string_pretty(&Explanation {
-                stdout,
-                "{}",
-                serde_json::to_string_pretty(&Explanation {
                 code: rule.code(),
                 linter: linter.name(),
                 summary: rule.message_formats()[0],
-                })?
+            })?);
-            )?;
+        }
+    };
+
+    match format {
+        HelpFormat::Json | HelpFormat::Text => {
+            writeln!(stdout, "{output}")?;
+        }
+        HelpFormat::Markdown => {
+            let parser = Parser::new_ext(
+                &output,
+                Options::ENABLE_TASKLISTS | Options::ENABLE_STRIKETHROUGH,
+            );
+
+            let cwd = std::env::current_dir()?;
+            let env = &Environment::for_local_directory(&cwd)?;
+
+            let terminal = if SHOULD_COLORIZE.should_colorize() {
+                TerminalProgram::detect()
+            } else {
+                TerminalProgram::Dumb
+            };
+
+            let settings = &Settings {
+                resource_access: ResourceAccess::LocalOnly,
+                syntax_set: SyntaxSet::load_defaults_newlines(),
+                terminal_capabilities: terminal.capabilities(),
+                terminal_size: TerminalSize::detect().unwrap_or_default(),
+            };
+
+            mdcat::push_tty(settings, env, &mut stdout, parser)?;
         }
     };
     Ok(())

crates/ruff_cli/src/commands/linter.rs

@@ -47,6 +47,30 @@ pub fn linter(format: HelpFormat) {
                 println!("{}", serde_json::to_string_pretty(&linters).unwrap());
             }
         }
+
+        HelpFormat::Markdown => {
+            #[allow(clippy::print_stdout)]
+            {
+                println!("| {:>6} | {:<27} |", "Prefix", "Name");
+                println!("| {:>6} | {:<27} |", "------", "-".repeat(27));
+            }
+            for linter in Linter::iter() {
+                let prefix = match linter.common_prefix() {
+                    "" => linter
+                        .upstream_categories()
+                        .unwrap()
+                        .iter()
+                        .map(|UpstreamCategory(prefix, ..)| prefix.as_ref())
+                        .join("/"),
+                    prefix => prefix.to_string(),
+                };
+
+                #[allow(clippy::print_stdout)]
+                {
+                    println!("| {:>6} | {:<27} |", prefix, linter.name());
+                }
+            }
+        }
     }
 }
 

crates/ruff_dev/src/generate_docs.rs

@@ -40,7 +40,7 @@ pub fn main(args: &Args) -> Result<()> {
             output.push_str(explanation.trim());
 
             if args.dry_run {
-                println!("{}", output);
+                println!("{output}");
             } else {
                 fs::create_dir_all("docs/rules")?;
                 fs::write(format!("docs/rules/{}.md", rule.as_ref()), output)?;