Document LinterResult::has_syntax_error and add Parsed::has_no_syntax_errors (#16443)

Summary
--

This is a follow up addressing the comments on #16425. As @dhruvmanila
pointed out, the naming is a bit tricky. I went with `has_no_errors` to
try to differentiate it from `is_valid`. It actually ends up negated in
most uses, so it would be more convenient to have `has_any_errors` or
`has_errors`, but I thought it would sound too much like the opposite of
`is_valid` in that case. I'm definitely open to suggestions here.

Test Plan
--

Existing tests.

crates/ruff_db/src/parsed.rs

@@ -102,7 +102,7 @@ mod tests {
 
         let parsed = parsed_module(&db, file);
 
-        assert!(parsed.is_valid());
+        assert!(parsed.has_valid_syntax());
 
         Ok(())
     }
@@ -118,7 +118,7 @@ mod tests {
 
         let parsed = parsed_module(&db, file);
 
-        assert!(parsed.is_valid());
+        assert!(parsed.has_valid_syntax());
 
         Ok(())
     }
@@ -134,7 +134,7 @@ mod tests {
 
         let parsed = parsed_module(&db, virtual_file.file());
 
-        assert!(parsed.is_valid());
+        assert!(parsed.has_valid_syntax());
 
         Ok(())
     }
@@ -150,7 +150,7 @@ mod tests {
 
         let parsed = parsed_module(&db, virtual_file.file());
 
-        assert!(parsed.is_valid());
+        assert!(parsed.has_valid_syntax());
 
         Ok(())
     }
@@ -181,6 +181,6 @@ else:
 
         let parsed = parsed_module(&db, file);
 
-        assert!(parsed.is_valid());
+        assert!(parsed.has_valid_syntax());
     }
 }

crates/ruff_linter/src/linter.rs

@@ -42,6 +42,8 @@ pub struct LinterResult {
     pub messages: Vec<Message>,
     /// A flag indicating the presence of syntax errors in the source file.
     /// If `true`, at least one syntax error was detected in the source file.
+    ///
+    /// This includes both [`ParseError`]s and [`UnsupportedSyntaxError`]s.
     pub has_syntax_error: bool,
 }
 
@@ -133,7 +135,7 @@ pub fn check_path(
     }
 
     // Run the AST-based rules only if there are no syntax errors.
-    if parsed.is_valid() {
+    if parsed.has_valid_syntax() {
         let use_ast = settings
             .rules
             .iter_enabled()
@@ -283,7 +285,7 @@ pub fn check_path(
             locator,
             comment_ranges,
             &directives.noqa_line_for,
-            parsed.is_valid(),
+            parsed.has_valid_syntax(),
             &per_file_ignores,
             settings,
         );
@@ -294,7 +296,7 @@ pub fn check_path(
         }
     }
 
-    if parsed.is_valid() {
+    if parsed.has_valid_syntax() {
         // Remove fixes for any rules marked as unfixable.
         for diagnostic in &mut diagnostics {
             if !settings.rules.should_fix(diagnostic.kind.rule()) {
@@ -445,7 +447,7 @@ pub fn lint_only(
             &locator,
             &directives,
         ),
-        has_syntax_error: !parsed.is_valid() || !parsed.unsupported_syntax_errors().is_empty(),
+        has_syntax_error: parsed.has_syntax_errors(),
     }
 }
 
@@ -546,7 +548,7 @@ pub fn lint_fix<'a>(
         );
 
         if iterations == 0 {
-            is_valid_syntax = parsed.is_valid() && parsed.unsupported_syntax_errors().is_empty();
+            is_valid_syntax = parsed.has_no_syntax_errors();
         } else {
             // If the source code was parseable on the first pass, but is no
             // longer parseable on a subsequent pass, then we've introduced a

crates/ruff_linter/src/test.rs

@@ -141,7 +141,7 @@ pub(crate) fn test_contents<'a>(
         target_version,
     );
 
-    let source_has_errors = !parsed.is_valid();
+    let source_has_errors = parsed.has_invalid_syntax();
 
     // Detect fixes that don't converge after multiple iterations.
     let mut iterations = 0;
@@ -207,7 +207,7 @@ pub(crate) fn test_contents<'a>(
                 target_version,
             );
 
-            if !parsed.is_valid() && !source_has_errors {
+            if parsed.has_invalid_syntax() && !source_has_errors {
                 // Previous fix introduced a syntax error, abort
                 let fixes = print_diagnostics(diagnostics, path, source_kind);
                 let syntax_errors =

crates/ruff_python_parser/src/lib.rs

@@ -342,21 +342,47 @@ impl<T> Parsed<T> {
         self.errors
     }
 
-    /// Returns `true` if the parsed source code is valid i.e., it has no syntax errors.
+    /// Returns `true` if the parsed source code is valid i.e., it has no [`ParseError`]s.
     ///
-    /// Note that this does not include version-related
-    /// [`unsupported_syntax_errors`](Parsed::unsupported_syntax_errors).
-    pub fn is_valid(&self) -> bool {
+    /// Note that this does not include version-related [`UnsupportedSyntaxError`]s.
+    ///
+    /// See [`Parsed::has_no_syntax_errors`] for a version that takes these into account.
+    pub fn has_valid_syntax(&self) -> bool {
         self.errors.is_empty()
     }
 
+    /// Returns `true` if the parsed source code is invalid i.e., it has [`ParseError`]s.
+    ///
+    /// Note that this does not include version-related [`UnsupportedSyntaxError`]s.
+    ///
+    /// See [`Parsed::has_no_syntax_errors`] for a version that takes these into account.
+    pub fn has_invalid_syntax(&self) -> bool {
+        !self.has_valid_syntax()
+    }
+
+    /// Returns `true` if the parsed source code does not contain any [`ParseError`]s *or*
+    /// [`UnsupportedSyntaxError`]s.
+    ///
+    /// See [`Parsed::has_valid_syntax`] for a version specific to [`ParseError`]s.
+    pub fn has_no_syntax_errors(&self) -> bool {
+        self.has_valid_syntax() && self.unsupported_syntax_errors.is_empty()
+    }
+
+    /// Returns `true` if the parsed source code contains any [`ParseError`]s *or*
+    /// [`UnsupportedSyntaxError`]s.
+    ///
+    /// See [`Parsed::has_invalid_syntax`] for a version specific to [`ParseError`]s.
+    pub fn has_syntax_errors(&self) -> bool {
+        !self.has_no_syntax_errors()
+    }
+
     /// Returns the [`Parsed`] output as a [`Result`], returning [`Ok`] if it has no syntax errors,
     /// or [`Err`] containing the first [`ParseError`] encountered.
     ///
     /// Note that any [`unsupported_syntax_errors`](Parsed::unsupported_syntax_errors) will not
     /// cause [`Err`] to be returned.
     pub fn as_result(&self) -> Result<&Parsed<T>, &[ParseError]> {
-        if self.is_valid() {
+        if self.has_valid_syntax() {
             Ok(self)
         } else {
             Err(&self.errors)
@@ -369,7 +395,7 @@ impl<T> Parsed<T> {
     /// Note that any [`unsupported_syntax_errors`](Parsed::unsupported_syntax_errors) will not
     /// cause [`Err`] to be returned.
     pub(crate) fn into_result(self) -> Result<Parsed<T>, ParseError> {
-        if self.is_valid() {
+        if self.has_valid_syntax() {
             Ok(self)
         } else {
             Err(self.into_errors().into_iter().next().unwrap())

crates/ruff_python_parser/tests/fixtures.rs

@@ -39,9 +39,7 @@ fn test_valid_syntax(input_path: &Path) {
     });
     let parsed = parse_unchecked(&source, options);
 
-    let is_valid = parsed.is_valid() && parsed.unsupported_syntax_errors().is_empty();
-
-    if !is_valid {
+    if parsed.has_syntax_errors() {
         let line_index = LineIndex::from_source_text(&source);
         let source_code = SourceCode::new(&source, &line_index);
 
@@ -101,10 +99,8 @@ fn test_invalid_syntax(input_path: &Path) {
     });
     let parsed = parse_unchecked(&source, options);
 
-    let is_valid = parsed.is_valid() && parsed.unsupported_syntax_errors().is_empty();
-
     assert!(
-        !is_valid,
+        parsed.has_syntax_errors(),
         "{input_path:?}: Expected parser to generate at least one syntax error for a program containing syntax errors."
     );
 
@@ -224,7 +220,7 @@ f'{foo!r'
     println!("AST:\n----\n{:#?}", parsed.syntax());
     println!("Tokens:\n-------\n{:#?}", parsed.tokens());
 
-    if !parsed.is_valid() {
+    if parsed.has_invalid_syntax() {
         println!("Errors:\n-------");
 
         let line_index = LineIndex::from_source_text(source);

fuzz/fuzz_targets/red_knot_check_invalid_syntax.rs

@@ -135,7 +135,7 @@ fn do_fuzz(case: &[u8]) -> Corpus {
     };
 
     let parsed = parse_unchecked(code, ParseOptions::from(Mode::Module));
-    if parsed.is_valid() {
+    if parsed.has_valid_syntax() {
         return Corpus::Reject;
     }