Remove E999 as a rule, disallow any disablement methods for syntax error (#11901)

## Summary

This PR updates the way syntax errors are handled throughout the linter.

The main change is that it's now not considered as a rule which involves
the following changes:
* Update `Message` to be an enum with two variants - one for diagnostic
message and the other for syntax error message
* Provide methods on the new message enum to query information required
by downstream usages

This means that the syntax errors cannot be hidden / disabled via any
disablement methods. These are:
1. Configuration via `select`, `ignore`, `per-file-ignores`, and their
`extend-*` variants
	```console
$ cargo run -- check ~/playground/ruff/src/lsp.py --extend-select=E999
--no-preview --no-cache
	    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.10s
Running `target/debug/ruff check /Users/dhruv/playground/ruff/src/lsp.py
--extend-select=E999 --no-preview --no-cache`
warning: Rule `E999` is deprecated and will be removed in a future
release. Syntax errors will always be shown regardless of whether this
rule is selected or not.
/Users/dhruv/playground/ruff/src/lsp.py:1:8: F401 [*] `abc` imported but
unused
	  |
	1 | import abc
	  |        ^^^ F401
	2 | from pathlib import Path
	3 | import os
	  |
	  = help: Remove unused import: `abc`
	```
3. Command-line flags via `--select`, `--ignore`, `--per-file-ignores`,
and their `--extend-*` variants
	```console
$ cargo run -- check ~/playground/ruff/src/lsp.py --no-cache
--config=~/playground/ruff/pyproject.toml
	    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.11s
Running `target/debug/ruff check /Users/dhruv/playground/ruff/src/lsp.py
--no-cache --config=/Users/dhruv/playground/ruff/pyproject.toml`
warning: Rule `E999` is deprecated and will be removed in a future
release. Syntax errors will always be shown regardless of whether this
rule is selected or not.
/Users/dhruv/playground/ruff/src/lsp.py:1:8: F401 [*] `abc` imported but
unused
	  |
	1 | import abc
	  |        ^^^ F401
	2 | from pathlib import Path
	3 | import os
	  |
	  = help: Remove unused import: `abc`
	```

This also means that the **output format** needs to be updated:
1. The `code`, `noqa_row`, `url` fields in the JSON output is optional
(`null` for syntax errors)
2. Other formats are changed accordingly
For each format, a new test case specific to syntax errors have been
added. Please refer to the snapshot output for the exact format for
syntax error message.

The output of the `--statistics` flag will have a blank entry for syntax
errors:
```
315     F821    [ ] undefined-name
119             [ ] syntax-error
103     F811    [ ] redefined-while-unused
```

The **language server** is updated to consider the syntax errors by
convert them into LSP diagnostic format separately.

### Preview

There are no quick fixes provided to disable syntax errors. This will
automatically work for `ruff-lsp` because the `noqa_row` field will be
`null` in that case.
<img width="772" alt="Screenshot 2024-06-26 at 14 57 08"
src="aaac827e-4777-4ac8-8c68-eaf9f2c36774">

Even with `noqa` comment, the syntax error is displayed:
<img width="763" alt="Screenshot 2024-06-26 at 14 59 51"
src="ba1afb68-7eaf-4b44-91af-6d93246475e2">

Rule documentation page:
<img width="1371" alt="Screenshot 2024-06-26 at 16 48 07"
src="524f01df-d91f-4ac0-86cc-40e76b318b24">


## Test Plan

- [x] Disablement methods via config shows a warning
	- [x] `select`, `extend-select`
	- [ ] ~`ignore`~ _doesn't show any message_
- [ ] ~`per-file-ignores`, `extend-per-file-ignores`~ _doesn't show any
message_
- [x] Disablement methods via command-line flag shows a warning
	- [x] `--select`, `--extend-select`
	- [ ] ~`--ignore`~ _doesn't show any message_
- [ ] ~`--per-file-ignores`, `--extend-per-file-ignores`~ _doesn't show
any message_
- [x] File with syntax errors should exit with code 1
- [x] Language server
	- [x] Should show diagnostics for syntax errors
	- [x] Should not recommend a quick fix edit for adding `noqa` comment
	- [x] Same for `ruff-lsp`

resolves: #8447

crates/ruff/src/cache.rs

@@ -19,7 +19,7 @@ use tempfile::NamedTempFile;
 
 use ruff_cache::{CacheKey, CacheKeyHasher};
 use ruff_diagnostics::{DiagnosticKind, Fix};
-use ruff_linter::message::Message;
+use ruff_linter::message::{DiagnosticMessage, Message};
 use ruff_linter::{warn_user, VERSION};
 use ruff_macros::CacheKey;
 use ruff_notebook::NotebookIndex;
@@ -333,13 +333,15 @@ impl FileCache {
                 let file = SourceFileBuilder::new(path.to_string_lossy(), &*lint.source).finish();
                 lint.messages
                     .iter()
-                    .map(|msg| Message {
+                    .map(|msg| {
+                        Message::Diagnostic(DiagnosticMessage {
                             kind: msg.kind.clone(),
                             range: msg.range,
                             fix: msg.fix.clone(),
                             file: file.clone(),
                             noqa_offset: msg.noqa_offset,
                         })
+                    })
                     .collect()
             };
             let notebook_indexes = if let Some(notebook_index) = lint.notebook_index.as_ref() {
@@ -412,18 +414,19 @@ impl LintCacheData {
         notebook_index: Option<NotebookIndex>,
     ) -> Self {
         let source = if let Some(msg) = messages.first() {
-            msg.file.source_text().to_owned()
+            msg.source_file().source_text().to_owned()
         } else {
             String::new() // No messages, no need to keep the source!
         };
 
         let messages = messages
             .iter()
+            .filter_map(|message| message.as_diagnostic_message())
             .map(|msg| {
                 // Make sure that all message use the same source file.
                 assert_eq!(
-                    msg.file,
+                    &msg.file,
-                    messages.first().unwrap().file,
+                    messages.first().unwrap().source_file(),
                     "message uses a different source file"
                 );
                 CacheMessage {
@@ -571,6 +574,7 @@ mod tests {
     use test_case::test_case;
 
     use ruff_cache::CACHE_DIR_NAME;
+    use ruff_linter::message::Message;
     use ruff_linter::settings::flags;
     use ruff_linter::settings::types::UnsafeFixes;
     use ruff_python_ast::PySourceType;
@@ -633,11 +637,7 @@ mod tests {
                     UnsafeFixes::Enabled,
                 )
                 .unwrap();
-                if diagnostics
+                if diagnostics.messages.iter().any(Message::is_syntax_error) {
-                    .messages
-                    .iter()
-                    .any(|m| m.kind.name == "SyntaxError")
-                {
                     parse_errors.push(path.clone());
                 }
                 paths.push(path);

crates/ruff/src/diagnostics.rs

@@ -10,18 +10,18 @@ use std::path::Path;
 use anyhow::{Context, Result};
 use colored::Colorize;
 use log::{debug, error, warn};
+use ruff_linter::codes::Rule;
 use rustc_hash::FxHashMap;
 
 use ruff_diagnostics::Diagnostic;
 use ruff_linter::linter::{lint_fix, lint_only, FixTable, FixerResult, LinterResult, ParseSource};
 use ruff_linter::logging::DisplayParseError;
-use ruff_linter::message::Message;
+use ruff_linter::message::{Message, SyntaxErrorMessage};
 use ruff_linter::pyproject_toml::lint_pyproject_toml;
-use ruff_linter::registry::AsRule;
 use ruff_linter::settings::types::UnsafeFixes;
 use ruff_linter::settings::{flags, LinterSettings};
 use ruff_linter::source_kind::{SourceError, SourceKind};
-use ruff_linter::{fs, IOError, SyntaxError};
+use ruff_linter::{fs, IOError};
 use ruff_notebook::{Notebook, NotebookError, NotebookIndex};
 use ruff_python_ast::{PySourceType, SourceType, TomlSourceType};
 use ruff_source_file::SourceFileBuilder;
@@ -55,37 +55,22 @@ impl Diagnostics {
         path: Option<&Path>,
         settings: &LinterSettings,
     ) -> Self {
-        let diagnostic = match err {
+        match err {
             // IO errors.
             SourceError::Io(_)
             | SourceError::Notebook(NotebookError::Io(_) | NotebookError::Json(_)) => {
+                if settings.rules.enabled(Rule::IOError) {
+                    let name = path.map_or_else(|| "-".into(), Path::to_string_lossy);
+                    let source_file = SourceFileBuilder::new(name, "").finish();
+                    Self::new(
+                        vec![Message::from_diagnostic(
                             Diagnostic::new(
                                 IOError {
                                     message: err.to_string(),
                                 },
                                 TextRange::default(),
-                )
-            }
-            // Syntax errors.
-            SourceError::Notebook(
-                NotebookError::InvalidJson(_)
-                | NotebookError::InvalidSchema(_)
-                | NotebookError::InvalidFormat(_),
-            ) => Diagnostic::new(
-                SyntaxError {
-                    message: err.to_string(),
-                },
-                TextRange::default(),
                             ),
-        };
+                            source_file,
-
-        if settings.rules.enabled(diagnostic.kind.rule()) {
-            let name = path.map_or_else(|| "-".into(), Path::to_string_lossy);
-            let dummy = SourceFileBuilder::new(name, "").finish();
-            Self::new(
-                vec![Message::from_diagnostic(
-                    diagnostic,
-                    dummy,
                             TextSize::default(),
                         )],
                         FxHashMap::default(),
@@ -108,6 +93,25 @@ impl Diagnostics {
                     Self::default()
                 }
             }
+            // Syntax errors.
+            SourceError::Notebook(
+                NotebookError::InvalidJson(_)
+                | NotebookError::InvalidSchema(_)
+                | NotebookError::InvalidFormat(_),
+            ) => {
+                let name = path.map_or_else(|| "-".into(), Path::to_string_lossy);
+                let dummy = SourceFileBuilder::new(name, "").finish();
+                Self::new(
+                    vec![Message::SyntaxError(SyntaxErrorMessage {
+                        message: err.to_string(),
+                        range: TextRange::default(),
+                        file: dummy,
+                    })],
+                    FxHashMap::default(),
+                )
+            }
+        }
+    }
 }
 
 impl Add for Diagnostics {

crates/ruff/src/printer.rs

@@ -13,11 +13,11 @@ use ruff_linter::fs::relativize_path;
 use ruff_linter::logging::LogLevel;
 use ruff_linter::message::{
     AzureEmitter, Emitter, EmitterContext, GithubEmitter, GitlabEmitter, GroupedEmitter,
-    JsonEmitter, JsonLinesEmitter, JunitEmitter, PylintEmitter, RdjsonEmitter, SarifEmitter,
+    JsonEmitter, JsonLinesEmitter, JunitEmitter, Message, MessageKind, PylintEmitter,
-    TextEmitter,
+    RdjsonEmitter, SarifEmitter, TextEmitter,
 };
 use ruff_linter::notify_user;
-use ruff_linter::registry::{AsRule, Rule};
+use ruff_linter::registry::Rule;
 use ruff_linter::settings::flags::{self};
 use ruff_linter::settings::types::{OutputFormat, UnsafeFixes};
 
@@ -37,12 +37,13 @@ bitflags! {
 
 #[derive(Serialize)]
 struct ExpandedStatistics {
-    code: SerializeRuleAsCode,
+    code: Option<SerializeRuleAsCode>,
-    name: SerializeRuleAsTitle,
+    name: SerializeMessageKindAsTitle,
     count: usize,
     fixable: bool,
 }
 
+#[derive(Copy, Clone)]
 struct SerializeRuleAsCode(Rule);
 
 impl Serialize for SerializeRuleAsCode {
@@ -66,26 +67,26 @@ impl From<Rule> for SerializeRuleAsCode {
     }
 }
 
-struct SerializeRuleAsTitle(Rule);
+struct SerializeMessageKindAsTitle(MessageKind);
 
-impl Serialize for SerializeRuleAsTitle {
+impl Serialize for SerializeMessageKindAsTitle {
     fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
     where
         S: serde::Serializer,
     {
-        serializer.serialize_str(self.0.as_ref())
+        serializer.serialize_str(self.0.as_str())
     }
 }
 
-impl Display for SerializeRuleAsTitle {
+impl Display for SerializeMessageKindAsTitle {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self.0.as_ref())
+        f.write_str(self.0.as_str())
     }
 }
 
-impl From<Rule> for SerializeRuleAsTitle {
+impl From<MessageKind> for SerializeMessageKindAsTitle {
-    fn from(rule: Rule) -> Self {
+    fn from(kind: MessageKind) -> Self {
-        Self(rule)
+        Self(kind)
     }
 }
 
@@ -341,24 +342,23 @@ impl Printer {
         let statistics: Vec<ExpandedStatistics> = diagnostics
             .messages
             .iter()
-            .map(|message| (message.kind.rule(), message.fix.is_some()))
+            .sorted_by_key(|message| (message.rule(), message.fixable()))
-            .sorted()
+            .fold(vec![], |mut acc: Vec<(&Message, usize)>, message| {
-            .fold(vec![], |mut acc, (rule, fixable)| {
+                if let Some((prev_message, count)) = acc.last_mut() {
-                if let Some((prev_rule, _, count)) = acc.last_mut() {
+                    if prev_message.rule() == message.rule() {
-                    if *prev_rule == rule {
                         *count += 1;
                         return acc;
                     }
                 }
-                acc.push((rule, fixable, 1));
+                acc.push((message, 1));
                 acc
             })
             .iter()
-            .map(|(rule, fixable, count)| ExpandedStatistics {
+            .map(|&(message, count)| ExpandedStatistics {
-                code: (*rule).into(),
+                code: message.rule().map(std::convert::Into::into),
-                name: (*rule).into(),
+                name: message.kind().into(),
-                count: *count,
+                count,
-                fixable: *fixable,
+                fixable: message.fixable(),
             })
             .sorted_by_key(|statistic| Reverse(statistic.count))
             .collect();
@@ -381,7 +381,12 @@ impl Printer {
                 );
                 let code_width = statistics
                     .iter()
-                    .map(|statistic| statistic.code.to_string().len())
+                    .map(|statistic| {
+                        statistic
+                            .code
+                            .map_or_else(String::new, |rule| rule.to_string())
+                            .len()
+                    })
                     .max()
                     .unwrap();
                 let any_fixable = statistics.iter().any(|statistic| statistic.fixable);
@@ -395,7 +400,11 @@ impl Printer {
                         writer,
                         "{:>count_width$}\t{:<code_width$}\t{}{}",
                         statistic.count.to_string().bold(),
-                        statistic.code.to_string().red().bold(),
+                        statistic
+                            .code
+                            .map_or_else(String::new, |rule| rule.to_string())
+                            .red()
+                            .bold(),
                         if any_fixable {
                             if statistic.fixable {
                                 &fixable
@@ -545,7 +554,7 @@ impl FixableStatistics {
         let mut unapplicable_unsafe = 0;
 
         for message in &diagnostics.messages {
-            if let Some(fix) = &message.fix {
+            if let Some(fix) = message.fix() {
                 if fix.applies(unsafe_fixes.required_applicability()) {
                     applicable += 1;
                 } else {

crates/ruff/tests/integration_test.rs

@@ -798,10 +798,10 @@ fn stdin_parse_error() {
     success: false
     exit_code: 1
     ----- stdout -----
-    -:1:16: E999 SyntaxError: Expected one or more symbol names after import
+    -:1:16: SyntaxError: Expected one or more symbol names after import
       |
     1 | from foo import
-      |                ^ E999
+      |                ^
       |
 
     Found 1 error.
@@ -819,18 +819,18 @@ fn stdin_multiple_parse_error() {
     success: false
     exit_code: 1
     ----- stdout -----
-    -:1:16: E999 SyntaxError: Expected one or more symbol names after import
+    -:1:16: SyntaxError: Expected one or more symbol names after import
       |
     1 | from foo import
-      |                ^ E999
+      |                ^
     2 | bar =
       |
 
-    -:2:6: E999 SyntaxError: Expected an expression
+    -:2:6: SyntaxError: Expected an expression
       |
     1 | from foo import
     2 | bar =
-      |      ^ E999
+      |      ^
       |
 
     Found 2 errors.
@@ -840,6 +840,50 @@ fn stdin_multiple_parse_error() {
     "###);
 }
 
+#[test]
+fn parse_error_not_included() {
+    // Select any rule except for `E999`, syntax error should still be shown.
+    let mut cmd = RuffCheck::default().args(["--select=I"]).build();
+    assert_cmd_snapshot!(cmd
+        .pass_stdin("foo =\n"), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    -:1:6: SyntaxError: Expected an expression
+      |
+    1 | foo =
+      |      ^
+      |
+
+    Found 1 error.
+
+    ----- stderr -----
+    error: Failed to parse at 1:6: Expected an expression
+    "###);
+}
+
+#[test]
+fn deprecated_parse_error_selection() {
+    let mut cmd = RuffCheck::default().args(["--select=E999"]).build();
+    assert_cmd_snapshot!(cmd
+        .pass_stdin("foo =\n"), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    -:1:6: SyntaxError: Expected an expression
+      |
+    1 | foo =
+      |      ^
+      |
+
+    Found 1 error.
+
+    ----- stderr -----
+    warning: Rule `E999` is deprecated and will be removed in a future release. Syntax errors will always be shown regardless of whether this rule is selected or not.
+    error: Failed to parse at 1:6: Expected an expression
+    "###);
+}
+
 #[test]
 fn full_output_preview() {
     let mut cmd = RuffCheck::default().args(["--preview"]).build();

crates/ruff_linter/resources/test/fixtures/flake8_commas/COM81.py

@@ -510,7 +510,7 @@ image[:,]
 
 image[:,:,]
 
-lambda x, :
+lambda x, : x
 
 # ==> unpack.py <==
 def function(

crates/ruff_linter/resources/test/fixtures/pycodestyle/E999.py

@@ -1,4 +0,0 @@
-
-def x():
-
-

crates/ruff_linter/src/codes.rs

@@ -125,7 +125,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Pycodestyle, "E742") => (RuleGroup::Stable, rules::pycodestyle::rules::AmbiguousClassName),
         (Pycodestyle, "E743") => (RuleGroup::Stable, rules::pycodestyle::rules::AmbiguousFunctionName),
         (Pycodestyle, "E902") => (RuleGroup::Stable, rules::pycodestyle::rules::IOError),
-        (Pycodestyle, "E999") => (RuleGroup::Stable, rules::pycodestyle::rules::SyntaxError),
+        (Pycodestyle, "E999") => (RuleGroup::Deprecated, rules::pycodestyle::rules::SyntaxError),
 
         // pycodestyle warnings
         (Pycodestyle, "W191") => (RuleGroup::Stable, rules::pycodestyle::rules::TabIndentation),

crates/ruff_linter/src/lib.rs

@@ -11,7 +11,7 @@ pub use registry::clap_completion::RuleParser;
 #[cfg(feature = "clap")]
 pub use rule_selector::clap_completion::RuleSelectorParser;
 pub use rule_selector::RuleSelector;
-pub use rules::pycodestyle::rules::{IOError, SyntaxError};
+pub use rules::pycodestyle::rules::IOError;
 
 pub const VERSION: &str = env!("CARGO_PKG_VERSION");
 

crates/ruff_linter/src/linter.rs

@@ -30,7 +30,6 @@ use crate::logging::DisplayParseError;
 use crate::message::Message;
 use crate::noqa::add_noqa;
 use crate::registry::{AsRule, Rule, RuleSet};
-use crate::rules::pycodestyle;
 #[cfg(any(feature = "test-rules", test))]
 use crate::rules::ruff::rules::test_rules::{self, TestRule, TEST_RULES};
 use crate::settings::types::UnsafeFixes;
@@ -85,7 +84,6 @@ pub fn check_path(
 ) -> LinterResult<Vec<Diagnostic>> {
     // Aggregate all diagnostics.
     let mut diagnostics = vec![];
-    let mut error = None;
 
     let tokens = parsed.tokens();
     let comment_ranges = indexer.comment_ranges();
@@ -142,7 +140,8 @@ pub fn check_path(
         ));
     }
 
-    // Run the AST-based rules.
+    // Run the AST-based rules only if there are no syntax errors.
+    if parsed.is_valid() {
         let use_ast = settings
             .rules
             .iter_enabled()
@@ -153,8 +152,6 @@ pub fn check_path(
                 .iter_enabled()
                 .any(|rule_code| rule_code.lint_source().is_imports());
         if use_ast || use_imports || use_doc_lines {
-        match parsed.as_result() {
-            Ok(parsed) => {
             let cell_offsets = source_kind.as_ipy_notebook().map(Notebook::cell_offsets);
             let notebook_index = source_kind.as_ipy_notebook().map(Notebook::index);
             if use_ast {
@@ -192,19 +189,6 @@ pub fn check_path(
                 doc_lines.extend(doc_lines_from_ast(parsed.suite(), locator));
             }
         }
-            Err(parse_errors) => {
-                // Always add a diagnostic for the syntax error, regardless of whether
-                // `Rule::SyntaxError` is enabled. We avoid propagating the syntax error
-                // if it's disabled via any of the usual mechanisms (e.g., `noqa`,
-                // `per-file-ignores`), and the easiest way to detect that suppression is
-                // to see if the diagnostic persists to the end of the function.
-                for parse_error in parse_errors {
-                    pycodestyle::rules::syntax_error(&mut diagnostics, parse_error, locator);
-                }
-                // TODO(dhruvmanila): Remove this clone
-                error = parse_errors.iter().next().cloned();
-            }
-        }
     }
 
     // Deduplicate and reorder any doc lines.
@@ -305,7 +289,7 @@ pub fn check_path(
             locator,
             comment_ranges,
             &directives.noqa_line_for,
-            error.is_none(),
+            parsed.is_valid(),
             &per_file_ignores,
             settings,
         );
@@ -316,23 +300,6 @@ pub fn check_path(
         }
     }
 
-    // If there was a syntax error, check if it should be discarded.
-    if error.is_some() {
-        // If the syntax error was removed by _any_ of the above disablement methods (e.g., a
-        // `noqa` directive, or a `per-file-ignore`), discard it.
-        if !diagnostics
-            .iter()
-            .any(|diagnostic| diagnostic.kind.rule() == Rule::SyntaxError)
-        {
-            error = None;
-        }
-
-        // If the syntax error _diagnostic_ is disabled, discard the _diagnostic_.
-        if !settings.rules.enabled(Rule::SyntaxError) {
-            diagnostics.retain(|diagnostic| diagnostic.kind.rule() != Rule::SyntaxError);
-        }
-    }
-
     // Remove fixes for any rules marked as unfixable.
     for diagnostic in &mut diagnostics {
         if !settings.rules.should_fix(diagnostic.kind.rule()) {
@@ -352,7 +319,7 @@ pub fn check_path(
         }
     }
 
-    LinterResult::new(diagnostics, error)
+    LinterResult::new(diagnostics, parsed.errors().iter().next().cloned())
 }
 
 const MAX_ITERATIONS: usize = 100;
@@ -474,12 +441,15 @@ pub fn lint_only(
         &parsed,
     );
 
-    result.map(|diagnostics| diagnostics_to_messages(diagnostics, path, &locator, &directives))
+    result.map(|diagnostics| {
+        diagnostics_to_messages(diagnostics, parsed.errors(), path, &locator, &directives)
+    })
 }
 
 /// Convert from diagnostics to messages.
 fn diagnostics_to_messages(
     diagnostics: Vec<Diagnostic>,
+    parse_errors: &[ParseError],
     path: &Path,
     locator: &Locator,
     directives: &Directives,
@@ -495,12 +465,13 @@ fn diagnostics_to_messages(
         builder.finish()
     });
 
-    diagnostics
+    parse_errors
-        .into_iter()
+        .iter()
-        .map(|diagnostic| {
+        .map(|parse_error| Message::from_parse_error(parse_error, locator, file.deref().clone()))
+        .chain(diagnostics.into_iter().map(|diagnostic| {
             let noqa_offset = directives.noqa_line_for.resolve(diagnostic.start());
             Message::from_diagnostic(diagnostic, file.deref().clone(), noqa_offset)
-        })
+        }))
         .collect()
 }
 
@@ -609,7 +580,7 @@ pub fn lint_fix<'a>(
 
         return Ok(FixerResult {
             result: result.map(|diagnostics| {
-                diagnostics_to_messages(diagnostics, path, &locator, &directives)
+                diagnostics_to_messages(diagnostics, parsed.errors(), path, &locator, &directives)
             }),
             transformed,
             fixed,

crates/ruff_linter/src/message/azure.rs

@@ -3,7 +3,6 @@ use std::io::Write;
 use ruff_source_file::SourceLocation;
 
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::AsRule;
 
 /// Generate error logging commands for Azure Pipelines format.
 /// See [documentation](https://learn.microsoft.com/en-us/azure/devops/pipelines/scripts/logging-commands?view=azure-devops&tabs=bash#logissue-log-an-error-or-warning)
@@ -29,12 +28,14 @@ impl Emitter for AzureEmitter {
             writeln!(
                 writer,
                 "##vso[task.logissue type=error\
-                        ;sourcepath={filename};linenumber={line};columnnumber={col};code={code};]{body}",
+                        ;sourcepath={filename};linenumber={line};columnnumber={col};{code}]{body}",
                 filename = message.filename(),
                 line = location.row,
                 col = location.column,
-                code = message.kind.rule().noqa_code(),
+                code = message
-                body = message.kind.body,
+                    .rule()
+                    .map_or_else(String::new, |rule| format!("code={};", rule.noqa_code())),
+                body = message.body(),
             )?;
         }
 
@@ -46,7 +47,9 @@ impl Emitter for AzureEmitter {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::AzureEmitter;
 
     #[test]
@@ -56,4 +59,12 @@ mod tests {
 
         assert_snapshot!(content);
     }
+
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = AzureEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
 }

crates/ruff_linter/src/message/diff.rs

@@ -27,8 +27,8 @@ pub(super) struct Diff<'a> {
 
 impl<'a> Diff<'a> {
     pub(crate) fn from_message(message: &'a Message) -> Option<Diff> {
-        message.fix.as_ref().map(|fix| Diff {
+        message.fix().map(|fix| Diff {
-            source_code: &message.file,
+            source_code: message.source_file(),
             fix,
         })
     }

crates/ruff_linter/src/message/github.rs

@@ -4,7 +4,6 @@ use ruff_source_file::SourceLocation;
 
 use crate::fs::relativize_path;
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::AsRule;
 
 /// Generate error workflow command in GitHub Actions format.
 /// See: [GitHub documentation](https://docs.github.com/en/actions/reference/workflow-commands-for-github-actions#setting-an-error-message)
@@ -32,9 +31,8 @@ impl Emitter for GithubEmitter {
 
             write!(
                 writer,
-                "::error title=Ruff \
+                "::error title=Ruff{code},file={file},line={row},col={column},endLine={end_row},endColumn={end_column}::",
-                         ({code}),file={file},line={row},col={column},endLine={end_row},endColumn={end_column}::",
+                code = message.rule().map_or_else(String::new, |rule| format!(" ({})", rule.noqa_code())),
-                code = message.kind.rule().noqa_code(),
                 file = message.filename(),
                 row = source_location.row,
                 column = source_location.column,
@@ -42,15 +40,19 @@ impl Emitter for GithubEmitter {
                 end_column = end_location.column,
             )?;
 
-            writeln!(
+            write!(
                 writer,
-                "{path}:{row}:{column}: {code} {body}",
+                "{path}:{row}:{column}:",
                 path = relativize_path(message.filename()),
                 row = location.row,
                 column = location.column,
-                code = message.kind.rule().noqa_code(),
-                body = message.kind.body,
             )?;
+
+            if let Some(rule) = message.rule() {
+                write!(writer, " {}", rule.noqa_code())?;
+            }
+
+            writeln!(writer, " {}", message.body())?;
         }
 
         Ok(())
@@ -61,7 +63,9 @@ impl Emitter for GithubEmitter {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::GithubEmitter;
 
     #[test]
@@ -71,4 +75,12 @@ mod tests {
 
         assert_snapshot!(content);
     }
+
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = GithubEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
 }

crates/ruff_linter/src/message/gitlab.rs

@@ -9,7 +9,6 @@ use serde_json::json;
 
 use crate::fs::{relativize_path, relativize_path_to};
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::AsRule;
 
 /// Generate JSON with violations in GitLab CI format
 //  https://docs.gitlab.com/ee/ci/testing/code_quality.html#implement-a-custom-tool
@@ -91,8 +90,14 @@ impl Serialize for SerializedMessages<'_> {
             }
             fingerprints.insert(message_fingerprint);
 
+            let description = if let Some(rule) = message.rule() {
+                format!("({}) {}", rule.noqa_code(), message.body())
+            } else {
+                message.body().to_string()
+            };
+
             let value = json!({
-                "description": format!("({}) {}", message.kind.rule().noqa_code(), message.kind.body),
+                "description": description,
                 "severity": "major",
                 "fingerprint": format!("{:x}", message_fingerprint),
                 "location": {
@@ -110,18 +115,10 @@ impl Serialize for SerializedMessages<'_> {
 
 /// Generate a unique fingerprint to identify a violation.
 fn fingerprint(message: &Message, project_path: &str, salt: u64) -> u64 {
-    let Message {
-        kind,
-        range: _,
-        fix: _fix,
-        file: _,
-        noqa_offset: _,
-    } = message;
-
     let mut hasher = DefaultHasher::new();
 
     salt.hash(&mut hasher);
-    kind.name.hash(&mut hasher);
+    message.name().hash(&mut hasher);
     project_path.hash(&mut hasher);
 
     hasher.finish()
@@ -131,7 +128,9 @@ fn fingerprint(message: &Message, project_path: &str, salt: u64) -> u64 {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::GitlabEmitter;
 
     #[test]
@@ -142,6 +141,14 @@ mod tests {
         assert_snapshot!(redact_fingerprint(&content));
     }
 
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = GitlabEmitter::default();
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(redact_fingerprint(&content));
+    }
+
     // Redact the fingerprint because the default hasher isn't stable across platforms.
     fn redact_fingerprint(content: &str) -> String {
         static FINGERPRINT_HAY_KEY: &str = r#""fingerprint": ""#;

crates/ruff_linter/src/message/grouped.rs

@@ -205,7 +205,9 @@ impl std::fmt::Write for PadAdapter<'_> {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::GroupedEmitter;
     use crate::settings::types::UnsafeFixes;
 
@@ -217,6 +219,14 @@ mod tests {
         assert_snapshot!(content);
     }
 
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = GroupedEmitter::default();
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
+
     #[test]
     fn show_source() {
         let mut emitter = GroupedEmitter::default().with_show_source(true);

crates/ruff_linter/src/message/json.rs

@@ -10,7 +10,6 @@ use ruff_source_file::{OneIndexed, SourceCode, SourceLocation};
 use ruff_text_size::Ranged;
 
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::AsRule;
 
 #[derive(Default)]
 pub struct JsonEmitter;
@@ -50,20 +49,22 @@ impl Serialize for ExpandedMessages<'_> {
 }
 
 pub(crate) fn message_to_json_value(message: &Message, context: &EmitterContext) -> Value {
-    let source_code = message.file.to_source_code();
+    let source_code = message.source_file().to_source_code();
     let notebook_index = context.notebook_index(message.filename());
 
-    let fix = message.fix.as_ref().map(|fix| {
+    let fix = message.fix().map(|fix| {
         json!({
             "applicability": fix.applicability(),
-            "message": message.kind.suggestion.as_deref(),
+            "message": message.suggestion(),
             "edits": &ExpandedEdits { edits: fix.edits(), source_code: &source_code, notebook_index },
         })
     });
 
     let mut start_location = source_code.source_location(message.start());
     let mut end_location = source_code.source_location(message.end());
-    let mut noqa_location = source_code.source_location(message.noqa_offset);
+    let mut noqa_location = message
+        .noqa_offset()
+        .map(|offset| source_code.source_location(offset));
     let mut notebook_cell_index = None;
 
     if let Some(notebook_index) = notebook_index {
@@ -74,19 +75,19 @@ pub(crate) fn message_to_json_value(message: &Message, context: &EmitterContext)
         );
         start_location = notebook_index.translate_location(&start_location);
         end_location = notebook_index.translate_location(&end_location);
-        noqa_location = notebook_index.translate_location(&noqa_location);
+        noqa_location = noqa_location.map(|location| notebook_index.translate_location(&location));
     }
 
     json!({
-        "code": message.kind.rule().noqa_code().to_string(),
+        "code": message.rule().map(|rule| rule.noqa_code().to_string()),
-        "url": message.kind.rule().url(),
+        "url": message.rule().and_then(|rule| rule.url()),
-        "message": message.kind.body,
+        "message": message.body(),
         "fix": fix,
         "cell": notebook_cell_index,
         "location": start_location,
         "end_location": end_location,
         "filename": message.filename(),
-        "noqa_row": noqa_location.row
+        "noqa_row": noqa_location.map(|location| location.row)
     })
 }
 
@@ -170,7 +171,7 @@ mod tests {
 
     use crate::message::tests::{
         capture_emitter_notebook_output, capture_emitter_output, create_messages,
-        create_notebook_messages,
+        create_notebook_messages, create_syntax_error_messages,
     };
     use crate::message::JsonEmitter;
 
@@ -182,6 +183,14 @@ mod tests {
         assert_snapshot!(content);
     }
 
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = JsonEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
+
     #[test]
     fn notebook_output() {
         let mut emitter = JsonEmitter;

crates/ruff_linter/src/message/json_lines.rs

@@ -29,7 +29,7 @@ mod tests {
     use crate::message::json_lines::JsonLinesEmitter;
     use crate::message::tests::{
         capture_emitter_notebook_output, capture_emitter_output, create_messages,
-        create_notebook_messages,
+        create_notebook_messages, create_syntax_error_messages,
     };
 
     #[test]
@@ -40,6 +40,14 @@ mod tests {
         assert_snapshot!(content);
     }
 
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = JsonLinesEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
+
     #[test]
     fn notebook_output() {
         let mut emitter = JsonLinesEmitter;

crates/ruff_linter/src/message/junit.rs

@@ -8,7 +8,6 @@ use ruff_source_file::SourceLocation;
 use crate::message::{
     group_messages_by_filename, Emitter, EmitterContext, Message, MessageWithLocation,
 };
-use crate::registry::AsRule;
 
 #[derive(Default)]
 pub struct JunitEmitter;
@@ -44,7 +43,7 @@ impl Emitter for JunitEmitter {
                         start_location,
                     } = message;
                     let mut status = TestCaseStatus::non_success(NonSuccessKind::Failure);
-                    status.set_message(message.kind.body.clone());
+                    status.set_message(message.body());
                     let location = if context.is_notebook(message.filename()) {
                         // We can't give a reasonable location for the structured formats,
                         // so we show one that's clearly a fallback
@@ -57,10 +56,14 @@ impl Emitter for JunitEmitter {
                         "line {row}, col {col}, {body}",
                         row = location.row,
                         col = location.column,
-                        body = message.kind.body
+                        body = message.body()
                     ));
                     let mut case = TestCase::new(
-                        format!("org.ruff.{}", message.kind.rule().noqa_code()),
+                        if let Some(rule) = message.rule() {
+                            format!("org.ruff.{}", rule.noqa_code())
+                        } else {
+                            "org.ruff".to_string()
+                        },
                         status,
                     );
                     let file_path = Path::new(filename);
@@ -88,7 +91,9 @@ impl Emitter for JunitEmitter {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::JunitEmitter;
 
     #[test]
@@ -98,4 +103,12 @@ mod tests {
 
         assert_snapshot!(content);
     }
+
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = JunitEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
 }

crates/ruff_linter/src/message/mod.rs

@@ -14,13 +14,18 @@ pub use json_lines::JsonLinesEmitter;
 pub use junit::JunitEmitter;
 pub use pylint::PylintEmitter;
 pub use rdjson::RdjsonEmitter;
-use ruff_diagnostics::{Diagnostic, DiagnosticKind, Fix};
-use ruff_notebook::NotebookIndex;
-use ruff_source_file::{SourceFile, SourceLocation};
-use ruff_text_size::{Ranged, TextRange, TextSize};
 pub use sarif::SarifEmitter;
 pub use text::TextEmitter;
 
+use ruff_diagnostics::{Diagnostic, DiagnosticKind, Fix};
+use ruff_notebook::NotebookIndex;
+use ruff_python_parser::ParseError;
+use ruff_source_file::{Locator, SourceFile, SourceLocation};
+use ruff_text_size::{Ranged, TextLen, TextRange, TextSize};
+
+use crate::logging::DisplayParseErrorType;
+use crate::registry::{AsRule, Rule};
+
 mod azure;
 mod diff;
 mod github;
@@ -34,8 +39,17 @@ mod rdjson;
 mod sarif;
 mod text;
 
+/// Message represents either a diagnostic message corresponding to a rule violation or a syntax
+/// error message raised by the parser.
 #[derive(Debug, PartialEq, Eq)]
-pub struct Message {
+pub enum Message {
+    Diagnostic(DiagnosticMessage),
+    SyntaxError(SyntaxErrorMessage),
+}
+
+/// A diagnostic message corresponding to a rule violation.
+#[derive(Debug, PartialEq, Eq)]
+pub struct DiagnosticMessage {
     pub kind: DiagnosticKind,
     pub range: TextRange,
     pub fix: Option<Fix>,
@@ -43,37 +57,174 @@ pub struct Message {
     pub noqa_offset: TextSize,
 }
 
+/// A syntax error message raised by the parser.
+#[derive(Debug, PartialEq, Eq)]
+pub struct SyntaxErrorMessage {
+    pub message: String,
+    pub range: TextRange,
+    pub file: SourceFile,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum MessageKind {
+    Diagnostic(Rule),
+    SyntaxError,
+}
+
+impl MessageKind {
+    pub fn as_str(&self) -> &str {
+        match self {
+            MessageKind::Diagnostic(rule) => rule.as_ref(),
+            MessageKind::SyntaxError => "syntax-error",
+        }
+    }
+}
+
 impl Message {
+    /// Create a [`Message`] from the given [`Diagnostic`] corresponding to a rule violation.
     pub fn from_diagnostic(
         diagnostic: Diagnostic,
         file: SourceFile,
         noqa_offset: TextSize,
-    ) -> Self {
+    ) -> Message {
-        Self {
+        Message::Diagnostic(DiagnosticMessage {
             range: diagnostic.range(),
             kind: diagnostic.kind,
             fix: diagnostic.fix,
             file,
             noqa_offset,
+        })
+    }
+
+    /// Create a [`Message`] from the given [`ParseError`].
+    pub fn from_parse_error(
+        parse_error: &ParseError,
+        locator: &Locator,
+        file: SourceFile,
+    ) -> Message {
+        // Try to create a non-empty range so that the diagnostic can print a caret at the right
+        // position. This requires that we retrieve the next character, if any, and take its length
+        // to maintain char-boundaries.
+        let len = locator
+            .after(parse_error.location.start())
+            .chars()
+            .next()
+            .map_or(TextSize::new(0), TextLen::text_len);
+
+        Message::SyntaxError(SyntaxErrorMessage {
+            message: format!(
+                "SyntaxError: {}",
+                DisplayParseErrorType::new(&parse_error.error)
+            ),
+            range: TextRange::at(parse_error.location.start(), len),
+            file,
+        })
+    }
+
+    pub const fn as_diagnostic_message(&self) -> Option<&DiagnosticMessage> {
+        match self {
+            Message::Diagnostic(m) => Some(m),
+            Message::SyntaxError(_) => None,
         }
     }
 
+    /// Returns `true` if `self` is a syntax error message.
+    pub const fn is_syntax_error(&self) -> bool {
+        matches!(self, Message::SyntaxError(_))
+    }
+
+    /// Returns a message kind.
+    pub fn kind(&self) -> MessageKind {
+        match self {
+            Message::Diagnostic(m) => MessageKind::Diagnostic(m.kind.rule()),
+            Message::SyntaxError(_) => MessageKind::SyntaxError,
+        }
+    }
+
+    /// Returns the name used to represent the diagnostic.
+    pub fn name(&self) -> &str {
+        match self {
+            Message::Diagnostic(m) => &m.kind.name,
+            Message::SyntaxError(_) => "SyntaxError",
+        }
+    }
+
+    /// Returns the message body to display to the user.
+    pub fn body(&self) -> &str {
+        match self {
+            Message::Diagnostic(m) => &m.kind.body,
+            Message::SyntaxError(m) => &m.message,
+        }
+    }
+
+    /// Returns the fix suggestion for the violation.
+    pub fn suggestion(&self) -> Option<&str> {
+        match self {
+            Message::Diagnostic(m) => m.kind.suggestion.as_deref(),
+            Message::SyntaxError(_) => None,
+        }
+    }
+
+    /// Returns the offset at which the `noqa` comment will be placed if it's a diagnostic message.
+    pub fn noqa_offset(&self) -> Option<TextSize> {
+        match self {
+            Message::Diagnostic(m) => Some(m.noqa_offset),
+            Message::SyntaxError(_) => None,
+        }
+    }
+
+    /// Returns the [`Fix`] for the message, if there is any.
+    pub fn fix(&self) -> Option<&Fix> {
+        match self {
+            Message::Diagnostic(m) => m.fix.as_ref(),
+            Message::SyntaxError(_) => None,
+        }
+    }
+
+    /// Returns `true` if the message contains a [`Fix`].
+    pub fn fixable(&self) -> bool {
+        self.fix().is_some()
+    }
+
+    /// Returns the [`Rule`] corresponding to the diagnostic message.
+    pub fn rule(&self) -> Option<Rule> {
+        match self {
+            Message::Diagnostic(m) => Some(m.kind.rule()),
+            Message::SyntaxError(_) => None,
+        }
+    }
+
+    /// Returns the filename for the message.
     pub fn filename(&self) -> &str {
-        self.file.name()
+        self.source_file().name()
     }
 
+    /// Computes the start source location for the message.
     pub fn compute_start_location(&self) -> SourceLocation {
-        self.file.to_source_code().source_location(self.start())
+        self.source_file()
+            .to_source_code()
+            .source_location(self.start())
     }
 
+    /// Computes the end source location for the message.
     pub fn compute_end_location(&self) -> SourceLocation {
-        self.file.to_source_code().source_location(self.end())
+        self.source_file()
+            .to_source_code()
+            .source_location(self.end())
+    }
+
+    /// Returns the [`SourceFile`] which the message belongs to.
+    pub fn source_file(&self) -> &SourceFile {
+        match self {
+            Message::Diagnostic(m) => &m.file,
+            Message::SyntaxError(m) => &m.file,
+        }
     }
 }
 
 impl Ord for Message {
     fn cmp(&self, other: &Self) -> Ordering {
-        (&self.file, self.start()).cmp(&(&other.file, other.start()))
+        (self.source_file(), self.start()).cmp(&(other.source_file(), other.start()))
     }
 }
 
@@ -85,7 +236,10 @@ impl PartialOrd for Message {
 
 impl Ranged for Message {
     fn range(&self) -> TextRange {
-        self.range
+        match self {
+            Message::Diagnostic(m) => m.range,
+            Message::SyntaxError(m) => m.range,
+        }
     }
 }
 
@@ -155,11 +309,30 @@ mod tests {
 
     use ruff_diagnostics::{Diagnostic, DiagnosticKind, Edit, Fix};
     use ruff_notebook::NotebookIndex;
-    use ruff_source_file::{OneIndexed, SourceFileBuilder};
+    use ruff_python_parser::{parse_unchecked, Mode};
+    use ruff_source_file::{Locator, OneIndexed, SourceFileBuilder};
     use ruff_text_size::{Ranged, TextRange, TextSize};
 
     use crate::message::{Emitter, EmitterContext, Message};
 
+    pub(super) fn create_syntax_error_messages() -> Vec<Message> {
+        let source = r"from os import
+
+if call(foo
+    def bar():
+        pass
+";
+        let locator = Locator::new(source);
+        let source_file = SourceFileBuilder::new("syntax_errors.py", source).finish();
+        parse_unchecked(source, Mode::Module)
+            .errors()
+            .iter()
+            .map(|parse_error| {
+                Message::from_parse_error(parse_error, &locator, source_file.clone())
+            })
+            .collect()
+    }
+
     pub(super) fn create_messages() -> Vec<Message> {
         let fib = r#"import os
 

crates/ruff_linter/src/message/pylint.rs

@@ -4,7 +4,6 @@ use ruff_source_file::OneIndexed;
 
 use crate::fs::relativize_path;
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::AsRule;
 
 /// Generate violations in Pylint format.
 /// See: [Flake8 documentation](https://flake8.pycqa.org/en/latest/internal/formatters.html#pylint-formatter)
@@ -27,12 +26,20 @@ impl Emitter for PylintEmitter {
                 message.compute_start_location().row
             };
 
+            let body = if let Some(rule) = message.rule() {
+                format!(
+                    "[{code}] {body}",
+                    code = rule.noqa_code(),
+                    body = message.body()
+                )
+            } else {
+                message.body().to_string()
+            };
+
             writeln!(
                 writer,
-                "{path}:{row}: [{code}] {body}",
+                "{path}:{row}: {body}",
                 path = relativize_path(message.filename()),
-                code = message.kind.rule().noqa_code(),
-                body = message.kind.body,
             )?;
         }
 
@@ -44,7 +51,9 @@ impl Emitter for PylintEmitter {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::PylintEmitter;
 
     #[test]
@@ -54,4 +63,12 @@ mod tests {
 
         assert_snapshot!(content);
     }
+
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = PylintEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
 }

crates/ruff_linter/src/message/rdjson.rs

@@ -9,7 +9,6 @@ use ruff_source_file::SourceCode;
 use ruff_text_size::Ranged;
 
 use crate::message::{Emitter, EmitterContext, Message, SourceLocation};
-use crate::registry::AsRule;
 
 #[derive(Default)]
 pub struct RdjsonEmitter;
@@ -58,34 +57,34 @@ impl Serialize for ExpandedMessages<'_> {
 }
 
 fn message_to_rdjson_value(message: &Message) -> Value {
-    let source_code = message.file.to_source_code();
+    let source_code = message.source_file().to_source_code();
 
     let start_location = source_code.source_location(message.start());
     let end_location = source_code.source_location(message.end());
 
-    if let Some(fix) = message.fix.as_ref() {
+    if let Some(fix) = message.fix() {
         json!({
-            "message": message.kind.body,
+            "message": message.body(),
             "location": {
                 "path": message.filename(),
                 "range": rdjson_range(&start_location, &end_location),
             },
             "code": {
-                "value": message.kind.rule().noqa_code().to_string(),
+                "value": message.rule().map(|rule| rule.noqa_code().to_string()),
-                "url": message.kind.rule().url(),
+                "url": message.rule().and_then(|rule| rule.url()),
             },
             "suggestions": rdjson_suggestions(fix.edits(), &source_code),
         })
     } else {
         json!({
-            "message": message.kind.body,
+            "message": message.body(),
             "location": {
                 "path": message.filename(),
                 "range": rdjson_range(&start_location, &end_location),
             },
             "code": {
-                "value": message.kind.rule().noqa_code().to_string(),
+                "value": message.rule().map(|rule| rule.noqa_code().to_string()),
-                "url": message.kind.rule().url(),
+                "url": message.rule().and_then(|rule| rule.url()),
             },
         })
     }
@@ -125,7 +124,9 @@ fn rdjson_range(start: &SourceLocation, end: &SourceLocation) -> Value {
 mod tests {
     use insta::assert_snapshot;
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::RdjsonEmitter;
 
     #[test]
@@ -135,4 +136,12 @@ mod tests {
 
         assert_snapshot!(content);
     }
+
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = RdjsonEmitter;
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
 }

crates/ruff_linter/src/message/sarif.rs

@@ -3,17 +3,16 @@ use std::io::Write;
 use anyhow::Result;
 use serde::{Serialize, Serializer};
 use serde_json::json;
+use strum::IntoEnumIterator;
 
 use ruff_source_file::OneIndexed;
 
 use crate::codes::Rule;
 use crate::fs::normalize_path;
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::{AsRule, Linter, RuleNamespace};
+use crate::registry::{Linter, RuleNamespace};
 use crate::VERSION;
 
-use strum::IntoEnumIterator;
-
 pub struct SarifEmitter;
 
 impl Emitter for SarifEmitter {
@@ -103,7 +102,7 @@ impl Serialize for SarifRule<'_> {
 
 #[derive(Debug)]
 struct SarifResult {
-    rule: Rule,
+    rule: Option<Rule>,
     level: String,
     message: String,
     uri: String,
@@ -120,9 +119,9 @@ impl SarifResult {
         let end_location = message.compute_end_location();
         let path = normalize_path(message.filename());
         Ok(Self {
-            rule: message.kind.rule(),
+            rule: message.rule(),
             level: "error".to_string(),
-            message: message.kind.name.clone(),
+            message: message.name().to_string(),
             uri: url::Url::from_file_path(&path)
                 .map_err(|()| anyhow::anyhow!("Failed to convert path to URL: {}", path.display()))?
                 .to_string(),
@@ -140,9 +139,9 @@ impl SarifResult {
         let end_location = message.compute_end_location();
         let path = normalize_path(message.filename());
         Ok(Self {
-            rule: message.kind.rule(),
+            rule: message.rule(),
             level: "error".to_string(),
-            message: message.kind.name.clone(),
+            message: message.name().to_string(),
             uri: path.display().to_string(),
             start_line: start_location.row,
             start_column: start_location.column,
@@ -175,7 +174,7 @@ impl Serialize for SarifResult {
                     }
                 }
             }],
-            "ruleId": self.rule.noqa_code().to_string(),
+            "ruleId": self.rule.map(|rule| rule.noqa_code().to_string()),
         })
         .serialize(serializer)
     }
@@ -184,7 +183,9 @@ impl Serialize for SarifResult {
 #[cfg(test)]
 mod tests {
 
-    use crate::message::tests::{capture_emitter_output, create_messages};
+    use crate::message::tests::{
+        capture_emitter_output, create_messages, create_syntax_error_messages,
+    };
     use crate::message::SarifEmitter;
 
     fn get_output() -> String {
@@ -198,6 +199,13 @@ mod tests {
         serde_json::from_str::<serde_json::Value>(&content).unwrap();
     }
 
+    #[test]
+    fn valid_syntax_error_json() {
+        let mut emitter = SarifEmitter {};
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+        serde_json::from_str::<serde_json::Value>(&content).unwrap();
+    }
+
     #[test]
     fn test_results() {
         let content = get_output();

crates/ruff_linter/src/message/snapshots/ruff_linter__message__azure__tests__syntax_errors.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff_linter/src/message/azure.rs
+expression: content
+---
+##vso[task.logissue type=error;sourcepath=syntax_errors.py;linenumber=1;columnnumber=15;]SyntaxError: Expected one or more symbol names after import
+##vso[task.logissue type=error;sourcepath=syntax_errors.py;linenumber=3;columnnumber=12;]SyntaxError: Expected ')', found newline

crates/ruff_linter/src/message/snapshots/ruff_linter__message__github__tests__syntax_errors.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff_linter/src/message/github.rs
+expression: content
+---
+::error title=Ruff,file=syntax_errors.py,line=1,col=15,endLine=2,endColumn=1::syntax_errors.py:1:15: SyntaxError: Expected one or more symbol names after import
+::error title=Ruff,file=syntax_errors.py,line=3,col=12,endLine=4,endColumn=1::syntax_errors.py:3:12: SyntaxError: Expected ')', found newline

crates/ruff_linter/src/message/snapshots/ruff_linter__message__gitlab__tests__syntax_errors.snap

@@ -0,0 +1,30 @@
+---
+source: crates/ruff_linter/src/message/gitlab.rs
+expression: redact_fingerprint(&content)
+---
+[
+  {
+    "description": "SyntaxError: Expected one or more symbol names after import",
+    "fingerprint": "<redacted>",
+    "location": {
+      "lines": {
+        "begin": 1,
+        "end": 2
+      },
+      "path": "syntax_errors.py"
+    },
+    "severity": "major"
+  },
+  {
+    "description": "SyntaxError: Expected ')', found newline",
+    "fingerprint": "<redacted>",
+    "location": {
+      "lines": {
+        "begin": 3,
+        "end": 4
+      },
+      "path": "syntax_errors.py"
+    },
+    "severity": "major"
+  }
+]

crates/ruff_linter/src/message/snapshots/ruff_linter__message__grouped__tests__syntax_errors.snap

@@ -0,0 +1,7 @@
+---
+source: crates/ruff_linter/src/message/grouped.rs
+expression: content
+---
+syntax_errors.py:
+  1:15 SyntaxError: Expected one or more symbol names after import
+  3:12 SyntaxError: Expected ')', found newline

crates/ruff_linter/src/message/snapshots/ruff_linter__message__json__tests__syntax_errors.snap

@@ -0,0 +1,40 @@
+---
+source: crates/ruff_linter/src/message/json.rs
+expression: content
+---
+[
+  {
+    "cell": null,
+    "code": null,
+    "end_location": {
+      "column": 1,
+      "row": 2
+    },
+    "filename": "syntax_errors.py",
+    "fix": null,
+    "location": {
+      "column": 15,
+      "row": 1
+    },
+    "message": "SyntaxError: Expected one or more symbol names after import",
+    "noqa_row": null,
+    "url": null
+  },
+  {
+    "cell": null,
+    "code": null,
+    "end_location": {
+      "column": 1,
+      "row": 4
+    },
+    "filename": "syntax_errors.py",
+    "fix": null,
+    "location": {
+      "column": 12,
+      "row": 3
+    },
+    "message": "SyntaxError: Expected ')', found newline",
+    "noqa_row": null,
+    "url": null
+  }
+]

crates/ruff_linter/src/message/snapshots/ruff_linter__message__json_lines__tests__syntax_errors.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff_linter/src/message/json_lines.rs
+expression: content
+---
+{"cell":null,"code":null,"end_location":{"column":1,"row":2},"filename":"syntax_errors.py","fix":null,"location":{"column":15,"row":1},"message":"SyntaxError: Expected one or more symbol names after import","noqa_row":null,"url":null}
+{"cell":null,"code":null,"end_location":{"column":1,"row":4},"filename":"syntax_errors.py","fix":null,"location":{"column":12,"row":3},"message":"SyntaxError: Expected ')', found newline","noqa_row":null,"url":null}

crates/ruff_linter/src/message/snapshots/ruff_linter__message__junit__tests__syntax_errors.snap

@@ -0,0 +1,15 @@
+---
+source: crates/ruff_linter/src/message/junit.rs
+expression: content
+---
+<?xml version="1.0" encoding="UTF-8"?>
+<testsuites name="ruff" tests="2" failures="2" errors="0">
+    <testsuite name="syntax_errors.py" tests="2" disabled="0" errors="0" failures="2" package="org.ruff">
+        <testcase name="org.ruff" classname="syntax_errors" line="1" column="15">
+            <failure message="SyntaxError: Expected one or more symbol names after import">line 1, col 15, SyntaxError: Expected one or more symbol names after import</failure>
+        </testcase>
+        <testcase name="org.ruff" classname="syntax_errors" line="3" column="12">
+            <failure message="SyntaxError: Expected &apos;)&apos;, found newline">line 3, col 12, SyntaxError: Expected &apos;)&apos;, found newline</failure>
+        </testcase>
+    </testsuite>
+</testsuites>

crates/ruff_linter/src/message/snapshots/ruff_linter__message__pylint__tests__syntax_errors.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff_linter/src/message/pylint.rs
+expression: content
+---
+syntax_errors.py:1: SyntaxError: Expected one or more symbol names after import
+syntax_errors.py:3: SyntaxError: Expected ')', found newline

crates/ruff_linter/src/message/snapshots/ruff_linter__message__rdjson__tests__syntax_errors.snap

@@ -0,0 +1,53 @@
+---
+source: crates/ruff_linter/src/message/rdjson.rs
+expression: content
+---
+{
+  "diagnostics": [
+    {
+      "code": {
+        "url": null,
+        "value": null
+      },
+      "location": {
+        "path": "syntax_errors.py",
+        "range": {
+          "end": {
+            "column": 1,
+            "line": 2
+          },
+          "start": {
+            "column": 15,
+            "line": 1
+          }
+        }
+      },
+      "message": "SyntaxError: Expected one or more symbol names after import"
+    },
+    {
+      "code": {
+        "url": null,
+        "value": null
+      },
+      "location": {
+        "path": "syntax_errors.py",
+        "range": {
+          "end": {
+            "column": 1,
+            "line": 4
+          },
+          "start": {
+            "column": 12,
+            "line": 3
+          }
+        }
+      },
+      "message": "SyntaxError: Expected ')', found newline"
+    }
+  ],
+  "severity": "warning",
+  "source": {
+    "name": "ruff",
+    "url": "https://docs.astral.sh/ruff"
+  }
+}

crates/ruff_linter/src/message/snapshots/ruff_linter__message__text__tests__syntax_errors.snap

@@ -0,0 +1,22 @@
+---
+source: crates/ruff_linter/src/message/text.rs
+expression: content
+---
+syntax_errors.py:1:15: SyntaxError: Expected one or more symbol names after import
+  |
+1 | from os import
+  |               ^
+2 | 
+3 | if call(foo
+4 |     def bar():
+  |
+
+syntax_errors.py:3:12: SyntaxError: Expected ')', found newline
+  |
+1 | from os import
+2 | 
+3 | if call(foo
+  |            ^
+4 |     def bar():
+5 |         pass
+  |

crates/ruff_linter/src/message/text.rs

@@ -15,7 +15,6 @@ use crate::fs::relativize_path;
 use crate::line_width::{IndentWidth, LineWidthBuilder};
 use crate::message::diff::Diff;
 use crate::message::{Emitter, EmitterContext, Message};
-use crate::registry::AsRule;
 use crate::settings::types::UnsafeFixes;
 use crate::text_helpers::ShowNonprinting;
 
@@ -146,28 +145,33 @@ pub(super) struct RuleCodeAndBody<'a> {
 
 impl Display for RuleCodeAndBody<'_> {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        let kind = &self.message.kind;
         if self.show_fix_status {
-            if let Some(fix) = self.message.fix.as_ref() {
+            if let Some(fix) = self.message.fix() {
                 // Do not display an indicator for unapplicable fixes
                 if fix.applies(self.unsafe_fixes.required_applicability()) {
+                    if let Some(rule) = self.message.rule() {
+                        write!(f, "{} ", rule.noqa_code().to_string().red().bold())?;
+                    }
                     return write!(
                         f,
-                        "{code} {fix}{body}",
+                        "{fix}{body}",
-                        code = kind.rule().noqa_code().to_string().red().bold(),
                         fix = format_args!("[{}] ", "*".cyan()),
-                        body = kind.body,
+                        body = self.message.body(),
                     );
                 }
             }
         };
 
+        if let Some(rule) = self.message.rule() {
             write!(
                 f,
                 "{code} {body}",
-            code = kind.rule().noqa_code().to_string().red().bold(),
+                code = rule.noqa_code().to_string().red().bold(),
-            body = kind.body,
+                body = self.message.body(),
             )
+        } else {
+            f.write_str(self.message.body())
+        }
     }
 }
 
@@ -178,11 +182,7 @@ pub(super) struct MessageCodeFrame<'a> {
 
 impl Display for MessageCodeFrame<'_> {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
-        let Message {
+        let suggestion = self.message.suggestion();
-            kind, file, range, ..
-        } = self.message;
-
-        let suggestion = kind.suggestion.as_deref();
         let footer = if suggestion.is_some() {
             vec![Annotation {
                 id: None,
@@ -193,9 +193,9 @@ impl Display for MessageCodeFrame<'_> {
             Vec::new()
         };
 
-        let source_code = file.to_source_code();
+        let source_code = self.message.source_file().to_source_code();
 
-        let content_start_index = source_code.line_index(range.start());
+        let content_start_index = source_code.line_index(self.message.start());
         let mut start_index = content_start_index.saturating_sub(2);
 
         // If we're working with a Jupyter Notebook, skip the lines which are
@@ -218,7 +218,7 @@ impl Display for MessageCodeFrame<'_> {
             start_index = start_index.saturating_add(1);
         }
 
-        let content_end_index = source_code.line_index(range.end());
+        let content_end_index = source_code.line_index(self.message.end());
         let mut end_index = content_end_index
             .saturating_add(2)
             .min(OneIndexed::from_zero_indexed(source_code.line_count()));
@@ -249,7 +249,7 @@ impl Display for MessageCodeFrame<'_> {
 
         let source = replace_whitespace(
             source_code.slice(TextRange::new(start_offset, end_offset)),
-            range - start_offset,
+            self.message.range() - start_offset,
         );
 
         let source_text = source.text.show_nonprinting();
@@ -260,7 +260,10 @@ impl Display for MessageCodeFrame<'_> {
 
         let char_length = source.text[source.annotation_range].chars().count();
 
-        let label = kind.rule().noqa_code().to_string();
+        let label = self
+            .message
+            .rule()
+            .map_or_else(String::new, |rule| rule.noqa_code().to_string());
 
         let snippet = Snippet {
             title: None,
@@ -356,7 +359,7 @@ mod tests {
 
     use crate::message::tests::{
         capture_emitter_notebook_output, capture_emitter_output, create_messages,
-        create_notebook_messages,
+        create_notebook_messages, create_syntax_error_messages,
     };
     use crate::message::TextEmitter;
     use crate::settings::types::UnsafeFixes;
@@ -401,4 +404,12 @@ mod tests {
 
         assert_snapshot!(content);
     }
+
+    #[test]
+    fn syntax_errors() {
+        let mut emitter = TextEmitter::default().with_show_source(true);
+        let content = capture_emitter_output(&mut emitter, &create_syntax_error_messages());
+
+        assert_snapshot!(content);
+    }
 }

crates/ruff_linter/src/noqa.rs

@@ -1063,7 +1063,7 @@ mod tests {
 
     use crate::generate_noqa_edits;
     use crate::noqa::{add_noqa_inner, Directive, NoqaMapping, ParsedFileExemption};
-    use crate::rules::pycodestyle::rules::AmbiguousVariableName;
+    use crate::rules::pycodestyle::rules::{AmbiguousVariableName, UselessSemicolon};
     use crate::rules::pyflakes::rules::UnusedVariable;
     use crate::rules::pyupgrade::rules::PrintfStringFormatting;
 
@@ -1380,4 +1380,36 @@ print(
             ))]
         );
     }
+
+    #[test]
+    fn syntax_error() {
+        let path = Path::new("/tmp/foo.txt");
+        let source = "\
+foo;
+bar =
+";
+        let diagnostics = [Diagnostic::new(
+            UselessSemicolon,
+            TextRange::new(4.into(), 5.into()),
+        )];
+        let noqa_line_for = NoqaMapping::default();
+        let comment_ranges = CommentRanges::default();
+        let edits = generate_noqa_edits(
+            path,
+            &diagnostics,
+            &Locator::new(source),
+            &comment_ranges,
+            &[],
+            &noqa_line_for,
+            LineEnding::Lf,
+        );
+        assert_eq!(
+            edits,
+            vec![Some(Edit::replacement(
+                "  # noqa: E703\n".to_string(),
+                4.into(),
+                5.into()
+            ))]
+        );
+    }
 }

crates/ruff_linter/src/rules/flake8_commas/snapshots/ruff_linter__rules__flake8_commas__tests__COM81.py.snap

@@ -601,7 +601,7 @@ COM81.py:511:10: COM819 [*] Trailing comma prohibited
 511 | image[:,:,]
     |          ^ COM819
 512 | 
-513 | lambda x, :
+513 | lambda x, : x
     |
     = help: Remove trailing comma
 
@@ -612,14 +612,14 @@ COM81.py:511:10: COM819 [*] Trailing comma prohibited
 511     |-image[:,:,]
     511 |+image[:,:]
 512 512 | 
-513 513 | lambda x, :
+513 513 | lambda x, : x
 514 514 | 
 
 COM81.py:513:9: COM819 [*] Trailing comma prohibited
     |
 511 | image[:,:,]
 512 | 
-513 | lambda x, :
+513 | lambda x, : x
     |         ^ COM819
 514 | 
 515 | # ==> unpack.py <==
@@ -630,8 +630,8 @@ COM81.py:513:9: COM819 [*] Trailing comma prohibited
 510 510 | 
 511 511 | image[:,:,]
 512 512 | 
-513     |-lambda x, :
+513     |-lambda x, : x
-    513 |+lambda x :
+    513 |+lambda x : x
 514 514 | 
 515 515 | # ==> unpack.py <==
 516 516 | def function(
@@ -798,6 +798,14 @@ COM81.py:565:13: COM812 [*] Trailing comma missing
 567 567 | 
 568 568 | (
 
+COM81.py:569:5: SyntaxError: Starred expression cannot be used here
+    |
+568 | (
+569 |     *args
+    |     ^
+570 | )
+    |
+
 COM81.py:573:10: COM812 [*] Trailing comma missing
     |
 572 | {

crates/ruff_linter/src/rules/pycodestyle/mod.rs

@@ -50,7 +50,6 @@ mod tests {
     #[test_case(Rule::NoneComparison, Path::new("E711.py"))]
     #[test_case(Rule::NotInTest, Path::new("E713.py"))]
     #[test_case(Rule::NotIsTest, Path::new("E714.py"))]
-    #[test_case(Rule::SyntaxError, Path::new("E999.py"))]
     #[test_case(Rule::TabIndentation, Path::new("W19.py"))]
     #[test_case(Rule::TrailingWhitespace, Path::new("W29.py"))]
     #[test_case(Rule::TrailingWhitespace, Path::new("W291.py"))]

crates/ruff_linter/src/rules/pycodestyle/rules/errors.rs

@@ -1,11 +1,5 @@
-use ruff_python_parser::ParseError;
+use ruff_diagnostics::Violation;
-use ruff_text_size::{TextLen, TextRange, TextSize};
-
-use ruff_diagnostics::{Diagnostic, Violation};
 use ruff_macros::{derive_message_formats, violation};
-use ruff_source_file::Locator;
-
-use crate::logging::DisplayParseErrorType;
 
 /// ## What it does
 /// This is not a regular diagnostic; instead, it's raised when a file cannot be read
@@ -43,6 +37,10 @@ impl Violation for IOError {
     }
 }
 
+/// ## Deprecated
+/// This rule has been deprecated and will be removed in a future release. Syntax errors will
+/// always be shown regardless of whether this rule is selected or not.
+///
 /// ## What it does
 /// Checks for code that contains syntax errors.
 ///
@@ -74,27 +72,3 @@ impl Violation for SyntaxError {
         format!("SyntaxError: {message}")
     }
 }
-
-/// E901
-pub(crate) fn syntax_error(
-    diagnostics: &mut Vec<Diagnostic>,
-    parse_error: &ParseError,
-    locator: &Locator,
-) {
-    let rest = locator.after(parse_error.location.start());
-
-    // Try to create a non-empty range so that the diagnostic can print a caret at the
-    // right position. This requires that we retrieve the next character, if any, and take its length
-    // to maintain char-boundaries.
-    let len = rest
-        .chars()
-        .next()
-        .map_or(TextSize::new(0), TextLen::text_len);
-
-    diagnostics.push(Diagnostic::new(
-        SyntaxError {
-            message: format!("{}", DisplayParseErrorType::new(&parse_error.error)),
-        },
-        TextRange::at(parse_error.location.start(), len),
-    ));
-}

crates/ruff_linter/src/rules/pycodestyle/rules/mod.rs

@@ -5,8 +5,8 @@ pub(crate) use bare_except::*;
 pub(crate) use blank_lines::*;
 pub(crate) use compound_statements::*;
 pub(crate) use doc_line_too_long::*;
+pub use errors::IOError;
 pub(crate) use errors::*;
-pub use errors::{IOError, SyntaxError};
 pub(crate) use invalid_escape_sequence::*;
 pub(crate) use lambda_assignment::*;
 pub(crate) use line_too_long::*;

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E111_E11.py.snap

@@ -21,4 +21,42 @@ E11.py:6:1: E111 Indentation is not a multiple of 4
 8 | if False:
   |
 
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
 
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
+
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E112_E11.py.snap

@@ -11,6 +11,36 @@ E11.py:9:1: E112 Expected an indented block
 11 | print()
    |
 
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
+
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
+
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
 E11.py:45:1: E112 Expected an indented block
    |
 43 | #: E112
@@ -21,4 +51,12 @@ E11.py:45:1: E112 Expected an indented block
 47 | if False:
    |
 
-
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E113_E11.py.snap

@@ -1,6 +1,16 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
+
 E11.py:12:1: E113 Unexpected indentation
    |
 10 | #: E113
@@ -11,4 +21,32 @@ E11.py:12:1: E113 Unexpected indentation
 14 | mimetype = 'application/x-directory'
    |
 
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
 
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E114_E11.py.snap

@@ -1,6 +1,36 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
+
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
+
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
 E11.py:15:1: E114 Indentation is not a multiple of 4 (comment)
    |
 13 | #: E114 E116
@@ -11,4 +41,12 @@ E11.py:15:1: E114 Indentation is not a multiple of 4 (comment)
 17 | #: E116 E116 E116
    |
 
-
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E115_E11.py.snap

@@ -1,6 +1,36 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
+
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
+
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
 E11.py:30:1: E115 Expected an indented block (comment)
    |
 28 | def start(self):
@@ -61,4 +91,12 @@ E11.py:35:1: E115 Expected an indented block (comment)
 37 | #: E117
    |
 
-
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E116_E11.py.snap

@@ -1,6 +1,36 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
+
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
+
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
 E11.py:15:1: E116 Unexpected indentation (comment)
    |
 13 | #: E114 E116
@@ -41,4 +71,12 @@ E11.py:26:1: E116 Unexpected indentation (comment)
 28 | def start(self):
    |
 
-
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E117_E11.py.snap

@@ -11,6 +11,36 @@ E11.py:6:1: E117 Over-indented
 8 | if False:
   |
 
+E11.py:9:1: SyntaxError: Expected an indented block after `if` statement
+   |
+ 7 | #: E112
+ 8 | if False:
+ 9 | print()
+   | ^
+10 | #: E113
+11 | print()
+   |
+
+E11.py:12:1: SyntaxError: Unexpected indentation
+   |
+10 | #: E113
+11 | print()
+12 |     print()
+   | ^
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   |
+
+E11.py:14:1: SyntaxError: Expected a statement
+   |
+12 |     print()
+13 | #: E114 E116
+14 | mimetype = 'application/x-directory'
+   | ^
+15 |      # 'httpd/unix-directory'
+16 | create_date = False
+   |
+
 E11.py:39:1: E117 Over-indented
    |
 37 | #: E117
@@ -31,4 +61,12 @@ E11.py:42:1: E117 Over-indented
 44 | if False:  #
    |
 
-
+E11.py:45:1: SyntaxError: Expected an indented block after `if` statement
+   |
+43 | #: E112
+44 | if False:  #
+45 | print()
+   | ^
+46 | #:
+47 | if False:
+   |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E999_E999.py.snap

@@ -1,9 +0,0 @@
----
-source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
----
-E999.py:2:9: E999 SyntaxError: Expected an indented block after function definition
-  |
-2 | def x():
-  |         ^ E999
-3 | 
-  |

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__W191_W19.py.snap

@@ -8,6 +8,22 @@ W19.py:1:1: W191 Indentation contains tabs
 2 |     multiline string with tab in it'''
   |
 
+W19.py:1:1: SyntaxError: Unexpected indentation
+  |
+1 |     '''File starts with a tab
+  | ^^^^
+2 |     multiline string with tab in it'''
+  |
+
+W19.py:5:1: SyntaxError: Expected a statement
+  |
+4 | #: W191
+5 | if False:
+  | ^
+6 |     print  # indented with 1 tab
+7 | #:
+  |
+
 W19.py:6:1: W191 Indentation contains tabs
   |
 4 | #: W191

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__white_space_syntax_error_compatibility.snap

@@ -1,4 +1,8 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
-
+E2_syntax_error.py:1:10: SyntaxError: Expected an expression
+  |
+1 | a = (1 or)
+  |          ^
+  |

crates/ruff_linter/src/rules/pyflakes/mod.rs

@@ -2414,7 +2414,7 @@ mod tests {
     fn used_in_lambda() {
         flakes(
             r"import fu;
-        lambda: fu
+lambda: fu
         ",
             &[],
         );
@@ -2433,7 +2433,7 @@ mod tests {
     fn used_in_slice_obj() {
         flakes(
             r#"import fu;
-        "meow"[::fu]
+"meow"[::fu]
         "#,
             &[],
         );
@@ -3040,16 +3040,6 @@ mod tests {
             &[],
         );
 
-        flakes(
-            r#"
-        from interior import decorate
-        @decorate('value", &[]);
-        def f():
-            return "hello"
-        "#,
-            &[],
-        );
-
         flakes(
             r#"
         @decorate

crates/ruff_linter/src/test.rs

@@ -16,6 +16,7 @@ use ruff_notebook::NotebookError;
 use ruff_python_ast::PySourceType;
 use ruff_python_codegen::Stylist;
 use ruff_python_index::Indexer;
+use ruff_python_parser::ParseError;
 use ruff_python_trivia::textwrap::dedent;
 use ruff_source_file::{Locator, SourceFileBuilder};
 use ruff_text_size::Ranged;
@@ -26,7 +27,6 @@ use crate::linter::{check_path, LinterResult};
 use crate::message::{Emitter, EmitterContext, Message, TextEmitter};
 use crate::packaging::detect_package_root;
 use crate::registry::AsRule;
-use crate::rules::pycodestyle::rules::syntax_error;
 use crate::settings::types::UnsafeFixes;
 use crate::settings::{flags, LinterSettings};
 use crate::source_kind::SourceKind;
@@ -188,7 +188,7 @@ pub(crate) fn test_contents<'a>(
 
             let LinterResult {
                 data: fixed_diagnostics,
-                error: fixed_error,
+                ..
             } = check_path(
                 path,
                 None,
@@ -203,14 +203,11 @@ pub(crate) fn test_contents<'a>(
                 &parsed,
             );
 
-            if let Some(fixed_error) = fixed_error {
+            if !parsed.is_valid() && !source_has_errors {
-                if !source_has_errors {
                 // Previous fix introduced a syntax error, abort
                 let fixes = print_diagnostics(diagnostics, path, source_kind);
-
+                let syntax_errors =
-                    let mut syntax_diagnostics = Vec::new();
+                    print_syntax_errors(parsed.errors(), path, &locator, &transformed);
-                    syntax_error(&mut syntax_diagnostics, &fixed_error, &locator);
-                    let syntax_errors = print_diagnostics(syntax_diagnostics, path, &transformed);
 
                 panic!(
                     r#"Fixed source has a syntax error where the source document does not. This is a bug in one of the generated fixes:
@@ -222,7 +219,6 @@ Source with applied fixes:
                     transformed.source_code()
                 );
             }
-            }
 
             diagnostics = fixed_diagnostics;
         }
@@ -260,11 +256,40 @@ Source with applied fixes:
 
             Message::from_diagnostic(diagnostic, source_code.clone(), noqa)
         })
+        .chain(
+            parsed
+                .errors()
+                .iter()
+                .map(|parse_error| {
+                    Message::from_parse_error(parse_error, &locator, source_code.clone())
+                })
+        )
         .sorted()
         .collect();
     (messages, transformed)
 }
 
+fn print_syntax_errors(
+    errors: &[ParseError],
+    path: &Path,
+    locator: &Locator,
+    source: &SourceKind,
+) -> String {
+    let filename = path.file_name().unwrap().to_string_lossy();
+    let source_file = SourceFileBuilder::new(filename.as_ref(), source.source_code()).finish();
+
+    let messages: Vec<_> = errors
+        .iter()
+        .map(|parse_error| Message::from_parse_error(parse_error, locator, source_file.clone()))
+        .collect();
+
+    if let Some(notebook) = source.as_ipy_notebook() {
+        print_jupyter_messages(&messages, path, notebook)
+    } else {
+        print_messages(&messages)
+    }
+}
+
 fn print_diagnostics(diagnostics: Vec<Diagnostic>, path: &Path, source: &SourceKind) -> String {
     let filename = path.file_name().unwrap().to_string_lossy();
     let source_file = SourceFileBuilder::new(filename.as_ref(), source.source_code()).finish();

crates/ruff_server/src/lint.rs

@@ -1,5 +1,6 @@
 //! Access to the Ruff linting API for the LSP
 
+use ruff_python_parser::ParseError;
 use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
 
@@ -153,7 +154,10 @@ pub(crate) fn check(query: &DocumentQuery, encoding: PositionEncoding) -> Diagno
         .zip(noqa_edits)
         .map(|(diagnostic, noqa_edit)| {
             to_lsp_diagnostic(diagnostic, &noqa_edit, &source_kind, &index, encoding)
-        });
+        })
+        .chain(parsed.errors().iter().map(|parse_error| {
+            parse_error_to_lsp_diagnostic(parse_error, &source_kind, &index, encoding)
+        }));
 
     if let Some(notebook) = query.as_notebook() {
         for (index, diagnostic) in lsp_diagnostics {
@@ -287,6 +291,45 @@ fn to_lsp_diagnostic(
     )
 }
 
+fn parse_error_to_lsp_diagnostic(
+    parse_error: &ParseError,
+    source_kind: &SourceKind,
+    index: &LineIndex,
+    encoding: PositionEncoding,
+) -> (usize, lsp_types::Diagnostic) {
+    let range: lsp_types::Range;
+    let cell: usize;
+
+    if let Some(notebook_index) = source_kind.as_ipy_notebook().map(Notebook::index) {
+        NotebookRange { cell, range } = parse_error.location.to_notebook_range(
+            source_kind.source_code(),
+            index,
+            notebook_index,
+            encoding,
+        );
+    } else {
+        cell = usize::default();
+        range = parse_error
+            .location
+            .to_range(source_kind.source_code(), index, encoding);
+    }
+
+    (
+        cell,
+        lsp_types::Diagnostic {
+            range,
+            severity: Some(lsp_types::DiagnosticSeverity::ERROR),
+            tags: None,
+            code: None,
+            code_description: None,
+            source: Some(DIAGNOSTIC_NAME.into()),
+            message: format!("SyntaxError: {}", &parse_error.error),
+            related_information: None,
+            data: None,
+        },
+    )
+}
+
 fn diagnostic_edit_range(
     range: TextRange,
     source_kind: &SourceKind,

crates/ruff_workspace/src/configuration.rs

@@ -968,9 +968,13 @@ impl LintConfiguration {
         if preview.mode.is_disabled() {
             for selection in deprecated_selectors.iter().sorted() {
                 let (prefix, code) = selection.prefix_and_code();
-                warn_user_once_by_message!(
+                let rule = format!("{prefix}{code}");
-                    "Rule `{prefix}{code}` is deprecated and will be removed in a future release.",
+                let mut message =
-                );
+                    format!("Rule `{rule}` is deprecated and will be removed in a future release.");
+                if matches!(rule.as_str(), "E999") {
+                    message.push_str(" Syntax errors will always be shown regardless of whether this rule is selected or not.");
+                }
+                warn_user_once_by_message!("{message}");
             }
         } else {
             let deprecated_selectors = deprecated_selectors.iter().sorted().collect::<Vec<_>>();

fuzz/fuzz_targets/ruff_formatter_validity.rs

@@ -43,8 +43,8 @@ fn do_fuzz(case: &[u8]) -> Corpus {
 
     let mut warnings = HashMap::new();
 
-    for msg in linter_results.data {
+    for msg in &linter_results.data {
-        let count: &mut usize = warnings.entry(msg.kind.name).or_default();
+        let count: &mut usize = warnings.entry(msg.name()).or_default();
         *count += 1;
     }
 
@@ -67,8 +67,8 @@ fn do_fuzz(case: &[u8]) -> Corpus {
             "formatter introduced a parse error"
         );
 
-        for msg in linter_results.data {
+        for msg in &linter_results.data {
-            if let Some(count) = warnings.get_mut(&msg.kind.name) {
+            if let Some(count) = warnings.get_mut(msg.name()) {
                 if let Some(decremented) = count.checked_sub(1) {
                     *count = decremented;
                 } else {