Implement a --show-source setting (#698)

Cargo.toml

@@ -13,6 +13,7 @@ edition = "2021"
 name = "ruff"
 
 [dependencies]
+annotate-snippets = { version = "0.9.1", features = ["color"] }
 anyhow = { version = "1.0.66" }
 atty = { version = "0.2.14" }
 bincode = { version = "1.3.3" }

README.md

@@ -191,7 +191,7 @@ ruff path/to/code/ --select F401 --select F403
 See `ruff --help` for more:
 
 ```shell
-ruff: An extremely fast Python linter.
+Ruff: An extremely fast Python linter.
 
 Usage: ruff [OPTIONS] <FILES>...
 
@@ -231,10 +231,12 @@ Options:
           List of mappings from file pattern to code to exclude
       --format <FORMAT>
           Output serialization format for error messages [default: text] [possible values: text, json]
+      --show-source
+          Show violations with source code
       --show-files
-          See the files ruff will be run against with the current settings
+          See the files Ruff will be run against with the current settings
       --show-settings
-          See ruff's settings
+          See Ruff's settings
       --add-noqa
           Enable automatic additions of noqa directives to failing lines
       --dummy-variable-rgx <DUMMY_VARIABLE_RGX>
@@ -244,7 +246,7 @@ Options:
       --line-length <LINE_LENGTH>
           Set the line-length for length-associated checks and automatic formatting
       --max-complexity <MAX_COMPLEXITY>
-          Set the maximum cyclomatic complexity for complexity-associated checks
+          Max McCabe complexity allowed for a function
       --stdin-filename <STDIN_FILENAME>
           The name of the file when passing it through stdin
   -h, --help

flake8_to_ruff/src/converter.rs

@@ -259,6 +259,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: None,
@@ -295,6 +296,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: None,
@@ -331,6 +333,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: None,
@@ -367,6 +370,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: None,
@@ -403,6 +407,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: Some(flake8_quotes::settings::Options {
@@ -482,6 +487,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: None,
@@ -519,6 +525,7 @@ mod tests {
             per_file_ignores: None,
             dummy_variable_rgx: None,
             target_version: None,
+            show_source: None,
             flake8_annotations: None,
             flake8_bugbear: None,
             flake8_quotes: Some(flake8_quotes::settings::Options {

src/cli.rs

@@ -13,7 +13,7 @@ use crate::settings::configuration::Configuration;
 use crate::settings::types::{PatternPrefixPair, PerFileIgnore, PythonVersion};
 
 #[derive(Debug, Parser)]
-#[command(author, about = "ruff: An extremely fast Python linter.")]
+#[command(author, about = "Ruff: An extremely fast Python linter.")]
 #[command(version)]
 pub struct Cli {
     #[arg(required = true)]
@@ -72,10 +72,13 @@ pub struct Cli {
     /// Output serialization format for error messages.
     #[arg(long, value_enum, default_value_t=SerializationFormat::Text)]
     pub format: SerializationFormat,
-    /// See the files ruff will be run against with the current settings.
+    /// Show violations with source code.
+    #[arg(long)]
+    pub show_source: bool,
+    /// See the files Ruff will be run against with the current settings.
     #[arg(long)]
     pub show_files: bool,
-    /// See ruff's settings.
+    /// See Ruff's settings.
     #[arg(long)]
     pub show_settings: bool,
     /// Enable automatic additions of noqa directives to failing lines.

src/linter.rs

@@ -22,7 +22,7 @@ use crate::check_tokens::check_tokens;
 use crate::checks::{Check, CheckCode, CheckKind, LintSource};
 use crate::code_gen::SourceGenerator;
 use crate::directives::Directives;
-use crate::message::Message;
+use crate::message::{Message, Source};
 use crate::noqa::add_noqa;
 use crate::settings::Settings;
 use crate::source_code_locator::SourceCodeLocator;
@@ -176,7 +176,15 @@ pub fn lint_stdin(
     // Convert to messages.
     Ok(checks
         .into_iter()
-        .map(|check| Message::from_check(path.to_string_lossy().to_string(), check))
+        .map(|check| {
+            let filename = path.to_string_lossy().to_string();
+            let source = if settings.show_source {
+                Some(Source::from_check(&check, &locator))
+            } else {
+                None
+            };
+            Message::from_check(check, filename, source)
+        })
         .collect())
 }
 
@@ -233,7 +241,15 @@ pub fn lint_path(
     // Convert to messages.
     let messages: Vec<Message> = checks
         .into_iter()
-        .map(|check| Message::from_check(path.to_string_lossy().to_string(), check))
+        .map(|check| {
+            let filename = path.to_string_lossy().to_string();
+            let source = if settings.show_source {
+                Some(Source::from_check(&check, &locator))
+            } else {
+                None
+            };
+            Message::from_check(check, filename, source)
+        })
         .collect();
     #[cfg(not(target_family = "wasm"))]
     cache::set(path, &metadata, settings, autofix, &messages, mode);

src/main.rs

@@ -117,6 +117,7 @@ fn run_once(
                             location: Default::default(),
                             end_location: Default::default(),
                             filename: path.to_string_lossy().to_string(),
+                            source: None,
                         }]
                     } else {
                         error!("Failed to check {}: {message}", path.to_string_lossy());
@@ -281,6 +282,9 @@ fn inner_main() -> Result<ExitCode> {
     if let Some(fix) = fix {
         configuration.fix = fix;
     }
+    if cli.show_source {
+        configuration.show_source = true;
+    }
 
     if cli.show_settings && cli.show_files {
         eprintln!("Error: specify --show-settings or show-files (not both).");

src/message.rs

@@ -2,12 +2,16 @@ use std::cmp::Ordering;
 use std::fmt;
 use std::path::Path;
 
+use annotate_snippets::display_list::{DisplayList, FormatOptions};
+use annotate_snippets::snippet::{Annotation, AnnotationType, Slice, Snippet, SourceAnnotation};
 use colored::Colorize;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
 
+use crate::ast::types::Range;
 use crate::checks::{Check, CheckKind};
 use crate::fs::relativize_path;
+use crate::source_code_locator::SourceCodeLocator;
 
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Message {
@@ -16,16 +20,18 @@ pub struct Message {
     pub location: Location,
     pub end_location: Location,
     pub filename: String,
+    pub source: Option<Source>,
 }
 
 impl Message {
-    pub fn from_check(filename: String, check: Check) -> Self {
+    pub fn from_check(check: Check, filename: String, source: Option<Source>) -> Self {
         Self {
             kind: check.kind,
             fixed: check.fix.map(|fix| fix.applied).unwrap_or_default(),
             location: Location::new(check.location.row(), check.location.column() + 1),
             end_location: Location::new(check.end_location.row(), check.end_location.column() + 1),
             filename,
+            source,
         }
     }
 }
@@ -48,8 +54,7 @@ impl PartialOrd for Message {
 
 impl fmt::Display for Message {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(
-            f,
+        let label = format!(
             "{}{}{}{}{}{} {} {}",
             relativize_path(Path::new(&self.filename)).white().bold(),
             ":".cyan(),
@@ -58,7 +63,71 @@ impl fmt::Display for Message {
             self.location.column(),
             ":".cyan(),
             self.kind.code().as_ref().red().bold(),
-            self.kind.body()
-        )
+            self.kind.body(),
+        );
+        match &self.source {
+            None => write!(f, "{}", label),
+            Some(source) => {
+                let snippet = Snippet {
+                    title: Some(Annotation {
+                        label: Some(&label),
+                        annotation_type: AnnotationType::Error,
+                        // The ID (error number) is already encoded in the `label`.
+                        id: None,
+                    }),
+                    footer: vec![],
+                    slices: vec![Slice {
+                        source: &source.contents,
+                        line_start: self.location.row(),
+                        annotations: vec![SourceAnnotation {
+                            label: self.kind.code().as_ref(),
+                            annotation_type: AnnotationType::Error,
+                            range: source.range,
+                        }],
+                        // The origin (file name, line number, and column number) is already encoded
+                        // in the `label`.
+                        origin: None,
+                        fold: false,
+                    }],
+                    opt: FormatOptions {
+                        color: true,
+                        ..Default::default()
+                    },
+                };
+                // `split_once(' ')` strips "error: " from `message`.
+                let message = DisplayList::from(snippet).to_string();
+                let (_, message) = message.split_once(' ').unwrap();
+                write!(f, "{}", message)
+            }
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Source {
+    pub contents: String,
+    pub range: (usize, usize),
+}
+
+impl Source {
+    pub fn from_check(check: &Check, locator: &SourceCodeLocator) -> Self {
+        let source = locator.slice_source_code_range(&Range {
+            location: Location::new(check.location.row(), 0),
+            end_location: Location::new(check.end_location.row() + 1, 0),
+        });
+        let num_chars_in_range = locator
+            .slice_source_code_range(&Range {
+                location: check.location,
+                end_location: check.end_location,
+            })
+            .chars()
+            .count();
+        Source {
+            contents: source.to_string(),
+            range: (
+                check.location.column(),
+                check.location.column() + num_chars_in_range,
+            ),
+        }
     }
 }

src/settings/configuration.rs

@@ -31,6 +31,7 @@ pub struct Configuration {
     pub select: Vec<CheckCodePrefix>,
     pub src: Vec<PathBuf>,
     pub target_version: PythonVersion,
+    pub show_source: bool,
     // Plugins
     pub flake8_annotations: flake8_annotations::settings::Settings,
     pub flake8_bugbear: flake8_bugbear::settings::Settings,
@@ -134,6 +135,7 @@ impl Configuration {
                         .collect()
                 })
                 .unwrap_or_default(),
+            show_source: options.show_source.unwrap_or_default(),
             // Plugins
             flake8_annotations: options
                 .flake8_annotations